Merge branch 'master' into metadataDecoratorOption

# Conflicts:
#	src/compiler/diagnosticMessages.json

package-lock.json

@@ -288,9 +288,9 @@
             }
         },
         "@octokit/core": {
-            "version": "3.3.1",
-            "resolved": "https://registry.npmjs.org/@octokit/core/-/core-3.3.1.tgz",
-            "integrity": "sha512-Dc5NNQOYjgZU5S1goN6A/E500yXOfDUFRGQB8/2Tl16AcfvS3H9PudyOe3ZNE/MaVyHPIfC0htReHMJb1tMrvw==",
+            "version": "3.4.0",
+            "resolved": "https://registry.npmjs.org/@octokit/core/-/core-3.4.0.tgz",
+            "integrity": "sha512-6/vlKPP8NF17cgYXqucdshWqmMZGXkuvtcrWCgU5NOI0Pl2GjlmZyWgBMrU8zJ3v2MJlM6++CiB45VKYmhiWWg==",
             "dev": true,
             "requires": {
                 "@octokit/auth-token": "^2.4.4",
@@ -422,9 +422,9 @@
             }
         },
         "@types/chai": {
-            "version": "4.2.15",
-            "resolved": "https://registry.npmjs.org/@types/chai/-/chai-4.2.15.tgz",
-            "integrity": "sha512-rYff6FI+ZTKAPkJUoyz7Udq3GaoDZnxYDEvdEdFZASiA7PoErltHezDishqQiSDWrGxvxmplH304jyzQmjp0AQ==",
+            "version": "4.2.16",
+            "resolved": "https://registry.npmjs.org/@types/chai/-/chai-4.2.16.tgz",
+            "integrity": "sha512-vI5iOAsez9+roLS3M3+Xx7w+WRuDtSmF8bQkrbcIJ2sC1PcDgVoA0WGpa+bIrJ+y8zqY2oi//fUctkxtIcXJCw==",
             "dev": true
         },
         "@types/convert-source-map": {
@@ -1374,9 +1374,9 @@
             "dev": true
         },
         "before-after-hook": {
-            "version": "2.2.0",
-            "resolved": "https://registry.npmjs.org/before-after-hook/-/before-after-hook-2.2.0.tgz",
-            "integrity": "sha512-jH6rKQIfroBbhEXVmI7XmXe3ix5S/PgJqpzdDPnR8JGLHWNYLsYZ6tK5iWOF/Ra3oqEX0NobXGlzbiylIzVphQ==",
+            "version": "2.2.1",
+            "resolved": "https://registry.npmjs.org/before-after-hook/-/before-after-hook-2.2.1.tgz",
+            "integrity": "sha512-/6FKxSTWoJdbsLDF8tdIjaRiFXiE6UHsEHE3OPI/cwPURCVi1ukP0gmLn7XWEiFk5TcwQjjY5PWsU+j+tgXgmw==",
             "dev": true
         },
         "binary-extensions": {
@@ -5679,9 +5679,9 @@
                     }
                 },
                 "y18n": {
-                    "version": "5.0.5",
-                    "resolved": "https://registry.npmjs.org/y18n/-/y18n-5.0.5.tgz",
-                    "integrity": "sha512-hsRUr4FFrvhhRH12wOdfs38Gy7k2FFzB9qgN9v3aLykRq0dRcdcpz5C9FxdS2NuhOrI/628b/KSTJ3rwHysYSg==",
+                    "version": "5.0.6",
+                    "resolved": "https://registry.npmjs.org/y18n/-/y18n-5.0.6.tgz",
+                    "integrity": "sha512-PlVX4Y0lDTN6E2V4ES2tEdyvXkeKzxa8c/vo0pxPr/TqbztddTP0yn7zZylIyiAuxerqj0Q5GhpJ1YJCP8LaZQ==",
                     "dev": true
                 },
                 "yargs": {

src/compiler/checker.ts

@@ -1778,8 +1778,8 @@ namespace ts {
         /**
          * Resolve a given name for a given meaning at a given location. An error is reported if the name was not found and
          * the `nameNotFoundMessage` argument is not `undefined`.
-         * 
-         * ***NOTE**: You should not call this directly. This function is intended to be used only by `resolveName`, 
+         *
+         * ***NOTE**: You should not call this directly. This function is intended to be used only by `resolveName`,
          * `resolveEntityName`, and `getSuggestedSymbolForNonexistentSymbol`.
          *
          * @param location The location at which to begin name resolution.
@@ -2572,6 +2572,7 @@ namespace ts {
          * module.exports = <EntityNameExpression>
          * {<Identifier>}
          * {name: <EntityNameExpression>}
+         * const { x } = require ...
          */
         function isAliasSymbolDeclaration(node: Node): boolean {
             return node.kind === SyntaxKind.ImportEqualsDeclaration
@@ -5276,9 +5277,26 @@ namespace ts {
                 return factory.createKeywordTypeNode(SyntaxKind.AnyKeyword);
             }
 
+            function shouldUsePlaceholderForProperty(propertySymbol: Symbol, context: NodeBuilderContext) {
+                // Use placeholders for reverse mapped types we've either already descended into, or which
+                // are nested reverse mappings within a mapping over a non-anonymous type. The later is a restriction mostly just to
+                // reduce the blowup in printback size from doing, eg, a deep reverse mapping over `Window`.
+                // Since anonymous types usually come from expressions, this allows us to preserve the output
+                // for deep mappings which likely come from expressions, while truncating those parts which
+                // come from mappings over library functions.
+                return !!(getCheckFlags(propertySymbol) & CheckFlags.ReverseMapped)
+                    && (
+                        contains(context.reverseMappedStack, propertySymbol as ReverseMappedSymbol)
+                        || (
+                            context.reverseMappedStack?.[0]
+                            && !(getObjectFlags(last(context.reverseMappedStack).propertyType) & ObjectFlags.Anonymous)
+                        )
+                    );
+            }
+
             function addPropertyToElementList(propertySymbol: Symbol, context: NodeBuilderContext, typeElements: TypeElement[]) {
                 const propertyIsReverseMapped = !!(getCheckFlags(propertySymbol) & CheckFlags.ReverseMapped);
-                const propertyType = propertyIsReverseMapped && context.flags & NodeBuilderFlags.InReverseMappedType ?
+                const propertyType = shouldUsePlaceholderForProperty(propertySymbol, context) ?
                     anyType : getTypeOfSymbol(propertySymbol);
                 const saveEnclosingDeclaration = context.enclosingDeclaration;
                 context.enclosingDeclaration = undefined;
@@ -5309,16 +5327,20 @@ namespace ts {
                     }
                 }
                 else {
-                    const savedFlags = context.flags;
-                    context.flags |= propertyIsReverseMapped ? NodeBuilderFlags.InReverseMappedType : 0;
                     let propertyTypeNode: TypeNode;
-                    if (propertyIsReverseMapped && !!(savedFlags & NodeBuilderFlags.InReverseMappedType)) {
+                    if (shouldUsePlaceholderForProperty(propertySymbol, context)) {
                         propertyTypeNode = createElidedInformationPlaceholder(context);
                     }
                     else {
+                        if (propertyIsReverseMapped) {
+                            context.reverseMappedStack ||= [];
+                            context.reverseMappedStack.push(propertySymbol as ReverseMappedSymbol);
+                        }
                         propertyTypeNode = propertyType ? serializeTypeForDeclaration(context, propertyType, propertySymbol, saveEnclosingDeclaration) : factory.createKeywordTypeNode(SyntaxKind.AnyKeyword);
+                        if (propertyIsReverseMapped) {
+                            context.reverseMappedStack!.pop();
+                        }
                     }
-                    context.flags = savedFlags;
 
                     const modifiers = isReadonlySymbol(propertySymbol) ? [factory.createToken(SyntaxKind.ReadonlyKeyword)] : undefined;
                     if (modifiers) {
@@ -6139,10 +6161,14 @@ namespace ts {
             function serializeReturnTypeForSignature(context: NodeBuilderContext, type: Type, signature: Signature, includePrivateSymbol?: (s: Symbol) => void, bundled?: boolean) {
                 if (type !== errorType && context.enclosingDeclaration) {
                     const annotation = signature.declaration && getEffectiveReturnTypeNode(signature.declaration);
-                    if (!!findAncestor(annotation, n => n === context.enclosingDeclaration) && annotation && instantiateType(getTypeFromTypeNode(annotation), signature.mapper) === type && existingTypeNodeIsNotReferenceOrIsReferenceWithCompatibleTypeArgumentCount(annotation, type)) {
-                        const result = serializeExistingTypeNode(context, annotation, includePrivateSymbol, bundled);
-                        if (result) {
-                            return result;
+                    if (!!findAncestor(annotation, n => n === context.enclosingDeclaration) && annotation) {
+                        const annotated = getTypeFromTypeNode(annotation);
+                        const thisInstantiated = annotated.flags & TypeFlags.TypeParameter && (annotated as TypeParameter).isThisType ? instantiateType(annotated, signature.mapper) : annotated;
+                        if (thisInstantiated === type && existingTypeNodeIsNotReferenceOrIsReferenceWithCompatibleTypeArgumentCount(annotation, type)) {
+                            const result = serializeExistingTypeNode(context, annotation, includePrivateSymbol, bundled);
+                            if (result) {
+                                return result;
+                            }
                         }
                     }
                 }
@@ -7846,6 +7872,7 @@ namespace ts {
             typeParameterNamesByText?: Set<string>;
             usedSymbolNames?: Set<string>;
             remappedSymbolNames?: ESMap<SymbolId, string>;
+            reverseMappedStack?: ReverseMappedSymbol[];
         }
 
         function isDefaultBindingContext(location: Node) {
@@ -11000,6 +11027,14 @@ namespace ts {
             }
         }
 
+        type ReplaceableIndexedAccessType = IndexedAccessType & { objectType: TypeParameter, indexType: TypeParameter };
+        function replaceIndexedAccess(instantiable: Type, type: ReplaceableIndexedAccessType, replacement: Type) {
+            // map type.indexType to 0
+            // map type.objectType to `[TReplacement]`
+            // thus making the indexed access `[TReplacement][0]` or `TReplacement`
+            return instantiateType(instantiable, createTypeMapper([type.indexType, type.objectType], [getLiteralType(0), createTupleType([replacement])]));
+        }
+
         function getIndexInfoOfIndexSymbol(indexSymbol: Symbol, indexKind: IndexKind) {
             const declaration = getIndexDeclarationOfIndexSymbol(indexSymbol, indexKind);
             if (!declaration) return undefined;
@@ -11020,8 +11055,21 @@ namespace ts {
                 inferredProp.declarations = prop.declarations;
                 inferredProp.nameType = getSymbolLinks(prop).nameType;
                 inferredProp.propertyType = getTypeOfSymbol(prop);
-                inferredProp.mappedType = type.mappedType;
-                inferredProp.constraintType = type.constraintType;
+                if (type.constraintType.type.flags & TypeFlags.IndexedAccess
+                    && (type.constraintType.type as IndexedAccessType).objectType.flags & TypeFlags.TypeParameter
+                    && (type.constraintType.type as IndexedAccessType).indexType.flags & TypeFlags.TypeParameter) {
+                    // A reverse mapping of `{[K in keyof T[K_1]]: T[K_1]}` is the same as that of `{[K in keyof T]: T}`, since all we care about is
+                    // inferring to the "type parameter" (or indexed access) shared by the constraint and template. So, to reduce the number of
+                    // type identities produced, we simplify such indexed access occurences
+                    const newTypeParam = (type.constraintType.type as IndexedAccessType).objectType;
+                    const newMappedType = replaceIndexedAccess(type.mappedType, type.constraintType.type as ReplaceableIndexedAccessType, newTypeParam);
+                    inferredProp.mappedType = newMappedType as MappedType;
+                    inferredProp.constraintType = getIndexType(newTypeParam) as IndexType;
+                }
+                else {
+                    inferredProp.mappedType = type.mappedType;
+                    inferredProp.constraintType = type.constraintType;
+                }
                 members.set(prop.escapedName, inferredProp);
             }
             setStructuredTypeMembers(type, members, emptyArray, emptyArray, stringIndexInfo, undefined);
@@ -12070,6 +12118,10 @@ namespace ts {
             return false;
         }
 
+        function isOptionalPropertyDeclaration(node: Declaration) {
+            return isPropertyDeclaration(node) && node.questionToken;
+        }
+
         function isOptionalJSDocPropertyLikeTag(node: Node): node is JSDocPropertyLikeTag {
             if (!isJSDocPropertyLikeTag(node)) {
                 return false;
@@ -12984,9 +13036,17 @@ namespace ts {
 
         function getConditionalFlowTypeOfType(type: Type, node: Node) {
             let constraints: Type[] | undefined;
+            let covariant = true;
             while (node && !isStatement(node) && node.kind !== SyntaxKind.JSDocComment) {
                 const parent = node.parent;
-                if (parent.kind === SyntaxKind.ConditionalType && node === (<ConditionalTypeNode>parent).trueType) {
+                // only consider variance flipped by parameter locations - `keyof` types would usually be considered variance inverting, but
+                // often get used in indexed accesses where they behave sortof invariantly, but our checking is lax
+                if (parent.kind === SyntaxKind.Parameter) {
+                    covariant = !covariant;
+                }
+                // Always substitute on type parameters, regardless of variance, since even
+                // in contravarrying positions, they may be reliant on subtuted constraints to be valid
+                if ((covariant || type.flags & TypeFlags.TypeParameter) && parent.kind === SyntaxKind.ConditionalType && node === (<ConditionalTypeNode>parent).trueType) {
                     const constraint = getImpliedConstraint(type, (<ConditionalTypeNode>parent).checkType, (<ConditionalTypeNode>parent).extendsType);
                     if (constraint) {
                         constraints = append(constraints, constraint);
@@ -13898,7 +13958,7 @@ namespace ts {
             const typeKey = !origin ? getTypeListId(types) :
                 origin.flags & TypeFlags.Union ? `|${getTypeListId((<UnionType>origin).types)}` :
                 origin.flags & TypeFlags.Intersection ? `&${getTypeListId((<IntersectionType>origin).types)}` :
-                `#${(<IndexType>origin).type.id}`;
+                `#${(<IndexType>origin).type.id}|${getTypeListId(types)}`; // origin type id alone is insufficient, as `keyof x` may resolve to multiple WIP values while `x` is still resolving
             const id = typeKey + getAliasId(aliasSymbol, aliasTypeArguments);
             let type = unionTypes.get(id);
             if (!type) {
@@ -18409,6 +18469,11 @@ namespace ts {
                     }
                 }
                 else if (target.flags & TypeFlags.TemplateLiteral) {
+                    if (source.flags & TypeFlags.TemplateLiteral) {
+                        // Report unreliable variance for type variables referenced in template literal type placeholders.
+                        // For example, `foo-${number}` is related to `foo-${string}` even though number isn't related to string.
+                        instantiateType(source, makeFunctionTypeMapper(reportUnreliableMarkers));
+                    }
                     const result = inferTypesFromTemplateLiteralType(source, target as TemplateLiteralType);
                     if (result && every(result, (r, i) => isValidTypeForTemplateLiteralPlaceholder(r, (target as TemplateLiteralType).types[i]))) {
                         return Ternary.True;
@@ -18453,20 +18518,6 @@ namespace ts {
                         return result;
                     }
                 }
-                else if (source.flags & TypeFlags.TemplateLiteral) {
-                    if (target.flags & TypeFlags.TemplateLiteral &&
-                        (source as TemplateLiteralType).texts.length === (target as TemplateLiteralType).texts.length &&
-                        (source as TemplateLiteralType).types.length === (target as TemplateLiteralType).types.length &&
-                        every((source as TemplateLiteralType).texts, (t, i) => t === (target as TemplateLiteralType).texts[i]) &&
-                        every((instantiateType(source, makeFunctionTypeMapper(reportUnreliableMarkers)) as TemplateLiteralType).types, (t, i) => !!((target as TemplateLiteralType).types[i].flags & (TypeFlags.Any | TypeFlags.String)) || !!isRelatedTo(t, (target as TemplateLiteralType).types[i], /*reportErrors*/ false))) {
-                        return Ternary.True;
-                    }
-                    const constraint = getBaseConstraintOfType(source);
-                    if (constraint && constraint !== source && (result = isRelatedTo(constraint, target, reportErrors))) {
-                        resetErrorInfo(saveErrorInfo);
-                        return result;
-                    }
-                }
                 else if (source.flags & TypeFlags.StringMapping) {
                     if (target.flags & TypeFlags.StringMapping && (<StringMappingType>source).symbol === (<StringMappingType>target).symbol) {
                         if (result = isRelatedTo((<StringMappingType>source).type, (<StringMappingType>target).type, reportErrors)) {
@@ -19694,14 +19745,12 @@ namespace ts {
         function isDeeplyNestedType(type: Type, stack: Type[], depth: number): boolean {
             if (depth >= 5) {
                 const identity = getRecursionIdentity(type);
-                if (identity) {
-                    let count = 0;
-                    for (let i = 0; i < depth; i++) {
-                        if (getRecursionIdentity(stack[i]) === identity) {
-                            count++;
-                            if (count >= 5) {
-                                return true;
-                            }
+                let count = 0;
+                for (let i = 0; i < depth; i++) {
+                    if (getRecursionIdentity(stack[i]) === identity) {
+                        count++;
+                        if (count >= 5) {
+                            return true;
                         }
                     }
                 }
@@ -19709,15 +19758,20 @@ namespace ts {
             return false;
         }
 
-        // Types with constituents that could circularly reference the type have a recursion identity. The recursion
-        // identity is some object that is common to instantiations of the type with the same origin.
-        function getRecursionIdentity(type: Type): object | undefined {
+        // The recursion identity of a type is an object identity that is shared among multiple instantiations of the type.
+        // We track recursion identities in order to identify deeply nested and possibly infinite type instantiations with
+        // the same origin. For example, when type parameters are in scope in an object type such as { x: T }, all
+        // instantiations of that type have the same recursion identity. The default recursion identity is the object
+        // identity of the type, meaning that every type is unique. Generally, types with constituents that could circularly
+        // reference the type have a recursion identity that differs from the object identity.
+        function getRecursionIdentity(type: Type): object {
+            // Object and array literals are known not to contain recursive references and don't need a recursion identity.
             if (type.flags & TypeFlags.Object && !isObjectOrArrayLiteralType(type)) {
                 if (getObjectFlags(type) && ObjectFlags.Reference && (type as TypeReference).node) {
                     // Deferred type references are tracked through their associated AST node. This gives us finer
                     // granularity than using their associated target because each manifest type reference has a
                     // unique AST node.
-                    return (type as TypeReference).node;
+                    return (type as TypeReference).node!;
                 }
                 if (type.symbol && !(getObjectFlags(type) & ObjectFlags.Anonymous && type.symbol.flags & SymbolFlags.Class)) {
                     // We track all object types that have an associated symbol (representing the origin of the type), but
@@ -19729,6 +19783,9 @@ namespace ts {
                     return type.target;
                 }
             }
+            if (type.flags & TypeFlags.TypeParameter) {
+                return type.symbol;
+            }
             if (type.flags & TypeFlags.IndexedAccess) {
                 // Identity is the leftmost object type in a chain of indexed accesses, eg, in A[P][Q] it is A
                 do {
@@ -19740,7 +19797,7 @@ namespace ts {
                 // The root object represents the origin of the conditional type
                 return (type as ConditionalType).root;
             }
-            return undefined;
+            return type;
         }
 
         function isPropertyIdenticalTo(sourceProp: Symbol, targetProp: Symbol): boolean {
@@ -20732,7 +20789,11 @@ namespace ts {
         }
 
         function getTypeOfReverseMappedSymbol(symbol: ReverseMappedSymbol) {
-            return inferReverseMappedType(symbol.propertyType, symbol.mappedType, symbol.constraintType);
+            const links = getSymbolLinks(symbol);
+            if (!links.type) {
+                links.type = inferReverseMappedType(symbol.propertyType, symbol.mappedType, symbol.constraintType);
+            }
+            return links.type;
         }
 
         function inferReverseMappedType(sourceType: Type, target: MappedType, constraint: IndexType): Type {
@@ -21157,16 +21218,16 @@ namespace ts {
                 // We stop inferring and report a circularity if we encounter duplicate recursion identities on both
                 // the source side and the target side.
                 const saveExpandingFlags = expandingFlags;
-                const sourceIdentity = getRecursionIdentity(source) || source;
-                const targetIdentity = getRecursionIdentity(target) || target;
-                if (sourceIdentity && contains(sourceStack, sourceIdentity)) expandingFlags |= ExpandingFlags.Source;
-                if (targetIdentity && contains(targetStack, targetIdentity)) expandingFlags |= ExpandingFlags.Target;
+                const sourceIdentity = getRecursionIdentity(source);
+                const targetIdentity = getRecursionIdentity(target);
+                if (contains(sourceStack, sourceIdentity)) expandingFlags |= ExpandingFlags.Source;
+                if (contains(targetStack, targetIdentity)) expandingFlags |= ExpandingFlags.Target;
                 if (expandingFlags !== ExpandingFlags.Both) {
-                    if (sourceIdentity) (sourceStack || (sourceStack = [])).push(sourceIdentity);
-                    if (targetIdentity) (targetStack || (targetStack = [])).push(targetIdentity);
+                    (sourceStack || (sourceStack = [])).push(sourceIdentity);
+                    (targetStack || (targetStack = [])).push(targetIdentity);
                     action(source, target);
-                    if (targetIdentity) targetStack.pop();
-                    if (sourceIdentity) sourceStack.pop();
+                    targetStack.pop();
+                    sourceStack.pop();
                 }
                 else {
                     inferencePriority = InferencePriority.Circularity;
@@ -23807,7 +23868,7 @@ namespace ts {
             // an dotted name expression, and if the location is not an assignment target, obtain the type
             // of the expression (which will reflect control flow analysis). If the expression indeed
             // resolved to the given symbol, return the narrowed type.
-            if (location.kind === SyntaxKind.Identifier) {
+            if (location.kind === SyntaxKind.Identifier || location.kind === SyntaxKind.PrivateIdentifier) {
                 if (isRightSideOfQualifiedNameOrPropertyAccess(location)) {
                     location = location.parent;
                 }
@@ -24071,7 +24132,7 @@ namespace ts {
                 }
             }
             else if (isAlias) {
-                declaration = symbol.declarations?.find(isSomeImportDeclaration);
+                declaration = getDeclarationOfAliasSymbol(symbol);
             }
             else {
                 return type;
@@ -27256,9 +27317,10 @@ namespace ts {
             let diagnosticMessage;
             const declarationName = idText(right);
             if (isInPropertyInitializer(node)
+                && !isOptionalPropertyDeclaration(valueDeclaration)
                 && !(isAccessExpression(node) && isAccessExpression(node.expression))
                 && !isBlockScopedNameDeclaredBeforeUse(valueDeclaration, right)
-                && !isPropertyDeclaredInAncestorClass(prop)) {
+                && (compilerOptions.useDefineForClassFields || !isPropertyDeclaredInAncestorClass(prop))) {
                 diagnosticMessage = error(right, Diagnostics.Property_0_is_used_before_its_initialization, declarationName);
             }
             else if (valueDeclaration.kind === SyntaxKind.ClassDeclaration &&
@@ -35514,8 +35576,8 @@ namespace ts {
                 errorAndMaybeSuggestAwait(
                     condExpr,
                     /*maybeMissingAwait*/ true,
-                    Diagnostics.This_condition_will_always_return_0_since_the_types_1_and_2_have_no_overlap,
-                    "true", getTypeNameForErrorDisplay(type), "false");
+                    Diagnostics.This_condition_will_always_return_true_since_this_0_appears_to_always_be_defined,
+                    getTypeNameForErrorDisplay(type));
                 return;
             }
 
@@ -35548,7 +35610,7 @@ namespace ts {
             const isUsed = isBinaryExpression(condExpr.parent) && isFunctionUsedInBinaryExpressionChain(condExpr.parent, testedSymbol)
                 || body && isFunctionUsedInConditionBody(condExpr, body, testedNode, testedSymbol);
             if (!isUsed) {
-                error(location, Diagnostics.This_condition_will_always_return_true_since_the_function_is_always_defined_Did_you_mean_to_call_it_instead);
+                error(location, Diagnostics.This_condition_will_always_return_true_since_this_function_appears_to_always_be_defined_Did_you_mean_to_call_it_instead);
             }
         }
 
@@ -36832,6 +36894,7 @@ namespace ts {
             switch (name.escapedText) {
                 case "any":
                 case "unknown":
+                case "never":
                 case "number":
                 case "bigint":
                 case "boolean":
@@ -42219,21 +42282,6 @@ namespace ts {
         }
     }
 
-    function isSomeImportDeclaration(decl: Node): boolean {
-        switch (decl.kind) {
-            case SyntaxKind.ImportClause: // For default import
-            case SyntaxKind.ImportEqualsDeclaration:
-            case SyntaxKind.NamespaceImport:
-            case SyntaxKind.ImportSpecifier: // For rename import `x as y`
-                return true;
-            case SyntaxKind.Identifier:
-                // For regular import, `decl` is an Identifier under the ImportSpecifier.
-                return decl.parent.kind === SyntaxKind.ImportSpecifier;
-            default:
-                return false;
-        }
-    }
-
     namespace JsxNames {
         export const JSX = "JSX" as __String;
         export const IntrinsicElements = "IntrinsicElements" as __String;

src/compiler/commandLineParser.ts

@@ -875,6 +875,7 @@ namespace ts {
         {
             name: "metadataDecorator",
             type: "string",
+            affectsEmit: true,
             category: Diagnostics.Advanced_Options,
             description: Diagnostics.Specify_the_name_of_the_metadata_decorator_function_to_use_when_emitDecoratorMetadata_is_set
         },

src/compiler/diagnosticMessages.json

@@ -15,7 +15,7 @@
         "category": "Error",
         "code": 1006
     },
-    "The parser expected to find a '}' to match the '{' token here.": {
+    "The parser expected to find a '{1}' to match the '{0}' token here.": {
         "category": "Error",
         "code": 1007
     },
@@ -3181,7 +3181,7 @@
         "category": "Error",
         "code": 2773
     },
-    "This condition will always return true since the function is always defined. Did you mean to call it instead?": {
+    "This condition will always return true since this function appears to always be defined. Did you mean to call it instead?": {
         "category": "Error",
         "code": 2774
     },
@@ -3289,7 +3289,7 @@
         "category": "Error",
         "code": 2800
     },
-    "This condition will always return true since the Promise is always truthy.": {
+    "This condition will always return true since this '{0}' appears to always be defined.": {
         "category": "Error",
         "code": 2801
     },
@@ -3321,18 +3321,22 @@
         "category": "Error",
         "code": 2808
     },
-    "Namespace '{0}' from module '{1}' has no exported member '{2}'.": {
+    "Declaration or statement expected. This '=' follows a block of statements, so if you intended to write a destructuring assignment, you might need to wrap the the whole assignment in parentheses.": {
         "category": "Error",
         "code": 2809
     },
-    "'{0}' from module '{1}' has no exported member named '{2}'. Did you mean '{3}'?": {
+    "Namespace '{0}' from module '{1}' has no exported member '{2}'.": {
         "category": "Error",
         "code": 2810
     },
-    "Cannot find namespace '{0}'. Did you mean '{1}?": {
+    "'{0}' from module '{1}' has no exported member named '{2}'. Did you mean '{3}'?": {
         "category": "Error",
         "code": 2811
     },
+    "Cannot find namespace '{0}'. Did you mean '{1}?": {
+        "category": "Error",
+        "code": 2812
+    },
 
     "Import declaration '{0}' is using private name '{1}'.": {
         "category": "Error",

src/compiler/parser.ts

@@ -551,6 +551,7 @@ namespace ts {
             case SyntaxKind.JSDocPrivateTag:
             case SyntaxKind.JSDocProtectedTag:
             case SyntaxKind.JSDocReadonlyTag:
+            case SyntaxKind.JSDocDeprecatedTag:
                 return visitNode(cbNode, (node as JSDocTag).tagName)
                  || (typeof (node as JSDoc).comment === "string" ? undefined : visitNodes(cbNode, cbNodes, (node as JSDoc).comment as NodeArray<JSDocText | JSDocLink> | undefined));
             case SyntaxKind.PartiallyEmittedExpression:
@@ -1335,24 +1336,27 @@ namespace ts {
             return inContext(NodeFlags.AwaitContext);
         }
 
-        function parseErrorAtCurrentToken(message: DiagnosticMessage, arg0?: any): void {
-            parseErrorAt(scanner.getTokenPos(), scanner.getTextPos(), message, arg0);
+        function parseErrorAtCurrentToken(message: DiagnosticMessage, arg0?: any): DiagnosticWithDetachedLocation | undefined {
+            return parseErrorAt(scanner.getTokenPos(), scanner.getTextPos(), message, arg0);
         }
 
-        function parseErrorAtPosition(start: number, length: number, message: DiagnosticMessage, arg0?: any): void {
+        function parseErrorAtPosition(start: number, length: number, message: DiagnosticMessage, arg0?: any): DiagnosticWithDetachedLocation | undefined {
             // Don't report another error if it would just be at the same position as the last error.
             const lastError = lastOrUndefined(parseDiagnostics);
+            let result: DiagnosticWithDetachedLocation | undefined;
             if (!lastError || start !== lastError.start) {
-                parseDiagnostics.push(createDetachedDiagnostic(fileName, start, length, message, arg0));
+                result = createDetachedDiagnostic(fileName, start, length, message, arg0);
+                parseDiagnostics.push(result);
             }
 
