Merge branch 'master' into isInMultiLineComment

src/compiler/checker.ts

@@ -5788,8 +5788,7 @@ namespace ts {
         }
 
         function isGenericMappedType(type: Type) {
-            return getObjectFlags(type) & ObjectFlags.Mapped &&
-                maybeTypeOfKind(getConstraintTypeFromMappedType(<MappedType>type), TypeFlags.TypeVariable | TypeFlags.Index);
+            return getObjectFlags(type) & ObjectFlags.Mapped && isGenericIndexType(getConstraintTypeFromMappedType(<MappedType>type));
         }
 
         function resolveStructuredTypeMembers(type: StructuredType): ResolvedType {
@@ -5901,6 +5900,10 @@ namespace ts {
         }
 
         function getConstraintOfIndexedAccess(type: IndexedAccessType) {
+            const transformed = getTransformedIndexedAccessType(type);
+            if (transformed) {
+                return transformed;
+            }
             const baseObjectType = getBaseConstraintOfType(type.objectType);
             const baseIndexType = getBaseConstraintOfType(type.indexType);
             return baseObjectType || baseIndexType ? getIndexedAccessType(baseObjectType || type.objectType, baseIndexType || type.indexType) : undefined;
@@ -5972,11 +5975,18 @@ namespace ts {
                     return stringType;
                 }
                 if (t.flags & TypeFlags.IndexedAccess) {
+                    const transformed = getTransformedIndexedAccessType(<IndexedAccessType>t);
+                    if (transformed) {
+                        return getBaseConstraint(transformed);
+                    }
                     const baseObjectType = getBaseConstraint((<IndexedAccessType>t).objectType);
                     const baseIndexType = getBaseConstraint((<IndexedAccessType>t).indexType);
                     const baseIndexedAccess = baseObjectType && baseIndexType ? getIndexedAccessType(baseObjectType, baseIndexType) : undefined;
                     return baseIndexedAccess && baseIndexedAccess !== unknownType ? getBaseConstraint(baseIndexedAccess) : undefined;
                 }
+                if (isGenericMappedType(t)) {
+                    return emptyObjectType;
+                }
                 return t;
             }
         }
@@ -7604,26 +7614,73 @@ namespace ts {
             return instantiateType(getTemplateTypeFromMappedType(type), templateMapper);
         }
 
-        function getIndexedAccessType(objectType: Type, indexType: Type, accessNode?: ElementAccessExpression | IndexedAccessTypeNode) {
-            // If the index type is generic, if the object type is generic and doesn't originate in an expression,
-            // or if the object type is a mapped type with a generic constraint, we are performing a higher-order
-            // index access where we cannot meaningfully access the properties of the object type. Note that for a
-            // generic T and a non-generic K, we eagerly resolve T[K] if it originates in an expression. This is to
-            // preserve backwards compatibility. For example, an element access 'this["foo"]' has always been resolved
-            // eagerly using the constraint type of 'this' at the given location.
-            if (maybeTypeOfKind(indexType, TypeFlags.TypeVariable | TypeFlags.Index) ||
-                maybeTypeOfKind(objectType, TypeFlags.TypeVariable) && !(accessNode && accessNode.kind === SyntaxKind.ElementAccessExpression) ||
-                isGenericMappedType(objectType)) {
+        function isGenericObjectType(type: Type): boolean {
+            return type.flags & TypeFlags.TypeVariable ? true :
+                getObjectFlags(type) & ObjectFlags.Mapped ? isGenericIndexType(getConstraintTypeFromMappedType(<MappedType>type)) :
+                type.flags & TypeFlags.UnionOrIntersection ? forEach((<UnionOrIntersectionType>type).types, isGenericObjectType) :
+                false;
+        }
+
+        function isGenericIndexType(type: Type): boolean {
+            return type.flags & (TypeFlags.TypeVariable | TypeFlags.Index) ? true :
+                type.flags & TypeFlags.UnionOrIntersection ? forEach((<UnionOrIntersectionType>type).types, isGenericIndexType) :
+                false;
+        }
+
+        // Return true if the given type is a non-generic object type with a string index signature and no
+        // other members.
+        function isStringIndexOnlyType(type: Type) {
+            if (type.flags & TypeFlags.Object && !isGenericMappedType(type)) {
+                const t = resolveStructuredTypeMembers(<ObjectType>type);
+                return t.properties.length === 0 &&
+                    t.callSignatures.length === 0 && t.constructSignatures.length === 0 &&
+                    t.stringIndexInfo && !t.numberIndexInfo;
+            }
+            return false;
+        }
+
+        // Given an indexed access type T[K], if T is an intersection containing one or more generic types and one or
+        // more object types with only a string index signature, e.g. '(U & V & { [x: string]: D })[K]', return a
+        // transformed type of the form '(U & V)[K] | D'. This allows us to properly reason about higher order indexed
+        // access types with default property values as expressed by D.
+        function getTransformedIndexedAccessType(type: IndexedAccessType): Type {
+            const objectType = type.objectType;
+            if (objectType.flags & TypeFlags.Intersection && isGenericObjectType(objectType) && some((<IntersectionType>objectType).types, isStringIndexOnlyType)) {
+                const regularTypes: Type[] = [];
+                const stringIndexTypes: Type[] = [];
+                for (const t of (<IntersectionType>objectType).types) {
+                    if (isStringIndexOnlyType(t)) {
+                        stringIndexTypes.push(getIndexTypeOfType(t, IndexKind.String));
+                    }
+                    else {
+                        regularTypes.push(t);
+                    }
+                }
+                return getUnionType([
+                    getIndexedAccessType(getIntersectionType(regularTypes), type.indexType),
+                    getIntersectionType(stringIndexTypes)
+                ]);
+            }
+            return undefined;
+        }
+
+        function getIndexedAccessType(objectType: Type, indexType: Type, accessNode?: ElementAccessExpression | IndexedAccessTypeNode): Type {
+            // If the object type is a mapped type { [P in K]: E }, where K is generic, we instantiate E using a mapper
+            // that substitutes the index type for P. For example, for an index access { [P in K]: Box<T[P]> }[X], we
+            // construct the type Box<T[X]>.
+            if (isGenericMappedType(objectType)) {
+                return getIndexedAccessForMappedType(<MappedType>objectType, indexType, accessNode);
+            }
+            // Otherwise, if the index type is generic, or if the object type is generic and doesn't originate in an
+            // expression, we are performing a higher-order index access where we cannot meaningfully access the properties
+            // of the object type. Note that for a generic T and a non-generic K, we eagerly resolve T[K] if it originates
+            // in an expression. This is to preserve backwards compatibility. For example, an element access 'this["foo"]'
+            // has always been resolved eagerly using the constraint type of 'this' at the given location.
+            if (isGenericIndexType(indexType) || !(accessNode && accessNode.kind === SyntaxKind.ElementAccessExpression) && isGenericObjectType(objectType)) {
                 if (objectType.flags & TypeFlags.Any) {
                     return objectType;
                 }
-                // If the object type is a mapped type { [P in K]: E }, we instantiate E using a mapper that substitutes
-                // the index type for P. For example, for an index access { [P in K]: Box<T[P]> }[X], we construct the
-                // type Box<T[X]>.
-                if (isGenericMappedType(objectType)) {
-                    return getIndexedAccessForMappedType(<MappedType>objectType, indexType, accessNode);
-                }
-                // Otherwise we defer the operation by creating an indexed access type.
+                // Defer the operation by creating an indexed access type.
                 const id = objectType.id + "," + indexType.id;
                 let type = indexedAccessTypes.get(id);
                 if (!type) {
@@ -8017,7 +8074,7 @@ namespace ts {
 
         function cloneTypeMapper(mapper: TypeMapper): TypeMapper {
             return mapper && isInferenceContext(mapper) ?
-                createInferenceContext(mapper.signature, mapper.flags | InferenceFlags.NoDefault, mapper.inferences) :
+                createInferenceContext(mapper.signature, mapper.flags | InferenceFlags.NoDefault, mapper.compareTypes, mapper.inferences) :
                 mapper;
         }
 