             // Mark that we've encountered an error.  We'll set an appropriate bit on the next
             // node we finish so that it can't be reused incrementally.
             parseErrorBeforeNextFinishedNode = true;
+            return result;
         }
 
-        function parseErrorAt(start: number, end: number, message: DiagnosticMessage, arg0?: any): void {
-            parseErrorAtPosition(start, end - start, message, arg0);
+        function parseErrorAt(start: number, end: number, message: DiagnosticMessage, arg0?: any): DiagnosticWithDetachedLocation | undefined {
+            return parseErrorAtPosition(start, end - start, message, arg0);
         }
 
         function parseErrorAtRange(range: TextRange, message: DiagnosticMessage, arg0?: any): void {
@@ -1542,6 +1546,20 @@ namespace ts {
             return false;
         }
 
+        function parseExpectedMatchingBrackets(openKind: SyntaxKind, closeKind: SyntaxKind, openPosition: number) {
+            if (token() === closeKind) {
+                nextToken();
+                return;
+            }
+            const lastError = parseErrorAtCurrentToken(Diagnostics._0_expected, tokenToString(closeKind));
+            if (lastError) {
+                addRelatedInfo(
+                    lastError,
+                    createDetachedDiagnostic(fileName, openPosition, 1, Diagnostics.The_parser_expected_to_find_a_1_to_match_the_0_token_here, tokenToString(openKind), tokenToString(closeKind))
+                );
+            }
+        }
+
         function parseOptional(t: SyntaxKind): boolean {
             if (token() === t) {
                 nextToken();
@@ -2092,8 +2110,7 @@ namespace ts {
 
             while (!isListTerminator(kind)) {
                 if (isListElement(kind, /*inErrorRecovery*/ false)) {
-                    const element = parseListElement(kind, parseElement);
-                    list.push(element);
+                    list.push(parseListElement(kind, parseElement));
 
                     continue;
                 }
@@ -5426,10 +5443,11 @@ namespace ts {
 
         function parseArrayLiteralExpression(): ArrayLiteralExpression {
             const pos = getNodePos();
+            const openBracketPosition = scanner.getTokenPos();
             parseExpected(SyntaxKind.OpenBracketToken);
             const multiLine = scanner.hasPrecedingLineBreak();
             const elements = parseDelimitedList(ParsingContext.ArrayLiteralMembers, parseArgumentOrArrayLiteralElement);
-            parseExpected(SyntaxKind.CloseBracketToken);
+            parseExpectedMatchingBrackets(SyntaxKind.OpenBracketToken, SyntaxKind.CloseBracketToken, openBracketPosition);
             return finishNode(factory.createArrayLiteralExpression(elements, multiLine), pos);
         }
 
@@ -5498,15 +5516,7 @@ namespace ts {
             parseExpected(SyntaxKind.OpenBraceToken);
             const multiLine = scanner.hasPrecedingLineBreak();
             const properties = parseDelimitedList(ParsingContext.ObjectLiteralMembers, parseObjectLiteralElement, /*considerSemicolonAsDelimiter*/ true);
-            if (!parseExpected(SyntaxKind.CloseBraceToken)) {
-                const lastError = lastOrUndefined(parseDiagnostics);
-                if (lastError && lastError.code === Diagnostics._0_expected.code) {
-                    addRelatedInfo(
-                        lastError,
-                        createDetachedDiagnostic(fileName, openBracePosition, 1, Diagnostics.The_parser_expected_to_find_a_to_match_the_token_here)
-                    );
-                }
-            }
+            parseExpectedMatchingBrackets(SyntaxKind.OpenBraceToken, SyntaxKind.CloseBraceToken, openBracePosition);
             return finishNode(factory.createObjectLiteralExpression(properties, multiLine), pos);
         }
 
@@ -5591,16 +5601,14 @@ namespace ts {
             if (parseExpected(SyntaxKind.OpenBraceToken, diagnosticMessage) || ignoreMissingOpenBrace) {
                 const multiLine = scanner.hasPrecedingLineBreak();
                 const statements = parseList(ParsingContext.BlockStatements, parseStatement);
-                if (!parseExpected(SyntaxKind.CloseBraceToken)) {
-                    const lastError = lastOrUndefined(parseDiagnostics);
-                    if (lastError && lastError.code === Diagnostics._0_expected.code) {
-                        addRelatedInfo(
-                            lastError,
-                            createDetachedDiagnostic(fileName, openBracePosition, 1, Diagnostics.The_parser_expected_to_find_a_to_match_the_token_here)
-                        );
-                    }
+                parseExpectedMatchingBrackets(SyntaxKind.OpenBraceToken, SyntaxKind.CloseBraceToken, openBracePosition);
+                const result = finishNode(factory.createBlock(statements, multiLine), pos);
+                if (token() === SyntaxKind.EqualsToken) {
+                    parseErrorAtCurrentToken(Diagnostics.Declaration_or_statement_expected_This_follows_a_block_of_statements_so_if_you_intended_to_write_a_destructuring_assignment_you_might_need_to_wrap_the_the_whole_assignment_in_parentheses);
+                    nextToken();
                 }
-                return finishNode(factory.createBlock(statements, multiLine), pos);
+
+                return result;
             }
             else {
                 const statements = createMissingList<Statement>();
@@ -5647,9 +5655,10 @@ namespace ts {
         function parseIfStatement(): IfStatement {
             const pos = getNodePos();
             parseExpected(SyntaxKind.IfKeyword);
+            const openParenPosition = scanner.getTokenPos();
             parseExpected(SyntaxKind.OpenParenToken);
             const expression = allowInAnd(parseExpression);
-            parseExpected(SyntaxKind.CloseParenToken);
+            parseExpectedMatchingBrackets(SyntaxKind.OpenParenToken, SyntaxKind.CloseParenToken, openParenPosition);
             const thenStatement = parseStatement();
             const elseStatement = parseOptional(SyntaxKind.ElseKeyword) ? parseStatement() : undefined;
             return finishNode(factory.createIfStatement(expression, thenStatement, elseStatement), pos);
@@ -5660,9 +5669,10 @@ namespace ts {
             parseExpected(SyntaxKind.DoKeyword);
             const statement = parseStatement();
             parseExpected(SyntaxKind.WhileKeyword);
+            const openParenPosition = scanner.getTokenPos();
             parseExpected(SyntaxKind.OpenParenToken);
             const expression = allowInAnd(parseExpression);
-            parseExpected(SyntaxKind.CloseParenToken);
+            parseExpectedMatchingBrackets(SyntaxKind.OpenParenToken, SyntaxKind.CloseParenToken, openParenPosition);
 
             // From: https://mail.mozilla.org/pipermail/es-discuss/2011-August/016188.html
             // 157 min --- All allen at wirfs-brock.com CONF --- "do{;}while(false)false" prohibited in
@@ -5675,9 +5685,10 @@ namespace ts {
         function parseWhileStatement(): WhileStatement {
             const pos = getNodePos();
             parseExpected(SyntaxKind.WhileKeyword);
+            const openParenPosition = scanner.getTokenPos();
             parseExpected(SyntaxKind.OpenParenToken);
             const expression = allowInAnd(parseExpression);
-            parseExpected(SyntaxKind.CloseParenToken);
+            parseExpectedMatchingBrackets(SyntaxKind.OpenParenToken, SyntaxKind.CloseParenToken, openParenPosition);
             const statement = parseStatement();
             return finishNode(factory.createWhileStatement(expression, statement), pos);
         }
@@ -5749,9 +5760,10 @@ namespace ts {
         function parseWithStatement(): WithStatement {
             const pos = getNodePos();
             parseExpected(SyntaxKind.WithKeyword);
+            const openParenPosition = scanner.getTokenPos();
             parseExpected(SyntaxKind.OpenParenToken);
             const expression = allowInAnd(parseExpression);
-            parseExpected(SyntaxKind.CloseParenToken);
+            parseExpectedMatchingBrackets(SyntaxKind.OpenParenToken, SyntaxKind.CloseParenToken, openParenPosition);
             const statement = doInsideOfContext(NodeFlags.InWithStatement, parseStatement);
             return finishNode(factory.createWithStatement(expression, statement), pos);
         }
@@ -7973,13 +7985,9 @@ namespace ts {
                             hasChildren = true;
                             if (child.kind === SyntaxKind.JSDocTypeTag) {
                                 if (childTypeTag) {
-                                    parseErrorAtCurrentToken(Diagnostics.A_JSDoc_typedef_comment_may_not_contain_multiple_type_tags);
-                                    const lastError = lastOrUndefined(parseDiagnostics);
+                                    const lastError = parseErrorAtCurrentToken(Diagnostics.A_JSDoc_typedef_comment_may_not_contain_multiple_type_tags);
                                     if (lastError) {
-                                        addRelatedInfo(
-                                            lastError,
-                                            createDetachedDiagnostic(fileName, 0, 0, Diagnostics.The_tag_was_first_specified_here)
-                                        );
+                                        addRelatedInfo(lastError, createDetachedDiagnostic(fileName, 0, 0, Diagnostics.The_tag_was_first_specified_here));
                                     }
                                     break;
                                 }
@@ -8011,7 +8019,7 @@ namespace ts {
                     }
 
                     const typedefTag = factory.createJSDocTypedefTag(tagName, typeExpression, fullName, comment);
-                    return finishNode(typedefTag, start);
+                    return finishNode(typedefTag, start, end);
                 }
 
                 function parseJSDocTypeNameWithNamespace(nested?: boolean) {

src/compiler/tsbuildPublic.ts

@@ -1717,7 +1717,11 @@ namespace ts {
                 continue;
             }
             const outputs = getAllProjectOutputs(parsed, !host.useCaseSensitiveFileNames());
+            if (!outputs.length) continue;
+            const inputFileNames = new Set(parsed.fileNames.map(f => toPath(state, f)));
             for (const output of outputs) {
+                // If output name is same as input file name, do not delete and ignore the error
+                if (inputFileNames.has(toPath(state, output))) continue;
                 if (host.fileExists(output)) {
                     if (filesToDelete) {
                         filesToDelete.push(output);

src/compiler/types.ts

@@ -4353,7 +4353,6 @@ namespace ts {
         InObjectTypeLiteral                     = 1 << 22,
         InTypeAlias                             = 1 << 23,    // Writing type in type alias declaration
         InInitialEntityName                     = 1 << 24,    // Set when writing the LHS of an entity name or entity name expression
-        InReverseMappedType                     = 1 << 25,
     }
 
     // Ensure the shared flags between this and `NodeBuilderFlags` stay in alignment

src/harness/client.ts

@@ -306,7 +306,8 @@ namespace ts.server {
                     fileName: entry.file,
                     textSpan: this.decodeSpan(entry),
                     kind: ScriptElementKind.unknown,
-                    name: ""
+                    name: "",
+                    unverified: entry.unverified,
                 })),
                 textSpan: this.decodeSpan(body.textSpan, request.arguments.file)
             };

src/harness/compilerImpl.ts

@@ -135,8 +135,6 @@ namespace compiler {
                     }
                 }
             }
-
-            this.diagnostics = diagnostics;
         }
 
         public get vfs(): vfs.FileSystem {

src/harness/fourslashImpl.ts

@@ -685,10 +685,10 @@ namespace FourSlash {
         }
 
         public verifyGoToDefinitionIs(endMarker: ArrayOrSingle<string>) {
-            this.verifyGoToXWorker(toArray(endMarker), () => this.getGoToDefinition());
+            this.verifyGoToXWorker(/*startMarker*/ undefined, toArray(endMarker), () => this.getGoToDefinition());
         }
 
-        public verifyGoToDefinition(arg0: any, endMarkerNames?: ArrayOrSingle<string> | { file: string }) {
+        public verifyGoToDefinition(arg0: any, endMarkerNames?: ArrayOrSingle<string | { marker: string, unverified?: boolean }> | { file: string, unverified?: boolean }) {
             this.verifyGoToX(arg0, endMarkerNames, () => this.getGoToDefinitionAndBoundSpan());
         }
 
@@ -705,7 +705,7 @@ namespace FourSlash {
                 this.languageService.getTypeDefinitionAtPosition(this.activeFile.fileName, this.currentCaretPosition));
         }
 
-        private verifyGoToX(arg0: any, endMarkerNames: ArrayOrSingle<string> | { file: string } | undefined, getDefs: () => readonly ts.DefinitionInfo[] | ts.DefinitionInfoAndBoundSpan | undefined) {
+        private verifyGoToX(arg0: any, endMarkerNames: ArrayOrSingle<string | { marker: string, unverified?: boolean }> | { file: string, unverified?: boolean } | undefined, getDefs: () => readonly ts.DefinitionInfo[] | ts.DefinitionInfoAndBoundSpan | undefined) {
             if (endMarkerNames) {
                 this.verifyGoToXPlain(arg0, endMarkerNames, getDefs);
             }
@@ -725,7 +725,7 @@ namespace FourSlash {
             }
         }
 
-        private verifyGoToXPlain(startMarkerNames: ArrayOrSingle<string>, endMarkerNames: ArrayOrSingle<string> | { file: string }, getDefs: () => readonly ts.DefinitionInfo[] | ts.DefinitionInfoAndBoundSpan | undefined) {
+        private verifyGoToXPlain(startMarkerNames: ArrayOrSingle<string>, endMarkerNames: ArrayOrSingle<string | { marker: string, unverified?: boolean }> | { file: string, unverified?: boolean }, getDefs: () => readonly ts.DefinitionInfo[] | ts.DefinitionInfoAndBoundSpan | undefined) {
             for (const start of toArray(startMarkerNames)) {
                 this.verifyGoToXSingle(start, endMarkerNames, getDefs);
             }
@@ -737,12 +737,12 @@ namespace FourSlash {
             }
         }
 
-        private verifyGoToXSingle(startMarkerName: string, endMarkerNames: ArrayOrSingle<string> | { file: string }, getDefs: () => readonly ts.DefinitionInfo[] | ts.DefinitionInfoAndBoundSpan | undefined) {
+        private verifyGoToXSingle(startMarkerName: string, endMarkerNames: ArrayOrSingle<string | { marker: string, unverified?: boolean }> | { file: string, unverified?: boolean }, getDefs: () => readonly ts.DefinitionInfo[] | ts.DefinitionInfoAndBoundSpan | undefined) {
             this.goToMarker(startMarkerName);
-            this.verifyGoToXWorker(toArray(endMarkerNames), getDefs, startMarkerName);
+            this.verifyGoToXWorker(startMarkerName, toArray(endMarkerNames), getDefs, startMarkerName);
         }
 
-        private verifyGoToXWorker(endMarkers: readonly (string | { file: string })[], getDefs: () => readonly ts.DefinitionInfo[] | ts.DefinitionInfoAndBoundSpan | undefined, startMarkerName?: string) {
+        private verifyGoToXWorker(startMarker: string | undefined, endMarkers: readonly (string | { marker?: string, file?: string, unverified?: boolean })[], getDefs: () => readonly ts.DefinitionInfo[] | ts.DefinitionInfoAndBoundSpan | undefined, startMarkerName?: string) {
             const defs = getDefs();
             let definitions: readonly ts.DefinitionInfo[];
             let testName: string;
@@ -763,8 +763,11 @@ namespace FourSlash {
             }
 
             ts.zipWith(endMarkers, definitions, (endMarkerOrFileResult, definition, i) => {
-                const expectedFileName = typeof endMarkerOrFileResult === "string" ? this.getMarkerByName(endMarkerOrFileResult).fileName : endMarkerOrFileResult.file;
-                const expectedPosition = typeof endMarkerOrFileResult === "string" ? this.getMarkerByName(endMarkerOrFileResult).position : 0;
+                const markerName = typeof endMarkerOrFileResult === "string" ? endMarkerOrFileResult : endMarkerOrFileResult.marker;
+                const marker = markerName !== undefined ? this.getMarkerByName(markerName) : undefined;
+                const expectedFileName = marker?.fileName || typeof endMarkerOrFileResult !== "string" && endMarkerOrFileResult.file;
+                ts.Debug.assert(typeof expectedFileName === "string");
+                const expectedPosition = marker?.position || 0;
                 if (ts.comparePaths(expectedFileName, definition.fileName, /*ignoreCase*/ true) !== ts.Comparison.EqualTo || expectedPosition !== definition.textSpan.start) {
                     const filesToDisplay = ts.deduplicate([expectedFileName, definition.fileName], ts.equateValues);
                     const markers = [{ text: "EXPECTED", fileName: expectedFileName, position: expectedPosition }, { text: "ACTUAL", fileName: definition.fileName, position: definition.textSpan.start }];
@@ -777,7 +780,15 @@ namespace FourSlash {
                         return `// @Filename: ${fileName}\n${fileContent}`;
                     }).join("\n\n");
 
-                    this.raiseError(`${testName} failed for definition ${endMarkerOrFileResult} (${i}): expected ${expectedFileName} at ${expectedPosition}, got ${definition.fileName} at ${definition.textSpan.start}\n\n${text}\n`);
+                    this.raiseError(`${testName} failed for definition ${markerName || expectedFileName} (${i}): expected ${expectedFileName} at ${expectedPosition}, got ${definition.fileName} at ${definition.textSpan.start}\n\n${text}\n`);
+                }
+                if (definition.unverified && (typeof endMarkerOrFileResult === "string" || !endMarkerOrFileResult.unverified)) {
+                    const isFileResult = typeof endMarkerOrFileResult !== "string" && !!endMarkerOrFileResult.file;
+                    this.raiseError(
+                        `${testName} failed for definition ${markerName || expectedFileName} (${i}): The actual definition was an \`unverified\` result. Use:\n\n` +
+                        `    verify.goToDefinition(${startMarker === undefined ? "startMarker" : `"${startMarker}"`}, { ${isFileResult ? `file: "${expectedFileName}"` : `marker: "${markerName}"`}, unverified: true })\n\n` +
+                        `if this is expected.`
+                    );
                 }
             });
         }

src/server/protocol.ts

@@ -1013,7 +1013,7 @@ namespace ts.server.protocol {
      * Definition response message.  Gives text range for definition.
      */
     export interface DefinitionResponse extends Response {
-        body?: FileSpanWithContext[];
+        body?: DefinitionInfo[];
     }
 
     export interface DefinitionInfoAndBoundSpanResponse extends Response {

src/server/session.ts

@@ -1224,6 +1224,7 @@ namespace ts.server {
                     containerName: info.containerName,
                     kind: info.kind,
                     name: info.name,
+                    ...info.unverified && { unverified: info.unverified },
                 };
             });
         }
@@ -1300,8 +1301,8 @@ namespace ts.server {
             }));
         }
 
-        private mapDefinitionInfo(definitions: readonly DefinitionInfo[], project: Project): readonly protocol.FileSpanWithContext[] {
-            return definitions.map(def => this.toFileSpanWithContext(def.fileName, def.textSpan, def.contextSpan, project));
+        private mapDefinitionInfo(definitions: readonly DefinitionInfo[], project: Project): readonly protocol.DefinitionInfo[] {
+            return definitions.map(def => ({ ...this.toFileSpanWithContext(def.fileName, def.textSpan, def.contextSpan, project), ...def.unverified && { unverified: def.unverified } }));
         }
 
         /*

src/services/codefixes/addMissingAwait.ts

@@ -14,6 +14,7 @@ namespace ts.codefix {
         Diagnostics.Operator_0_cannot_be_applied_to_type_1.code,
         Diagnostics.Operator_0_cannot_be_applied_to_types_1_and_2.code,
         Diagnostics.This_condition_will_always_return_0_since_the_types_1_and_2_have_no_overlap.code,
+        Diagnostics.This_condition_will_always_return_true_since_this_0_appears_to_always_be_defined.code,
         Diagnostics.Type_0_is_not_an_array_type.code,
         Diagnostics.Type_0_is_not_an_array_type_or_a_string_type.code,
         Diagnostics.Type_0_is_not_an_array_type_or_a_string_type_Use_compiler_option_downlevelIteration_to_allow_iterating_of_iterators.code,

src/services/codefixes/convertToAsyncFunction.ts

@@ -65,6 +65,10 @@ namespace ts.codefix {
         const isInJavascript = isInJSFile(functionToConvert);
         const setOfExpressionsToReturn = getAllPromiseExpressionsToReturn(functionToConvert, checker);
         const functionToConvertRenamed = renameCollidingVarNames(functionToConvert, checker, synthNamesMap);
+        if (!returnsPromise(functionToConvertRenamed, checker)) {
+            return;
+        }
+
         const returnStatements = functionToConvertRenamed.body && isBlock(functionToConvertRenamed.body) ? getReturnStatementsWithPromiseHandlers(functionToConvertRenamed.body, checker) : emptyArray;
         const transformer: Transformer = { checker, synthNamesMap, setOfExpressionsToReturn, isInJSFile: isInJavascript };
         if (!returnStatements.length) {

src/services/codefixes/convertToEs6Module.ts

@@ -436,7 +436,9 @@ namespace ts.codefix {
 
     /**
      * Convert `import x = require("x").`
-     * Also converts uses like `x.y()` to `y()` and uses a named import.
+     * Also:
+     * - Convert `x.default()` to `x()` to handle ES6 default export
+     * - Converts uses like `x.y()` to `y()` and uses a named import.
      */
     function convertSingleIdentifierImport(name: Identifier, moduleSpecifier: StringLiteralLike, checker: TypeChecker, identifiers: Identifiers, quotePreference: QuotePreference): ConvertedImports {
         const nameSymbol = checker.getSymbolAtLocation(name);
@@ -454,15 +456,23 @@ namespace ts.codefix {
 
             const { parent } = use;
             if (isPropertyAccessExpression(parent)) {
-                const { expression, name: { text: propertyName } } = parent;
-                Debug.assert(expression === use, "Didn't expect expression === use"); // Else shouldn't have been in `collectIdentifiers`
-                let idName = namedBindingsNames.get(propertyName);
-                if (idName === undefined) {
-                    idName = makeUniqueName(propertyName, identifiers);
-                    namedBindingsNames.set(propertyName, idName);
-                }
+                const { name: { text: propertyName } } = parent;
+                if (propertyName === "default") {
+                    needDefaultImport = true;
 
-                (useSitesToUnqualify ??= new Map()).set(parent, factory.createIdentifier(idName));
+                    const importDefaultName = use.getText();
+                    (useSitesToUnqualify ??= new Map()).set(parent, factory.createIdentifier(importDefaultName));
+                }
+                else {
+                    Debug.assert(parent.expression === use, "Didn't expect expression === use"); // Else shouldn't have been in `collectIdentifiers`
+                    let idName = namedBindingsNames.get(propertyName);
+                    if (idName === undefined) {
+                        idName = makeUniqueName(propertyName, identifiers);
+                        namedBindingsNames.set(propertyName, idName);
+                    }
+
+                    (useSitesToUnqualify ??= new Map()).set(parent, factory.createIdentifier(idName));
+                }
             }
             else {
                 needDefaultImport = true;

src/services/codefixes/fixMissingCallParentheses.ts

@@ -2,7 +2,7 @@
 namespace ts.codefix {
     const fixId = "fixMissingCallParentheses";
     const errorCodes = [
-        Diagnostics.This_condition_will_always_return_true_since_the_function_is_always_defined_Did_you_mean_to_call_it_instead.code,
+        Diagnostics.This_condition_will_always_return_true_since_this_function_appears_to_always_be_defined_Did_you_mean_to_call_it_instead.code,
     ];
 
     registerCodeFix({

src/services/completions.ts

@@ -1659,8 +1659,9 @@ namespace ts.Completions {
 
         function isContextTokenValueLocation(contextToken: Node) {
             return contextToken &&
-                contextToken.kind === SyntaxKind.TypeOfKeyword &&
-                (contextToken.parent.kind === SyntaxKind.TypeQuery || isTypeOfExpression(contextToken.parent));
+                ((contextToken.kind === SyntaxKind.TypeOfKeyword &&
+                    (contextToken.parent.kind === SyntaxKind.TypeQuery || isTypeOfExpression(contextToken.parent))) ||
+                (contextToken.kind === SyntaxKind.AssertsKeyword && contextToken.parent.kind === SyntaxKind.TypePredicate));
         }
 
         function isContextTokenTypeLocation(contextToken: Node): boolean {

src/services/documentRegistry.ts

@@ -83,12 +83,26 @@ namespace ts {
          * @param fileName The name of the file to be released
          * @param compilationSettings The compilation settings used to acquire the file
          */
+        /**@deprecated pass scriptKind for correctness */
         releaseDocument(fileName: string, compilationSettings: CompilerOptions): void;
-
+        /**
+         * Informs the DocumentRegistry that a file is not needed any longer.
+         *
+         * Note: It is not allowed to call release on a SourceFile that was not acquired from
+         * this registry originally.
+         *
+         * @param fileName The name of the file to be released
+         * @param compilationSettings The compilation settings used to acquire the file
+         * @param scriptKind The script kind of the file to be released
+         */
+        releaseDocument(fileName: string, compilationSettings: CompilerOptions, scriptKind: ScriptKind): void; // eslint-disable-line @typescript-eslint/unified-signatures
+        /**
+         * @deprecated pass scriptKind for correctness */
         releaseDocumentWithKey(path: Path, key: DocumentRegistryBucketKey): void;
+        releaseDocumentWithKey(path: Path, key: DocumentRegistryBucketKey, scriptKind: ScriptKind): void; // eslint-disable-line @typescript-eslint/unified-signatures
 
         /*@internal*/
-        getLanguageServiceRefCounts(path: Path): [string, number | undefined][];
+        getLanguageServiceRefCounts(path: Path, scriptKind: ScriptKind): [string, number | undefined][];
 
         reportStats(): string;
     }
@@ -110,6 +124,11 @@ namespace ts {
         languageServiceRefCount: number;
     }
 
+    type BucketEntry = DocumentRegistryEntry | ESMap<ScriptKind, DocumentRegistryEntry>;
+    function isDocumentRegistryEntry(entry: BucketEntry): entry is DocumentRegistryEntry {
+        return !!(entry as DocumentRegistryEntry).sourceFile;
+    }
+
     export function createDocumentRegistry(useCaseSensitiveFileNames?: boolean, currentDirectory?: string): DocumentRegistry {
         return createDocumentRegistryInternal(useCaseSensitiveFileNames, currentDirectory);
     }
@@ -118,18 +137,24 @@ namespace ts {
     export function createDocumentRegistryInternal(useCaseSensitiveFileNames?: boolean, currentDirectory = "", externalCache?: ExternalDocumentCache): DocumentRegistry {
         // Maps from compiler setting target (ES3, ES5, etc.) to all the cached documents we have
         // for those settings.
-        const buckets = new Map<string, ESMap<Path, DocumentRegistryEntry>>();
+        const buckets = new Map<DocumentRegistryBucketKey, ESMap<Path, BucketEntry>>();
         const getCanonicalFileName = createGetCanonicalFileName(!!useCaseSensitiveFileNames);
 
         function reportStats() {
             const bucketInfoArray = arrayFrom(buckets.keys()).filter(name => name && name.charAt(0) === "_").map(name => {
                 const entries = buckets.get(name)!;
-                const sourceFiles: { name: string; refCount: number; }[] = [];
+                const sourceFiles: { name: string; scriptKind: ScriptKind, refCount: number; }[] = [];
                 entries.forEach((entry, name) => {
-                    sourceFiles.push({
-                        name,
-                        refCount: entry.languageServiceRefCount
-                    });
+                    if (isDocumentRegistryEntry(entry)) {
+                        sourceFiles.push({
+                            name,
+                            scriptKind: entry.sourceFile.scriptKind,
+                            refCount: entry.languageServiceRefCount
+                        });
+                    }
+                    else {
+                        entry.forEach((value, scriptKind) => sourceFiles.push({ name, scriptKind, refCount: value.languageServiceRefCount }));
+                    }
                 });
                 sourceFiles.sort((x, y) => y.refCount - x.refCount);
                 return {
@@ -160,6 +185,12 @@ namespace ts {
             return acquireOrUpdateDocument(fileName, path, compilationSettings, key, scriptSnapshot, version, /*acquiring*/ false, scriptKind);
         }
 
+        function getDocumentRegistryEntry(bucketEntry: BucketEntry, scriptKind: ScriptKind | undefined) {
+            const entry = isDocumentRegistryEntry(bucketEntry) ? bucketEntry : bucketEntry.get(Debug.checkDefined(scriptKind, "If there are more than one scriptKind's for same document the scriptKind should be provided"));
+            Debug.assert(scriptKind === undefined || !entry || entry.sourceFile.scriptKind === scriptKind, `Script kind should match provided ScriptKind:${scriptKind} and sourceFile.scriptKind: ${entry?.sourceFile.scriptKind}, !entry: ${!entry}`);
+            return entry;
+        }
+
         function acquireOrUpdateDocument(
             fileName: string,
             path: Path,
@@ -169,10 +200,11 @@ namespace ts {
             version: string,
             acquiring: boolean,
             scriptKind?: ScriptKind): SourceFile {
-
-            const bucket = getOrUpdate(buckets, key, () => new Map<Path, DocumentRegistryEntry>());
-            let entry = bucket.get(path);
+            scriptKind = ensureScriptKind(fileName, scriptKind);
             const scriptTarget = scriptKind === ScriptKind.JSON ? ScriptTarget.JSON : compilationSettings.target || ScriptTarget.ES5;
+            const bucket = getOrUpdate(buckets, key, () => new Map());
+            const bucketEntry = bucket.get(path);
+            let entry = bucketEntry && getDocumentRegistryEntry(bucketEntry, scriptKind);
             if (!entry && externalCache) {
                 const sourceFile = externalCache.getDocument(key, path);
                 if (sourceFile) {
@@ -181,7 +213,7 @@ namespace ts {
                         sourceFile,
                         languageServiceRefCount: 0
                     };
-                    bucket.set(path, entry);
+                    setBucketEntry();
                 }
             }
 