@@ -8458,7 +8515,7 @@ namespace ts {
             ignoreReturnTypes: boolean,
             reportErrors: boolean,
             errorReporter: ErrorReporter,
-            compareTypes: (s: Type, t: Type, reportErrors?: boolean) => Ternary): Ternary {
+            compareTypes: TypeComparer): Ternary {
             // TODO (drosen): De-duplicate code between related functions.
             if (source === target) {
                 return Ternary.True;
@@ -8468,7 +8525,7 @@ namespace ts {
             }
 
             if (source.typeParameters) {
-                source = instantiateSignatureInContextOf(source, target);
+                source = instantiateSignatureInContextOf(source, target, /*contextualMapper*/ undefined, compareTypes);
             }
 
             let result = Ternary.True;
@@ -9614,6 +9671,11 @@ namespace ts {
                 if (sourceInfo) {
                     return indexInfoRelatedTo(sourceInfo, targetInfo, reportErrors);
                 }
+                if (isGenericMappedType(source)) {
+                    // A generic mapped type { [P in K]: T } is related to an index signature { [x: string]: U }
+                    // if T is related to U.
+                    return kind === IndexKind.String && isRelatedTo(getTemplateTypeFromMappedType(<MappedType>source), targetInfo.type, reportErrors);
+                }
                 if (isObjectLiteralType(source)) {
                     let related = Ternary.True;
                     if (kind === IndexKind.String) {
@@ -10216,13 +10278,14 @@ namespace ts {
             }
         }
 
-        function createInferenceContext(signature: Signature, flags: InferenceFlags, baseInferences?: InferenceInfo[]): InferenceContext {
+        function createInferenceContext(signature: Signature, flags: InferenceFlags, compareTypes?: TypeComparer, baseInferences?: InferenceInfo[]): InferenceContext {
             const inferences = baseInferences ? map(baseInferences, cloneInferenceInfo) : map(signature.typeParameters, createInferenceInfo);
             const context = mapper as InferenceContext;
             context.mappedTypes = signature.typeParameters;
             context.signature = signature;
             context.inferences = inferences;
             context.flags = flags;
+            context.compareTypes = compareTypes || compareTypesAssignable;
             return context;
 
             function mapper(t: Type): Type {
@@ -10325,6 +10388,19 @@ namespace ts {
             }
         }
 
+        function isPossiblyAssignableTo(source: Type, target: Type) {
+            const properties = getPropertiesOfObjectType(target);
+            for (const targetProp of properties) {
+                if (!(targetProp.flags & (SymbolFlags.Optional | SymbolFlags.Prototype))) {
+                    const sourceProp = getPropertyOfObjectType(source, targetProp.escapedName);
+                    if (!sourceProp) {
+                        return false;
+                    }
+                }
+            }
+            return true;
+        }
+
         function inferTypes(inferences: InferenceInfo[], originalSource: Type, originalTarget: Type, priority: InferencePriority = 0) {
             let symbolStack: Symbol[];
             let visited: Map<boolean>;
@@ -10518,10 +10594,14 @@ namespace ts {
                         return;
                     }
                 }
-                inferFromProperties(source, target);
-                inferFromSignatures(source, target, SignatureKind.Call);
-                inferFromSignatures(source, target, SignatureKind.Construct);
-                inferFromIndexTypes(source, target);
+                // Infer from the members of source and target only if the two types are possibly related. We check
+                // in both directions because we may be inferring for a co-variant or a contra-variant position.
+                if (isPossiblyAssignableTo(source, target) || isPossiblyAssignableTo(target, source)) {
+                    inferFromProperties(source, target);
+                    inferFromSignatures(source, target, SignatureKind.Call);
+                    inferFromSignatures(source, target, SignatureKind.Construct);
+                    inferFromIndexTypes(source, target);
+                }
             }
 
             function inferFromProperties(source: Type, target: Type) {
@@ -10653,7 +10733,7 @@ namespace ts {
                 const constraint = getConstraintOfTypeParameter(context.signature.typeParameters[index]);
                 if (constraint) {
                     const instantiatedConstraint = instantiateType(constraint, context);
-                    if (!isTypeAssignableTo(inferredType, getTypeWithThisArgument(instantiatedConstraint, inferredType))) {
+                    if (!context.compareTypes(inferredType, getTypeWithThisArgument(instantiatedConstraint, inferredType))) {
                         inference.inferredType = inferredType = instantiatedConstraint;
                     }
                 }
@@ -15054,8 +15134,8 @@ namespace ts {
         }
 
         // Instantiate a generic signature in the context of a non-generic signature (section 3.8.5 in TypeScript spec)
-        function instantiateSignatureInContextOf(signature: Signature, contextualSignature: Signature, contextualMapper?: TypeMapper): Signature {
-            const context = createInferenceContext(signature, InferenceFlags.InferUnionTypes);
+        function instantiateSignatureInContextOf(signature: Signature, contextualSignature: Signature, contextualMapper?: TypeMapper, compareTypes?: TypeComparer): Signature {
+            const context = createInferenceContext(signature, InferenceFlags.InferUnionTypes, compareTypes);
             forEachMatchingParameterType(contextualSignature, signature, (source, target) => {
                 // Type parameters from outer context referenced by source type are fixed by instantiation of the source type
                 inferTypes(context.inferences, instantiateType(source, contextualMapper || identityMapper), target);

src/compiler/core.ts

@@ -11,20 +11,6 @@ namespace ts {
 
 /* @internal */
 namespace ts {
-    /**
-     * Ternary values are defined such that
-     * x & y is False if either x or y is False.
-     * x & y is Maybe if either x or y is Maybe, but neither x or y is False.
-     * x & y is True if both x and y are True.
-     * x | y is False if both x and y are False.
-     * x | y is Maybe if either x or y is Maybe, but neither x or y is True.
-     * x | y is True if either x or y is True.
-     */
-    export const enum Ternary {
-        False = 0,
-        Maybe = 1,
-        True = -1
-    }
 
     // More efficient to create a collator once and use its `compare` than to call `a.localeCompare(b)` many times.
     export const collator: { compare(a: string, b: string): number } = typeof Intl === "object" && typeof Intl.Collator === "function" ? new Intl.Collator(/*locales*/ undefined, { usage: "sort", sensitivity: "accent" }) : undefined;

src/compiler/emitter.ts

@@ -1346,7 +1346,9 @@ namespace ts {
 
             emitExpression(node.left);
             increaseIndentIf(indentBeforeOperator, isCommaOperator ? " " : undefined);
+            emitLeadingCommentsOfPosition(node.operatorToken.pos);
             writeTokenNode(node.operatorToken);
+            emitTrailingCommentsOfPosition(node.operatorToken.end);
             increaseIndentIf(indentAfterOperator, " ");
             emitExpression(node.right);
             decreaseIndentIf(indentBeforeOperator, indentAfterOperator);

src/compiler/parser.ts

@@ -2061,7 +2061,7 @@ namespace ts {
             return <TemplateMiddle | TemplateTail>fragment;
         }
 
-        function parseLiteralLikeNode(kind: SyntaxKind): LiteralLikeNode {
+        function parseLiteralLikeNode(kind: SyntaxKind): LiteralExpression | LiteralLikeNode {
             const node = <LiteralExpression>createNode(kind);
             const text = scanner.getTokenValue();
             node.text = text;
@@ -2611,11 +2611,31 @@ namespace ts {
             return token() === SyntaxKind.DotToken ? undefined : node;
         }
 
-        function parseLiteralTypeNode(): LiteralTypeNode {
-            const node = <LiteralTypeNode>createNode(SyntaxKind.LiteralType);
-            node.literal = parseSimpleUnaryExpression();
-            finishNode(node);
-            return node;
+        function parseLiteralTypeNode(negative?: boolean): LiteralTypeNode {
+            const node = createNode(SyntaxKind.LiteralType) as LiteralTypeNode;
+            let unaryMinusExpression: PrefixUnaryExpression;
+            if (negative) {
+                unaryMinusExpression = createNode(SyntaxKind.PrefixUnaryExpression) as PrefixUnaryExpression;
+                unaryMinusExpression.operator = SyntaxKind.MinusToken;
+                nextToken();
+            }
+            let expression: UnaryExpression;
+            switch (token()) {
+                case SyntaxKind.StringLiteral:
+                case SyntaxKind.NumericLiteral:
+                    expression = parseLiteralLikeNode(token()) as LiteralExpression;
+                    break;
+                case SyntaxKind.TrueKeyword:
+                case SyntaxKind.FalseKeyword:
+                    expression = parseTokenNode();
+            }
+            if (negative) {
+                unaryMinusExpression.operand = expression;
+                finishNode(unaryMinusExpression);
+                expression = unaryMinusExpression;
+            }
+            node.literal = expression;
+            return finishNode(node);
         }
 
         function nextTokenIsNumericLiteral() {
@@ -2650,7 +2670,7 @@ namespace ts {
                 case SyntaxKind.FalseKeyword:
                     return parseLiteralTypeNode();
                 case SyntaxKind.MinusToken:
-                    return lookAhead(nextTokenIsNumericLiteral) ? parseLiteralTypeNode() : parseTypeReference();
+                    return lookAhead(nextTokenIsNumericLiteral) ? parseLiteralTypeNode(/*negative*/ true) : parseTypeReference();
                 case SyntaxKind.VoidKeyword:
                 case SyntaxKind.NullKeyword:
                     return parseTokenNode<TypeNode>();

src/compiler/types.ts

@@ -3425,11 +3425,29 @@ namespace ts {
         AnyDefault      = 1 << 2,  // Infer anyType for no inferences (otherwise emptyObjectType)
     }
 
+    /**
+     * Ternary values are defined such that
+     * x & y is False if either x or y is False.
+     * x & y is Maybe if either x or y is Maybe, but neither x or y is False.
+     * x & y is True if both x and y are True.
+     * x | y is False if both x and y are False.
+     * x | y is Maybe if either x or y is Maybe, but neither x or y is True.
+     * x | y is True if either x or y is True.
+     */
+    export const enum Ternary {
+        False = 0,
+        Maybe = 1,
+        True = -1
+    }
+
+    export type TypeComparer = (s: Type, t: Type, reportErrors?: boolean) => Ternary;
+
     /* @internal */
     export interface InferenceContext extends TypeMapper {
         signature: Signature;               // Generic signature for which inferences are made
         inferences: InferenceInfo[];        // Inferences made for each type parameter
         flags: InferenceFlags;              // Inference flags
+        compareTypes: TypeComparer;         // Type comparer function
     }
 
     /* @internal */

src/services/completions.ts

@@ -1000,7 +1000,7 @@ namespace ts.Completions {
                     const typeForObject = typeChecker.getTypeAtLocation(objectLikeContainer);
                     if (!typeForObject) return false;
                     // In a binding pattern, get only known properties. Everywhere else we will get all possible properties.
-                    typeMembers = typeChecker.getPropertiesOfType(typeForObject);
+                    typeMembers = typeChecker.getPropertiesOfType(typeForObject).filter((symbol) => !(getDeclarationModifierFlagsFromSymbol(symbol) & ModifierFlags.NonPublicAccessibilityModifier));
                     existingMembers = (<ObjectBindingPattern>objectLikeContainer).elements;
                 }
             }

tests/baselines/reference/commentOnBinaryOperator1.js

@@ -0,0 +1,25 @@
+//// [commentOnBinaryOperator1.ts]
+var a = 'some'
+    // comment
+    + 'text';
+
+var b = 'some'
+    /* comment */
+    + 'text';
+
+var c = 'some'
+    /* comment */
+    + /*comment1*/
+    'text';
+
+//// [commentOnBinaryOperator1.js]
+var a = 'some'
+    // comment
+    + 'text';
+var b = 'some'
+    /* comment */
+    + 'text';
+var c = 'some'
+    /* comment */
+    +/*comment1*/ 
+        'text';

tests/baselines/reference/commentOnBinaryOperator1.symbols

@@ -0,0 +1,19 @@
+=== tests/cases/compiler/commentOnBinaryOperator1.ts ===
+var a = 'some'
+>a : Symbol(a, Decl(commentOnBinaryOperator1.ts, 0, 3))
+
+    // comment
+    + 'text';
+
+var b = 'some'
+>b : Symbol(b, Decl(commentOnBinaryOperator1.ts, 4, 3))
+
+    /* comment */
+    + 'text';
+
+var c = 'some'
+>c : Symbol(c, Decl(commentOnBinaryOperator1.ts, 8, 3))
+
+    /* comment */
+    + /*comment1*/
+    'text';

tests/baselines/reference/commentOnBinaryOperator1.types

@@ -0,0 +1,29 @@
+=== tests/cases/compiler/commentOnBinaryOperator1.ts ===
+var a = 'some'
+>a : string
+>'some'    // comment    + 'text' : string
+>'some' : "some"
+
+    // comment
+    + 'text';
+>'text' : "text"
+
+var b = 'some'
+>b : string
+>'some'    /* comment */    + 'text' : string
+>'some' : "some"
+
+    /* comment */
+    + 'text';
+>'text' : "text"
+
+var c = 'some'
+>c : string
+>'some'    /* comment */    + /*comment1*/    'text' : string
+>'some' : "some"
+
+    /* comment */
+    + /*comment1*/
+    'text';
+>'text' : "text"
+

tests/baselines/reference/commentOnBinaryOperator2.js

@@ -0,0 +1,22 @@
+//// [commentOnBinaryOperator2.ts]
+var a = 'some'
+    // comment
+    + 'text';
+
+var b = 'some'
+    /* comment */
+    + 'text';
+
+var c = 'some'
+    /* comment */
+    + /*comment1*/
+    'text';
+
+//// [commentOnBinaryOperator2.js]
+var a = 'some'
+    + 'text';
+var b = 'some'
+    + 'text';
+var c = 'some'
+    +
+        'text';

tests/baselines/reference/commentOnBinaryOperator2.symbols

@@ -0,0 +1,19 @@
+=== tests/cases/compiler/commentOnBinaryOperator2.ts ===
+var a = 'some'
+>a : Symbol(a, Decl(commentOnBinaryOperator2.ts, 0, 3))
+
+    // comment
+    + 'text';
+
+var b = 'some'
+>b : Symbol(b, Decl(commentOnBinaryOperator2.ts, 4, 3))
+
+    /* comment */
+    + 'text';
+
+var c = 'some'
+>c : Symbol(c, Decl(commentOnBinaryOperator2.ts, 8, 3))
+
+    /* comment */
+    + /*comment1*/
+    'text';