@@ -195,7 +227,7 @@ namespace ts {
                     sourceFile,
                     languageServiceRefCount: 1,
                 };
-                bucket.set(path, entry);
+                setBucketEntry();
             }
             else {
                 // We have an entry for this file.  However, it may be for a different version of
@@ -221,28 +253,53 @@ namespace ts {
             Debug.assert(entry.languageServiceRefCount !== 0);
 
             return entry.sourceFile;
+
+            function setBucketEntry() {
+                if (!bucketEntry) {
+                    bucket.set(path, entry!);
+                }
+                else if (isDocumentRegistryEntry(bucketEntry)) {
+                    const scriptKindMap = new Map<ScriptKind, DocumentRegistryEntry>();
+                    scriptKindMap.set(bucketEntry.sourceFile.scriptKind, bucketEntry);
+                    scriptKindMap.set(scriptKind!, entry!);
+                    bucket.set(path, scriptKindMap);
+                }
+                else {
+                    bucketEntry.set(scriptKind!, entry!);
+                }
+            }
         }
 
-        function releaseDocument(fileName: string, compilationSettings: CompilerOptions): void {
+        function releaseDocument(fileName: string, compilationSettings: CompilerOptions, scriptKind?: ScriptKind): void {
             const path = toPath(fileName, currentDirectory, getCanonicalFileName);
             const key = getKeyForCompilationSettings(compilationSettings);
-            return releaseDocumentWithKey(path, key);
+            return releaseDocumentWithKey(path, key, scriptKind);
         }
 
-        function releaseDocumentWithKey(path: Path, key: DocumentRegistryBucketKey): void {
+        function releaseDocumentWithKey(path: Path, key: DocumentRegistryBucketKey, scriptKind?: ScriptKind): void {
             const bucket = Debug.checkDefined(buckets.get(key));
-            const entry = bucket.get(path)!;
+            const bucketEntry = bucket.get(path)!;
+            const entry = getDocumentRegistryEntry(bucketEntry, scriptKind)!;
             entry.languageServiceRefCount--;
 
             Debug.assert(entry.languageServiceRefCount >= 0);
             if (entry.languageServiceRefCount === 0) {
-                bucket.delete(path);
+                if (isDocumentRegistryEntry(bucketEntry)) {
+                    bucket.delete(path);
+                }
+                else {
+                    bucketEntry.delete(scriptKind!);
+                    if (bucketEntry.size === 1) {
+                        bucket.set(path, firstDefinedIterator(bucketEntry.values(), identity)!);
+                    }
+                }
             }
         }
 
-        function getLanguageServiceRefCounts(path: Path) {
+        function getLanguageServiceRefCounts(path: Path, scriptKind: ScriptKind) {
             return arrayFrom(buckets.entries(), ([key, bucket]): [string, number | undefined] => {
-                const entry = bucket.get(path);
+                const bucketEntry = bucket.get(path);
+                const entry = bucketEntry && getDocumentRegistryEntry(bucketEntry, scriptKind);
                 return [key, entry && entry.languageServiceRefCount];
             });
         }

src/services/findAllReferences.ts

@@ -1180,7 +1180,9 @@ namespace ts.FindAllReferences {
             for (const indirectUser of indirectUsers) {
                 for (const node of getPossibleSymbolReferenceNodes(indirectUser, isDefaultExport ? "default" : exportName)) {
                     // Import specifiers should be handled by importSearches
-                    if (isIdentifier(node) && !isImportOrExportSpecifier(node.parent) && checker.getSymbolAtLocation(node) === exportSymbol) {
+                    const symbol = checker.getSymbolAtLocation(node);
+                    const hasExportAssignmentDeclaration = some(symbol?.declarations, d => tryCast(d, isExportAssignment) ? true : false);
+                    if (isIdentifier(node) && !isImportOrExportSpecifier(node.parent) && (symbol === exportSymbol || hasExportAssignmentDeclaration)) {
                         cb(node);
                     }
                 }

src/services/goToDefinition.ts

@@ -146,7 +146,7 @@ namespace ts.GoToDefinition {
                         end: node.getEnd(),
                         fileName: node.text
                     },
-                    unverified: !!verifiedFileName,
+                    unverified: !verifiedFileName,
                 };
             }
         }

src/services/jsDoc.ts

@@ -44,6 +44,7 @@ namespace ts.JsDoc {
         "kind",
         "lends",
         "license",
+        "link",
         "listens",
         "member",
         "memberof",

src/services/refactors/convertExport.ts

@@ -48,7 +48,7 @@ namespace ts.refactor {
     });
 
     // If a VariableStatement, will have exactly one VariableDeclaration, with an Identifier for a name.
-    type ExportToConvert = FunctionDeclaration | ClassDeclaration | InterfaceDeclaration | EnumDeclaration | NamespaceDeclaration | TypeAliasDeclaration | VariableStatement;
+    type ExportToConvert = FunctionDeclaration | ClassDeclaration | InterfaceDeclaration | EnumDeclaration | NamespaceDeclaration | TypeAliasDeclaration | VariableStatement | ExportAssignment;
     interface ExportInfo {
         readonly exportNode: ExportToConvert;
         readonly exportName: Identifier; // This is exportNode.name except for VariableStatement_s.
@@ -67,7 +67,8 @@ namespace ts.refactor {
 
         const exportingModuleSymbol = isSourceFile(exportNode.parent) ? exportNode.parent.symbol : exportNode.parent.parent.symbol;
 
-        const flags = getSyntacticModifierFlags(exportNode);
+        const flags = getSyntacticModifierFlags(exportNode) || ((isExportAssignment(exportNode) && !exportNode.isExportEquals) ? ModifierFlags.ExportDefault : ModifierFlags.None);
+
         const wasDefault = !!(flags & ModifierFlags.Default);
         // If source file already has a default export, don't offer refactor.
         if (!(flags & ModifierFlags.Export) || !wasDefault && exportingModuleSymbol.exports!.has(InternalSymbolName.Default)) {
@@ -95,6 +96,11 @@ namespace ts.refactor {
                 Debug.assert(!wasDefault, "Can't have a default flag here");
                 return isIdentifier(decl.name) ? { exportNode: vs, exportName: decl.name, wasDefault, exportingModuleSymbol } : undefined;
             }
+            case SyntaxKind.ExportAssignment: {
+                const node = exportNode as ExportAssignment;
+                const exp = node.expression as Identifier;
+                return node.isExportEquals ? undefined : { exportNode: node, exportName: exp, wasDefault, exportingModuleSymbol };
+            }
             default:
                 return undefined;
         }
@@ -107,7 +113,14 @@ namespace ts.refactor {
 
     function changeExport(exportingSourceFile: SourceFile, { wasDefault, exportNode, exportName }: ExportInfo, changes: textChanges.ChangeTracker, checker: TypeChecker): void {
         if (wasDefault) {
-            changes.delete(exportingSourceFile, Debug.checkDefined(findModifier(exportNode, SyntaxKind.DefaultKeyword), "Should find a default keyword in modifier list"));
+            if (isExportAssignment(exportNode) && !exportNode.isExportEquals) {
+                const exp = exportNode.expression as Identifier;
+                const spec = makeExportSpecifier(exp.text, exp.text);
+                changes.replaceNode(exportingSourceFile, exportNode, factory.createExportDeclaration(/*decorators*/ undefined, /*modifiers*/ undefined, /*isTypeOnly*/ false, factory.createNamedExports([spec])));
+            }
+            else {
+                changes.delete(exportingSourceFile, Debug.checkDefined(findModifier(exportNode, SyntaxKind.DefaultKeyword), "Should find a default keyword in modifier list"));
+            }
         }
         else {
             const exportKeyword = Debug.checkDefined(findModifier(exportNode, SyntaxKind.ExportKeyword), "Should find an export keyword in modifier list");
@@ -134,7 +147,7 @@ namespace ts.refactor {
                     changes.insertNodeAfter(exportingSourceFile, exportNode, factory.createExportDefault(factory.createIdentifier(exportName.text)));
                     break;
                 default:
-                    Debug.assertNever(exportNode, `Unexpected exportNode kind ${(exportNode as ExportToConvert).kind}`);
+                    Debug.fail(`Unexpected exportNode kind ${(exportNode as ExportToConvert).kind}`);
             }
         }
     }

src/services/services.ts

@@ -1444,7 +1444,7 @@ namespace ts {
             // not part of the new program.
             function onReleaseOldSourceFile(oldSourceFile: SourceFile, oldOptions: CompilerOptions) {
                 const oldSettingsKey = documentRegistry.getKeyForCompilationSettings(oldOptions);
-                documentRegistry.releaseDocumentWithKey(oldSourceFile.resolvedPath, oldSettingsKey);
+                documentRegistry.releaseDocumentWithKey(oldSourceFile.resolvedPath, oldSettingsKey, oldSourceFile.scriptKind);
             }
 
             function getOrCreateSourceFile(fileName: string, languageVersion: ScriptTarget, onError?: (message: string) => void, shouldCreateNewSourceFile?: boolean): SourceFile | undefined {
@@ -1493,9 +1493,13 @@ namespace ts {
                         // We do not support the scenario where a host can modify a registered
                         // file's script kind, i.e. in one project some file is treated as ".ts"
                         // and in another as ".js"
-                        Debug.assertEqual(hostFileInformation.scriptKind, oldSourceFile.scriptKind, "Registered script kind should match new script kind.");
-
-                        return documentRegistry.updateDocumentWithKey(fileName, path, newSettings, documentRegistryBucketKey, hostFileInformation.scriptSnapshot, hostFileInformation.version, hostFileInformation.scriptKind);
+                        if (hostFileInformation.scriptKind === oldSourceFile.scriptKind) {
+                            return documentRegistry.updateDocumentWithKey(fileName, path, newSettings, documentRegistryBucketKey, hostFileInformation.scriptSnapshot, hostFileInformation.version, hostFileInformation.scriptKind);
+                        }
+                        else {
+                            // Release old source file and fall through to aquire new file with new script kind
+                            documentRegistry.releaseDocumentWithKey(oldSourceFile.resolvedPath, documentRegistry.getKeyForCompilationSettings(program.getCompilerOptions()), oldSourceFile.scriptKind);
+                        }
                     }
 
                     // We didn't already have the file.  Fall through and acquire it from the registry.
@@ -1531,7 +1535,7 @@ namespace ts {
                 // Use paths to ensure we are using correct key and paths as document registry could be created with different current directory than host
                 const key = documentRegistry.getKeyForCompilationSettings(program.getCompilerOptions());
                 forEach(program.getSourceFiles(), f =>
-                    documentRegistry.releaseDocumentWithKey(f.resolvedPath, key));
+                    documentRegistry.releaseDocumentWithKey(f.resolvedPath, key, f.scriptKind));
                 program = undefined!; // TODO: GH#18217
             }
             host = undefined!;

src/services/suggestionDiagnostics.ts

@@ -118,10 +118,9 @@ namespace ts {
             returnsPromise(node, checker);
     }
 
-    function returnsPromise(node: FunctionLikeDeclaration, checker: TypeChecker): boolean {
-        const functionType = checker.getTypeAtLocation(node);
-        const callSignatures = checker.getSignaturesOfType(functionType, SignatureKind.Call);
-        const returnType = callSignatures.length ? checker.getReturnTypeOfSignature(callSignatures[0]) : undefined;
+    export function returnsPromise(node: FunctionLikeDeclaration, checker: TypeChecker): boolean {
+        const signature = checker.getSignatureFromDeclaration(node);
+        const returnType = signature ? checker.getReturnTypeOfSignature(signature) : undefined;
         return !!returnType && !!checker.getPromisedTypeOfPromise(returnType);
     }
 

src/services/utilities.ts

@@ -2516,8 +2516,10 @@ namespace ts {
     }
 
     /* @internal */
-    export function needsParentheses(expression: Expression) {
-        return isBinaryExpression(expression) && expression.operatorToken.kind === SyntaxKind.CommaToken || isObjectLiteralExpression(expression);
+    export function needsParentheses(expression: Expression): boolean {
+        return isBinaryExpression(expression) && expression.operatorToken.kind === SyntaxKind.CommaToken
+            || isObjectLiteralExpression(expression)
+            || isAsExpression(expression) && isObjectLiteralExpression(expression.expression);
     }
 
     export function getContextualTypeFromParent(node: Expression, checker: TypeChecker): Type | undefined {

src/testRunner/tsconfig.json

@@ -113,6 +113,7 @@
         "unittests/services/textChanges.ts",
         "unittests/services/transpile.ts",
         "unittests/tsbuild/amdModulesWithOut.ts",
+        "unittests/tsbuild/clean.ts",
         "unittests/tsbuild/configFileErrors.ts",
         "unittests/tsbuild/configFileExtends.ts",
         "unittests/tsbuild/containerOnlyReferenced.ts",

src/testRunner/unittests/services/convertToAsyncFunction.ts

@@ -1680,6 +1680,24 @@ import { fn } from "./module";
 function [#|f|]() {
     return Promise.resolve(0).then(fn);
 }
+`);
+
+        _testConvertToAsyncFunctionFailed("convertToAsyncFunction__NoSuggestionInFunctionsWithNonFixableReturnStatements1", `
+function f(x: number): Promise<void>;
+function f(): void;
+function [#|f|](x?: number): Promise<void> | void {
+    if (!x) return;
+    return fetch('').then(() => {});
+}
+`);
+
+        _testConvertToAsyncFunctionFailed("convertToAsyncFunction__NoSuggestionInFunctionsWithNonFixableReturnStatements2", `
+function f(x: number): Promise<void>;
+function f(): number;
+function [#|f|](x?: number): Promise<void> | number {
+    if (x) return x;
+    return fetch('').then(() => {});
+}
 `);
 
     });

src/testRunner/unittests/tsbuild/clean.ts

@@ -0,0 +1,16 @@
+namespace ts {
+    describe("unittests:: tsbuild - clean", () => {
+        verifyTsc({
+            scenario: "clean",
+            subScenario: `file name and output name clashing`,
+            commandLineArgs: ["--b", "/src/tsconfig.json", "-clean"],
+            fs: () => loadProjectFromFiles({
+                "/src/index.js": "",
+                "/src/bar.ts": "",
+                "/src/tsconfig.json": JSON.stringify({
+                    compilerOptions: { allowJs: true },
+                }),
+            }),
+        });
+    });
+}

src/testRunner/unittests/tsserver/documentRegistry.ts

@@ -27,7 +27,7 @@ namespace ts.projectSystem {
             assert.isDefined(moduleInfo);
             assert.equal(moduleInfo.isOrphan(), moduleIsOrphan);
             const key = service.documentRegistry.getKeyForCompilationSettings(project.getCompilationSettings());
-            assert.deepEqual(service.documentRegistry.getLanguageServiceRefCounts(moduleInfo.path), [[key, moduleIsOrphan ? undefined : 1]]);
+            assert.deepEqual(service.documentRegistry.getLanguageServiceRefCounts(moduleInfo.path, moduleInfo.scriptKind), [[key, moduleIsOrphan ? undefined : 1]]);
         }
 
         function createServiceAndHost() {

src/testRunner/unittests/tsserver/dynamicFiles.ts

@@ -121,6 +121,28 @@ var x = 10;`
             service.openClientFile(file.path);
             checkNumberOfProjects(service, { configuredProjects: 1 });
         });
+
+        it("when changing scriptKind of the untitled files", () => {
+            const host = createServerHost([libFile], { useCaseSensitiveFileNames: true });
+            const service = createProjectService(host, { useInferredProjectPerProjectRoot: true });
+            service.openClientFile(untitledFile, "const x = 10;", ScriptKind.TS, tscWatch.projectRoot);
+            checkNumberOfProjects(service, { inferredProjects: 1 });
+            checkProjectActualFiles(service.inferredProjects[0], [untitledFile, libFile.path]);
+            const program = service.inferredProjects[0].getCurrentProgram()!;
+            const sourceFile = program.getSourceFile(untitledFile)!;
+
+            // Close untitled file
+            service.closeClientFile(untitledFile);
+
+            // Open untitled file with different mode
+            service.openClientFile(untitledFile, "const x = 10;", ScriptKind.TSX, tscWatch.projectRoot);
+            checkNumberOfProjects(service, { inferredProjects: 1 });
+            checkProjectActualFiles(service.inferredProjects[0], [untitledFile, libFile.path]);
+            const newProgram = service.inferredProjects[0].getCurrentProgram()!;
+            const newSourceFile = newProgram.getSourceFile(untitledFile)!;
+            assert.notStrictEqual(newProgram, program);
+            assert.notStrictEqual(newSourceFile, sourceFile);
+        });
     });
 
     describe("unittests:: tsserver:: dynamicFiles:: ", () => {

src/testRunner/unittests/tsserver/partialSemanticServer.ts

@@ -218,7 +218,7 @@ function fooB() { }`
             assert.deepEqual(response.definitions, [{
                 file: file2.path,
                 start: { line: 1, offset: 1 },
-                end: { line: 1, offset: 1 }
+                end: { line: 1, offset: 1 },
             }]);
         });
     });

src/testRunner/unittests/tsserver/projectReferencesSourcemap.ts

@@ -4436,4 +4436,4 @@ ${dependencyTs.content}`);
             });
         });
     });
-}
+}

tests/baselines/reference/api/tsserverlibrary.d.ts

@@ -2299,8 +2299,7 @@ declare namespace ts {
         IgnoreErrors = 70221824,
         InObjectTypeLiteral = 4194304,
         InTypeAlias = 8388608,
-        InInitialEntityName = 16777216,
-        InReverseMappedType = 33554432
+        InInitialEntityName = 16777216
     }
     export enum TypeFormatFlags {
         None = 0,
@@ -6528,8 +6527,23 @@ declare namespace ts {
          * @param fileName The name of the file to be released
          * @param compilationSettings The compilation settings used to acquire the file
          */
+        /**@deprecated pass scriptKind for correctness */
         releaseDocument(fileName: string, compilationSettings: CompilerOptions): void;
+        /**
+         * Informs the DocumentRegistry that a file is not needed any longer.
+         *
+         * Note: It is not allowed to call release on a SourceFile that was not acquired from
+         * this registry originally.
+         *
+         * @param fileName The name of the file to be released
+         * @param compilationSettings The compilation settings used to acquire the file
+         * @param scriptKind The script kind of the file to be released
+         */
+        releaseDocument(fileName: string, compilationSettings: CompilerOptions, scriptKind: ScriptKind): void;
+        /**
+         * @deprecated pass scriptKind for correctness */
         releaseDocumentWithKey(path: Path, key: DocumentRegistryBucketKey): void;
+        releaseDocumentWithKey(path: Path, key: DocumentRegistryBucketKey, scriptKind: ScriptKind): void;
         reportStats(): string;
     }
     type DocumentRegistryBucketKey = string & {
@@ -7400,7 +7414,7 @@ declare namespace ts.server.protocol {
      * Definition response message.  Gives text range for definition.
      */
     interface DefinitionResponse extends Response {
-        body?: FileSpanWithContext[];
+        body?: DefinitionInfo[];
     }
     interface DefinitionInfoAndBoundSpanResponse extends Response {
         body?: DefinitionInfoAndBoundSpan;

tests/baselines/reference/api/typescript.d.ts

@@ -2299,8 +2299,7 @@ declare namespace ts {
         IgnoreErrors = 70221824,
         InObjectTypeLiteral = 4194304,
         InTypeAlias = 8388608,
-        InInitialEntityName = 16777216,
-        InReverseMappedType = 33554432
+        InInitialEntityName = 16777216
     }
     export enum TypeFormatFlags {
         None = 0,
@@ -6528,8 +6527,23 @@ declare namespace ts {
          * @param fileName The name of the file to be released
          * @param compilationSettings The compilation settings used to acquire the file
          */
+        /**@deprecated pass scriptKind for correctness */
         releaseDocument(fileName: string, compilationSettings: CompilerOptions): void;
+        /**
+         * Informs the DocumentRegistry that a file is not needed any longer.
+         *
+         * Note: It is not allowed to call release on a SourceFile that was not acquired from
+         * this registry originally.
+         *
+         * @param fileName The name of the file to be released
+         * @param compilationSettings The compilation settings used to acquire the file
+         * @param scriptKind The script kind of the file to be released
+         */
+        releaseDocument(fileName: string, compilationSettings: CompilerOptions, scriptKind: ScriptKind): void;
+        /**
+         * @deprecated pass scriptKind for correctness */
         releaseDocumentWithKey(path: Path, key: DocumentRegistryBucketKey): void;
+        releaseDocumentWithKey(path: Path, key: DocumentRegistryBucketKey, scriptKind: ScriptKind): void;
         reportStats(): string;
     }
     type DocumentRegistryBucketKey = string & {

tests/baselines/reference/assignmentLHSIsValue.errors.txt

@@ -13,14 +13,15 @@ tests/cases/conformance/expressions/assignmentOperator/assignmentLHSIsValue.ts(2
 tests/cases/conformance/expressions/assignmentOperator/assignmentLHSIsValue.ts(30,1): error TS2364: The left-hand side of an assignment expression must be a variable or a property access.
 tests/cases/conformance/expressions/assignmentOperator/assignmentLHSIsValue.ts(31,1): error TS2364: The left-hand side of an assignment expression must be a variable or a property access.
 tests/cases/conformance/expressions/assignmentOperator/assignmentLHSIsValue.ts(32,1): error TS2364: The left-hand side of an assignment expression must be a variable or a property access.
-tests/cases/conformance/expressions/assignmentOperator/assignmentLHSIsValue.ts(35,9): error TS1128: Declaration or statement expected.
+tests/cases/conformance/expressions/assignmentOperator/assignmentLHSIsValue.ts(35,9): error TS2809: Declaration or statement expected. This '=' follows a block of statements, so if you intended to write a destructuring assignment, you might need to wrap the the whole assignment in parentheses.
 tests/cases/conformance/expressions/assignmentOperator/assignmentLHSIsValue.ts(38,2): error TS2364: The left-hand side of an assignment expression must be a variable or a property access.
 tests/cases/conformance/expressions/assignmentOperator/assignmentLHSIsValue.ts(38,6): error TS2364: The left-hand side of an assignment expression must be a variable or a property access.
 tests/cases/conformance/expressions/assignmentOperator/assignmentLHSIsValue.ts(42,36): error TS1034: 'super' must be followed by an argument list or member access.
 tests/cases/conformance/expressions/assignmentOperator/assignmentLHSIsValue.ts(44,19): error TS1034: 'super' must be followed by an argument list or member access.
 tests/cases/conformance/expressions/assignmentOperator/assignmentLHSIsValue.ts(46,27): error TS1034: 'super' must be followed by an argument list or member access.
-tests/cases/conformance/expressions/assignmentOperator/assignmentLHSIsValue.ts(50,20): error TS1128: Declaration or statement expected.
-tests/cases/conformance/expressions/assignmentOperator/assignmentLHSIsValue.ts(51,11): error TS1005: ';' expected.
+tests/cases/conformance/expressions/assignmentOperator/assignmentLHSIsValue.ts(50,20): error TS2809: Declaration or statement expected. This '=' follows a block of statements, so if you intended to write a destructuring assignment, you might need to wrap the the whole assignment in parentheses.
+tests/cases/conformance/expressions/assignmentOperator/assignmentLHSIsValue.ts(51,11): error TS2809: Declaration or statement expected. This '=' follows a block of statements, so if you intended to write a destructuring assignment, you might need to wrap the the whole assignment in parentheses.
+tests/cases/conformance/expressions/assignmentOperator/assignmentLHSIsValue.ts(51,13): error TS1005: ';' expected.
 tests/cases/conformance/expressions/assignmentOperator/assignmentLHSIsValue.ts(54,1): error TS2364: The left-hand side of an assignment expression must be a variable or a property access.
 tests/cases/conformance/expressions/assignmentOperator/assignmentLHSIsValue.ts(57,1): error TS2364: The left-hand side of an assignment expression must be a variable or a property access.
 tests/cases/conformance/expressions/assignmentOperator/assignmentLHSIsValue.ts(58,2): error TS2631: Cannot assign to 'M' because it is a namespace.
@@ -38,7 +39,7 @@ tests/cases/conformance/expressions/assignmentOperator/assignmentLHSIsValue.ts(6
 tests/cases/conformance/expressions/assignmentOperator/assignmentLHSIsValue.ts(70,1): error TS2364: The left-hand side of an assignment expression must be a variable or a property access.
 
 
-==== tests/cases/conformance/expressions/assignmentOperator/assignmentLHSIsValue.ts (38 errors) ====
+==== tests/cases/conformance/expressions/assignmentOperator/assignmentLHSIsValue.ts (39 errors) ====
     // expected error for all the LHS of assignments
     var value: any;
     
@@ -105,7 +106,7 @@ tests/cases/conformance/expressions/assignmentOperator/assignmentLHSIsValue.ts(7
     // object literals
     { a: 0} = value;
             ~
-!!! error TS1128: Declaration or statement expected.
+!!! error TS2809: Declaration or statement expected. This '=' follows a block of statements, so if you intended to write a destructuring assignment, you might need to wrap the the whole assignment in parentheses.
     