tests/baselines/reference/commentOnBinaryOperator2.types

@@ -0,0 +1,29 @@
+=== tests/cases/compiler/commentOnBinaryOperator2.ts ===
+var a = 'some'
+>a : string
+>'some'    // comment    + 'text' : string
+>'some' : "some"
+
+    // comment
+    + 'text';
+>'text' : "text"
+
+var b = 'some'
+>b : string
+>'some'    /* comment */    + 'text' : string
+>'some' : "some"
+
+    /* comment */
+    + 'text';
+>'text' : "text"
+
+var c = 'some'
+>c : string
+>'some'    /* comment */    + /*comment1*/    'text' : string
+>'some' : "some"
+
+    /* comment */
+    + /*comment1*/
+    'text';
+>'text' : "text"
+

tests/baselines/reference/commentsArgumentsOfCallExpression2.js

@@ -14,7 +14,7 @@ foo(
 function foo(/*c1*/ x, /*d1*/ y, /*e1*/ w) { }
 var a, b;
 foo(/*c2*/ 1, /*d2*/ 1 + 2, /*e1*/ a + b);
-foo(/*c3*/ function () { }, /*d2*/ function () { }, /*e2*/ a + b);
+foo(/*c3*/ function () { }, /*d2*/ function () { }, /*e2*/ a +/*e3*/  b);
 foo(/*c3*/ function () { }, /*d3*/ function () { }, /*e3*/ (a + b));
 foo(
 /*c4*/ function () { }, 

tests/baselines/reference/deferredLookupTypeResolution.js

@@ -0,0 +1,64 @@
+//// [deferredLookupTypeResolution.ts]
+// Repro from #17456
+
+type StringContains<S extends string, L extends string> = (
+    { [K in S]:      'true' } &
+    { [key: string]: 'false' }
+  )[L]
+
+type ObjectHasKey<O, L extends string> = StringContains<keyof O, L>
+
+type First<T> = ObjectHasKey<T, '0'>;  // Should be deferred
+
+type T1 = ObjectHasKey<{ a: string }, 'a'>;  // 'true'
+type T2 = ObjectHasKey<{ a: string }, 'b'>;  // 'false'
+
+// Verify that mapped type isn't eagerly resolved in type-to-string operation
+
+declare function f1<A extends string, B extends string>(a: A, b: B): { [P in A | B]: any };
+
+function f2<A extends string>(a: A) {
+    return f1(a, 'x');
+}
+
+function f3(x: 'a' | 'b') {
+    return f2(x);
+}
+
+
+//// [deferredLookupTypeResolution.js]
+"use strict";
+// Repro from #17456
+function f2(a) {
+    return f1(a, 'x');
+}
+function f3(x) {
+    return f2(x);
+}
+
+
+//// [deferredLookupTypeResolution.d.ts]
+declare type StringContains<S extends string, L extends string> = ({
+    [K in S]: 'true';
+} & {
+    [key: string]: 'false';
+})[L];
+declare type ObjectHasKey<O, L extends string> = StringContains<keyof O, L>;
+declare type First<T> = ObjectHasKey<T, '0'>;
+declare type T1 = ObjectHasKey<{
+    a: string;
+}, 'a'>;
+declare type T2 = ObjectHasKey<{
+    a: string;
+}, 'b'>;
+declare function f1<A extends string, B extends string>(a: A, b: B): {
+    [P in A | B]: any;
+};
+declare function f2<A extends string>(a: A): {
+    [P in A | "x"]: any;
+};
+declare function f3(x: 'a' | 'b'): {
+    a: any;
+    b: any;
+    x: any;
+};

tests/baselines/reference/deferredLookupTypeResolution.symbols

@@ -0,0 +1,76 @@
+=== tests/cases/compiler/deferredLookupTypeResolution.ts ===
+// Repro from #17456
+
+type StringContains<S extends string, L extends string> = (
+>StringContains : Symbol(StringContains, Decl(deferredLookupTypeResolution.ts, 0, 0))
+>S : Symbol(S, Decl(deferredLookupTypeResolution.ts, 2, 20))
+>L : Symbol(L, Decl(deferredLookupTypeResolution.ts, 2, 37))
+
+    { [K in S]:      'true' } &
+>K : Symbol(K, Decl(deferredLookupTypeResolution.ts, 3, 7))
+>S : Symbol(S, Decl(deferredLookupTypeResolution.ts, 2, 20))
+
+    { [key: string]: 'false' }
+>key : Symbol(key, Decl(deferredLookupTypeResolution.ts, 4, 7))
+
+  )[L]
+>L : Symbol(L, Decl(deferredLookupTypeResolution.ts, 2, 37))
+
+type ObjectHasKey<O, L extends string> = StringContains<keyof O, L>
+>ObjectHasKey : Symbol(ObjectHasKey, Decl(deferredLookupTypeResolution.ts, 5, 6))
+>O : Symbol(O, Decl(deferredLookupTypeResolution.ts, 7, 18))
+>L : Symbol(L, Decl(deferredLookupTypeResolution.ts, 7, 20))
+>StringContains : Symbol(StringContains, Decl(deferredLookupTypeResolution.ts, 0, 0))
+>O : Symbol(O, Decl(deferredLookupTypeResolution.ts, 7, 18))
+>L : Symbol(L, Decl(deferredLookupTypeResolution.ts, 7, 20))
+
+type First<T> = ObjectHasKey<T, '0'>;  // Should be deferred
+>First : Symbol(First, Decl(deferredLookupTypeResolution.ts, 7, 67))
+>T : Symbol(T, Decl(deferredLookupTypeResolution.ts, 9, 11))
+>ObjectHasKey : Symbol(ObjectHasKey, Decl(deferredLookupTypeResolution.ts, 5, 6))
+>T : Symbol(T, Decl(deferredLookupTypeResolution.ts, 9, 11))
+
+type T1 = ObjectHasKey<{ a: string }, 'a'>;  // 'true'
+>T1 : Symbol(T1, Decl(deferredLookupTypeResolution.ts, 9, 37))
+>ObjectHasKey : Symbol(ObjectHasKey, Decl(deferredLookupTypeResolution.ts, 5, 6))
+>a : Symbol(a, Decl(deferredLookupTypeResolution.ts, 11, 24))
+
+type T2 = ObjectHasKey<{ a: string }, 'b'>;  // 'false'
+>T2 : Symbol(T2, Decl(deferredLookupTypeResolution.ts, 11, 43))
+>ObjectHasKey : Symbol(ObjectHasKey, Decl(deferredLookupTypeResolution.ts, 5, 6))
+>a : Symbol(a, Decl(deferredLookupTypeResolution.ts, 12, 24))
+
+// Verify that mapped type isn't eagerly resolved in type-to-string operation
+
+declare function f1<A extends string, B extends string>(a: A, b: B): { [P in A | B]: any };
+>f1 : Symbol(f1, Decl(deferredLookupTypeResolution.ts, 12, 43))
+>A : Symbol(A, Decl(deferredLookupTypeResolution.ts, 16, 20))
+>B : Symbol(B, Decl(deferredLookupTypeResolution.ts, 16, 37))
+>a : Symbol(a, Decl(deferredLookupTypeResolution.ts, 16, 56))
+>A : Symbol(A, Decl(deferredLookupTypeResolution.ts, 16, 20))
+>b : Symbol(b, Decl(deferredLookupTypeResolution.ts, 16, 61))
+>B : Symbol(B, Decl(deferredLookupTypeResolution.ts, 16, 37))
+>P : Symbol(P, Decl(deferredLookupTypeResolution.ts, 16, 72))
+>A : Symbol(A, Decl(deferredLookupTypeResolution.ts, 16, 20))
+>B : Symbol(B, Decl(deferredLookupTypeResolution.ts, 16, 37))
+
+function f2<A extends string>(a: A) {
+>f2 : Symbol(f2, Decl(deferredLookupTypeResolution.ts, 16, 91))
+>A : Symbol(A, Decl(deferredLookupTypeResolution.ts, 18, 12))
+>a : Symbol(a, Decl(deferredLookupTypeResolution.ts, 18, 30))
+>A : Symbol(A, Decl(deferredLookupTypeResolution.ts, 18, 12))
+
+    return f1(a, 'x');
+>f1 : Symbol(f1, Decl(deferredLookupTypeResolution.ts, 12, 43))
+>a : Symbol(a, Decl(deferredLookupTypeResolution.ts, 18, 30))
+}
+
+function f3(x: 'a' | 'b') {
+>f3 : Symbol(f3, Decl(deferredLookupTypeResolution.ts, 20, 1))
+>x : Symbol(x, Decl(deferredLookupTypeResolution.ts, 22, 12))
+
+    return f2(x);
+>f2 : Symbol(f2, Decl(deferredLookupTypeResolution.ts, 16, 91))
+>x : Symbol(x, Decl(deferredLookupTypeResolution.ts, 22, 12))
+}
+

tests/baselines/reference/deferredLookupTypeResolution.types

@@ -0,0 +1,79 @@
+=== tests/cases/compiler/deferredLookupTypeResolution.ts ===
+// Repro from #17456
+
+type StringContains<S extends string, L extends string> = (
+>StringContains : ({ [K in S]: "true"; } & { [key: string]: "false"; })[L]
+>S : S
+>L : L
+
+    { [K in S]:      'true' } &
+>K : K
+>S : S
+
+    { [key: string]: 'false' }
+>key : string
+
+  )[L]
+>L : L
+
+type ObjectHasKey<O, L extends string> = StringContains<keyof O, L>
+>ObjectHasKey : ({ [K in S]: "true"; } & { [key: string]: "false"; })[L]
+>O : O
+>L : L
+>StringContains : ({ [K in S]: "true"; } & { [key: string]: "false"; })[L]
+>O : O
+>L : L
+
+type First<T> = ObjectHasKey<T, '0'>;  // Should be deferred
+>First : ({ [K in S]: "true"; } & { [key: string]: "false"; })["0"]
+>T : T
+>ObjectHasKey : ({ [K in S]: "true"; } & { [key: string]: "false"; })[L]
+>T : T
+
+type T1 = ObjectHasKey<{ a: string }, 'a'>;  // 'true'
+>T1 : "true"
+>ObjectHasKey : ({ [K in S]: "true"; } & { [key: string]: "false"; })[L]
+>a : string
+
+type T2 = ObjectHasKey<{ a: string }, 'b'>;  // 'false'
+>T2 : "false"
+>ObjectHasKey : ({ [K in S]: "true"; } & { [key: string]: "false"; })[L]
+>a : string
+
+// Verify that mapped type isn't eagerly resolved in type-to-string operation
+
+declare function f1<A extends string, B extends string>(a: A, b: B): { [P in A | B]: any };
+>f1 : <A extends string, B extends string>(a: A, b: B) => { [P in A | B]: any; }
+>A : A
+>B : B
+>a : A
+>A : A
+>b : B
+>B : B
+>P : P
+>A : A
+>B : B
+
+function f2<A extends string>(a: A) {
+>f2 : <A extends string>(a: A) => { [P in A | B]: any; }
+>A : A
+>a : A
+>A : A
+
+    return f1(a, 'x');
+>f1(a, 'x') : { [P in A | B]: any; }
+>f1 : <A extends string, B extends string>(a: A, b: B) => { [P in A | B]: any; }
+>a : A
+>'x' : "x"
+}
+
+function f3(x: 'a' | 'b') {
+>f3 : (x: "a" | "b") => { a: any; b: any; x: any; }
+>x : "a" | "b"
+
+    return f2(x);
+>f2(x) : { a: any; b: any; x: any; }
+>f2 : <A extends string>(a: A) => { [P in A | B]: any; }
+>x : "a" | "b"
+}
+

tests/baselines/reference/deferredLookupTypeResolution2.errors.txt

@@ -0,0 +1,31 @@
+tests/cases/compiler/deferredLookupTypeResolution2.ts(14,13): error TS2536: Type '({ [K in S]: "true"; } & { [key: string]: "false"; })["1"]' cannot be used to index type '{ true: "true"; }'.
+tests/cases/compiler/deferredLookupTypeResolution2.ts(19,21): error TS2536: Type '({ true: "otherwise"; } & { [k: string]: "true"; })[({ [K in S]: "true"; } & { [key: string]: "false"; })["1"]]' cannot be used to index type '{ true: "true"; }'.
+
+
+==== tests/cases/compiler/deferredLookupTypeResolution2.ts (2 errors) ====
+    // Repro from #17456
+    
+    type StringContains<S extends string, L extends string> = ({ [K in S]: 'true' } & { [key: string]: 'false'})[L];
+    
+    type ObjectHasKey<O, L extends string> = StringContains<keyof O, L>;
+    
+    type A<T> = ObjectHasKey<T, '0'>;
+    
+    type B = ObjectHasKey<[string, number], '1'>;  // "true"
+    type C = ObjectHasKey<[string, number], '2'>;  // "false"
+    type D = A<[string]>;  // "true"
+    
+    // Error, "false" not handled
+    type E<T> = { true: 'true' }[ObjectHasKey<T, '1'>];
+                ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+!!! error TS2536: Type '({ [K in S]: "true"; } & { [key: string]: "false"; })["1"]' cannot be used to index type '{ true: "true"; }'.
+    
+    type Juxtapose<T> = ({ true: 'otherwise' } & { [k: string]: 'true' })[ObjectHasKey<T, '1'>];
+    
+    // Error, "otherwise" is missing
+    type DeepError<T> = { true: 'true' }[Juxtapose<T>];
+                        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+!!! error TS2536: Type '({ true: "otherwise"; } & { [k: string]: "true"; })[({ [K in S]: "true"; } & { [key: string]: "false"; })["1"]]' cannot be used to index type '{ true: "true"; }'.
+    
+    type DeepOK<T> = { true: 'true', otherwise: 'false' }[Juxtapose<T>];
+    