     // array literals
     ['', ''] = value;
@@ -132,9 +133,11 @@ tests/cases/conformance/expressions/assignmentOperator/assignmentLHSIsValue.ts(7
     // function expression
     function bar() { } = value;
                        ~
-!!! error TS1128: Declaration or statement expected.
+!!! error TS2809: Declaration or statement expected. This '=' follows a block of statements, so if you intended to write a destructuring assignment, you might need to wrap the the whole assignment in parentheses.
     () => { } = value;
               ~
+!!! error TS2809: Declaration or statement expected. This '=' follows a block of statements, so if you intended to write a destructuring assignment, you might need to wrap the the whole assignment in parentheses.
+                ~~~~~
 !!! error TS1005: ';' expected.
     
     // function calls

tests/baselines/reference/assignmentLHSIsValue.types

@@ -146,7 +146,7 @@ function bar() { } = value;
 >value : any
 
 () => { } = value;
->() => { } : () => void
+>() => { } = : () => void
 >value : any
 
 // function calls

tests/baselines/reference/bluebirdStaticThis.errors.txt

@@ -1,10 +1,10 @@
 tests/cases/compiler/bluebirdStaticThis.ts(5,22): error TS2420: Class 'Promise<R>' incorrectly implements interface 'Thenable<R>'.
   Property 'then' is missing in type 'Promise<R>' but required in type 'Thenable<R>'.
-tests/cases/compiler/bluebirdStaticThis.ts(22,51): error TS2809: Namespace 'Promise' from module 'tests/cases/compiler/bluebirdStaticThis' has no exported member 'Resolver'.
-tests/cases/compiler/bluebirdStaticThis.ts(57,109): error TS2809: Namespace 'Promise' from module 'tests/cases/compiler/bluebirdStaticThis' has no exported member 'Inspection'.
-tests/cases/compiler/bluebirdStaticThis.ts(58,91): error TS2809: Namespace 'Promise' from module 'tests/cases/compiler/bluebirdStaticThis' has no exported member 'Inspection'.
-tests/cases/compiler/bluebirdStaticThis.ts(59,91): error TS2809: Namespace 'Promise' from module 'tests/cases/compiler/bluebirdStaticThis' has no exported member 'Inspection'.
-tests/cases/compiler/bluebirdStaticThis.ts(60,73): error TS2809: Namespace 'Promise' from module 'tests/cases/compiler/bluebirdStaticThis' has no exported member 'Inspection'.
+tests/cases/compiler/bluebirdStaticThis.ts(22,51): error TS2810: Namespace 'Promise' from module 'tests/cases/compiler/bluebirdStaticThis' has no exported member 'Resolver'.
+tests/cases/compiler/bluebirdStaticThis.ts(57,109): error TS2810: Namespace 'Promise' from module 'tests/cases/compiler/bluebirdStaticThis' has no exported member 'Inspection'.
+tests/cases/compiler/bluebirdStaticThis.ts(58,91): error TS2810: Namespace 'Promise' from module 'tests/cases/compiler/bluebirdStaticThis' has no exported member 'Inspection'.
+tests/cases/compiler/bluebirdStaticThis.ts(59,91): error TS2810: Namespace 'Promise' from module 'tests/cases/compiler/bluebirdStaticThis' has no exported member 'Inspection'.
+tests/cases/compiler/bluebirdStaticThis.ts(60,73): error TS2810: Namespace 'Promise' from module 'tests/cases/compiler/bluebirdStaticThis' has no exported member 'Inspection'.
 
 
 ==== tests/cases/compiler/bluebirdStaticThis.ts (6 errors) ====
@@ -35,7 +35,7 @@ tests/cases/compiler/bluebirdStaticThis.ts(60,73): error TS2809: Namespace 'Prom
     
         static defer<R>(dit: typeof Promise): Promise.Resolver<R>;
                                                       ~~~~~~~~
-!!! error TS2809: Namespace 'Promise' from module 'tests/cases/compiler/bluebirdStaticThis' has no exported member 'Resolver'.
+!!! error TS2810: Namespace 'Promise' from module 'tests/cases/compiler/bluebirdStaticThis' has no exported member 'Resolver'.
     
         static cast<R>(dit: typeof Promise, value: Promise.Thenable<R>): Promise<R>;
         static cast<R>(dit: typeof Promise, value: R): Promise<R>;
@@ -72,16 +72,16 @@ tests/cases/compiler/bluebirdStaticThis.ts(60,73): error TS2809: Namespace 'Prom
     
         static settle<R>(dit: typeof Promise, values: Promise.Thenable<Promise.Thenable<R>[]>): Promise<Promise.Inspection<R>[]>;
                                                                                                                 ~~~~~~~~~~
-!!! error TS2809: Namespace 'Promise' from module 'tests/cases/compiler/bluebirdStaticThis' has no exported member 'Inspection'.
+!!! error TS2810: Namespace 'Promise' from module 'tests/cases/compiler/bluebirdStaticThis' has no exported member 'Inspection'.
         static settle<R>(dit: typeof Promise, values: Promise.Thenable<R[]>): Promise<Promise.Inspection<R>[]>;
                                                                                               ~~~~~~~~~~
-!!! error TS2809: Namespace 'Promise' from module 'tests/cases/compiler/bluebirdStaticThis' has no exported member 'Inspection'.
+!!! error TS2810: Namespace 'Promise' from module 'tests/cases/compiler/bluebirdStaticThis' has no exported member 'Inspection'.
         static settle<R>(dit: typeof Promise, values: Promise.Thenable<R>[]): Promise<Promise.Inspection<R>[]>;
                                                                                               ~~~~~~~~~~
-!!! error TS2809: Namespace 'Promise' from module 'tests/cases/compiler/bluebirdStaticThis' has no exported member 'Inspection'.
+!!! error TS2810: Namespace 'Promise' from module 'tests/cases/compiler/bluebirdStaticThis' has no exported member 'Inspection'.
         static settle<R>(dit: typeof Promise, values: R[]): Promise<Promise.Inspection<R>[]>;
                                                                             ~~~~~~~~~~
-!!! error TS2809: Namespace 'Promise' from module 'tests/cases/compiler/bluebirdStaticThis' has no exported member 'Inspection'.
+!!! error TS2810: Namespace 'Promise' from module 'tests/cases/compiler/bluebirdStaticThis' has no exported member 'Inspection'.
     
         static any<R>(dit: typeof Promise, values: Promise.Thenable<Promise.Thenable<R>[]>): Promise<R>;
         static any<R>(dit: typeof Promise, values: Promise.Thenable<R[]>): Promise<R>;

tests/baselines/reference/callOfConditionalTypeWithConcreteBranches.js

@@ -0,0 +1,53 @@
+//// [callOfConditionalTypeWithConcreteBranches.ts]
+type Q<T> = number extends T ? (n: number) => void : never;
+function fn<T>(arg: Q<T>) {
+  // Expected: OK
+  // Actual: Cannot convert 10 to number & T
+  arg(10);
+}
+// Legal invocations are not problematic
+fn<string | number>(m => m.toFixed());
+fn<number>(m => m.toFixed());
+
+// Ensure the following real-world example that relies on substitution still works
+type ExtractParameters<T> = "parameters" extends keyof T
+  // The above allows "parameters" to index `T` since all later
+  // instances are actually implicitly `"parameters" & keyof T`
+  ?  {
+        [K in keyof T["parameters"]]: T["parameters"][K];
+      }[keyof T["parameters"]]
+  : {};
+
+// Original example, but with inverted variance
+type Q2<T> = number extends T ? (cb: (n: number) => void) => void : never;
+function fn2<T>(arg: Q2<T>) {
+  function useT(_arg: T): void {}
+  // Expected: OK
+  arg(arg => useT(arg));
+}
+// Legal invocations are not problematic
+fn2<string | number>(m => m(42));
+fn2<number>(m => m(42));
+
+// webidl-conversions example where substituion must occur, despite contravariance of the position
+// due to the invariant usage in `Parameters`
+
+type X<V> = V extends (...args: any[]) => any ? (...args: Parameters<V>) => void : Function;
+
+//// [callOfConditionalTypeWithConcreteBranches.js]
+function fn(arg) {
+    // Expected: OK
+    // Actual: Cannot convert 10 to number & T
+    arg(10);
+}
+// Legal invocations are not problematic
+fn(function (m) { return m.toFixed(); });
+fn(function (m) { return m.toFixed(); });
+function fn2(arg) {
+    function useT(_arg) { }
+    // Expected: OK
+    arg(function (arg) { return useT(arg); });
+}
+// Legal invocations are not problematic
+fn2(function (m) { return m(42); });
+fn2(function (m) { return m(42); });

tests/baselines/reference/callOfConditionalTypeWithConcreteBranches.symbols

@@ -0,0 +1,105 @@
+=== tests/cases/compiler/callOfConditionalTypeWithConcreteBranches.ts ===
+type Q<T> = number extends T ? (n: number) => void : never;
+>Q : Symbol(Q, Decl(callOfConditionalTypeWithConcreteBranches.ts, 0, 0))
+>T : Symbol(T, Decl(callOfConditionalTypeWithConcreteBranches.ts, 0, 7))
+>T : Symbol(T, Decl(callOfConditionalTypeWithConcreteBranches.ts, 0, 7))
+>n : Symbol(n, Decl(callOfConditionalTypeWithConcreteBranches.ts, 0, 32))
+
+function fn<T>(arg: Q<T>) {
+>fn : Symbol(fn, Decl(callOfConditionalTypeWithConcreteBranches.ts, 0, 59))
+>T : Symbol(T, Decl(callOfConditionalTypeWithConcreteBranches.ts, 1, 12))
+>arg : Symbol(arg, Decl(callOfConditionalTypeWithConcreteBranches.ts, 1, 15))
+>Q : Symbol(Q, Decl(callOfConditionalTypeWithConcreteBranches.ts, 0, 0))
+>T : Symbol(T, Decl(callOfConditionalTypeWithConcreteBranches.ts, 1, 12))
+
+  // Expected: OK
+  // Actual: Cannot convert 10 to number & T
+  arg(10);
+>arg : Symbol(arg, Decl(callOfConditionalTypeWithConcreteBranches.ts, 1, 15))
+}
+// Legal invocations are not problematic
+fn<string | number>(m => m.toFixed());
+>fn : Symbol(fn, Decl(callOfConditionalTypeWithConcreteBranches.ts, 0, 59))
+>m : Symbol(m, Decl(callOfConditionalTypeWithConcreteBranches.ts, 7, 20))
+>m.toFixed : Symbol(Number.toFixed, Decl(lib.es5.d.ts, --, --))
+>m : Symbol(m, Decl(callOfConditionalTypeWithConcreteBranches.ts, 7, 20))
+>toFixed : Symbol(Number.toFixed, Decl(lib.es5.d.ts, --, --))
+
+fn<number>(m => m.toFixed());
+>fn : Symbol(fn, Decl(callOfConditionalTypeWithConcreteBranches.ts, 0, 59))
+>m : Symbol(m, Decl(callOfConditionalTypeWithConcreteBranches.ts, 8, 11))
+>m.toFixed : Symbol(Number.toFixed, Decl(lib.es5.d.ts, --, --))
+>m : Symbol(m, Decl(callOfConditionalTypeWithConcreteBranches.ts, 8, 11))
+>toFixed : Symbol(Number.toFixed, Decl(lib.es5.d.ts, --, --))
+
+// Ensure the following real-world example that relies on substitution still works
+type ExtractParameters<T> = "parameters" extends keyof T
+>ExtractParameters : Symbol(ExtractParameters, Decl(callOfConditionalTypeWithConcreteBranches.ts, 8, 29))
+>T : Symbol(T, Decl(callOfConditionalTypeWithConcreteBranches.ts, 11, 23))
+>T : Symbol(T, Decl(callOfConditionalTypeWithConcreteBranches.ts, 11, 23))
+
+  // The above allows "parameters" to index `T` since all later
+  // instances are actually implicitly `"parameters" & keyof T`
+  ?  {
+        [K in keyof T["parameters"]]: T["parameters"][K];
+>K : Symbol(K, Decl(callOfConditionalTypeWithConcreteBranches.ts, 15, 9))
+>T : Symbol(T, Decl(callOfConditionalTypeWithConcreteBranches.ts, 11, 23))
+>T : Symbol(T, Decl(callOfConditionalTypeWithConcreteBranches.ts, 11, 23))
+>K : Symbol(K, Decl(callOfConditionalTypeWithConcreteBranches.ts, 15, 9))
+
+      }[keyof T["parameters"]]
+>T : Symbol(T, Decl(callOfConditionalTypeWithConcreteBranches.ts, 11, 23))
+
+  : {};
+
+// Original example, but with inverted variance
+type Q2<T> = number extends T ? (cb: (n: number) => void) => void : never;
+>Q2 : Symbol(Q2, Decl(callOfConditionalTypeWithConcreteBranches.ts, 17, 7))
+>T : Symbol(T, Decl(callOfConditionalTypeWithConcreteBranches.ts, 20, 8))
+>T : Symbol(T, Decl(callOfConditionalTypeWithConcreteBranches.ts, 20, 8))
+>cb : Symbol(cb, Decl(callOfConditionalTypeWithConcreteBranches.ts, 20, 33))
+>n : Symbol(n, Decl(callOfConditionalTypeWithConcreteBranches.ts, 20, 38))
+
+function fn2<T>(arg: Q2<T>) {
+>fn2 : Symbol(fn2, Decl(callOfConditionalTypeWithConcreteBranches.ts, 20, 74))
+>T : Symbol(T, Decl(callOfConditionalTypeWithConcreteBranches.ts, 21, 13))
+>arg : Symbol(arg, Decl(callOfConditionalTypeWithConcreteBranches.ts, 21, 16))
+>Q2 : Symbol(Q2, Decl(callOfConditionalTypeWithConcreteBranches.ts, 17, 7))
+>T : Symbol(T, Decl(callOfConditionalTypeWithConcreteBranches.ts, 21, 13))
+
+  function useT(_arg: T): void {}
+>useT : Symbol(useT, Decl(callOfConditionalTypeWithConcreteBranches.ts, 21, 29))
+>_arg : Symbol(_arg, Decl(callOfConditionalTypeWithConcreteBranches.ts, 22, 16))
+>T : Symbol(T, Decl(callOfConditionalTypeWithConcreteBranches.ts, 21, 13))
+
+  // Expected: OK
+  arg(arg => useT(arg));
+>arg : Symbol(arg, Decl(callOfConditionalTypeWithConcreteBranches.ts, 21, 16))
+>arg : Symbol(arg, Decl(callOfConditionalTypeWithConcreteBranches.ts, 24, 6))
+>useT : Symbol(useT, Decl(callOfConditionalTypeWithConcreteBranches.ts, 21, 29))
+>arg : Symbol(arg, Decl(callOfConditionalTypeWithConcreteBranches.ts, 24, 6))
+}
+// Legal invocations are not problematic
+fn2<string | number>(m => m(42));
+>fn2 : Symbol(fn2, Decl(callOfConditionalTypeWithConcreteBranches.ts, 20, 74))
+>m : Symbol(m, Decl(callOfConditionalTypeWithConcreteBranches.ts, 27, 21))
+>m : Symbol(m, Decl(callOfConditionalTypeWithConcreteBranches.ts, 27, 21))
+
+fn2<number>(m => m(42));
+>fn2 : Symbol(fn2, Decl(callOfConditionalTypeWithConcreteBranches.ts, 20, 74))
+>m : Symbol(m, Decl(callOfConditionalTypeWithConcreteBranches.ts, 28, 12))
+>m : Symbol(m, Decl(callOfConditionalTypeWithConcreteBranches.ts, 28, 12))
+
+// webidl-conversions example where substituion must occur, despite contravariance of the position
+// due to the invariant usage in `Parameters`
+
+type X<V> = V extends (...args: any[]) => any ? (...args: Parameters<V>) => void : Function;
+>X : Symbol(X, Decl(callOfConditionalTypeWithConcreteBranches.ts, 28, 24))
+>V : Symbol(V, Decl(callOfConditionalTypeWithConcreteBranches.ts, 33, 7))
+>V : Symbol(V, Decl(callOfConditionalTypeWithConcreteBranches.ts, 33, 7))
+>args : Symbol(args, Decl(callOfConditionalTypeWithConcreteBranches.ts, 33, 23))
+>args : Symbol(args, Decl(callOfConditionalTypeWithConcreteBranches.ts, 33, 49))
+>Parameters : Symbol(Parameters, Decl(lib.es5.d.ts, --, --))
+>V : Symbol(V, Decl(callOfConditionalTypeWithConcreteBranches.ts, 33, 7))
+>Function : Symbol(Function, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
+

tests/baselines/reference/callOfConditionalTypeWithConcreteBranches.types

@@ -0,0 +1,99 @@
+=== tests/cases/compiler/callOfConditionalTypeWithConcreteBranches.ts ===
+type Q<T> = number extends T ? (n: number) => void : never;
+>Q : Q<T>
+>n : number
+
+function fn<T>(arg: Q<T>) {
+>fn : <T>(arg: Q<T>) => void
+>arg : Q<T>
+
+  // Expected: OK
+  // Actual: Cannot convert 10 to number & T
+  arg(10);
+>arg(10) : void
+>arg : Q<T>
+>10 : 10
+}
+// Legal invocations are not problematic
+fn<string | number>(m => m.toFixed());
+>fn<string | number>(m => m.toFixed()) : void
+>fn : <T>(arg: Q<T>) => void
+>m => m.toFixed() : (m: number) => string
+>m : number
+>m.toFixed() : string
+>m.toFixed : (fractionDigits?: number) => string
+>m : number
+>toFixed : (fractionDigits?: number) => string
+
+fn<number>(m => m.toFixed());
+>fn<number>(m => m.toFixed()) : void
+>fn : <T>(arg: Q<T>) => void
+>m => m.toFixed() : (m: number) => string
+>m : number
+>m.toFixed() : string
+>m.toFixed : (fractionDigits?: number) => string
+>m : number
+>toFixed : (fractionDigits?: number) => string
+
+// Ensure the following real-world example that relies on substitution still works
+type ExtractParameters<T> = "parameters" extends keyof T
+>ExtractParameters : ExtractParameters<T>
+
+  // The above allows "parameters" to index `T` since all later
+  // instances are actually implicitly `"parameters" & keyof T`
+  ?  {
+        [K in keyof T["parameters"]]: T["parameters"][K];
+      }[keyof T["parameters"]]
+  : {};
+
+// Original example, but with inverted variance
+type Q2<T> = number extends T ? (cb: (n: number) => void) => void : never;
+>Q2 : Q2<T>
+>cb : (n: number) => void
+>n : number
+
+function fn2<T>(arg: Q2<T>) {
+>fn2 : <T>(arg: Q2<T>) => void
+>arg : Q2<T>
+
+  function useT(_arg: T): void {}
+>useT : (_arg: T) => void
+>_arg : T
+
+  // Expected: OK
+  arg(arg => useT(arg));
+>arg(arg => useT(arg)) : void
+>arg : Q2<T>
+>arg => useT(arg) : (arg: T & number) => void
+>arg : T & number
+>useT(arg) : void
+>useT : (_arg: T) => void
+>arg : T & number
+}
+// Legal invocations are not problematic
+fn2<string | number>(m => m(42));
+>fn2<string | number>(m => m(42)) : void
+>fn2 : <T>(arg: Q2<T>) => void
+>m => m(42) : (m: (n: number) => void) => void
+>m : (n: number) => void
+>m(42) : void
+>m : (n: number) => void
+>42 : 42
+
+fn2<number>(m => m(42));
+>fn2<number>(m => m(42)) : void
+>fn2 : <T>(arg: Q2<T>) => void
+>m => m(42) : (m: (n: number) => void) => void
+>m : (n: number) => void
+>m(42) : void
+>m : (n: number) => void
+>42 : 42
+
+// webidl-conversions example where substituion must occur, despite contravariance of the position
+// due to the invariant usage in `Parameters`
+
+type X<V> = V extends (...args: any[]) => any ? (...args: Parameters<V>) => void : Function;
+>X : X<V>
+>args : any[]
+>args : Parameters<V>
+

tests/baselines/reference/circularlyConstrainedMappedTypeContainingConditionalNoInfiniteInstantiationDepth.errors.txt

@@ -1,196 +0,0 @@
-tests/cases/compiler/circularlyConstrainedMappedTypeContainingConditionalNoInfiniteInstantiationDepth.ts(63,84): error TS2344: Type 'GetProps<C>' does not satisfy the constraint 'Shared<TInjectedProps, GetProps<C>>'.
-  Type 'unknown' is not assignable to type 'Shared<TInjectedProps, GetProps<C>>'.
-    Type 'Matching<TInjectedProps, GetProps<C>>' is not assignable to type 'Shared<TInjectedProps, GetProps<C>>'.
-      Type 'P extends keyof TInjectedProps ? TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : TInjectedProps[P] : GetProps<C>[P]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-        Type 'GetProps<C>[P] | (TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : TInjectedProps[P])' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-          Type 'GetProps<C>[P]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-            Type 'GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-              Type 'GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-                Type 'GetProps<C>[P]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-                  Type 'Extract<keyof TInjectedProps, keyof GetProps<C>> extends keyof TInjectedProps ? TInjectedProps[Extract<keyof TInjectedProps, keyof GetProps<C>>] extends GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>] ? GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>] : TInjectedProps[Extract<keyof TInjectedProps, keyof GetProps<C>>] : GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-                    Type 'GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>] | (TInjectedProps[Extract<keyof TInjectedProps, keyof GetProps<C>>] extends GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>] ? GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>] : TInjectedProps[Extract<keyof TInjectedProps, keyof GetProps<C>>])' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-                      Type 'GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-                        Type 'GetProps<C>[Extract<string, keyof GetProps<C>>] | GetProps<C>[Extract<number, keyof GetProps<C>>] | GetProps<C>[Extract<symbol, keyof GetProps<C>>]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-                          Type 'GetProps<C>[Extract<string, keyof GetProps<C>>]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-                            Type 'GetProps<C>[keyof GetProps<C> & string]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-                              Type 'GetProps<C>[string]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-                                Type 'GetProps<C>[string]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-                                  Type 'GetProps<C>[keyof GetProps<C> & string]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-                                    Type 'GetProps<C>[Extract<string, keyof GetProps<C>>]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-                                      Type 'GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-                                        Type '(Extract<string, keyof GetProps<C>> extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] extends GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] ? GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] : TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] : GetProps<C>[Extract<string, keyof GetProps<C>>]) | (Extract<number, keyof GetProps<C>> extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & Extract<number, keyof GetProps<C>>] extends GetProps<C>[keyof TInjectedProps & Extract<number, keyof GetProps<C>>] ? GetProps<C>[keyof TInjectedProps & Extract<number, keyof GetProps<C>>] : TInjectedProps[keyof TInjectedProps & Extract<number, keyof GetProps<C>>] : GetProps<C>[Extract<number, keyof GetProps<C>>]) | (Extract<symbol, keyof GetProps<C>> extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & Extract<symbol, keyof GetProps<C>>] extends GetProps<C>[keyof TInjectedProps & Extract<symbol, keyof GetProps<C>>] ? GetProps<C>[keyof TInjectedProps & Extract<symbol, keyof GetProps<C>>] : TInjectedProps[keyof TInjectedProps & Extract<symbol, keyof GetProps<C>>] : GetProps<C>[Extract<symbol, keyof GetProps<C>>])' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-                                          Type 'Extract<string, keyof GetProps<C>> extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] extends GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] ? GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] : TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] : GetProps<C>[Extract<string, keyof GetProps<C>>]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-                                            Type '(TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] extends GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] ? GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] : TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>]) | GetProps<C>[Extract<string, keyof GetProps<C>>]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-                                              Type 'TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] extends GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] ? GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] : TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-                                                Type 'TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] | GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-                                                  Type 'TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-                                                    Type 'TInjectedProps[string]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-                                                      Type 'TInjectedProps[string]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-                                                        Type 'TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-                                                          Type 'TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] extends GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] ? GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] : TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-                                                            Type 'keyof GetProps<C> & string extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string] extends GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] ? GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] : TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string] : GetProps<C>[keyof GetProps<C> & string]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-                                                              Type '(TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string] extends GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] ? GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] : TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string]) | GetProps<C>[keyof GetProps<C> & string]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-                                                                Type 'TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string] extends GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] ? GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] : TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-                                                                  Type 'TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string] | GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-                                                                    Type 'TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-                                                                      Type 'TInjectedProps[string]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-                                                                        Type 'TInjectedProps[string]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-                                                                          Type 'TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-                                                                            Type 'TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string] extends GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] ? GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] : TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-                                                                              Type 'string extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & string] extends GetProps<C>[keyof TInjectedProps & string] ? GetProps<C>[keyof TInjectedProps & string] : TInjectedProps[keyof TInjectedProps & string] : GetProps<C>[string]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-                                                                                Type 'string extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & string] extends GetProps<C>[keyof TInjectedProps & string] ? GetProps<C>[keyof TInjectedProps & string] : TInjectedProps[keyof TInjectedProps & string] : GetProps<C>[string]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-                                                                                  Type 'keyof GetProps<C> & string extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string] extends GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] ? GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] : TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string] : GetProps<C>[keyof GetProps<C> & string]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-                                                                                    Type '(TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string] extends GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] ? GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] : TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string]) | GetProps<C>[keyof GetProps<C> & string]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-                                                                                      Type 'TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string] extends GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] ? GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] : TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-                                                                                        Type 'TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string] | GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-                                                                                          Type 'TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-                                                                                            Type 'TInjectedProps[string]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-                                                                                              Type 'Extract<string, keyof GetProps<C>> extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] extends GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] ? GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] : TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] : GetProps<C>[Extract<string, keyof GetProps<C>>]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-                                                                                                Type '(TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] extends GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] ? GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] : TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>]) | GetProps<C>[Extract<string, keyof GetProps<C>>]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-                                                                                                  Type 'TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] extends GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] ? GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] : TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-                                                                                                    Type 'TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] | GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-                                                                                                      Type 'TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-                                                                                                        Type 'TInjectedProps[string]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-                                                                                                          Type 'Extract<keyof TInjectedProps, keyof GetProps<C>> extends keyof TInjectedProps ? TInjectedProps[Extract<keyof TInjectedProps, keyof GetProps<C>>] extends GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>] ? GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>] : TInjectedProps[Extract<keyof TInjectedProps, keyof GetProps<C>>] : GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-                                                                                                            Type 'GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>] | (TInjectedProps[Extract<keyof TInjectedProps, keyof GetProps<C>>] extends GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>] ? GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>] : TInjectedProps[Extract<keyof TInjectedProps, keyof GetProps<C>>])' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-                                                                                                              Type 'GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-                                                                                                                Type 'P extends keyof TInjectedProps ? TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : TInjectedProps[P] : GetProps<C>[P]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-                                                                                                                  Type 'GetProps<C>[P] | (TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : TInjectedProps[P])' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-                                                                                                                    Type 'GetProps<C>[P]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-                                                                                                                      Type 'GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-                                                                                                                        Type 'GetProps<C>[Extract<string, keyof GetProps<C>>] | GetProps<C>[Extract<number, keyof GetProps<C>>] | GetProps<C>[Extract<symbol, keyof GetProps<C>>]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-                                                                                                                          Type 'GetProps<C>[Extract<string, keyof GetProps<C>>]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-                                                                                                                            Type 'GetProps<C>[keyof GetProps<C> & string]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-                                                                                                                              Type 'GetProps<C>[string]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-
-
-==== tests/cases/compiler/circularlyConstrainedMappedTypeContainingConditionalNoInfiniteInstantiationDepth.ts (1 errors) ====
-    declare class Component<P> {
-        constructor(props: Readonly<P>);
-        constructor(props: P, context?: any);
-        readonly props: Readonly<P> & Readonly<{ children?: {} }>;
-    }
-    interface ComponentClass<P = {}> {
-        new (props: P, context?: any): Component<P>;
-        propTypes?: WeakValidationMap<P>;
-        defaultProps?: Partial<P>;
-        displayName?: string;
-    }
-    interface FunctionComponent<P = {}> {
-        (props: P & { children?: {} }, context?: any): {} | null;
-        propTypes?: WeakValidationMap<P>;
-        defaultProps?: Partial<P>;
-        displayName?: string;
-    }
-    
-    export declare const nominalTypeHack: unique symbol;
-    export interface Validator<T> {
-        (props: object, propName: string, componentName: string, location: string, propFullName: string): Error | null;
-        [nominalTypeHack]?: T;
-    }
-    type WeakValidationMap<T> = {
-        [K in keyof T]?: null extends T[K]
-            ? Validator<T[K] | null | undefined>
-            : undefined extends T[K]
-            ? Validator<T[K] | null | undefined>
-            : Validator<T[K]>
-    };
-    type ComponentType<P = {}> = ComponentClass<P> | FunctionComponent<P>;
-    
-    export type Shared<
-        InjectedProps,
-        DecorationTargetProps extends Shared<InjectedProps, DecorationTargetProps>
-        > = {
-            [P in Extract<keyof InjectedProps, keyof DecorationTargetProps>]?: InjectedProps[P] extends DecorationTargetProps[P] ? DecorationTargetProps[P] : never;
-        };
-    
-    // Infers prop type from component C
-    export type GetProps<C> = C extends ComponentType<infer P> ? P : never;
-    
-    export type ConnectedComponentClass<
-        C extends ComponentType<any>,
-        P
-    > = ComponentClass<P> & {
-        WrappedComponent: C;
-    };
-    
-    export type Matching<InjectedProps, DecorationTargetProps> = {
-        [P in keyof DecorationTargetProps]: P extends keyof InjectedProps
-            ? InjectedProps[P] extends DecorationTargetProps[P]
-                ? DecorationTargetProps[P]
-                : InjectedProps[P]
-            : DecorationTargetProps[P];
-    };
-    
-    export type Omit<T, K extends keyof T> = Pick<T, Exclude<keyof T, K>>;
-    
-    export type InferableComponentEnhancerWithProps<TInjectedProps, TNeedsProps> =
-        <C extends ComponentType<Matching<TInjectedProps, GetProps<C>>>>(
-            component: C
-        ) => ConnectedComponentClass<C, Omit<GetProps<C>, keyof Shared<TInjectedProps, GetProps<C>>> & TNeedsProps>;
-                                                                                       ~~~~~~~~~~~
-!!! error TS2344: Type 'GetProps<C>' does not satisfy the constraint 'Shared<TInjectedProps, GetProps<C>>'.
-!!! error TS2344:   Type 'unknown' is not assignable to type 'Shared<TInjectedProps, GetProps<C>>'.
-!!! error TS2344:     Type 'Matching<TInjectedProps, GetProps<C>>' is not assignable to type 'Shared<TInjectedProps, GetProps<C>>'.
-!!! error TS2344:       Type 'P extends keyof TInjectedProps ? TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : TInjectedProps[P] : GetProps<C>[P]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-!!! error TS2344:         Type 'GetProps<C>[P] | (TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : TInjectedProps[P])' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-!!! error TS2344:           Type 'GetProps<C>[P]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-!!! error TS2344:             Type 'GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-!!! error TS2344:               Type 'GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-!!! error TS2344:                 Type 'GetProps<C>[P]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-!!! error TS2344:                   Type 'Extract<keyof TInjectedProps, keyof GetProps<C>> extends keyof TInjectedProps ? TInjectedProps[Extract<keyof TInjectedProps, keyof GetProps<C>>] extends GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>] ? GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>] : TInjectedProps[Extract<keyof TInjectedProps, keyof GetProps<C>>] : GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-!!! error TS2344:                     Type 'GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>] | (TInjectedProps[Extract<keyof TInjectedProps, keyof GetProps<C>>] extends GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>] ? GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>] : TInjectedProps[Extract<keyof TInjectedProps, keyof GetProps<C>>])' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-!!! error TS2344:                       Type 'GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-!!! error TS2344:                         Type 'GetProps<C>[Extract<string, keyof GetProps<C>>] | GetProps<C>[Extract<number, keyof GetProps<C>>] | GetProps<C>[Extract<symbol, keyof GetProps<C>>]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-!!! error TS2344:                           Type 'GetProps<C>[Extract<string, keyof GetProps<C>>]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-!!! error TS2344:                             Type 'GetProps<C>[keyof GetProps<C> & string]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-!!! error TS2344:                               Type 'GetProps<C>[string]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-!!! error TS2344:                                 Type 'GetProps<C>[string]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-!!! error TS2344:                                   Type 'GetProps<C>[keyof GetProps<C> & string]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-!!! error TS2344:                                     Type 'GetProps<C>[Extract<string, keyof GetProps<C>>]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-!!! error TS2344:                                       Type 'GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-!!! error TS2344:                                         Type '(Extract<string, keyof GetProps<C>> extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] extends GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] ? GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] : TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] : GetProps<C>[Extract<string, keyof GetProps<C>>]) | (Extract<number, keyof GetProps<C>> extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & Extract<number, keyof GetProps<C>>] extends GetProps<C>[keyof TInjectedProps & Extract<number, keyof GetProps<C>>] ? GetProps<C>[keyof TInjectedProps & Extract<number, keyof GetProps<C>>] : TInjectedProps[keyof TInjectedProps & Extract<number, keyof GetProps<C>>] : GetProps<C>[Extract<number, keyof GetProps<C>>]) | (Extract<symbol, keyof GetProps<C>> extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & Extract<symbol, keyof GetProps<C>>] extends GetProps<C>[keyof TInjectedProps & Extract<symbol, keyof GetProps<C>>] ? GetProps<C>[keyof TInjectedProps & Extract<symbol, keyof GetProps<C>>] : TInjectedProps[keyof TInjectedProps & Extract<symbol, keyof GetProps<C>>] : GetProps<C>[Extract<symbol, keyof GetProps<C>>])' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-!!! error TS2344:                                           Type 'Extract<string, keyof GetProps<C>> extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] extends GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] ? GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] : TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] : GetProps<C>[Extract<string, keyof GetProps<C>>]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-!!! error TS2344:                                             Type '(TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] extends GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] ? GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] : TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>]) | GetProps<C>[Extract<string, keyof GetProps<C>>]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-!!! error TS2344:                                               Type 'TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] extends GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] ? GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] : TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-!!! error TS2344:                                                 Type 'TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] | GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-!!! error TS2344:                                                   Type 'TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-!!! error TS2344:                                                     Type 'TInjectedProps[string]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-!!! error TS2344:                                                       Type 'TInjectedProps[string]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-!!! error TS2344:                                                         Type 'TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-!!! error TS2344:                                                           Type 'TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] extends GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] ? GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] : TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-!!! error TS2344:                                                             Type 'keyof GetProps<C> & string extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string] extends GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] ? GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] : TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string] : GetProps<C>[keyof GetProps<C> & string]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-!!! error TS2344:                                                               Type '(TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string] extends GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] ? GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] : TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string]) | GetProps<C>[keyof GetProps<C> & string]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-!!! error TS2344:                                                                 Type 'TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string] extends GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] ? GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] : TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-!!! error TS2344:                                                                   Type 'TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string] | GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-!!! error TS2344:                                                                     Type 'TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-!!! error TS2344:                                                                       Type 'TInjectedProps[string]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-!!! error TS2344:                                                                         Type 'TInjectedProps[string]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-!!! error TS2344:                                                                           Type 'TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-!!! error TS2344:                                                                             Type 'TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string] extends GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] ? GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] : TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-!!! error TS2344:                                                                               Type 'string extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & string] extends GetProps<C>[keyof TInjectedProps & string] ? GetProps<C>[keyof TInjectedProps & string] : TInjectedProps[keyof TInjectedProps & string] : GetProps<C>[string]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
-!!! error TS2344:                                                                                 Type 'string extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & string] extends GetProps<C>[keyof TInjectedProps & string] ? GetProps<C>[keyof TInjectedProps & string] : TInjectedProps[keyof TInjectedProps & string] : GetProps<C>[string]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-!!! error TS2344:                                                                                   Type 'keyof GetProps<C> & string extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string] extends GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] ? GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] : TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string] : GetProps<C>[keyof GetProps<C> & string]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-!!! error TS2344:                                                                                     Type '(TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string] extends GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] ? GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] : TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string]) | GetProps<C>[keyof GetProps<C> & string]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-!!! error TS2344:                                                                                       Type 'TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string] extends GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] ? GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] : TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-!!! error TS2344:                                                                                         Type 'TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string] | GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-!!! error TS2344:                                                                                           Type 'TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-!!! error TS2344:                                                                                             Type 'TInjectedProps[string]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-!!! error TS2344:                                                                                               Type 'Extract<string, keyof GetProps<C>> extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] extends GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] ? GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] : TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] : GetProps<C>[Extract<string, keyof GetProps<C>>]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-!!! error TS2344:                                                                                                 Type '(TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] extends GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] ? GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] : TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>]) | GetProps<C>[Extract<string, keyof GetProps<C>>]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-!!! error TS2344:                                                                                                   Type 'TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] extends GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] ? GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] : TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-!!! error TS2344:                                                                                                     Type 'TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] | GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-!!! error TS2344:                                                                                                       Type 'TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-!!! error TS2344:                                                                                                         Type 'TInjectedProps[string]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-!!! error TS2344:                                                                                                           Type 'Extract<keyof TInjectedProps, keyof GetProps<C>> extends keyof TInjectedProps ? TInjectedProps[Extract<keyof TInjectedProps, keyof GetProps<C>>] extends GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>] ? GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>] : TInjectedProps[Extract<keyof TInjectedProps, keyof GetProps<C>>] : GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-!!! error TS2344:                                                                                                             Type 'GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>] | (TInjectedProps[Extract<keyof TInjectedProps, keyof GetProps<C>>] extends GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>] ? GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>] : TInjectedProps[Extract<keyof TInjectedProps, keyof GetProps<C>>])' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-!!! error TS2344:                                                                                                               Type 'GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-!!! error TS2344:                                                                                                                 Type 'P extends keyof TInjectedProps ? TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : TInjectedProps[P] : GetProps<C>[P]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-!!! error TS2344:                                                                                                                   Type 'GetProps<C>[P] | (TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : TInjectedProps[P])' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-!!! error TS2344:                                                                                                                     Type 'GetProps<C>[P]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-!!! error TS2344:                                                                                                                       Type 'GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-!!! error TS2344:                                                                                                                         Type 'GetProps<C>[Extract<string, keyof GetProps<C>>] | GetProps<C>[Extract<number, keyof GetProps<C>>] | GetProps<C>[Extract<symbol, keyof GetProps<C>>]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-!!! error TS2344:                                                                                                                           Type 'GetProps<C>[Extract<string, keyof GetProps<C>>]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-!!! error TS2344:                                                                                                                             Type 'GetProps<C>[keyof GetProps<C> & string]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-!!! error TS2344:                                                                                                                               Type 'GetProps<C>[string]' is not assignable to type 'TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never'.
-    