tests/baselines/reference/deferredLookupTypeResolution2.js

@@ -0,0 +1,55 @@
+//// [deferredLookupTypeResolution2.ts]
+// Repro from #17456
+
+type StringContains<S extends string, L extends string> = ({ [K in S]: 'true' } & { [key: string]: 'false'})[L];
+
+type ObjectHasKey<O, L extends string> = StringContains<keyof O, L>;
+
+type A<T> = ObjectHasKey<T, '0'>;
+
+type B = ObjectHasKey<[string, number], '1'>;  // "true"
+type C = ObjectHasKey<[string, number], '2'>;  // "false"
+type D = A<[string]>;  // "true"
+
+// Error, "false" not handled
+type E<T> = { true: 'true' }[ObjectHasKey<T, '1'>];
+
+type Juxtapose<T> = ({ true: 'otherwise' } & { [k: string]: 'true' })[ObjectHasKey<T, '1'>];
+
+// Error, "otherwise" is missing
+type DeepError<T> = { true: 'true' }[Juxtapose<T>];
+
+type DeepOK<T> = { true: 'true', otherwise: 'false' }[Juxtapose<T>];
+
+
+//// [deferredLookupTypeResolution2.js]
+"use strict";
+// Repro from #17456
+
+
+//// [deferredLookupTypeResolution2.d.ts]
+declare type StringContains<S extends string, L extends string> = ({
+    [K in S]: 'true';
+} & {
+    [key: string]: 'false';
+})[L];
+declare type ObjectHasKey<O, L extends string> = StringContains<keyof O, L>;
+declare type A<T> = ObjectHasKey<T, '0'>;
+declare type B = ObjectHasKey<[string, number], '1'>;
+declare type C = ObjectHasKey<[string, number], '2'>;
+declare type D = A<[string]>;
+declare type E<T> = {
+    true: 'true';
+}[ObjectHasKey<T, '1'>];
+declare type Juxtapose<T> = ({
+    true: 'otherwise';
+} & {
+    [k: string]: 'true';
+})[ObjectHasKey<T, '1'>];
+declare type DeepError<T> = {
+    true: 'true';
+}[Juxtapose<T>];
+declare type DeepOK<T> = {
+    true: 'true';
+    otherwise: 'false';
+}[Juxtapose<T>];

tests/baselines/reference/doNotInferUnrelatedTypes.js

@@ -0,0 +1,11 @@
+//// [doNotInferUnrelatedTypes.ts]
+// #16709
+declare function dearray<T>(ara: ReadonlyArray<T>): T;
+type LiteralType = "foo" | "bar";
+declare var alt: Array<LiteralType>;
+
+let foo: LiteralType = dearray(alt);
+
+
+//// [doNotInferUnrelatedTypes.js]
+var foo = dearray(alt);

tests/baselines/reference/doNotInferUnrelatedTypes.symbols

@@ -0,0 +1,24 @@
+=== tests/cases/compiler/doNotInferUnrelatedTypes.ts ===
+// #16709
+declare function dearray<T>(ara: ReadonlyArray<T>): T;
+>dearray : Symbol(dearray, Decl(doNotInferUnrelatedTypes.ts, 0, 0))
+>T : Symbol(T, Decl(doNotInferUnrelatedTypes.ts, 1, 25))
+>ara : Symbol(ara, Decl(doNotInferUnrelatedTypes.ts, 1, 28))
+>ReadonlyArray : Symbol(ReadonlyArray, Decl(lib.d.ts, --, --))
+>T : Symbol(T, Decl(doNotInferUnrelatedTypes.ts, 1, 25))
+>T : Symbol(T, Decl(doNotInferUnrelatedTypes.ts, 1, 25))
+
+type LiteralType = "foo" | "bar";
+>LiteralType : Symbol(LiteralType, Decl(doNotInferUnrelatedTypes.ts, 1, 54))
+
+declare var alt: Array<LiteralType>;
+>alt : Symbol(alt, Decl(doNotInferUnrelatedTypes.ts, 3, 11))
+>Array : Symbol(Array, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
+>LiteralType : Symbol(LiteralType, Decl(doNotInferUnrelatedTypes.ts, 1, 54))
+
+let foo: LiteralType = dearray(alt);
+>foo : Symbol(foo, Decl(doNotInferUnrelatedTypes.ts, 5, 3))
+>LiteralType : Symbol(LiteralType, Decl(doNotInferUnrelatedTypes.ts, 1, 54))
+>dearray : Symbol(dearray, Decl(doNotInferUnrelatedTypes.ts, 0, 0))
+>alt : Symbol(alt, Decl(doNotInferUnrelatedTypes.ts, 3, 11))
+

tests/baselines/reference/doNotInferUnrelatedTypes.types

@@ -0,0 +1,25 @@
+=== tests/cases/compiler/doNotInferUnrelatedTypes.ts ===
+// #16709
+declare function dearray<T>(ara: ReadonlyArray<T>): T;
+>dearray : <T>(ara: ReadonlyArray<T>) => T
+>T : T
+>ara : ReadonlyArray<T>
+>ReadonlyArray : ReadonlyArray<T>
+>T : T
+>T : T
+
+type LiteralType = "foo" | "bar";
+>LiteralType : LiteralType
+
+declare var alt: Array<LiteralType>;
+>alt : LiteralType[]
+>Array : T[]
+>LiteralType : LiteralType
+
+let foo: LiteralType = dearray(alt);
+>foo : LiteralType
+>LiteralType : LiteralType
+>dearray(alt) : LiteralType
+>dearray : <T>(ara: ReadonlyArray<T>) => T
+>alt : LiteralType[]
+

tests/baselines/reference/expressionTypeNodeShouldError.errors.txt

@@ -0,0 +1,90 @@
+tests/cases/compiler/base.d.ts(1,23): error TS1005: ',' expected.
+tests/cases/compiler/base.d.ts(1,34): error TS1005: '=' expected.
+tests/cases/compiler/boolean.ts(7,23): error TS1005: ',' expected.
+tests/cases/compiler/boolean.ts(7,24): error TS1134: Variable declaration expected.
+tests/cases/compiler/boolean.ts(11,16): error TS2304: Cannot find name 'document'.
+tests/cases/compiler/boolean.ts(12,22): error TS1005: ';' expected.
+tests/cases/compiler/number.ts(7,26): error TS1005: ',' expected.
+tests/cases/compiler/number.ts(7,27): error TS1134: Variable declaration expected.
+tests/cases/compiler/number.ts(11,16): error TS2304: Cannot find name 'document'.
+tests/cases/compiler/number.ts(12,20): error TS1005: ';' expected.
+tests/cases/compiler/string.ts(7,20): error TS1005: ',' expected.
+tests/cases/compiler/string.ts(7,21): error TS1134: Variable declaration expected.
+tests/cases/compiler/string.ts(11,15): error TS2304: Cannot find name 'document'.
+tests/cases/compiler/string.ts(12,19): error TS1005: ';' expected.
+
+
+==== tests/cases/compiler/base.d.ts (2 errors) ====
+    declare const x: "foo".charCodeAt(0);
+                          ~
+!!! error TS1005: ',' expected.
+                                     ~
+!!! error TS1005: '=' expected.
+    
+==== tests/cases/compiler/string.ts (4 errors) ====
+    interface String {
+        typeof<T>(x: T): T;
+    }
+    
+    class C {
+        foo() {
+            const x: "".typeof(this.foo);
+                       ~
+!!! error TS1005: ',' expected.
+                        ~~~~~~
+!!! error TS1134: Variable declaration expected.
+        }
+    }
+    
+    const nodes = document.getElementsByTagName("li");
+                  ~~~~~~~~
+!!! error TS2304: Cannot find name 'document'.
+    type ItemType = "".typeof(nodes.item(0));
+                      ~
+!!! error TS1005: ';' expected.
+    
+==== tests/cases/compiler/number.ts (4 errors) ====
+    interface Number {
+        typeof<T>(x: T): T;
+    }
+    
+    class C2 {
+        foo() {
+            const x: 3.141592.typeof(this.foo);
+                             ~
+!!! error TS1005: ',' expected.
+                              ~~~~~~
+!!! error TS1134: Variable declaration expected.
+        }
+    }
+    
+    const nodes2 = document.getElementsByTagName("li");
+                   ~~~~~~~~
+!!! error TS2304: Cannot find name 'document'.
+    type ItemType2 = 4..typeof(nodes.item(0));
+                       ~
+!!! error TS1005: ';' expected.
+    
+==== tests/cases/compiler/boolean.ts (4 errors) ====
+    interface Boolean {
+        typeof<T>(x: T): T;
+    }
+    
+    class C3 {
+        foo() {
+            const x: false.typeof(this.foo);
+                          ~
+!!! error TS1005: ',' expected.
+                           ~~~~~~
+!!! error TS1134: Variable declaration expected.
+        }
+    }
+    
+    const nodes3 = document.getElementsByTagName("li");
+                   ~~~~~~~~
+!!! error TS2304: Cannot find name 'document'.
+    type ItemType3 = true.typeof(nodes.item(0));
+                         ~
+!!! error TS1005: ';' expected.
+    
+    

tests/baselines/reference/expressionTypeNodeShouldError.js

@@ -0,0 +1,85 @@
+//// [tests/cases/compiler/expressionTypeNodeShouldError.ts] ////
+
+//// [base.d.ts]
+declare const x: "foo".charCodeAt(0);
+
+//// [string.ts]
+interface String {
+    typeof<T>(x: T): T;
+}
+
+class C {
+    foo() {
+        const x: "".typeof(this.foo);
+    }
+}
+
+const nodes = document.getElementsByTagName("li");
+type ItemType = "".typeof(nodes.item(0));
+
+//// [number.ts]
+interface Number {
+    typeof<T>(x: T): T;
+}
+
+class C2 {
+    foo() {
+        const x: 3.141592.typeof(this.foo);
+    }
+}
+
+const nodes2 = document.getElementsByTagName("li");
+type ItemType2 = 4..typeof(nodes.item(0));
+
+//// [boolean.ts]
+interface Boolean {
+    typeof<T>(x: T): T;
+}
+
+class C3 {
+    foo() {
+        const x: false.typeof(this.foo);
+    }
+}
+
+const nodes3 = document.getElementsByTagName("li");
+type ItemType3 = true.typeof(nodes.item(0));
+
+
+
+//// [string.js]
+var C = (function () {
+    function C() {
+    }
+    C.prototype.foo = function () {
+        var x;
+        typeof (this.foo);
+    };
+    return C;
+}());
+var nodes = document.getElementsByTagName("li");
+typeof (nodes.item(0));
+//// [number.js]
+var C2 = (function () {
+    function C2() {
+    }
+    C2.prototype.foo = function () {
+        var x;
+        typeof (this.foo);
+    };
+    return C2;
+}());
+var nodes2 = document.getElementsByTagName("li");
+typeof (nodes.item(0));
+//// [boolean.js]
+var C3 = (function () {
+    function C3() {
+    }
+    C3.prototype.foo = function () {
+        var x;
+        typeof (this.foo);
+    };
+    return C3;
+}());
+var nodes3 = document.getElementsByTagName("li");
+typeof (nodes.item(0));

tests/baselines/reference/indexSignatureAndMappedType.errors.txt

@@ -0,0 +1,47 @@
+tests/cases/compiler/indexSignatureAndMappedType.ts(6,5): error TS2322: Type '{ [key: string]: T; }' is not assignable to type 'Record<K, T>'.
+tests/cases/compiler/indexSignatureAndMappedType.ts(15,5): error TS2322: Type 'Record<K, U>' is not assignable to type '{ [key: string]: T; }'.
+  Type 'U' is not assignable to type 'T'.
+tests/cases/compiler/indexSignatureAndMappedType.ts(16,5): error TS2322: Type '{ [key: string]: T; }' is not assignable to type 'Record<K, U>'.
+
+
+==== tests/cases/compiler/indexSignatureAndMappedType.ts (3 errors) ====
+    // A mapped type { [P in K]: X }, where K is a generic type, is related to
+    // { [key: string]: Y } if X is related to Y.
+    
+    function f1<T, K extends string>(x: { [key: string]: T }, y: Record<K, T>) {
+        x = y;
+        y = x;  // Error
+        ~
+!!! error TS2322: Type '{ [key: string]: T; }' is not assignable to type 'Record<K, T>'.
+    }
+    
+    function f2<T>(x: { [key: string]: T }, y: Record<string, T>) {
+        x = y;
+        y = x;
+    }
+    
+    function f3<T, U, K extends string>(x: { [key: string]: T }, y: Record<K, U>) {
+        x = y;  // Error
+        ~
+!!! error TS2322: Type 'Record<K, U>' is not assignable to type '{ [key: string]: T; }'.
+!!! error TS2322:   Type 'U' is not assignable to type 'T'.
+        y = x;  // Error
+        ~
+!!! error TS2322: Type '{ [key: string]: T; }' is not assignable to type 'Record<K, U>'.
+    }
+    
+    // Repro from #14548
+    
+    type Dictionary = {
+        [key: string]: string;
+    };
+    
+    interface IBaseEntity {
+        name: string;
+        properties: Dictionary;
+    }
+    
+    interface IEntity<T extends string> extends IBaseEntity {
+        properties: Record<T, string>;
+    }
+    

tests/baselines/reference/indexSignatureAndMappedType.js

@@ -0,0 +1,73 @@
+//// [indexSignatureAndMappedType.ts]
+// A mapped type { [P in K]: X }, where K is a generic type, is related to
+// { [key: string]: Y } if X is related to Y.
+
+function f1<T, K extends string>(x: { [key: string]: T }, y: Record<K, T>) {
+    x = y;
+    y = x;  // Error
+}
+
+function f2<T>(x: { [key: string]: T }, y: Record<string, T>) {
+    x = y;
+    y = x;
+}
+
+function f3<T, U, K extends string>(x: { [key: string]: T }, y: Record<K, U>) {
+    x = y;  // Error
+    y = x;  // Error
+}
+
+// Repro from #14548
+
+type Dictionary = {
+    [key: string]: string;
+};
+
+interface IBaseEntity {
+    name: string;
+    properties: Dictionary;
+}
+
+interface IEntity<T extends string> extends IBaseEntity {
+    properties: Record<T, string>;
+}
+
+
+//// [indexSignatureAndMappedType.js]
+"use strict";
+// A mapped type { [P in K]: X }, where K is a generic type, is related to
+// { [key: string]: Y } if X is related to Y.
+function f1(x, y) {
+    x = y;
+    y = x; // Error
+}
+function f2(x, y) {
+    x = y;
+    y = x;
+}
+function f3(x, y) {
+    x = y; // Error
+    y = x; // Error
+}
+
+
+//// [indexSignatureAndMappedType.d.ts]
+declare function f1<T, K extends string>(x: {
+    [key: string]: T;
+}, y: Record<K, T>): void;
+declare function f2<T>(x: {
+    [key: string]: T;
+}, y: Record<string, T>): void;
+declare function f3<T, U, K extends string>(x: {
+    [key: string]: T;
+}, y: Record<K, U>): void;
+declare type Dictionary = {
+    [key: string]: string;
+};
+interface IBaseEntity {
+    name: string;
+    properties: Dictionary;
+}
+interface IEntity<T extends string> extends IBaseEntity {
+    properties: Record<T, string>;
+}