tests/baselines/reference/classUsedBeforeInitializedVariables.errors.txt

@@ -1,9 +1,9 @@
 tests/cases/compiler/classUsedBeforeInitializedVariables.ts(4,15): error TS2729: Property 'p4' is used before its initialization.
-tests/cases/compiler/classUsedBeforeInitializedVariables.ts(7,34): error TS2729: Property 'directlyAssigned' is used before its initialization.
-tests/cases/compiler/classUsedBeforeInitializedVariables.ts(16,15): error TS2729: Property 'withinObjectLiteral' is used before its initialization.
-tests/cases/compiler/classUsedBeforeInitializedVariables.ts(20,19): error TS2729: Property 'withinObjectLiteralGetterName' is used before its initialization.
-tests/cases/compiler/classUsedBeforeInitializedVariables.ts(26,19): error TS2729: Property 'withinObjectLiteralSetterName' is used before its initialization.
-tests/cases/compiler/classUsedBeforeInitializedVariables.ts(29,64): error TS2729: Property 'withinClassDeclarationExtension' is used before its initialization.
+tests/cases/compiler/classUsedBeforeInitializedVariables.ts(13,34): error TS2729: Property 'directlyAssigned' is used before its initialization.
+tests/cases/compiler/classUsedBeforeInitializedVariables.ts(22,15): error TS2729: Property 'withinObjectLiteral' is used before its initialization.
+tests/cases/compiler/classUsedBeforeInitializedVariables.ts(26,19): error TS2729: Property 'withinObjectLiteralGetterName' is used before its initialization.
+tests/cases/compiler/classUsedBeforeInitializedVariables.ts(32,19): error TS2729: Property 'withinObjectLiteralSetterName' is used before its initialization.
+tests/cases/compiler/classUsedBeforeInitializedVariables.ts(35,64): error TS2729: Property 'withinClassDeclarationExtension' is used before its initialization.
 
 
 ==== tests/cases/compiler/classUsedBeforeInitializedVariables.ts (6 errors) ====
@@ -15,11 +15,17 @@ tests/cases/compiler/classUsedBeforeInitializedVariables.ts(29,64): error TS2729
 !!! error TS2729: Property 'p4' is used before its initialization.
 !!! related TS2728 tests/cases/compiler/classUsedBeforeInitializedVariables.ts:5:5: 'p4' is declared here.
         p4 = 0;
+        p5?: number;
+    
+        p6?: string;
+        p7 = {
+            hello: (this.p6 = "string"),
+        };
     
         directlyAssigned: any = this.directlyAssigned;
                                      ~~~~~~~~~~~~~~~~
 !!! error TS2729: Property 'directlyAssigned' is used before its initialization.
-!!! related TS2728 tests/cases/compiler/classUsedBeforeInitializedVariables.ts:7:5: 'directlyAssigned' is declared here.
+!!! related TS2728 tests/cases/compiler/classUsedBeforeInitializedVariables.ts:13:5: 'directlyAssigned' is declared here.
     
         withinArrowFunction: any = () => this.withinArrowFunction;
     
@@ -31,14 +37,14 @@ tests/cases/compiler/classUsedBeforeInitializedVariables.ts(29,64): error TS2729
             [this.withinObjectLiteral]: true,
                   ~~~~~~~~~~~~~~~~~~~
 !!! error TS2729: Property 'withinObjectLiteral' is used before its initialization.
-!!! related TS2728 tests/cases/compiler/classUsedBeforeInitializedVariables.ts:15:5: 'withinObjectLiteral' is declared here.
+!!! related TS2728 tests/cases/compiler/classUsedBeforeInitializedVariables.ts:21:5: 'withinObjectLiteral' is declared here.
         };
     
         withinObjectLiteralGetterName: any = {
             get [this.withinObjectLiteralGetterName]() {
                       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 !!! error TS2729: Property 'withinObjectLiteralGetterName' is used before its initialization.
-!!! related TS2728 tests/cases/compiler/classUsedBeforeInitializedVariables.ts:19:5: 'withinObjectLiteralGetterName' is declared here.
+!!! related TS2728 tests/cases/compiler/classUsedBeforeInitializedVariables.ts:25:5: 'withinObjectLiteralGetterName' is declared here.
                 return true;
             }
         };
@@ -47,13 +53,15 @@ tests/cases/compiler/classUsedBeforeInitializedVariables.ts(29,64): error TS2729
             set [this.withinObjectLiteralSetterName](_: any) {}
                       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 !!! error TS2729: Property 'withinObjectLiteralSetterName' is used before its initialization.
-!!! related TS2728 tests/cases/compiler/classUsedBeforeInitializedVariables.ts:25:5: 'withinObjectLiteralSetterName' is declared here.
+!!! related TS2728 tests/cases/compiler/classUsedBeforeInitializedVariables.ts:31:5: 'withinObjectLiteralSetterName' is declared here.
         };
     
         withinClassDeclarationExtension: any = (class extends this.withinClassDeclarationExtension { });
                                                                    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 !!! error TS2729: Property 'withinClassDeclarationExtension' is used before its initialization.
-!!! related TS2728 tests/cases/compiler/classUsedBeforeInitializedVariables.ts:29:5: 'withinClassDeclarationExtension' is declared here.
+!!! related TS2728 tests/cases/compiler/classUsedBeforeInitializedVariables.ts:35:5: 'withinClassDeclarationExtension' is declared here.
+    
+        fromOptional = this.p5;
     
         // These error cases are ignored (not checked by control flow analysis)
     

tests/baselines/reference/classUsedBeforeInitializedVariables.js

@@ -4,6 +4,12 @@ class Test {
     p2 = this.p1;
     p3 = this.p4;
     p4 = 0;
+    p5?: number;
+
+    p6?: string;
+    p7 = {
+        hello: (this.p6 = "string"),
+    };
 
     directlyAssigned: any = this.directlyAssigned;
 
@@ -29,6 +35,8 @@ class Test {
 
     withinClassDeclarationExtension: any = (class extends this.withinClassDeclarationExtension { });
 
+    fromOptional = this.p5;
+
     // These error cases are ignored (not checked by control flow analysis)
 
     assignedByArrowFunction: any = (() => this.assignedByFunction)();
@@ -63,6 +71,9 @@ var Test = /** @class */ (function () {
         this.p2 = this.p1;
         this.p3 = this.p4;
         this.p4 = 0;
+        this.p7 = {
+            hello: (this.p6 = "string"),
+        };
         this.directlyAssigned = this.directlyAssigned;
         this.withinArrowFunction = function () { return _this.withinArrowFunction; };
         this.withinFunction = function () {
@@ -94,6 +105,7 @@ var Test = /** @class */ (function () {
             }
             return class_1;
         }(this.withinClassDeclarationExtension)));
+        this.fromOptional = this.p5;
         // These error cases are ignored (not checked by control flow analysis)
         this.assignedByArrowFunction = (function () { return _this.assignedByFunction; })();
         this.assignedByFunction = (function () {

tests/baselines/reference/classUsedBeforeInitializedVariables.symbols

@@ -20,76 +20,99 @@ class Test {
     p4 = 0;
 >p4 : Symbol(Test.p4, Decl(classUsedBeforeInitializedVariables.ts, 3, 17))
 
-    directlyAssigned: any = this.directlyAssigned;
->directlyAssigned : Symbol(Test.directlyAssigned, Decl(classUsedBeforeInitializedVariables.ts, 4, 11))
->this.directlyAssigned : Symbol(Test.directlyAssigned, Decl(classUsedBeforeInitializedVariables.ts, 4, 11))
+    p5?: number;
+>p5 : Symbol(Test.p5, Decl(classUsedBeforeInitializedVariables.ts, 4, 11))
+
+    p6?: string;
+>p6 : Symbol(Test.p6, Decl(classUsedBeforeInitializedVariables.ts, 5, 16))
+
+    p7 = {
+>p7 : Symbol(Test.p7, Decl(classUsedBeforeInitializedVariables.ts, 7, 16))
+
+        hello: (this.p6 = "string"),
+>hello : Symbol(hello, Decl(classUsedBeforeInitializedVariables.ts, 8, 10))
+>this.p6 : Symbol(Test.p6, Decl(classUsedBeforeInitializedVariables.ts, 5, 16))
 >this : Symbol(Test, Decl(classUsedBeforeInitializedVariables.ts, 0, 0))
->directlyAssigned : Symbol(Test.directlyAssigned, Decl(classUsedBeforeInitializedVariables.ts, 4, 11))
+>p6 : Symbol(Test.p6, Decl(classUsedBeforeInitializedVariables.ts, 5, 16))
+
+    };
+
+    directlyAssigned: any = this.directlyAssigned;
+>directlyAssigned : Symbol(Test.directlyAssigned, Decl(classUsedBeforeInitializedVariables.ts, 10, 6))
+>this.directlyAssigned : Symbol(Test.directlyAssigned, Decl(classUsedBeforeInitializedVariables.ts, 10, 6))
+>this : Symbol(Test, Decl(classUsedBeforeInitializedVariables.ts, 0, 0))
+>directlyAssigned : Symbol(Test.directlyAssigned, Decl(classUsedBeforeInitializedVariables.ts, 10, 6))
 
     withinArrowFunction: any = () => this.withinArrowFunction;
->withinArrowFunction : Symbol(Test.withinArrowFunction, Decl(classUsedBeforeInitializedVariables.ts, 6, 50))
->this.withinArrowFunction : Symbol(Test.withinArrowFunction, Decl(classUsedBeforeInitializedVariables.ts, 6, 50))
+>withinArrowFunction : Symbol(Test.withinArrowFunction, Decl(classUsedBeforeInitializedVariables.ts, 12, 50))
+>this.withinArrowFunction : Symbol(Test.withinArrowFunction, Decl(classUsedBeforeInitializedVariables.ts, 12, 50))
 >this : Symbol(Test, Decl(classUsedBeforeInitializedVariables.ts, 0, 0))
->withinArrowFunction : Symbol(Test.withinArrowFunction, Decl(classUsedBeforeInitializedVariables.ts, 6, 50))
+>withinArrowFunction : Symbol(Test.withinArrowFunction, Decl(classUsedBeforeInitializedVariables.ts, 12, 50))
 
     withinFunction: any = function () {
->withinFunction : Symbol(Test.withinFunction, Decl(classUsedBeforeInitializedVariables.ts, 8, 62))
+>withinFunction : Symbol(Test.withinFunction, Decl(classUsedBeforeInitializedVariables.ts, 14, 62))
 
         return this.withinFunction;
     };
 
     withinObjectLiteral: any = {
->withinObjectLiteral : Symbol(Test.withinObjectLiteral, Decl(classUsedBeforeInitializedVariables.ts, 12, 6))
+>withinObjectLiteral : Symbol(Test.withinObjectLiteral, Decl(classUsedBeforeInitializedVariables.ts, 18, 6))
 
         [this.withinObjectLiteral]: true,
->[this.withinObjectLiteral] : Symbol([this.withinObjectLiteral], Decl(classUsedBeforeInitializedVariables.ts, 14, 32))
->this.withinObjectLiteral : Symbol(Test.withinObjectLiteral, Decl(classUsedBeforeInitializedVariables.ts, 12, 6))
+>[this.withinObjectLiteral] : Symbol([this.withinObjectLiteral], Decl(classUsedBeforeInitializedVariables.ts, 20, 32))
+>this.withinObjectLiteral : Symbol(Test.withinObjectLiteral, Decl(classUsedBeforeInitializedVariables.ts, 18, 6))
 >this : Symbol(Test, Decl(classUsedBeforeInitializedVariables.ts, 0, 0))
->withinObjectLiteral : Symbol(Test.withinObjectLiteral, Decl(classUsedBeforeInitializedVariables.ts, 12, 6))
+>withinObjectLiteral : Symbol(Test.withinObjectLiteral, Decl(classUsedBeforeInitializedVariables.ts, 18, 6))
 
     };
 
     withinObjectLiteralGetterName: any = {
->withinObjectLiteralGetterName : Symbol(Test.withinObjectLiteralGetterName, Decl(classUsedBeforeInitializedVariables.ts, 16, 6))
+>withinObjectLiteralGetterName : Symbol(Test.withinObjectLiteralGetterName, Decl(classUsedBeforeInitializedVariables.ts, 22, 6))
 
         get [this.withinObjectLiteralGetterName]() {
->[this.withinObjectLiteralGetterName] : Symbol([this.withinObjectLiteralGetterName], Decl(classUsedBeforeInitializedVariables.ts, 18, 42))
->this.withinObjectLiteralGetterName : Symbol(Test.withinObjectLiteralGetterName, Decl(classUsedBeforeInitializedVariables.ts, 16, 6))
+>[this.withinObjectLiteralGetterName] : Symbol([this.withinObjectLiteralGetterName], Decl(classUsedBeforeInitializedVariables.ts, 24, 42))
+>this.withinObjectLiteralGetterName : Symbol(Test.withinObjectLiteralGetterName, Decl(classUsedBeforeInitializedVariables.ts, 22, 6))
 >this : Symbol(Test, Decl(classUsedBeforeInitializedVariables.ts, 0, 0))
->withinObjectLiteralGetterName : Symbol(Test.withinObjectLiteralGetterName, Decl(classUsedBeforeInitializedVariables.ts, 16, 6))
+>withinObjectLiteralGetterName : Symbol(Test.withinObjectLiteralGetterName, Decl(classUsedBeforeInitializedVariables.ts, 22, 6))
 
             return true;
         }
     };
 
     withinObjectLiteralSetterName: any = {
->withinObjectLiteralSetterName : Symbol(Test.withinObjectLiteralSetterName, Decl(classUsedBeforeInitializedVariables.ts, 22, 6))
+>withinObjectLiteralSetterName : Symbol(Test.withinObjectLiteralSetterName, Decl(classUsedBeforeInitializedVariables.ts, 28, 6))
 
         set [this.withinObjectLiteralSetterName](_: any) {}
->[this.withinObjectLiteralSetterName] : Symbol([this.withinObjectLiteralSetterName], Decl(classUsedBeforeInitializedVariables.ts, 24, 42))
->this.withinObjectLiteralSetterName : Symbol(Test.withinObjectLiteralSetterName, Decl(classUsedBeforeInitializedVariables.ts, 22, 6))
+>[this.withinObjectLiteralSetterName] : Symbol([this.withinObjectLiteralSetterName], Decl(classUsedBeforeInitializedVariables.ts, 30, 42))
+>this.withinObjectLiteralSetterName : Symbol(Test.withinObjectLiteralSetterName, Decl(classUsedBeforeInitializedVariables.ts, 28, 6))
 >this : Symbol(Test, Decl(classUsedBeforeInitializedVariables.ts, 0, 0))
->withinObjectLiteralSetterName : Symbol(Test.withinObjectLiteralSetterName, Decl(classUsedBeforeInitializedVariables.ts, 22, 6))
->_ : Symbol(_, Decl(classUsedBeforeInitializedVariables.ts, 25, 49))
+>withinObjectLiteralSetterName : Symbol(Test.withinObjectLiteralSetterName, Decl(classUsedBeforeInitializedVariables.ts, 28, 6))
+>_ : Symbol(_, Decl(classUsedBeforeInitializedVariables.ts, 31, 49))
 
     };
 
     withinClassDeclarationExtension: any = (class extends this.withinClassDeclarationExtension { });
->withinClassDeclarationExtension : Symbol(Test.withinClassDeclarationExtension, Decl(classUsedBeforeInitializedVariables.ts, 26, 6))
->this.withinClassDeclarationExtension : Symbol(Test.withinClassDeclarationExtension, Decl(classUsedBeforeInitializedVariables.ts, 26, 6))
+>withinClassDeclarationExtension : Symbol(Test.withinClassDeclarationExtension, Decl(classUsedBeforeInitializedVariables.ts, 32, 6))
+>this.withinClassDeclarationExtension : Symbol(Test.withinClassDeclarationExtension, Decl(classUsedBeforeInitializedVariables.ts, 32, 6))
 >this : Symbol(Test, Decl(classUsedBeforeInitializedVariables.ts, 0, 0))
->withinClassDeclarationExtension : Symbol(Test.withinClassDeclarationExtension, Decl(classUsedBeforeInitializedVariables.ts, 26, 6))
+>withinClassDeclarationExtension : Symbol(Test.withinClassDeclarationExtension, Decl(classUsedBeforeInitializedVariables.ts, 32, 6))
+
+    fromOptional = this.p5;
+>fromOptional : Symbol(Test.fromOptional, Decl(classUsedBeforeInitializedVariables.ts, 34, 100))
+>this.p5 : Symbol(Test.p5, Decl(classUsedBeforeInitializedVariables.ts, 4, 11))
+>this : Symbol(Test, Decl(classUsedBeforeInitializedVariables.ts, 0, 0))
+>p5 : Symbol(Test.p5, Decl(classUsedBeforeInitializedVariables.ts, 4, 11))
 
     // These error cases are ignored (not checked by control flow analysis)
 
     assignedByArrowFunction: any = (() => this.assignedByFunction)();
->assignedByArrowFunction : Symbol(Test.assignedByArrowFunction, Decl(classUsedBeforeInitializedVariables.ts, 28, 100))
->this.assignedByFunction : Symbol(Test.assignedByFunction, Decl(classUsedBeforeInitializedVariables.ts, 32, 69))
+>assignedByArrowFunction : Symbol(Test.assignedByArrowFunction, Decl(classUsedBeforeInitializedVariables.ts, 36, 27))
+>this.assignedByFunction : Symbol(Test.assignedByFunction, Decl(classUsedBeforeInitializedVariables.ts, 40, 69))
 >this : Symbol(Test, Decl(classUsedBeforeInitializedVariables.ts, 0, 0))
->assignedByFunction : Symbol(Test.assignedByFunction, Decl(classUsedBeforeInitializedVariables.ts, 32, 69))
+>assignedByFunction : Symbol(Test.assignedByFunction, Decl(classUsedBeforeInitializedVariables.ts, 40, 69))
 
     assignedByFunction: any = (function () {
->assignedByFunction : Symbol(Test.assignedByFunction, Decl(classUsedBeforeInitializedVariables.ts, 32, 69))
+>assignedByFunction : Symbol(Test.assignedByFunction, Decl(classUsedBeforeInitializedVariables.ts, 40, 69))
 
         return this.assignedByFunction;
     })();

tests/baselines/reference/classUsedBeforeInitializedVariables.types

@@ -22,6 +22,27 @@ class Test {
 >p4 : number
 >0 : 0
 
+    p5?: number;
+>p5 : number
+
+    p6?: string;
+>p6 : string
+
+    p7 = {
+>p7 : { hello: string; }
+>{        hello: (this.p6 = "string"),    } : { hello: string; }
+
+        hello: (this.p6 = "string"),
+>hello : string
+>(this.p6 = "string") : "string"
+>this.p6 = "string" : "string"
+>this.p6 : string
+>this : this
+>p6 : string
+>"string" : "string"
+
+    };
+
     directlyAssigned: any = this.directlyAssigned;
 >directlyAssigned : any
 >this.directlyAssigned : any
@@ -95,6 +116,12 @@ class Test {
 >this : this
 >withinClassDeclarationExtension : any
 
+    fromOptional = this.p5;
+>fromOptional : number
+>this.p5 : number
+>this : this
+>p5 : number
+
     // These error cases are ignored (not checked by control flow analysis)
 
     assignedByArrowFunction: any = (() => this.assignedByFunction)();

tests/baselines/reference/commonJsImportBindingElementNarrowType.symbols

@@ -0,0 +1,20 @@
+=== /bar.js ===
+const { a } = require("./foo");
+>a : Symbol(a, Decl(bar.js, 0, 7))
+>require : Symbol(require)
+>"./foo" : Symbol("/foo", Decl(foo.d.ts, 0, 0))
+
+if (a) {
+>a : Symbol(a, Decl(bar.js, 0, 7))
+
+  var x = a + 1;
+>x : Symbol(x, Decl(bar.js, 2, 5))
+>a : Symbol(a, Decl(bar.js, 0, 7))
+}
+=== /foo.d.ts ===
+// Regresion test for GH#41957
+
+
+export const a: number | null;
+>a : Symbol(a, Decl(foo.d.ts, 3, 12))
+

tests/baselines/reference/commonJsImportBindingElementNarrowType.types

@@ -0,0 +1,24 @@
+=== /bar.js ===
+const { a } = require("./foo");
+>a : number | null
+>require("./foo") : typeof import("/foo")
+>require : any
+>"./foo" : "./foo"
+
+if (a) {
+>a : number | null
+
+  var x = a + 1;
+>x : number
+>a + 1 : number
+>a : number
+>1 : 1
+}
+=== /foo.d.ts ===
+// Regresion test for GH#41957
+
+
+export const a: number | null;
+>a : number | null
+>null : null
+

tests/baselines/reference/constructorWithIncompleteTypeAnnotation.errors.txt

@@ -121,6 +121,7 @@ tests/cases/compiler/constructorWithIncompleteTypeAnnotation.ts(261,1): error TS
                     if (retValue != 0 ^=  {
                                       ~~
 !!! error TS1005: ')' expected.
+!!! related TS1007 tests/cases/compiler/constructorWithIncompleteTypeAnnotation.ts:22:20: The parser expected to find a ')' to match the '(' token here.
                                           ~
     
     

tests/baselines/reference/declarationEmitOverloadedPrivateInference.js

@@ -0,0 +1,56 @@
+//// [declarationEmitOverloadedPrivateInference.ts]
+function noArgs(): string {
+    return null as any;
+}
+
+function oneArg(input: string): string {
+    return null as any;
+}
+
+export class Wrapper {
+    private proxy<T, U>(fn: (options: T) => U): (options: T) => U;
+    private proxy<T, U>(fn: (options?: T) => U, noArgs: true): (options?: T) => U;
+
+    private proxy<T, U>(fn: (options: T) => U) {
+        return null as any;
+    }
+
+    public Proxies = {
+        Failure: this.proxy(noArgs, true),
+        Success: this.proxy(oneArg),
+    };
+}
+
+//// [declarationEmitOverloadedPrivateInference.js]
+"use strict";
+exports.__esModule = true;
+exports.Wrapper = void 0;
+function noArgs() {
+    return null;
+}
+function oneArg(input) {
+    return null;
+}
+var Wrapper = /** @class */ (function () {
+    function Wrapper() {
+        this.Proxies = {
+            Failure: this.proxy(noArgs, true),
+            Success: this.proxy(oneArg)
+        };
+    }
+    Wrapper.prototype.proxy = function (fn) {
+        return null;
+    };
+    return Wrapper;
+}());
+exports.Wrapper = Wrapper;
+
+
+//// [declarationEmitOverloadedPrivateInference.d.ts]
+export declare class Wrapper {
+    private proxy;
+    Proxies: {
+        Failure: (options?: unknown) => string;
+        Success: (options: string) => string;
+    };
+}

tests/baselines/reference/declarationEmitOverloadedPrivateInference.symbols

@@ -0,0 +1,73 @@
+=== tests/cases/compiler/declarationEmitOverloadedPrivateInference.ts ===
+function noArgs(): string {
+>noArgs : Symbol(noArgs, Decl(declarationEmitOverloadedPrivateInference.ts, 0, 0))
+
+    return null as any;
+}
+
+function oneArg(input: string): string {
+>oneArg : Symbol(oneArg, Decl(declarationEmitOverloadedPrivateInference.ts, 2, 1))
+>input : Symbol(input, Decl(declarationEmitOverloadedPrivateInference.ts, 4, 16))
+
+    return null as any;
+}
+
+export class Wrapper {
+>Wrapper : Symbol(Wrapper, Decl(declarationEmitOverloadedPrivateInference.ts, 6, 1))
+
+    private proxy<T, U>(fn: (options: T) => U): (options: T) => U;
+>proxy : Symbol(Wrapper.proxy, Decl(declarationEmitOverloadedPrivateInference.ts, 8, 22), Decl(declarationEmitOverloadedPrivateInference.ts, 9, 66), Decl(declarationEmitOverloadedPrivateInference.ts, 10, 82))
+>T : Symbol(T, Decl(declarationEmitOverloadedPrivateInference.ts, 9, 18))
+>U : Symbol(U, Decl(declarationEmitOverloadedPrivateInference.ts, 9, 20))
+>fn : Symbol(fn, Decl(declarationEmitOverloadedPrivateInference.ts, 9, 24))
+>options : Symbol(options, Decl(declarationEmitOverloadedPrivateInference.ts, 9, 29))
+>T : Symbol(T, Decl(declarationEmitOverloadedPrivateInference.ts, 9, 18))
+>U : Symbol(U, Decl(declarationEmitOverloadedPrivateInference.ts, 9, 20))
+>options : Symbol(options, Decl(declarationEmitOverloadedPrivateInference.ts, 9, 49))
+>T : Symbol(T, Decl(declarationEmitOverloadedPrivateInference.ts, 9, 18))
+>U : Symbol(U, Decl(declarationEmitOverloadedPrivateInference.ts, 9, 20))
+
+    private proxy<T, U>(fn: (options?: T) => U, noArgs: true): (options?: T) => U;
+>proxy : Symbol(Wrapper.proxy, Decl(declarationEmitOverloadedPrivateInference.ts, 8, 22), Decl(declarationEmitOverloadedPrivateInference.ts, 9, 66), Decl(declarationEmitOverloadedPrivateInference.ts, 10, 82))
+>T : Symbol(T, Decl(declarationEmitOverloadedPrivateInference.ts, 10, 18))
+>U : Symbol(U, Decl(declarationEmitOverloadedPrivateInference.ts, 10, 20))
+>fn : Symbol(fn, Decl(declarationEmitOverloadedPrivateInference.ts, 10, 24))
+>options : Symbol(options, Decl(declarationEmitOverloadedPrivateInference.ts, 10, 29))
+>T : Symbol(T, Decl(declarationEmitOverloadedPrivateInference.ts, 10, 18))
+>U : Symbol(U, Decl(declarationEmitOverloadedPrivateInference.ts, 10, 20))
+>noArgs : Symbol(noArgs, Decl(declarationEmitOverloadedPrivateInference.ts, 10, 47))
+>options : Symbol(options, Decl(declarationEmitOverloadedPrivateInference.ts, 10, 64))
+>T : Symbol(T, Decl(declarationEmitOverloadedPrivateInference.ts, 10, 18))
+>U : Symbol(U, Decl(declarationEmitOverloadedPrivateInference.ts, 10, 20))
+
+    private proxy<T, U>(fn: (options: T) => U) {
+>proxy : Symbol(Wrapper.proxy, Decl(declarationEmitOverloadedPrivateInference.ts, 8, 22), Decl(declarationEmitOverloadedPrivateInference.ts, 9, 66), Decl(declarationEmitOverloadedPrivateInference.ts, 10, 82))
+>T : Symbol(T, Decl(declarationEmitOverloadedPrivateInference.ts, 12, 18))
+>U : Symbol(U, Decl(declarationEmitOverloadedPrivateInference.ts, 12, 20))
+>fn : Symbol(fn, Decl(declarationEmitOverloadedPrivateInference.ts, 12, 24))
+>options : Symbol(options, Decl(declarationEmitOverloadedPrivateInference.ts, 12, 29))
+>T : Symbol(T, Decl(declarationEmitOverloadedPrivateInference.ts, 12, 18))
+>U : Symbol(U, Decl(declarationEmitOverloadedPrivateInference.ts, 12, 20))
+
+        return null as any;
+    }
+
+    public Proxies = {
+>Proxies : Symbol(Wrapper.Proxies, Decl(declarationEmitOverloadedPrivateInference.ts, 14, 5))
+
+        Failure: this.proxy(noArgs, true),
+>Failure : Symbol(Failure, Decl(declarationEmitOverloadedPrivateInference.ts, 16, 22))
+>this.proxy : Symbol(Wrapper.proxy, Decl(declarationEmitOverloadedPrivateInference.ts, 8, 22), Decl(declarationEmitOverloadedPrivateInference.ts, 9, 66), Decl(declarationEmitOverloadedPrivateInference.ts, 10, 82))
+>this : Symbol(Wrapper, Decl(declarationEmitOverloadedPrivateInference.ts, 6, 1))
+>proxy : Symbol(Wrapper.proxy, Decl(declarationEmitOverloadedPrivateInference.ts, 8, 22), Decl(declarationEmitOverloadedPrivateInference.ts, 9, 66), Decl(declarationEmitOverloadedPrivateInference.ts, 10, 82))
+>noArgs : Symbol(noArgs, Decl(declarationEmitOverloadedPrivateInference.ts, 0, 0))
+
+        Success: this.proxy(oneArg),
+>Success : Symbol(Success, Decl(declarationEmitOverloadedPrivateInference.ts, 17, 42))
+>this.proxy : Symbol(Wrapper.proxy, Decl(declarationEmitOverloadedPrivateInference.ts, 8, 22), Decl(declarationEmitOverloadedPrivateInference.ts, 9, 66), Decl(declarationEmitOverloadedPrivateInference.ts, 10, 82))
+>this : Symbol(Wrapper, Decl(declarationEmitOverloadedPrivateInference.ts, 6, 1))
+>proxy : Symbol(Wrapper.proxy, Decl(declarationEmitOverloadedPrivateInference.ts, 8, 22), Decl(declarationEmitOverloadedPrivateInference.ts, 9, 66), Decl(declarationEmitOverloadedPrivateInference.ts, 10, 82))
+>oneArg : Symbol(oneArg, Decl(declarationEmitOverloadedPrivateInference.ts, 2, 1))
+
+    };
+}

tests/baselines/reference/declarationEmitOverloadedPrivateInference.types

@@ -0,0 +1,68 @@
+=== tests/cases/compiler/declarationEmitOverloadedPrivateInference.ts ===
+function noArgs(): string {
+>noArgs : () => string
+
+    return null as any;
+>null as any : any
+>null : null
+}
+
+function oneArg(input: string): string {
+>oneArg : (input: string) => string
+>input : string
+
+    return null as any;
+>null as any : any
+>null : null
+}
+
+export class Wrapper {
+>Wrapper : Wrapper
+
+    private proxy<T, U>(fn: (options: T) => U): (options: T) => U;
+>proxy : { <T, U>(fn: (options: T) => U): (options: T) => U; <T, U>(fn: (options?: T) => U, noArgs: true): (options?: T) => U; }
+>fn : (options: T) => U
+>options : T
+>options : T
+
+    private proxy<T, U>(fn: (options?: T) => U, noArgs: true): (options?: T) => U;
+>proxy : { <T, U>(fn: (options: T) => U): (options: T) => U; <T, U>(fn: (options?: T) => U, noArgs: true): (options?: T) => U; }
+>fn : (options?: T) => U
+>options : T
+>noArgs : true
+>true : true
+>options : T
+
+    private proxy<T, U>(fn: (options: T) => U) {
+>proxy : { <T, U>(fn: (options: T) => U): (options: T) => U; <T, U>(fn: (options?: T) => U, noArgs: true): (options?: T) => U; }
+>fn : (options: T) => U
+>options : T
+
+        return null as any;
+>null as any : any
+>null : null
+    }
+
+    public Proxies = {
+>Proxies : { Failure: (options?: unknown) => string; Success: (options: string) => string; }
+>{        Failure: this.proxy(noArgs, true),        Success: this.proxy(oneArg),    } : { Failure: (options?: unknown) => string; Success: (options: string) => string; }
+
+        Failure: this.proxy(noArgs, true),
+>Failure : (options?: unknown) => string
+>this.proxy(noArgs, true) : (options?: unknown) => string
+>this.proxy : { <T, U>(fn: (options: T) => U): (options: T) => U; <T, U>(fn: (options?: T) => U, noArgs: true): (options?: T) => U; }
+>this : this
+>proxy : { <T, U>(fn: (options: T) => U): (options: T) => U; <T, U>(fn: (options?: T) => U, noArgs: true): (options?: T) => U; }
+>noArgs : () => string
+>true : true
+
+        Success: this.proxy(oneArg),
+>Success : (options: string) => string
+>this.proxy(oneArg) : (options: string) => string
+>this.proxy : { <T, U>(fn: (options: T) => U): (options: T) => U; <T, U>(fn: (options?: T) => U, noArgs: true): (options?: T) => U; }
+>this : this
+>proxy : { <T, U>(fn: (options: T) => U): (options: T) => U; <T, U>(fn: (options?: T) => U, noArgs: true): (options?: T) => U; }
+>oneArg : (input: string) => string
+
+    };
+}

tests/baselines/reference/declarationsWithRecursiveInternalTypesProduceUniqueTypeParams.types

@@ -38,13 +38,13 @@ export const updateIfChanged = <T>(t: T) => {
 >newU : U
 
         return Object.assign(
->Object.assign(            <K extends Key<U>>(key: K) =>                reduce<Value<K, U>>(u[key as keyof U] as Value<K, U>, (v: Value<K, U>) => {                    return update(Object.assign(Array.isArray(u) ? [] : {}, u, { [key]: v }));                }),            { map: (updater: (u: U) => U) => set(updater(u)), set }) : (<K extends keyof U>(key: K) => (<K extends keyof Value<K, U>>(key: K) => (<K extends keyof Value<K, Value<K, U>>>(key: K) => (<K extends keyof Value<K, Value<K, Value<K, U>>>>(key: K) => (<K extends keyof Value<K, Value<K, Value<K, Value<K, U>>>>>(key: K) => (<K extends keyof Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>(key: K) => (<K extends keyof Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>(key: K) => (<K extends keyof Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>(key: K) => (<K extends keyof Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>>(key: K) => (<K extends keyof Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>>>(key: K) => (<K extends keyof Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>>>>(key: K) => any & { map: (updater: (u: Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>>>>) => U) => T; set: (newU: Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>>>>) => T; }) & { map: (updater: (u: Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>>>) => U) => T; set: (newU: Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>>>) => T; }) & { map: (updater: (u: Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>>) => U) => T; set: (newU: Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>>) => T; }) & { map: (updater: (u: Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>) => U) => T; set: (newU: Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>) => T; }) & { map: (updater: (u: Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>) => U) => T; set: (newU: Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>) => T; }) & { map: (updater: (u: Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>) => U) => T; set: (newU: Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>) => T; }) & { map: (updater: (u: Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>) => U) => T; set: (newU: Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>) => T; }) & { map: (updater: (u: Value<K, Value<K, Value<K, Value<K, U>>>>) => U) => T; set: (newU: Value<K, Value<K, Value<K, Value<K, U>>>>) => T; }) & { map: (updater: (u: Value<K, Value<K, Value<K, U>>>) => U) => T; set: (newU: Value<K, Value<K, Value<K, U>>>) => T; }) & { map: (updater: (u: Value<K, Value<K, U>>) => U) => T; set: (newU: Value<K, Value<K, U>>) => T; }) & { map: (updater: (u: Value<K, U>) => U) => T; set: (newU: Value<K, U>) => T; }) & { map: (updater: (u: U) => U) => T; set: (newU: U) => T; }
+>Object.assign(            <K extends Key<U>>(key: K) =>                reduce<Value<K, U>>(u[key as keyof U] as Value<K, U>, (v: Value<K, U>) => {                    return update(Object.assign(Array.isArray(u) ? [] : {}, u, { [key]: v }));                }),            { map: (updater: (u: U) => U) => set(updater(u)), set }) : (<K extends keyof U>(key: K) => (<K extends keyof Value<K, U>>(key: K) => (<K extends keyof Value<K, Value<K, U>>>(key: K) => (<K extends keyof Value<K, Value<K, Value<K, U>>>>(key: K) => (<K extends keyof Value<K, Value<K, Value<K, Value<K, U>>>>>(key: K) => (<K extends keyof Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>(key: K) => (<K extends keyof Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>(key: K) => (<K extends keyof Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>(key: K) => (<K extends keyof Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>>(key: K) => (<K extends keyof Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>>>(key: K) => (<K extends keyof Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>>>>(key: K) => any & { map: (updater: (u: Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>>>>) => Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>>>>) => T; set: (newU: Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>>>>) => T; }) & { map: (updater: (u: Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>>>) => Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>>>) => T; set: (newU: Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>>>) => T; }) & { map: (updater: (u: Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>>) => Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>>) => T; set: (newU: Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>>) => T; }) & { map: (updater: (u: Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>) => Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>) => T; set: (newU: Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>) => T; }) & { map: (updater: (u: Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>) => Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>) => T; set: (newU: Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>) => T; }) & { map: (updater: (u: Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>) => Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>) => T; set: (newU: Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>) => T; }) & { map: (updater: (u: Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>) => Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>) => T; set: (newU: Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>) => T; }) & { map: (updater: (u: Value<K, Value<K, Value<K, Value<K, U>>>>) => Value<K, Value<K, Value<K, Value<K, U>>>>) => T; set: (newU: Value<K, Value<K, Value<K, Value<K, U>>>>) => T; }) & { map: (updater: (u: Value<K, Value<K, Value<K, U>>>) => Value<K, Value<K, Value<K, U>>>) => T; set: (newU: Value<K, Value<K, Value<K, U>>>) => T; }) & { map: (updater: (u: Value<K, Value<K, U>>) => Value<K, Value<K, U>>) => T; set: (newU: Value<K, Value<K, U>>) => T; }) & { map: (updater: (u: Value<K, U>) => Value<K, U>) => T; set: (newU: Value<K, U>) => T; }) & { map: (updater: (u: U) => U) => T; set: (newU: U) => T; }
 >Object.assign : { <T, U>(target: T, source: U): T & U; <T, U, V>(target: T, source1: U, source2: V): T & U & V; <T, U, V, W>(target: T, source1: U, source2: V, source3: W): T & U & V & W; (target: object, ...sources: any[]): any; }
 >Object : ObjectConstructor
 >assign : { <T, U>(target: T, source: U): T & U; <T, U, V>(target: T, source1: U, source2: V): T & U & V; <T, U, V, W>(target: T, source1: U, source2: V, source3: W): T & U & V & W; (target: object, ...sources: any[]): any; }
 
             <K extends Key<U>>(key: K) =>
-><K extends Key<U>>(key: K) =>                reduce<Value<K, U>>(u[key as keyof U] as Value<K, U>, (v: Value<K, U>) => {                    return update(Object.assign(Array.isArray(u) ? [] : {}, u, { [key]: v }));                }) : <K extends keyof U>(key: K) => (<K extends keyof Value<K, U>>(key: K) => (<K extends keyof Value<K, Value<K, U>>>(key: K) => (<K extends keyof Value<K, Value<K, Value<K, U>>>>(key: K) => (<K extends keyof Value<K, Value<K, Value<K, Value<K, U>>>>>(key: K) => (<K extends keyof Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>(key: K) => (<K extends keyof Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>(key: K) => (<K extends keyof Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>(key: K) => (<K extends keyof Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>>(key: K) => (<K extends keyof Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>>>(key: K) => (<K extends keyof Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>>>>(key: K) => any & { map: (updater: (u: Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>>>>) => U) => T; set: (newU: Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>>>>) => T; }) & { map: (updater: (u: Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>>>) => U) => T; set: (newU: Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>>>) => T; }) & { map: (updater: (u: Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>>) => U) => T; set: (newU: Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>>) => T; }) & { map: (updater: (u: Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>) => U) => T; set: (newU: Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>) => T; }) & { map: (updater: (u: Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>) => U) => T; set: (newU: Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>) => T; }) & { map: (updater: (u: Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>) => U) => T; set: (newU: Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>) => T; }) & { map: (updater: (u: Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>) => U) => T; set: (newU: Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>) => T; }) & { map: (updater: (u: Value<K, Value<K, Value<K, Value<K, U>>>>) => U) => T; set: (newU: Value<K, Value<K, Value<K, Value<K, U>>>>) => T; }) & { map: (updater: (u: Value<K, Value<K, Value<K, U>>>) => U) => T; set: (newU: Value<K, Value<K, Value<K, U>>>) => T; }) & { map: (updater: (u: Value<K, Value<K, U>>) => U) => T; set: (newU: Value<K, Value<K, U>>) => T; }) & { map: (updater: (u: Value<K, U>) => U) => T; set: (newU: Value<K, U>) => T; }
+><K extends Key<U>>(key: K) =>                reduce<Value<K, U>>(u[key as keyof U] as Value<K, U>, (v: Value<K, U>) => {                    return update(Object.assign(Array.isArray(u) ? [] : {}, u, { [key]: v }));                }) : <K extends keyof U>(key: K) => (<K extends keyof Value<K, U>>(key: K) => (<K extends keyof Value<K, Value<K, U>>>(key: K) => (<K extends keyof Value<K, Value<K, Value<K, U>>>>(key: K) => (<K extends keyof Value<K, Value<K, Value<K, Value<K, U>>>>>(key: K) => (<K extends keyof Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>(key: K) => (<K extends keyof Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>(key: K) => (<K extends keyof Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>(key: K) => (<K extends keyof Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>>(key: K) => (<K extends keyof Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>>>(key: K) => (<K extends keyof Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>>>>(key: K) => any & { map: (updater: (u: Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>>>>) => Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>>>>) => T; set: (newU: Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>>>>) => T; }) & { map: (updater: (u: Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>>>) => Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>>>) => T; set: (newU: Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>>>) => T; }) & { map: (updater: (u: Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>>) => Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>>) => T; set: (newU: Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>>) => T; }) & { map: (updater: (u: Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>) => Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>) => T; set: (newU: Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>>) => T; }) & { map: (updater: (u: Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>) => Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>) => T; set: (newU: Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>>) => T; }) & { map: (updater: (u: Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>) => Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>) => T; set: (newU: Value<K, Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>>) => T; }) & { map: (updater: (u: Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>) => Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>) => T; set: (newU: Value<K, Value<K, Value<K, Value<K, Value<K, U>>>>>) => T; }) & { map: (updater: (u: Value<K, Value<K, Value<K, Value<K, U>>>>) => Value<K, Value<K, Value<K, Value<K, U>>>>) => T; set: (newU: Value<K, Value<K, Value<K, Value<K, U>>>>) => T; }) & { map: (updater: (u: Value<K, Value<K, Value<K, U>>>) => Value<K, Value<K, Value<K, U>>>) => T; set: (newU: Value<K, Value<K, Value<K, U>>>) => T; }) & { map: (updater: (u: Value<K, Value<K, U>>) => Value<K, Value<K, U>>) => T; set: (newU: Value<K, Value<K, U>>) => T; }) & { map: (updater: (u: Value<K, U>) => Value<K, U>) => T; set: (newU: Value<K, U>) => T; }
 >key : K
 
                 reduce<Value<K, U>>(u[key as keyof U] as Value<K, U>, (v: Value<K, U>) => {

tests/baselines/reference/destructionAssignmentError.errors.txt

@@ -0,0 +1,27 @@
+tests/cases/compiler/destructionAssignmentError.ts(6,3): error TS2695: Left side of comma operator is unused and has no side effects.
+tests/cases/compiler/destructionAssignmentError.ts(6,10): error TS2809: Declaration or statement expected. This '=' follows a block of statements, so if you intended to write a destructuring assignment, you might need to wrap the the whole assignment in parentheses.
+tests/cases/compiler/destructionAssignmentError.ts(11,3): error TS2695: Left side of comma operator is unused and has no side effects.
+tests/cases/compiler/destructionAssignmentError.ts(12,1): error TS2809: Declaration or statement expected. This '=' follows a block of statements, so if you intended to write a destructuring assignment, you might need to wrap the the whole assignment in parentheses.
+
+
+==== tests/cases/compiler/destructionAssignmentError.ts (4 errors) ====
+    declare function fn(): { a: 1, b: 2 }
+    let a: number;
+    let b: number;
+    
+    ({ a, b } = fn());
+    { a, b } = fn();
+      ~
+!!! error TS2695: Left side of comma operator is unused and has no side effects.
+             ~
+!!! error TS2809: Declaration or statement expected. This '=' follows a block of statements, so if you intended to write a destructuring assignment, you might need to wrap the the whole assignment in parentheses.
+    
+    ({ a, b } =
+    fn());
+    
+    { a, b }
+      ~
+!!! error TS2695: Left side of comma operator is unused and has no side effects.
+    = fn();
+    ~
+!!! error TS2809: Declaration or statement expected. This '=' follows a block of statements, so if you intended to write a destructuring assignment, you might need to wrap the the whole assignment in parentheses.

tests/baselines/reference/destructionAssignmentError.js

@@ -0,0 +1,28 @@
+//// [destructionAssignmentError.ts]
+declare function fn(): { a: 1, b: 2 }
+let a: number;
+let b: number;
+
+({ a, b } = fn());
+{ a, b } = fn();
+
+({ a, b } =
+fn());
+
+{ a, b }
+= fn();
+
+//// [destructionAssignmentError.js]
+var _a, _b;
+var a;
+var b;
+(_a = fn(), a = _a.a, b = _a.b);
+{
+    a, b;
+}
+fn();
+(_b = fn(), a = _b.a, b = _b.b);
+{
+    a, b;
+}
+fn();

tests/baselines/reference/destructionAssignmentError.symbols

@@ -0,0 +1,36 @@
+=== tests/cases/compiler/destructionAssignmentError.ts ===
+declare function fn(): { a: 1, b: 2 }
+>fn : Symbol(fn, Decl(destructionAssignmentError.ts, 0, 0))
+>a : Symbol(a, Decl(destructionAssignmentError.ts, 0, 24))
+>b : Symbol(b, Decl(destructionAssignmentError.ts, 0, 30))
+
+let a: number;
+>a : Symbol(a, Decl(destructionAssignmentError.ts, 1, 3))
+
+let b: number;
+>b : Symbol(b, Decl(destructionAssignmentError.ts, 2, 3))
+
+({ a, b } = fn());
+>a : Symbol(a, Decl(destructionAssignmentError.ts, 4, 2))
+>b : Symbol(b, Decl(destructionAssignmentError.ts, 4, 5))
+>fn : Symbol(fn, Decl(destructionAssignmentError.ts, 0, 0))
+
+{ a, b } = fn();
+>a : Symbol(a, Decl(destructionAssignmentError.ts, 1, 3))
+>b : Symbol(b, Decl(destructionAssignmentError.ts, 2, 3))
+>fn : Symbol(fn, Decl(destructionAssignmentError.ts, 0, 0))
+
+({ a, b } =
+>a : Symbol(a, Decl(destructionAssignmentError.ts, 7, 2))
+>b : Symbol(b, Decl(destructionAssignmentError.ts, 7, 5))
+
+fn());
+>fn : Symbol(fn, Decl(destructionAssignmentError.ts, 0, 0))
+
+{ a, b }
+>a : Symbol(a, Decl(destructionAssignmentError.ts, 1, 3))
+>b : Symbol(b, Decl(destructionAssignmentError.ts, 2, 3))
+
+= fn();
+>fn : Symbol(fn, Decl(destructionAssignmentError.ts, 0, 0))
+

tests/baselines/reference/destructionAssignmentError.types

@@ -0,0 +1,48 @@
+=== tests/cases/compiler/destructionAssignmentError.ts ===
+declare function fn(): { a: 1, b: 2 }
+>fn : () => {    a: 1;    b: 2;}
+>a : 1
+>b : 2
+
+let a: number;
+>a : number
+
+let b: number;
+>b : number
+
+({ a, b } = fn());
+>({ a, b } = fn()) : { a: 1; b: 2; }
+>{ a, b } = fn() : { a: 1; b: 2; }
+>{ a, b } : { a: number; b: number; }
+>a : number
+>b : number
+>fn() : { a: 1; b: 2; }
+>fn : () => { a: 1; b: 2; }
+
+{ a, b } = fn();
+>a, b : number
+>a : number
+>b : number
+>fn() : { a: 1; b: 2; }
+>fn : () => { a: 1; b: 2; }
+
+({ a, b } =
+>({ a, b } =fn()) : { a: 1; b: 2; }
+>{ a, b } =fn() : { a: 1; b: 2; }
+>{ a, b } : { a: number; b: number; }
+>a : number
+>b : number
+
+fn());
+>fn() : { a: 1; b: 2; }
+>fn : () => { a: 1; b: 2; }
+
+{ a, b }
+>a, b : number
+>a : number
+>b : number
+
+= fn();
+>fn() : { a: 1; b: 2; }
+>fn : () => { a: 1; b: 2; }
+

tests/baselines/reference/errorRecoveryWithDotFollowedByNamespaceKeyword.errors.txt

@@ -16,5 +16,4 @@ tests/cases/compiler/errorRecoveryWithDotFollowedByNamespaceKeyword.ts(9,2): err
     }
      
 !!! error TS1005: '}' expected.
-!!! related TS1007 tests/cases/compiler/errorRecoveryWithDotFollowedByNamespaceKeyword.ts:3:19: The parser expected to find a '}' to match the '{' token here.
-!!! related TS1007 tests/cases/compiler/errorRecoveryWithDotFollowedByNamespaceKeyword.ts:2:20: The parser expected to find a '}' to match the '{' token here.
+!!! related TS1007 tests/cases/compiler/errorRecoveryWithDotFollowedByNamespaceKeyword.ts:3:19: The parser expected to find a '}' to match the '{' token here.

tests/baselines/reference/excessiveStackDepthFlatArray.errors.txt

@@ -0,0 +1,48 @@
+tests/cases/compiler/index.tsx(35,13): error TS2322: Type '{ key: string; }' is not assignable to type 'HTMLAttributes<HTMLLIElement>'.
+  Property 'key' does not exist on type 'HTMLAttributes<HTMLLIElement>'.
+
+
+==== tests/cases/compiler/index.tsx (1 errors) ====
+    interface MiddlewareArray<T> extends Array<T> {}
+    declare function configureStore(options: { middleware: MiddlewareArray<any> }): void;
+    
+    declare const defaultMiddleware: MiddlewareArray<any>;
+    configureStore({
+      middleware: [...defaultMiddleware], // Should not error
+    });
+    
+    declare namespace React {
+      type DetailedHTMLProps<E extends HTMLAttributes<T>, T> = E;
+      interface HTMLAttributes<T> {
+        children?: ReactNode;
+      }
+      type ReactNode = ReactChild | ReactFragment | boolean | null | undefined;
+      type ReactText = string | number;
+      type ReactChild = ReactText;
+      type ReactFragment = {} | ReactNodeArray;
+      interface ReactNodeArray extends Array<ReactNode> {}
+    }
+    declare namespace JSX {
+      interface IntrinsicElements {
+        ul: React.DetailedHTMLProps<React.HTMLAttributes<HTMLUListElement>, HTMLUListElement>;
+        li: React.DetailedHTMLProps<React.HTMLAttributes<HTMLLIElement>, HTMLLIElement>;
+      }
+    }
+    declare var React: any;
+    
+    const Component = () => {
+      const categories = ['Fruit', 'Vegetables'];
+    
+      return (
+        <ul>
+          <li>All</li>
+          {categories.map((category) => (
+            <li key={category}>{category}</li> // Error about 'key' only
+                ~~~
+!!! error TS2322: Type '{ key: string; }' is not assignable to type 'HTMLAttributes<HTMLLIElement>'.
+!!! error TS2322:   Property 'key' does not exist on type 'HTMLAttributes<HTMLLIElement>'.
+          ))}
+        </ul>
+      );
+    };
+    

tests/baselines/reference/excessiveStackDepthFlatArray.js

@@ -0,0 +1,58 @@
+//// [index.tsx]
+interface MiddlewareArray<T> extends Array<T> {}
+declare function configureStore(options: { middleware: MiddlewareArray<any> }): void;
+
+declare const defaultMiddleware: MiddlewareArray<any>;
+configureStore({
+  middleware: [...defaultMiddleware], // Should not error
+});
+
+declare namespace React {
+  type DetailedHTMLProps<E extends HTMLAttributes<T>, T> = E;
+  interface HTMLAttributes<T> {
+    children?: ReactNode;
+  }
+  type ReactNode = ReactChild | ReactFragment | boolean | null | undefined;
+  type ReactText = string | number;
+  type ReactChild = ReactText;
+  type ReactFragment = {} | ReactNodeArray;
+  interface ReactNodeArray extends Array<ReactNode> {}
+}
+declare namespace JSX {
+  interface IntrinsicElements {
+    ul: React.DetailedHTMLProps<React.HTMLAttributes<HTMLUListElement>, HTMLUListElement>;
+    li: React.DetailedHTMLProps<React.HTMLAttributes<HTMLLIElement>, HTMLLIElement>;
+  }
+}
+declare var React: any;
+
+const Component = () => {
+  const categories = ['Fruit', 'Vegetables'];
+
+  return (
+    <ul>
+      <li>All</li>
+      {categories.map((category) => (
+        <li key={category}>{category}</li> // Error about 'key' only
+      ))}
+    </ul>
+  );
+};
+
+
+//// [index.js]
+var __spreadArray = (this && this.__spreadArray) || function (to, from) {
+    for (var i = 0, il = from.length, j = to.length; i < il; i++, j++)
+        to[j] = from[i];
+    return to;
+};
+configureStore({
+    middleware: __spreadArray([], defaultMiddleware)
+});
+var Component = function () {
+    var categories = ['Fruit', 'Vegetables'];
+    return (React.createElement("ul", null,
+        React.createElement("li", null, "All"),
+        categories.map(function (category) { return (React.createElement("li", { key: category }, category) // Error about 'key' only
+        ); })));
+};

tests/baselines/reference/excessiveStackDepthFlatArray.symbols

@@ -0,0 +1,128 @@
+=== tests/cases/compiler/index.tsx ===
+interface MiddlewareArray<T> extends Array<T> {}
+>MiddlewareArray : Symbol(MiddlewareArray, Decl(index.tsx, 0, 0))
+>T : Symbol(T, Decl(index.tsx, 0, 26))
+>Array : Symbol(Array, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es2015.core.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --) ... and 2 more)
+>T : Symbol(T, Decl(index.tsx, 0, 26))
+
+declare function configureStore(options: { middleware: MiddlewareArray<any> }): void;
+>configureStore : Symbol(configureStore, Decl(index.tsx, 0, 48))
+>options : Symbol(options, Decl(index.tsx, 1, 32))
+>middleware : Symbol(middleware, Decl(index.tsx, 1, 42))
+>MiddlewareArray : Symbol(MiddlewareArray, Decl(index.tsx, 0, 0))
+
+declare const defaultMiddleware: MiddlewareArray<any>;
+>defaultMiddleware : Symbol(defaultMiddleware, Decl(index.tsx, 3, 13))
+>MiddlewareArray : Symbol(MiddlewareArray, Decl(index.tsx, 0, 0))
+
+configureStore({
+>configureStore : Symbol(configureStore, Decl(index.tsx, 0, 48))
+
+  middleware: [...defaultMiddleware], // Should not error
+>middleware : Symbol(middleware, Decl(index.tsx, 4, 16))
+>defaultMiddleware : Symbol(defaultMiddleware, Decl(index.tsx, 3, 13))
+
+});
+
+declare namespace React {
+>React : Symbol(React, Decl(index.tsx, 6, 3), Decl(index.tsx, 25, 11))
+
+  type DetailedHTMLProps<E extends HTMLAttributes<T>, T> = E;
+>DetailedHTMLProps : Symbol(DetailedHTMLProps, Decl(index.tsx, 8, 25))
+>E : Symbol(E, Decl(index.tsx, 9, 25))
+>HTMLAttributes : Symbol(HTMLAttributes, Decl(index.tsx, 9, 61))
+>T : Symbol(T, Decl(index.tsx, 9, 53))
+>T : Symbol(T, Decl(index.tsx, 9, 53))
+>E : Symbol(E, Decl(index.tsx, 9, 25))
+
+  interface HTMLAttributes<T> {
+>HTMLAttributes : Symbol(HTMLAttributes, Decl(index.tsx, 9, 61))
+>T : Symbol(T, Decl(index.tsx, 10, 27))
+
+    children?: ReactNode;
+>children : Symbol(HTMLAttributes.children, Decl(index.tsx, 10, 31))
+>ReactNode : Symbol(ReactNode, Decl(index.tsx, 12, 3))
+  }
+  type ReactNode = ReactChild | ReactFragment | boolean | null | undefined;
+>ReactNode : Symbol(ReactNode, Decl(index.tsx, 12, 3))
+>ReactChild : Symbol(ReactChild, Decl(index.tsx, 14, 35))
+>ReactFragment : Symbol(ReactFragment, Decl(index.tsx, 15, 30))
+
+  type ReactText = string | number;
+>ReactText : Symbol(ReactText, Decl(index.tsx, 13, 75))
+
+  type ReactChild = ReactText;
+>ReactChild : Symbol(ReactChild, Decl(index.tsx, 14, 35))
+>ReactText : Symbol(ReactText, Decl(index.tsx, 13, 75))
+
+  type ReactFragment = {} | ReactNodeArray;
+>ReactFragment : Symbol(ReactFragment, Decl(index.tsx, 15, 30))
+>ReactNodeArray : Symbol(ReactNodeArray, Decl(index.tsx, 16, 43))
+
+  interface ReactNodeArray extends Array<ReactNode> {}
+>ReactNodeArray : Symbol(ReactNodeArray, Decl(index.tsx, 16, 43))
+>Array : Symbol(Array, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es2015.core.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --) ... and 2 more)
+>ReactNode : Symbol(ReactNode, Decl(index.tsx, 12, 3))
+}
+declare namespace JSX {
+>JSX : Symbol(JSX, Decl(index.tsx, 18, 1))
+
+  interface IntrinsicElements {
+>IntrinsicElements : Symbol(IntrinsicElements, Decl(index.tsx, 19, 23))
+
+    ul: React.DetailedHTMLProps<React.HTMLAttributes<HTMLUListElement>, HTMLUListElement>;
+>ul : Symbol(IntrinsicElements.ul, Decl(index.tsx, 20, 31))
+>React : Symbol(React, Decl(index.tsx, 6, 3), Decl(index.tsx, 25, 11))
+>DetailedHTMLProps : Symbol(React.DetailedHTMLProps, Decl(index.tsx, 8, 25))
+>React : Symbol(React, Decl(index.tsx, 6, 3), Decl(index.tsx, 25, 11))
+>HTMLAttributes : Symbol(React.HTMLAttributes, Decl(index.tsx, 9, 61))
+>HTMLUListElement : Symbol(HTMLUListElement, Decl(lib.dom.d.ts, --, --), Decl(lib.dom.d.ts, --, --))
+>HTMLUListElement : Symbol(HTMLUListElement, Decl(lib.dom.d.ts, --, --), Decl(lib.dom.d.ts, --, --))
+
+    li: React.DetailedHTMLProps<React.HTMLAttributes<HTMLLIElement>, HTMLLIElement>;
+>li : Symbol(IntrinsicElements.li, Decl(index.tsx, 21, 90))
+>React : Symbol(React, Decl(index.tsx, 6, 3), Decl(index.tsx, 25, 11))
+>DetailedHTMLProps : Symbol(React.DetailedHTMLProps, Decl(index.tsx, 8, 25))
+>React : Symbol(React, Decl(index.tsx, 6, 3), Decl(index.tsx, 25, 11))
+>HTMLAttributes : Symbol(React.HTMLAttributes, Decl(index.tsx, 9, 61))
+>HTMLLIElement : Symbol(HTMLLIElement, Decl(lib.dom.d.ts, --, --), Decl(lib.dom.d.ts, --, --))
+>HTMLLIElement : Symbol(HTMLLIElement, Decl(lib.dom.d.ts, --, --), Decl(lib.dom.d.ts, --, --))
+  }
+}
+declare var React: any;
+>React : Symbol(React, Decl(index.tsx, 6, 3), Decl(index.tsx, 25, 11))
+
+const Component = () => {
+>Component : Symbol(Component, Decl(index.tsx, 27, 5))
+
+  const categories = ['Fruit', 'Vegetables'];
+>categories : Symbol(categories, Decl(index.tsx, 28, 7))
+
+  return (
+    <ul>
+>ul : Symbol(JSX.IntrinsicElements.ul, Decl(index.tsx, 20, 31))
+
+      <li>All</li>
+>li : Symbol(JSX.IntrinsicElements.li, Decl(index.tsx, 21, 90))
+>li : Symbol(JSX.IntrinsicElements.li, Decl(index.tsx, 21, 90))
+
+      {categories.map((category) => (
+>categories.map : Symbol(Array.map, Decl(lib.es5.d.ts, --, --))
+>categories : Symbol(categories, Decl(index.tsx, 28, 7))
+>map : Symbol(Array.map, Decl(lib.es5.d.ts, --, --))
+>category : Symbol(category, Decl(index.tsx, 33, 23))
+
+        <li key={category}>{category}</li> // Error about 'key' only
+>li : Symbol(JSX.IntrinsicElements.li, Decl(index.tsx, 21, 90))
+>key : Symbol(key, Decl(index.tsx, 34, 11))
+>category : Symbol(category, Decl(index.tsx, 33, 23))
+>category : Symbol(category, Decl(index.tsx, 33, 23))
+>li : Symbol(JSX.IntrinsicElements.li, Decl(index.tsx, 21, 90))
+
+      ))}
+    </ul>
+>ul : Symbol(JSX.IntrinsicElements.ul, Decl(index.tsx, 20, 31))
+
+  );
+};
+

tests/baselines/reference/excessiveStackDepthFlatArray.types

@@ -0,0 +1,108 @@
+=== tests/cases/compiler/index.tsx ===
+interface MiddlewareArray<T> extends Array<T> {}
+declare function configureStore(options: { middleware: MiddlewareArray<any> }): void;
+>configureStore : (options: {    middleware: MiddlewareArray<any>;}) => void
+>options : { middleware: MiddlewareArray<any>; }
+>middleware : MiddlewareArray<any>
+
+declare const defaultMiddleware: MiddlewareArray<any>;
+>defaultMiddleware : MiddlewareArray<any>
+
+configureStore({
+>configureStore({  middleware: [...defaultMiddleware], // Should not error}) : void
+>configureStore : (options: { middleware: MiddlewareArray<any>; }) => void
+>{  middleware: [...defaultMiddleware], // Should not error} : { middleware: any[]; }
+
+  middleware: [...defaultMiddleware], // Should not error
+>middleware : any[]
+>[...defaultMiddleware] : any[]
+>...defaultMiddleware : any
+>defaultMiddleware : MiddlewareArray<any>
+
+});
+
+declare namespace React {
+  type DetailedHTMLProps<E extends HTMLAttributes<T>, T> = E;
+>DetailedHTMLProps : E
+
+  interface HTMLAttributes<T> {
+    children?: ReactNode;
+>children : ReactNode
+  }
+  type ReactNode = ReactChild | ReactFragment | boolean | null | undefined;
+>ReactNode : ReactNode
+>null : null
+
+  type ReactText = string | number;
+>ReactText : ReactText
+
+  type ReactChild = ReactText;
+>ReactChild : ReactText
+
+  type ReactFragment = {} | ReactNodeArray;
+>ReactFragment : ReactFragment
+
+  interface ReactNodeArray extends Array<ReactNode> {}
+}
+declare namespace JSX {
+  interface IntrinsicElements {
+    ul: React.DetailedHTMLProps<React.HTMLAttributes<HTMLUListElement>, HTMLUListElement>;
+>ul : React.HTMLAttributes<HTMLUListElement>
+>React : any
+>React : any
+
+    li: React.DetailedHTMLProps<React.HTMLAttributes<HTMLLIElement>, HTMLLIElement>;
+>li : React.HTMLAttributes<HTMLLIElement>
+>React : any
+>React : any
+  }
+}
+declare var React: any;
+>React : any
+
+const Component = () => {
+>Component : () => any
+>() => {  const categories = ['Fruit', 'Vegetables'];  return (    <ul>      <li>All</li>      {categories.map((category) => (        <li key={category}>{category}</li> // Error about 'key' only      ))}    </ul>  );} : () => any
+
+  const categories = ['Fruit', 'Vegetables'];
+>categories : string[]
+>['Fruit', 'Vegetables'] : string[]
+>'Fruit' : "Fruit"
+>'Vegetables' : "Vegetables"
+
+  return (
+>(    <ul>      <li>All</li>      {categories.map((category) => (        <li key={category}>{category}</li> // Error about 'key' only      ))}    </ul>  ) : any
+
+    <ul>
+><ul>      <li>All</li>      {categories.map((category) => (        <li key={category}>{category}</li> // Error about 'key' only      ))}    </ul> : any
+>ul : any
+
+      <li>All</li>
+><li>All</li> : any
+>li : any
+>li : any
+
+      {categories.map((category) => (
+>categories.map((category) => (        <li key={category}>{category}</li> // Error about 'key' only      )) : any[]
+>categories.map : <U>(callbackfn: (value: string, index: number, array: string[]) => U, thisArg?: any) => U[]
+>categories : string[]
+>map : <U>(callbackfn: (value: string, index: number, array: string[]) => U, thisArg?: any) => U[]
+>(category) => (        <li key={category}>{category}</li> // Error about 'key' only      ) : (category: string) => any
+>category : string
+>(        <li key={category}>{category}</li> // Error about 'key' only      ) : any
+
+        <li key={category}>{category}</li> // Error about 'key' only
+><li key={category}>{category}</li> : any
+>li : any
+>key : string
+>category : string
+>category : string
+>li : any
+
+      ))}
+    </ul>
+>ul : any
+
+  );
+};
+

tests/baselines/reference/flatArrayNoExcessiveStackDepth.errors.txt

@@ -0,0 +1,44 @@
+tests/cases/compiler/flatArrayNoExcessiveStackDepth.ts(20,5): error TS2322: Type 'Arr extends readonly (infer InnerArr)[] ? FlatArray<InnerArr, 0 | 2 | 1 | -1 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20> : Arr' is not assignable to type 'FlatArray<Arr, D>'.
+  Type 'unknown' is not assignable to type 'FlatArray<Arr, D>'.
+    Type 'unknown' is not assignable to type 'Arr extends readonly (infer InnerArr)[] ? FlatArray<InnerArr, [-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20][D]> : Arr'.
+      Type 'Arr extends readonly (infer InnerArr)[] ? FlatArray<InnerArr, 0 | 2 | 1 | -1 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20> : Arr' is not assignable to type 'Arr extends readonly (infer InnerArr)[] ? FlatArray<InnerArr, [-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20][D]> : Arr'.
+        Type 'unknown' is not assignable to type 'Arr extends readonly (infer InnerArr)[] ? FlatArray<InnerArr, [-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20][D]> : Arr'.
+          Type 'FlatArray<InnerArr, 0 | 2 | 1 | -1 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20>' is not assignable to type 'FlatArray<InnerArr, [-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20][D]>'.
+            Type 'InnerArr' is not assignable to type 'FlatArray<InnerArr, [-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20][D]>'.
+              Type 'InnerArr' is not assignable to type '(InnerArr extends readonly (infer InnerArr)[] ? FlatArray<InnerArr, [-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20][[-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20][D]]> : InnerArr) & InnerArr'.
+                Type 'InnerArr' is not assignable to type 'InnerArr extends readonly (infer InnerArr)[] ? FlatArray<InnerArr, [-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20][[-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20][D]]> : InnerArr'.
+
+
+==== tests/cases/compiler/flatArrayNoExcessiveStackDepth.ts (1 errors) ====
+    // Repro from #43493
+    
+    declare const foo: unknown[];
+    const bar = foo.flatMap(bar => bar as Foo);
+    
+    interface Foo extends Array<string> {}
+    
+    // Repros from comments in #43249
+    
+    const repro_43249 = (value: unknown) => {
+        if (typeof value !== "string") {
+            throw new Error("No");
+        }
+        const match = value.match(/anything/) || [];
+        const [, extracted] = match;
+    };
+    
+    function f<Arr, D extends number>(x: FlatArray<Arr, any>, y: FlatArray<Arr, D>) {
+        x = y;
+        y = x;  // Error
+        ~
+!!! error TS2322: Type 'Arr extends readonly (infer InnerArr)[] ? FlatArray<InnerArr, 0 | 2 | 1 | -1 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20> : Arr' is not assignable to type 'FlatArray<Arr, D>'.
+!!! error TS2322:   Type 'unknown' is not assignable to type 'FlatArray<Arr, D>'.
+!!! error TS2322:     Type 'unknown' is not assignable to type 'Arr extends readonly (infer InnerArr)[] ? FlatArray<InnerArr, [-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20][D]> : Arr'.
+!!! error TS2322:       Type 'Arr extends readonly (infer InnerArr)[] ? FlatArray<InnerArr, 0 | 2 | 1 | -1 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20> : Arr' is not assignable to type 'Arr extends readonly (infer InnerArr)[] ? FlatArray<InnerArr, [-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20][D]> : Arr'.
+!!! error TS2322:         Type 'unknown' is not assignable to type 'Arr extends readonly (infer InnerArr)[] ? FlatArray<InnerArr, [-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20][D]> : Arr'.
+!!! error TS2322:           Type 'FlatArray<InnerArr, 0 | 2 | 1 | -1 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20>' is not assignable to type 'FlatArray<InnerArr, [-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20][D]>'.
+!!! error TS2322:             Type 'InnerArr' is not assignable to type 'FlatArray<InnerArr, [-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20][D]>'.
+!!! error TS2322:               Type 'InnerArr' is not assignable to type '(InnerArr extends readonly (infer InnerArr)[] ? FlatArray<InnerArr, [-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20][[-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20][D]]> : InnerArr) & InnerArr'.
+!!! error TS2322:                 Type 'InnerArr' is not assignable to type 'InnerArr extends readonly (infer InnerArr)[] ? FlatArray<InnerArr, [-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20][[-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20][D]]> : InnerArr'.
+    }
+    

tests/baselines/reference/flatArrayNoExcessiveStackDepth.js

@@ -0,0 +1,49 @@
+//// [flatArrayNoExcessiveStackDepth.ts]
+// Repro from #43493
+
+declare const foo: unknown[];
+const bar = foo.flatMap(bar => bar as Foo);
+
+interface Foo extends Array<string> {}
+
+// Repros from comments in #43249
+
+const repro_43249 = (value: unknown) => {
+    if (typeof value !== "string") {
+        throw new Error("No");
+    }
+    const match = value.match(/anything/) || [];
+    const [, extracted] = match;
+};
+
+function f<Arr, D extends number>(x: FlatArray<Arr, any>, y: FlatArray<Arr, D>) {
+    x = y;
+    y = x;  // Error
+}
+
+
+//// [flatArrayNoExcessiveStackDepth.js]
+"use strict";
+// Repro from #43493
+const bar = foo.flatMap(bar => bar);
+// Repros from comments in #43249
+const repro_43249 = (value) => {
+    if (typeof value !== "string") {
+        throw new Error("No");
+    }
+    const match = value.match(/anything/) || [];
+    const [, extracted] = match;
+};
+function f(x, y) {
+    x = y;
+    y = x; // Error
+}
+
+
+//// [flatArrayNoExcessiveStackDepth.d.ts]
+declare const foo: unknown[];
+declare const bar: string[];
+interface Foo extends Array<string> {
+}
+declare const repro_43249: (value: unknown) => void;
+declare function f<Arr, D extends number>(x: FlatArray<Arr, any>, y: FlatArray<Arr, D>): void;

tests/baselines/reference/flatArrayNoExcessiveStackDepth.symbols

@@ -0,0 +1,64 @@
+=== tests/cases/compiler/flatArrayNoExcessiveStackDepth.ts ===
+// Repro from #43493
+
+declare const foo: unknown[];
+>foo : Symbol(foo, Decl(flatArrayNoExcessiveStackDepth.ts, 2, 13))
+
+const bar = foo.flatMap(bar => bar as Foo);
+>bar : Symbol(bar, Decl(flatArrayNoExcessiveStackDepth.ts, 3, 5))
+>foo.flatMap : Symbol(Array.flatMap, Decl(lib.es2019.array.d.ts, --, --))
+>foo : Symbol(foo, Decl(flatArrayNoExcessiveStackDepth.ts, 2, 13))
+>flatMap : Symbol(Array.flatMap, Decl(lib.es2019.array.d.ts, --, --))
+>bar : Symbol(bar, Decl(flatArrayNoExcessiveStackDepth.ts, 3, 24))
+>bar : Symbol(bar, Decl(flatArrayNoExcessiveStackDepth.ts, 3, 24))
+>Foo : Symbol(Foo, Decl(flatArrayNoExcessiveStackDepth.ts, 3, 43))
+
+interface Foo extends Array<string> {}
+>Foo : Symbol(Foo, Decl(flatArrayNoExcessiveStackDepth.ts, 3, 43))
+>Array : Symbol(Array, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es2015.core.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --) ... and 2 more)
+
+// Repros from comments in #43249
+
+const repro_43249 = (value: unknown) => {
+>repro_43249 : Symbol(repro_43249, Decl(flatArrayNoExcessiveStackDepth.ts, 9, 5))
+>value : Symbol(value, Decl(flatArrayNoExcessiveStackDepth.ts, 9, 21))
+
+    if (typeof value !== "string") {
+>value : Symbol(value, Decl(flatArrayNoExcessiveStackDepth.ts, 9, 21))
+
+        throw new Error("No");
+>Error : Symbol(Error, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
+    }
+    const match = value.match(/anything/) || [];
+>match : Symbol(match, Decl(flatArrayNoExcessiveStackDepth.ts, 13, 9))
+>value.match : Symbol(String.match, Decl(lib.es5.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --))
+>value : Symbol(value, Decl(flatArrayNoExcessiveStackDepth.ts, 9, 21))
+>match : Symbol(String.match, Decl(lib.es5.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --))
+
+    const [, extracted] = match;
+>extracted : Symbol(extracted, Decl(flatArrayNoExcessiveStackDepth.ts, 14, 12))
+>match : Symbol(match, Decl(flatArrayNoExcessiveStackDepth.ts, 13, 9))
+
+};
+
+function f<Arr, D extends number>(x: FlatArray<Arr, any>, y: FlatArray<Arr, D>) {
+>f : Symbol(f, Decl(flatArrayNoExcessiveStackDepth.ts, 15, 2))
+>Arr : Symbol(Arr, Decl(flatArrayNoExcessiveStackDepth.ts, 17, 11))
+>D : Symbol(D, Decl(flatArrayNoExcessiveStackDepth.ts, 17, 15))
+>x : Symbol(x, Decl(flatArrayNoExcessiveStackDepth.ts, 17, 34))
+>FlatArray : Symbol(FlatArray, Decl(lib.es2019.array.d.ts, --, --))
+>Arr : Symbol(Arr, Decl(flatArrayNoExcessiveStackDepth.ts, 17, 11))
+>y : Symbol(y, Decl(flatArrayNoExcessiveStackDepth.ts, 17, 57))
+>FlatArray : Symbol(FlatArray, Decl(lib.es2019.array.d.ts, --, --))
+>Arr : Symbol(Arr, Decl(flatArrayNoExcessiveStackDepth.ts, 17, 11))
+>D : Symbol(D, Decl(flatArrayNoExcessiveStackDepth.ts, 17, 15))
+
+    x = y;
+>x : Symbol(x, Decl(flatArrayNoExcessiveStackDepth.ts, 17, 34))
+>y : Symbol(y, Decl(flatArrayNoExcessiveStackDepth.ts, 17, 57))
+
+    y = x;  // Error
+>y : Symbol(y, Decl(flatArrayNoExcessiveStackDepth.ts, 17, 57))
+>x : Symbol(x, Decl(flatArrayNoExcessiveStackDepth.ts, 17, 34))
+}
+

tests/baselines/reference/flatArrayNoExcessiveStackDepth.types

@@ -0,0 +1,70 @@
+=== tests/cases/compiler/flatArrayNoExcessiveStackDepth.ts ===
+// Repro from #43493
+
+declare const foo: unknown[];
+>foo : unknown[]
+
+const bar = foo.flatMap(bar => bar as Foo);
+>bar : string[]
+>foo.flatMap(bar => bar as Foo) : string[]
+>foo.flatMap : <U, This = undefined>(callback: (this: This, value: unknown, index: number, array: unknown[]) => U | readonly U[], thisArg?: This | undefined) => U[]
+>foo : unknown[]
+>flatMap : <U, This = undefined>(callback: (this: This, value: unknown, index: number, array: unknown[]) => U | readonly U[], thisArg?: This | undefined) => U[]
+>bar => bar as Foo : (this: undefined, bar: unknown) => Foo
+>bar : unknown
+>bar as Foo : Foo
+>bar : unknown
+
+interface Foo extends Array<string> {}
+
+// Repros from comments in #43249
+
+const repro_43249 = (value: unknown) => {
+>repro_43249 : (value: unknown) => void
+>(value: unknown) => {    if (typeof value !== "string") {        throw new Error("No");    }    const match = value.match(/anything/) || [];    const [, extracted] = match;} : (value: unknown) => void
+>value : unknown
+
+    if (typeof value !== "string") {
+>typeof value !== "string" : boolean
+>typeof value : "string" | "number" | "bigint" | "boolean" | "symbol" | "undefined" | "object" | "function"
+>value : unknown
+>"string" : "string"
+
+        throw new Error("No");
+>new Error("No") : Error
+>Error : ErrorConstructor
+>"No" : "No"
+    }
+    const match = value.match(/anything/) || [];
+>match : RegExpMatchArray
+>value.match(/anything/) || [] : RegExpMatchArray
+>value.match(/anything/) : RegExpMatchArray | null
+>value.match : { (regexp: string | RegExp): RegExpMatchArray | null; (matcher: { [Symbol.match](string: string): RegExpMatchArray | null; }): RegExpMatchArray | null; }
+>value : string
+>match : { (regexp: string | RegExp): RegExpMatchArray | null; (matcher: { [Symbol.match](string: string): RegExpMatchArray | null; }): RegExpMatchArray | null; }
+>/anything/ : RegExp
+>[] : never[]
+
+    const [, extracted] = match;
+> : undefined
+>extracted : string
+>match : RegExpMatchArray
+
+};
+
+function f<Arr, D extends number>(x: FlatArray<Arr, any>, y: FlatArray<Arr, D>) {
+>f : <Arr, D extends number>(x: FlatArray<Arr, any>, y: FlatArray<Arr, D>) => void
+>x : FlatArray<Arr, any>
+>y : FlatArray<Arr, D>
+
+    x = y;
+>x = y : FlatArray<Arr, D>
+>x : FlatArray<Arr, any>
+>y : FlatArray<Arr, D>
+
+    y = x;  // Error
+>y = x : Arr extends readonly (infer InnerArr)[] ? FlatArray<InnerArr, 0 | 2 | 1 | -1 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20> : Arr
+>y : FlatArray<Arr, D>
+>x : Arr extends readonly (infer InnerArr)[] ? FlatArray<InnerArr, 0 | 2 | 1 | -1 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20> : Arr
+}
+

tests/baselines/reference/genericFunctionInference2.types

@@ -19,7 +19,7 @@ declare const foo: Reducer<MyState['combined']['foo']>;
 
 const myReducer1: Reducer<MyState> = combineReducers({
 >myReducer1 : Reducer<MyState>
->combineReducers({    combined: combineReducers({ foo }),}) : Reducer<{ combined: { foo: any; }; }>
+>combineReducers({    combined: combineReducers({ foo }),}) : Reducer<{ combined: { foo: number; }; }>
 >combineReducers : <S>(reducers: { [K in keyof S]: Reducer<S[K]>; }) => Reducer<S>
 >{    combined: combineReducers({ foo }),} : { combined: Reducer<{ foo: number; }>; }
 
@@ -33,8 +33,8 @@ const myReducer1: Reducer<MyState> = combineReducers({
 });
 
 const myReducer2 = combineReducers({
->myReducer2 : Reducer<{ combined: { foo: any; }; }>
->combineReducers({    combined: combineReducers({ foo }),}) : Reducer<{ combined: { foo: any; }; }>
+>myReducer2 : Reducer<{ combined: { foo: number; }; }>
+>combineReducers({    combined: combineReducers({ foo }),}) : Reducer<{ combined: { foo: number; }; }>
 >combineReducers : <S>(reducers: { [K in keyof S]: Reducer<S[K]>; }) => Reducer<S>
 >{    combined: combineReducers({ foo }),} : { combined: Reducer<{ foo: number; }>; }
 

tests/baselines/reference/importedModuleAddToGlobal.errors.txt

@@ -1,4 +1,4 @@
-tests/cases/compiler/importedModuleAddToGlobal.ts(15,23): error TS2811: Cannot find namespace 'b'. Did you mean 'B?
+tests/cases/compiler/importedModuleAddToGlobal.ts(15,23): error TS2812: Cannot find namespace 'b'. Did you mean 'B?
 
 
 ==== tests/cases/compiler/importedModuleAddToGlobal.ts (1 errors) ====
@@ -18,6 +18,6 @@ tests/cases/compiler/importedModuleAddToGlobal.ts(15,23): error TS2811: Cannot f
         import a = A;
         function hello(): b.B { return null; }
                           ~
-!!! error TS2811: Cannot find namespace 'b'. Did you mean 'B?
+!!! error TS2812: Cannot find namespace 'b'. Did you mean 'B?
 !!! related TS2728 tests/cases/compiler/importedModuleAddToGlobal.ts:8:8: 'B' is declared here.
     }

tests/baselines/reference/interfacesWithPredefinedTypesAsNames.errors.txt

@@ -4,9 +4,11 @@ tests/cases/conformance/interfaces/interfaceDeclarations/interfacesWithPredefine
 tests/cases/conformance/interfaces/interfaceDeclarations/interfacesWithPredefinedTypesAsNames.ts(4,11): error TS2427: Interface name cannot be 'boolean'.
 tests/cases/conformance/interfaces/interfaceDeclarations/interfacesWithPredefinedTypesAsNames.ts(5,1): error TS2304: Cannot find name 'interface'.
 tests/cases/conformance/interfaces/interfaceDeclarations/interfacesWithPredefinedTypesAsNames.ts(5,11): error TS1005: ';' expected.
+tests/cases/conformance/interfaces/interfaceDeclarations/interfacesWithPredefinedTypesAsNames.ts(6,11): error TS2427: Interface name cannot be 'unknown'.
+tests/cases/conformance/interfaces/interfaceDeclarations/interfacesWithPredefinedTypesAsNames.ts(7,11): error TS2427: Interface name cannot be 'never'.
 
 
-==== tests/cases/conformance/interfaces/interfaceDeclarations/interfacesWithPredefinedTypesAsNames.ts (6 errors) ====
+==== tests/cases/conformance/interfaces/interfaceDeclarations/interfacesWithPredefinedTypesAsNames.ts (8 errors) ====
     interface any { }
               ~~~
 !!! error TS2427: Interface name cannot be 'any'.
@@ -23,4 +25,10 @@ tests/cases/conformance/interfaces/interfaceDeclarations/interfacesWithPredefine
     ~~~~~~~~~
 !!! error TS2304: Cannot find name 'interface'.
               ~~~~
-!!! error TS1005: ';' expected.
+!!! error TS1005: ';' expected.
+    interface unknown {}
+              ~~~~~~~
+!!! error TS2427: Interface name cannot be 'unknown'.
+    interface never {}
+              ~~~~~
+!!! error TS2427: Interface name cannot be 'never'.

tests/baselines/reference/interfacesWithPredefinedTypesAsNames.js

@@ -3,7 +3,9 @@ interface any { }
 interface number { }
 interface string { }
 interface boolean { }
-interface void {}
+interface void {}
+interface unknown {}
+interface never {}
 
 //// [interfacesWithPredefinedTypesAsNames.js]
 interface;

tests/baselines/reference/interfacesWithPredefinedTypesAsNames.symbols

@@ -12,3 +12,9 @@ interface boolean { }
 >boolean : Symbol(boolean, Decl(interfacesWithPredefinedTypesAsNames.ts, 2, 20))
 
 interface void {}
+interface unknown {}
+>unknown : Symbol(unknown, Decl(interfacesWithPredefinedTypesAsNames.ts, 4, 17))
+
+interface never {}
+>never : Symbol(never, Decl(interfacesWithPredefinedTypesAsNames.ts, 5, 20))
+

tests/baselines/reference/interfacesWithPredefinedTypesAsNames.types

@@ -8,3 +8,5 @@ interface void {}
 >void {} : undefined
 >{} : {}
 
+interface unknown {}
+interface never {}

tests/baselines/reference/internalAliasInterfaceInsideLocalModuleWithoutExportAccessError.errors.txt

@@ -1,4 +1,4 @@
-tests/cases/compiler/internalAliasInterfaceInsideLocalModuleWithoutExportAccessError.ts(11,10): error TS2809: Namespace 'c' from module 'tests/cases/compiler/internalAliasInterfaceInsideLocalModuleWithoutExportAccessError' has no exported member 'b'.
+tests/cases/compiler/internalAliasInterfaceInsideLocalModuleWithoutExportAccessError.ts(11,10): error TS2810: Namespace 'c' from module 'tests/cases/compiler/internalAliasInterfaceInsideLocalModuleWithoutExportAccessError' has no exported member 'b'.
 
 
 ==== tests/cases/compiler/internalAliasInterfaceInsideLocalModuleWithoutExportAccessError.ts (1 errors) ====
@@ -14,4 +14,4 @@ tests/cases/compiler/internalAliasInterfaceInsideLocalModuleWithoutExportAccessE
     
     var x: c.b;
              ~
-!!! error TS2809: Namespace 'c' from module 'tests/cases/compiler/internalAliasInterfaceInsideLocalModuleWithoutExportAccessError' has no exported member 'b'.
+!!! error TS2810: Namespace 'c' from module 'tests/cases/compiler/internalAliasInterfaceInsideLocalModuleWithoutExportAccessError' has no exported member 'b'.

tests/baselines/reference/internalAliasUninitializedModuleInsideLocalModuleWithoutExportAccessError.errors.txt

@@ -1,4 +1,4 @@
-tests/cases/compiler/internalAliasUninitializedModuleInsideLocalModuleWithoutExportAccessError.ts(16,17): error TS2809: Namespace 'c' from module 'tests/cases/compiler/internalAliasUninitializedModuleInsideLocalModuleWithoutExportAccessError' has no exported member 'b'.
+tests/cases/compiler/internalAliasUninitializedModuleInsideLocalModuleWithoutExportAccessError.ts(16,17): error TS2810: Namespace 'c' from module 'tests/cases/compiler/internalAliasUninitializedModuleInsideLocalModuleWithoutExportAccessError' has no exported member 'b'.
 
 
 ==== tests/cases/compiler/internalAliasUninitializedModuleInsideLocalModuleWithoutExportAccessError.ts (1 errors) ====
@@ -19,4 +19,4 @@ tests/cases/compiler/internalAliasUninitializedModuleInsideLocalModuleWithoutExp
     
     export var z: c.b.I;
                     ~
-!!! error TS2809: Namespace 'c' from module 'tests/cases/compiler/internalAliasUninitializedModuleInsideLocalModuleWithoutExportAccessError' has no exported member 'b'.
+!!! error TS2810: Namespace 'c' from module 'tests/cases/compiler/internalAliasUninitializedModuleInsideLocalModuleWithoutExportAccessError' has no exported member 'b'.

tests/baselines/reference/invalidInstantiatedModule.errors.txt

@@ -1,6 +1,6 @@
 tests/cases/conformance/internalModules/moduleDeclarations/invalidInstantiatedModule.ts(2,18): error TS2300: Duplicate identifier 'Point'.
 tests/cases/conformance/internalModules/moduleDeclarations/invalidInstantiatedModule.ts(3,16): error TS2300: Duplicate identifier 'Point'.
-tests/cases/conformance/internalModules/moduleDeclarations/invalidInstantiatedModule.ts(12,8): error TS2811: Cannot find namespace 'm'. Did you mean 'M?
+tests/cases/conformance/internalModules/moduleDeclarations/invalidInstantiatedModule.ts(12,8): error TS2812: Cannot find namespace 'm'. Did you mean 'M?
 
 
 ==== tests/cases/conformance/internalModules/moduleDeclarations/invalidInstantiatedModule.ts (3 errors) ====
@@ -21,7 +21,7 @@ tests/cases/conformance/internalModules/moduleDeclarations/invalidInstantiatedMo
     var m = M2;
     var p: m.Point; // Error
            ~
-!!! error TS2811: Cannot find namespace 'm'. Did you mean 'M?
+!!! error TS2812: Cannot find namespace 'm'. Did you mean 'M?
 !!! related TS2728 tests/cases/conformance/internalModules/moduleDeclarations/invalidInstantiatedModule.ts:1:8: 'M' is declared here.
     
     

tests/baselines/reference/isomorphicMappedTypeInference.js

@@ -350,12 +350,14 @@ declare function applySpec<T>(obj: Spec<T>): (...args: any[]) => T;
 declare var g1: (...args: any[]) => {
     sum: number;
     nested: {
-        mul: any;
+        mul: string;
     };
 };
 declare var g2: (...args: any[]) => {
     foo: {
-        bar: any;
+        bar: {
+            baz: boolean;
+        };
     };
 };
 declare const foo: <T>(object: T, partial: Partial<T>) => T;

tests/baselines/reference/isomorphicMappedTypeInference.types

@@ -434,8 +434,8 @@ declare function applySpec<T>(obj: Spec<T>): (...args: any[]) => T;
 
 // Infers g1: (...args: any[]) => { sum: number, nested: { mul: string } }
 var g1 = applySpec({
->g1 : (...args: any[]) => { sum: number; nested: { mul: any; }; }
->applySpec({    sum: (a: any) => 3,    nested: {        mul: (b: any) => "n"    }}) : (...args: any[]) => { sum: number; nested: { mul: any; }; }
+>g1 : (...args: any[]) => { sum: number; nested: { mul: string; }; }
+>applySpec({    sum: (a: any) => 3,    nested: {        mul: (b: any) => "n"    }}) : (...args: any[]) => { sum: number; nested: { mul: string; }; }
 >applySpec : <T>(obj: Spec<T>) => (...args: any[]) => T
 >{    sum: (a: any) => 3,    nested: {        mul: (b: any) => "n"    }} : { sum: (a: any) => number; nested: { mul: (b: any) => string; }; }
 
@@ -459,8 +459,8 @@ var g1 = applySpec({
 
 // Infers g2: (...args: any[]) => { foo: { bar: { baz: boolean } } }
 var g2 = applySpec({ foo: { bar: { baz: (x: any) => true } } });
->g2 : (...args: any[]) => { foo: { bar: any; }; }
->applySpec({ foo: { bar: { baz: (x: any) => true } } }) : (...args: any[]) => { foo: { bar: any; }; }
+>g2 : (...args: any[]) => { foo: { bar: { baz: boolean; }; }; }
+>applySpec({ foo: { bar: { baz: (x: any) => true } } }) : (...args: any[]) => { foo: { bar: { baz: boolean; }; }; }
 >applySpec : <T>(obj: Spec<T>) => (...args: any[]) => T
 >{ foo: { bar: { baz: (x: any) => true } } } : { foo: { bar: { baz: (x: any) => boolean; }; }; }
 >foo : { bar: { baz: (x: any) => boolean; }; }

tests/baselines/reference/jsDeclarationsInterfaces.js

@@ -135,10 +135,10 @@ export interface B {
 export interface C<T_1, U_1> {
     new (): string;
     new (x: T_1): U_1;
-    new <Q_6>(x: Q_6): T_1 & Q_6;
+    new <Q_4>(x: Q_4): T_1 & Q_4;
     (): number;
     (x: T_1): U_1;
-    <Q_4>(x: Q_4): T_1 & Q_4;
+    <Q_3>(x: Q_3): T_1 & Q_3;
     field: T_1 & U_1;
     optionalField?: T_1;
     readonly readonlyField: T_1 & U_1;

tests/baselines/reference/jsDeclarationsParameterTagReusesInputNodeInEmit1.errors.txt

@@ -18,7 +18,7 @@ tests/cases/conformance/jsdoc/declarations/file.js(6,5): error TS4084: Exported
     
 ==== tests/cases/conformance/jsdoc/declarations/file.js (3 errors) ====
     /** @typedef {import('./base')} BaseFactory */
-        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 !!! error TS4084: Exported type alias 'BaseFactory' has or is using private name 'Base' from module "tests/cases/conformance/jsdoc/declarations/base".
     /**
      * @callback BaseFactoryFactory

tests/baselines/reference/jsDocSignature-43394.baseline

@@ -0,0 +1,9 @@
+[
+  {
+    "marker": {
+      "fileName": "/tests/cases/fourslash/jsDocSignature-43394.ts",
+      "position": 58,
+      "name": ""
+    }
+  }
+]

tests/baselines/reference/keyofGenericExtendingClassDoubleLayer.js

@@ -0,0 +1,56 @@
+//// [keyofGenericExtendingClassDoubleLayer.ts]
+class Model<Attributes = any> {
+    public createdAt: Date;
+}
+
+type ModelAttributes<T> = Omit<T, keyof Model>;
+
+class AutoModel<T> extends Model<ModelAttributes<T>> {}
+
+class PersonModel extends AutoModel<PersonModel> {
+    public age: number;
+
+    toJson() {
+        let x: keyof this = 'createdAt';
+    }
+}
+
+
+//// [keyofGenericExtendingClassDoubleLayer.js]
+var __extends = (this && this.__extends) || (function () {
+    var extendStatics = function (d, b) {
+        extendStatics = Object.setPrototypeOf ||
+            ({ __proto__: [] } instanceof Array && function (d, b) { d.__proto__ = b; }) ||
+            function (d, b) { for (var p in b) if (Object.prototype.hasOwnProperty.call(b, p)) d[p] = b[p]; };
+        return extendStatics(d, b);
+    };
+    return function (d, b) {
+        if (typeof b !== "function" && b !== null)
+            throw new TypeError("Class extends value " + String(b) + " is not a constructor or null");
+        extendStatics(d, b);
+        function __() { this.constructor = d; }
+        d.prototype = b === null ? Object.create(b) : (__.prototype = b.prototype, new __());
+    };
+})();
+var Model = /** @class */ (function () {
+    function Model() {
+    }
+    return Model;
+}());
+var AutoModel = /** @class */ (function (_super) {
+    __extends(AutoModel, _super);
+    function AutoModel() {
+        return _super !== null && _super.apply(this, arguments) || this;
+    }
+    return AutoModel;
+}(Model));
+var PersonModel = /** @class */ (function (_super) {
+    __extends(PersonModel, _super);
+    function PersonModel() {
+        return _super !== null && _super.apply(this, arguments) || this;
+    }
+    PersonModel.prototype.toJson = function () {
+        var x = 'createdAt';
+    };
+    return PersonModel;
+}(AutoModel));

tests/baselines/reference/keyofGenericExtendingClassDoubleLayer.symbols

@@ -0,0 +1,40 @@
+=== tests/cases/compiler/keyofGenericExtendingClassDoubleLayer.ts ===
+class Model<Attributes = any> {
+>Model : Symbol(Model, Decl(keyofGenericExtendingClassDoubleLayer.ts, 0, 0))
+>Attributes : Symbol(Attributes, Decl(keyofGenericExtendingClassDoubleLayer.ts, 0, 12))
+
+    public createdAt: Date;
+>createdAt : Symbol(Model.createdAt, Decl(keyofGenericExtendingClassDoubleLayer.ts, 0, 31))
+>Date : Symbol(Date, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.scripthost.d.ts, --, --))
+}
+
+type ModelAttributes<T> = Omit<T, keyof Model>;
+>ModelAttributes : Symbol(ModelAttributes, Decl(keyofGenericExtendingClassDoubleLayer.ts, 2, 1))
+>T : Symbol(T, Decl(keyofGenericExtendingClassDoubleLayer.ts, 4, 21))
+>Omit : Symbol(Omit, Decl(lib.es5.d.ts, --, --))
+>T : Symbol(T, Decl(keyofGenericExtendingClassDoubleLayer.ts, 4, 21))
+>Model : Symbol(Model, Decl(keyofGenericExtendingClassDoubleLayer.ts, 0, 0))
+
+class AutoModel<T> extends Model<ModelAttributes<T>> {}
+>AutoModel : Symbol(AutoModel, Decl(keyofGenericExtendingClassDoubleLayer.ts, 4, 47))
+>T : Symbol(T, Decl(keyofGenericExtendingClassDoubleLayer.ts, 6, 16))
+>Model : Symbol(Model, Decl(keyofGenericExtendingClassDoubleLayer.ts, 0, 0))
+>ModelAttributes : Symbol(ModelAttributes, Decl(keyofGenericExtendingClassDoubleLayer.ts, 2, 1))
+>T : Symbol(T, Decl(keyofGenericExtendingClassDoubleLayer.ts, 6, 16))
+
+class PersonModel extends AutoModel<PersonModel> {
+>PersonModel : Symbol(PersonModel, Decl(keyofGenericExtendingClassDoubleLayer.ts, 6, 55))
+>AutoModel : Symbol(AutoModel, Decl(keyofGenericExtendingClassDoubleLayer.ts, 4, 47))
+>PersonModel : Symbol(PersonModel, Decl(keyofGenericExtendingClassDoubleLayer.ts, 6, 55))
+
+    public age: number;
+>age : Symbol(PersonModel.age, Decl(keyofGenericExtendingClassDoubleLayer.ts, 8, 50))
+
+    toJson() {
+>toJson : Symbol(PersonModel.toJson, Decl(keyofGenericExtendingClassDoubleLayer.ts, 9, 23))
+
+        let x: keyof this = 'createdAt';
+>x : Symbol(x, Decl(keyofGenericExtendingClassDoubleLayer.ts, 12, 11))
+    }
+}
+

tests/baselines/reference/keyofGenericExtendingClassDoubleLayer.types

@@ -0,0 +1,31 @@
+=== tests/cases/compiler/keyofGenericExtendingClassDoubleLayer.ts ===
+class Model<Attributes = any> {
+>Model : Model<Attributes>
+
+    public createdAt: Date;
+>createdAt : Date
+}
+
+type ModelAttributes<T> = Omit<T, keyof Model>;
+>ModelAttributes : ModelAttributes<T>
+
+class AutoModel<T> extends Model<ModelAttributes<T>> {}
+>AutoModel : AutoModel<T>
+>Model : Model<ModelAttributes<T>>
+
+class PersonModel extends AutoModel<PersonModel> {
+>PersonModel : PersonModel
+>AutoModel : AutoModel<PersonModel>
+
+    public age: number;
+>age : number
+
+    toJson() {
+>toJson : () => void
+
+        let x: keyof this = 'createdAt';
+>x : keyof this
+>'createdAt' : "createdAt"
+    }
+}
+

tests/baselines/reference/missingCloseBracketInArray.errors.txt

@@ -0,0 +1,8 @@
+tests/cases/compiler/missingCloseBracketInArray.ts(1,48): error TS1005: ']' expected.
+
+
+==== tests/cases/compiler/missingCloseBracketInArray.ts (1 errors) ====
+    var alphas:string[] = alphas = ["1","2","3","4"
+                                                   
+!!! error TS1005: ']' expected.
+!!! related TS1007 tests/cases/compiler/missingCloseBracketInArray.ts:1:32: The parser expected to find a ']' to match the '[' token here.

tests/baselines/reference/missingCloseBracketInArray.js

@@ -0,0 +1,5 @@
+//// [missingCloseBracketInArray.ts]
+var alphas:string[] = alphas = ["1","2","3","4"
+
+//// [missingCloseBracketInArray.js]
+var alphas = alphas = ["1", "2", "3", "4"];

tests/baselines/reference/missingCloseBracketInArray.symbols

@@ -0,0 +1,5 @@
+=== tests/cases/compiler/missingCloseBracketInArray.ts ===
+var alphas:string[] = alphas = ["1","2","3","4"
+>alphas : Symbol(alphas, Decl(missingCloseBracketInArray.ts, 0, 3))
+>alphas : Symbol(alphas, Decl(missingCloseBracketInArray.ts, 0, 3))
+

tests/baselines/reference/missingCloseBracketInArray.types

@@ -0,0 +1,11 @@
+=== tests/cases/compiler/missingCloseBracketInArray.ts ===
+var alphas:string[] = alphas = ["1","2","3","4"
+>alphas : string[]
+>alphas = ["1","2","3","4" : string[]
+>alphas : string[]
+>["1","2","3","4" : string[]
+>"1" : "1"
+>"2" : "2"
+>"3" : "3"
+>"4" : "4"
+

tests/baselines/reference/missingCloseParenStatements.errors.txt

@@ -0,0 +1,32 @@
+tests/cases/compiler/missingCloseParenStatements.ts(2,26): error TS1005: ')' expected.
+tests/cases/compiler/missingCloseParenStatements.ts(4,5): error TS1005: ')' expected.
+tests/cases/compiler/missingCloseParenStatements.ts(8,39): error TS1005: ')' expected.
+tests/cases/compiler/missingCloseParenStatements.ts(11,35): error TS1005: ')' expected.
+
+
+==== tests/cases/compiler/missingCloseParenStatements.ts (4 errors) ====
+    var a1, a2, a3 = 0;
+    if ( a1 && (a2 + a3 > 0) {
+                             ~
+!!! error TS1005: ')' expected.
+!!! related TS1007 tests/cases/compiler/missingCloseParenStatements.ts:2:4: The parser expected to find a ')' to match the '(' token here.
+        while( (a2 > 0) && a1
+        {
+        ~
+!!! error TS1005: ')' expected.
+!!! related TS1007 tests/cases/compiler/missingCloseParenStatements.ts:3:10: The parser expected to find a ')' to match the '(' token here.
+            do {
+                var i = i + 1;
+                a1 = a1 + i;
+                with ((a2 + a3 > 0) && a1 {
+                                          ~
+!!! error TS1005: ')' expected.
+!!! related TS1007 tests/cases/compiler/missingCloseParenStatements.ts:8:18: The parser expected to find a ')' to match the '(' token here.
+                    console.log(x);
+                  }
+            } while (i < 5 && (a1 > 5);
+                                      ~
+!!! error TS1005: ')' expected.
+!!! related TS1007 tests/cases/compiler/missingCloseParenStatements.ts:11:17: The parser expected to find a ')' to match the '(' token here.
+        }
+    }

tests/baselines/reference/missingCloseParenStatements.js

@@ -0,0 +1,28 @@
+//// [missingCloseParenStatements.ts]
+var a1, a2, a3 = 0;
+if ( a1 && (a2 + a3 > 0) {
+    while( (a2 > 0) && a1
+    {
+        do {
+            var i = i + 1;
+            a1 = a1 + i;
+            with ((a2 + a3 > 0) && a1 {
+                console.log(x);
+              }
+        } while (i < 5 && (a1 > 5);
+    }
+}
+
+//// [missingCloseParenStatements.js]
+var a1, a2, a3 = 0;
+if (a1 && (a2 + a3 > 0)) {
+    while ((a2 > 0) && a1) {
+        do {
+            var i = i + 1;
+            a1 = a1 + i;
+            with ((a2 + a3 > 0) && a1) {
+                console.log(x);
+            }
+        } while (i < 5 && (a1 > 5));
+    }
+}

tests/baselines/reference/missingCloseParenStatements.symbols

@@ -0,0 +1,37 @@
+=== tests/cases/compiler/missingCloseParenStatements.ts ===
+var a1, a2, a3 = 0;
+>a1 : Symbol(a1, Decl(missingCloseParenStatements.ts, 0, 3))
+>a2 : Symbol(a2, Decl(missingCloseParenStatements.ts, 0, 7))
+>a3 : Symbol(a3, Decl(missingCloseParenStatements.ts, 0, 11))
+
+if ( a1 && (a2 + a3 > 0) {
+>a1 : Symbol(a1, Decl(missingCloseParenStatements.ts, 0, 3))
+>a2 : Symbol(a2, Decl(missingCloseParenStatements.ts, 0, 7))
+>a3 : Symbol(a3, Decl(missingCloseParenStatements.ts, 0, 11))
+
+    while( (a2 > 0) && a1
+>a2 : Symbol(a2, Decl(missingCloseParenStatements.ts, 0, 7))
+>a1 : Symbol(a1, Decl(missingCloseParenStatements.ts, 0, 3))
+    {
+        do {
+            var i = i + 1;
+>i : Symbol(i, Decl(missingCloseParenStatements.ts, 5, 15))
+>i : Symbol(i, Decl(missingCloseParenStatements.ts, 5, 15))
+
+            a1 = a1 + i;
+>a1 : Symbol(a1, Decl(missingCloseParenStatements.ts, 0, 3))
+>a1 : Symbol(a1, Decl(missingCloseParenStatements.ts, 0, 3))
+>i : Symbol(i, Decl(missingCloseParenStatements.ts, 5, 15))
+
+            with ((a2 + a3 > 0) && a1 {
+>a2 : Symbol(a2, Decl(missingCloseParenStatements.ts, 0, 7))
+>a3 : Symbol(a3, Decl(missingCloseParenStatements.ts, 0, 11))
+>a1 : Symbol(a1, Decl(missingCloseParenStatements.ts, 0, 3))
+
+                console.log(x);
+              }
+        } while (i < 5 && (a1 > 5);
+>i : Symbol(i, Decl(missingCloseParenStatements.ts, 5, 15))
+>a1 : Symbol(a1, Decl(missingCloseParenStatements.ts, 0, 3))
+    }
+}

tests/baselines/reference/missingCloseParenStatements.types

@@ -0,0 +1,67 @@
+=== tests/cases/compiler/missingCloseParenStatements.ts ===
+var a1, a2, a3 = 0;
+>a1 : any
+>a2 : any
+>a3 : number
+>0 : 0
+
+if ( a1 && (a2 + a3 > 0) {
+>a1 && (a2 + a3 > 0) : boolean
+>a1 : any
+>(a2 + a3 > 0) : boolean
+>a2 + a3 > 0 : boolean
+>a2 + a3 : any
+>a2 : any
+>a3 : number
+>0 : 0
+
+    while( (a2 > 0) && a1
+>(a2 > 0) && a1 : any
+>(a2 > 0) : boolean
+>a2 > 0 : boolean
+>a2 : any
+>0 : 0
+>a1 : any
+    {
+        do {
+            var i = i + 1;
+>i : any
+>i + 1 : any
+>i : any
+>1 : 1
+
+            a1 = a1 + i;
+>a1 = a1 + i : any
+>a1 : any
+>a1 + i : any
+>a1 : any
+>i : any
+
+            with ((a2 + a3 > 0) && a1 {
+>(a2 + a3 > 0) && a1 : any
+>(a2 + a3 > 0) : boolean
+>a2 + a3 > 0 : boolean
+>a2 + a3 : any
+>a2 : any
+>a3 : number
+>0 : 0
+>a1 : any
+
+                console.log(x);
+>console.log(x) : any
+>console.log : any
+>console : any
+>log : any
+>x : any
+              }
+        } while (i < 5 && (a1 > 5);
+>i < 5 && (a1 > 5) : boolean
+>i < 5 : boolean
+>i : any
+>5 : 5
+>(a1 > 5) : boolean
+>a1 > 5 : boolean
+>a1 : any
+>5 : 5
+    }
+}

tests/baselines/reference/nestedClassDeclaration.errors.txt

@@ -32,7 +32,6 @@ tests/cases/conformance/classes/nestedClassDeclaration.ts(17,1): error TS1128: D
 !!! error TS2304: Cannot find name 'C4'.
                  ~
 !!! error TS1005: ',' expected.
-!!! related TS1007 tests/cases/conformance/classes/nestedClassDeclaration.ts:14:9: The parser expected to find a '}' to match the '{' token here.
         }
     }
     ~

tests/baselines/reference/objectLiteralWithSemicolons4.errors.txt

@@ -9,5 +9,4 @@ tests/cases/compiler/objectLiteralWithSemicolons4.ts(3,1): error TS1005: ',' exp
 !!! error TS18004: No value exists in scope for the shorthand property 'a'. Either declare one or provide an initializer.
     ;
     ~
-!!! error TS1005: ',' expected.
-!!! related TS1007 tests/cases/compiler/objectLiteralWithSemicolons4.ts:1:9: The parser expected to find a '}' to match the '{' token here.
+!!! error TS1005: ',' expected.

tests/baselines/reference/objectSpreadNegativeParse.errors.txt

@@ -28,7 +28,6 @@ tests/cases/conformance/types/spread/objectSpreadNegativeParse.ts(4,20): error T
 !!! error TS2304: Cannot find name 'matchMedia'.
                                ~
 !!! error TS1005: ',' expected.
-!!! related TS1007 tests/cases/conformance/types/spread/objectSpreadNegativeParse.ts:3:10: The parser expected to find a '}' to match the '{' token here.
                                   ~
 !!! error TS1128: Declaration or statement expected.
     let o10 = { ...get x() { return 12; }};

tests/baselines/reference/parseErrorIncorrectReturnToken.errors.txt

@@ -25,7 +25,6 @@ tests/cases/compiler/parseErrorIncorrectReturnToken.ts(12,1): error TS1128: Decl
         m(n: number) => string {
                      ~~
 !!! error TS1005: '{' expected.
-!!! related TS1007 tests/cases/compiler/parseErrorIncorrectReturnToken.ts:8:9: The parser expected to find a '}' to match the '{' token here.
                         ~~~~~~
 !!! error TS2693: 'string' only refers to a type, but is being used as a value here.
                                ~

tests/baselines/reference/parserErrorRecoveryIfStatement2.errors.txt

@@ -11,6 +11,7 @@ tests/cases/conformance/parser/ecmascript5/ErrorRecovery/IfStatements/parserErro
       }
       ~
 !!! error TS1005: ')' expected.
+!!! related TS1007 tests/cases/conformance/parser/ecmascript5/ErrorRecovery/IfStatements/parserErrorRecoveryIfStatement2.ts:3:8: The parser expected to find a ')' to match the '(' token here.
       f2() {
       }
       f3() {

tests/baselines/reference/parserErrorRecoveryIfStatement3.errors.txt

@@ -11,6 +11,7 @@ tests/cases/conformance/parser/ecmascript5/ErrorRecovery/IfStatements/parserErro
       }
       ~
 !!! error TS1005: ')' expected.
+!!! related TS1007 tests/cases/conformance/parser/ecmascript5/ErrorRecovery/IfStatements/parserErrorRecoveryIfStatement3.ts:3:8: The parser expected to find a ')' to match the '(' token here.
       f2() {
       }
       f3() {

tests/baselines/reference/parserFuzz1.errors.txt

@@ -20,5 +20,4 @@ tests/cases/conformance/parser/ecmascript5/ErrorRecovery/parserFuzz1.ts(2,15): e
         ~~~~~~
 !!! error TS1005: ';' expected.
                   
-!!! error TS1005: '{' expected.
-!!! related TS1007 tests/cases/conformance/parser/ecmascript5/ErrorRecovery/parserFuzz1.ts:1:9: The parser expected to find a '}' to match the '{' token here.
+!!! error TS1005: '{' expected.

tests/baselines/reference/parserUnfinishedTypeNameBeforeKeyword1.errors.txt

@@ -1,11 +1,11 @@
-tests/cases/conformance/parser/ecmascript5/ErrorRecovery/parserUnfinishedTypeNameBeforeKeyword1.ts(1,8): error TS2811: Cannot find namespace 'TypeModule1'. Did you mean 'TypeModule2?
+tests/cases/conformance/parser/ecmascript5/ErrorRecovery/parserUnfinishedTypeNameBeforeKeyword1.ts(1,8): error TS2812: Cannot find namespace 'TypeModule1'. Did you mean 'TypeModule2?
 tests/cases/conformance/parser/ecmascript5/ErrorRecovery/parserUnfinishedTypeNameBeforeKeyword1.ts(1,20): error TS1003: Identifier expected.
 
 
 ==== tests/cases/conformance/parser/ecmascript5/ErrorRecovery/parserUnfinishedTypeNameBeforeKeyword1.ts (2 errors) ====
     var x: TypeModule1.
            ~~~~~~~~~~~
-!!! error TS2811: Cannot find namespace 'TypeModule1'. Did you mean 'TypeModule2?
+!!! error TS2812: Cannot find namespace 'TypeModule1'. Did you mean 'TypeModule2?
                        
 !!! error TS1003: Identifier expected.
     module TypeModule2 {

tests/baselines/reference/primaryExpressionMods.errors.txt

@@ -1,5 +1,5 @@
 tests/cases/compiler/primaryExpressionMods.ts(7,8): error TS2709: Cannot use namespace 'M' as a type.
-tests/cases/compiler/primaryExpressionMods.ts(11,8): error TS2811: Cannot find namespace 'm'. Did you mean 'M?
+tests/cases/compiler/primaryExpressionMods.ts(11,8): error TS2812: Cannot find namespace 'm'. Did you mean 'M?
 
 
 ==== tests/cases/compiler/primaryExpressionMods.ts (2 errors) ====
@@ -17,6 +17,6 @@ tests/cases/compiler/primaryExpressionMods.ts(11,8): error TS2811: Cannot find n
     var x2 = m.a;           // Same as M.a
     var q: m.P;             // Error
            ~
-!!! error TS2811: Cannot find namespace 'm'. Did you mean 'M?
+!!! error TS2812: Cannot find namespace 'm'. Did you mean 'M?
 !!! related TS2728 tests/cases/compiler/primaryExpressionMods.ts:1:8: 'M' is declared here.