tests/baselines/reference/jsdocTypeTagCast.js

@@ -97,7 +97,7 @@ var a;
 /** @type {string} */
 var s;
 var a = ("" + 4);
-var s = "" + (4);
+var s = "" +/** @type {*} */  (4);
 var SomeBase = (function () {
     function SomeBase() {
         this.p = 42;
@@ -128,19 +128,19 @@ var someBase = new SomeBase();
 var someDerived = new SomeDerived();
 var someOther = new SomeOther();
 var someFakeClass = new SomeFakeClass();
-someBase = (someDerived);
-someBase = (someBase);
-someBase = (someOther); // Error
-someDerived = (someDerived);
-someDerived = (someBase);
-someDerived = (someOther); // Error
-someOther = (someDerived); // Error
-someOther = (someBase); // Error
-someOther = (someOther);
+someBase =/** @type {SomeBase} */  (someDerived);
+someBase =/** @type {SomeBase} */  (someBase);
+someBase =/** @type {SomeBase} */  (someOther); // Error
+someDerived =/** @type {SomeDerived} */  (someDerived);
+someDerived =/** @type {SomeDerived} */  (someBase);
+someDerived =/** @type {SomeDerived} */  (someOther); // Error
+someOther =/** @type {SomeOther} */  (someDerived); // Error
+someOther =/** @type {SomeOther} */  (someBase); // Error
+someOther =/** @type {SomeOther} */  (someOther);
 someFakeClass = someBase;
 someFakeClass = someDerived;
 someBase = someFakeClass; // Error
-someBase = (someFakeClass);
+someBase =/** @type {SomeBase} */  (someFakeClass);
 // Type assertion cannot be a type-predicate type
 /** @type {number | string} */
 var numOrStr;

tests/baselines/reference/parser15.4.4.14-9-2.js

@@ -41,9 +41,9 @@ function testcase() {
     var one = 1;
     var _float = -(4 / 3);
     var a = new Array(false, undefined, null, "0", obj, -1.3333333333333, "str", -0, true, +0, one, 1, 0, false, _float, -(4 / 3));
-    if (a.indexOf(-(4 / 3)) === 14 &&
-        a.indexOf(0) === 7 &&
-        a.indexOf(-0) === 7 &&
+    if (a.indexOf(-(4 / 3)) === 14 &&// a[14]=_float===-(4/3)
+        a.indexOf(0) === 7 &&// a[7] = +0, 0===+0
+        a.indexOf(-0) === 7 &&// a[7] = +0, -0===+0
         a.indexOf(1) === 10) {
         return true;
     }

tests/baselines/reference/parserGreaterThanTokenAmbiguity10.js

@@ -6,5 +6,6 @@
 
 //// [parserGreaterThanTokenAmbiguity10.js]
 1
-    >>>
+    // before
+    >>>// after
         2;

tests/baselines/reference/parserGreaterThanTokenAmbiguity15.js

@@ -6,5 +6,6 @@
 
 //// [parserGreaterThanTokenAmbiguity15.js]
 1
-    >>=
+    // before
+    >>=// after
         2;

tests/baselines/reference/parserGreaterThanTokenAmbiguity20.js

@@ -6,5 +6,6 @@
 
 //// [parserGreaterThanTokenAmbiguity20.js]
 1
-    >>>=
+    // Before
+    >>>=// after
         2;

tests/baselines/reference/parserGreaterThanTokenAmbiguity5.js

@@ -6,5 +6,6 @@
 
 //// [parserGreaterThanTokenAmbiguity5.js]
 1
-    >>
+    // before
+    >>// after
         2;

tests/baselines/reference/signatureInstantiationWithRecursiveConstraints.js

@@ -0,0 +1,30 @@
+//// [signatureInstantiationWithRecursiveConstraints.ts]
+// Repro from #17148
+
+class Foo {
+  myFunc<T extends Foo>(arg: T) {}
+}
+
+class Bar {
+  myFunc<T extends Bar>(arg: T) {}
+}
+
+const myVar: Foo = new Bar();
+
+
+//// [signatureInstantiationWithRecursiveConstraints.js]
+"use strict";
+// Repro from #17148
+var Foo = (function () {
+    function Foo() {
+    }
+    Foo.prototype.myFunc = function (arg) { };
+    return Foo;
+}());
+var Bar = (function () {
+    function Bar() {
+    }
+    Bar.prototype.myFunc = function (arg) { };
+    return Bar;
+}());
+var myVar = new Bar();

tests/baselines/reference/signatureInstantiationWithRecursiveConstraints.symbols

@@ -0,0 +1,30 @@
+=== tests/cases/compiler/signatureInstantiationWithRecursiveConstraints.ts ===
+// Repro from #17148
+
+class Foo {
+>Foo : Symbol(Foo, Decl(signatureInstantiationWithRecursiveConstraints.ts, 0, 0))
+
+  myFunc<T extends Foo>(arg: T) {}
+>myFunc : Symbol(Foo.myFunc, Decl(signatureInstantiationWithRecursiveConstraints.ts, 2, 11))
+>T : Symbol(T, Decl(signatureInstantiationWithRecursiveConstraints.ts, 3, 9))
+>Foo : Symbol(Foo, Decl(signatureInstantiationWithRecursiveConstraints.ts, 0, 0))
+>arg : Symbol(arg, Decl(signatureInstantiationWithRecursiveConstraints.ts, 3, 24))
+>T : Symbol(T, Decl(signatureInstantiationWithRecursiveConstraints.ts, 3, 9))
+}
+
+class Bar {
+>Bar : Symbol(Bar, Decl(signatureInstantiationWithRecursiveConstraints.ts, 4, 1))
+
+  myFunc<T extends Bar>(arg: T) {}
+>myFunc : Symbol(Bar.myFunc, Decl(signatureInstantiationWithRecursiveConstraints.ts, 6, 11))
+>T : Symbol(T, Decl(signatureInstantiationWithRecursiveConstraints.ts, 7, 9))
+>Bar : Symbol(Bar, Decl(signatureInstantiationWithRecursiveConstraints.ts, 4, 1))
+>arg : Symbol(arg, Decl(signatureInstantiationWithRecursiveConstraints.ts, 7, 24))
+>T : Symbol(T, Decl(signatureInstantiationWithRecursiveConstraints.ts, 7, 9))
+}
+
+const myVar: Foo = new Bar();
+>myVar : Symbol(myVar, Decl(signatureInstantiationWithRecursiveConstraints.ts, 10, 5))
+>Foo : Symbol(Foo, Decl(signatureInstantiationWithRecursiveConstraints.ts, 0, 0))
+>Bar : Symbol(Bar, Decl(signatureInstantiationWithRecursiveConstraints.ts, 4, 1))
+

tests/baselines/reference/signatureInstantiationWithRecursiveConstraints.types

@@ -0,0 +1,31 @@
+=== tests/cases/compiler/signatureInstantiationWithRecursiveConstraints.ts ===
+// Repro from #17148
+
+class Foo {
+>Foo : Foo
+
+  myFunc<T extends Foo>(arg: T) {}
+>myFunc : <T extends Foo>(arg: T) => void
+>T : T
+>Foo : Foo
+>arg : T
+>T : T
+}
+
+class Bar {
+>Bar : Bar
+
+  myFunc<T extends Bar>(arg: T) {}
+>myFunc : <T extends Bar>(arg: T) => void
+>T : T
+>Bar : Bar
+>arg : T
+>T : T
+}
+
+const myVar: Foo = new Bar();
+>myVar : Foo
+>Foo : Foo
+>new Bar() : Bar
+>Bar : typeof Bar
+

tests/baselines/reference/typeGuardsInConditionalExpression.js

@@ -138,7 +138,7 @@ function foo8(x) {
     var b;
     return typeof x === "string"
         ? x === "hello"
-        : ((b = x) &&
+        : ((b = x) &&//  number | boolean
             (typeof x === "boolean"
                 ? x // boolean
                 : x == 10)); // boolean

tests/cases/compiler/commentOnBinaryOperator1.ts

@@ -0,0 +1,12 @@
+var a = 'some'
+    // comment
+    + 'text';
+
+var b = 'some'
+    /* comment */
+    + 'text';
+
+var c = 'some'
+    /* comment */
+    + /*comment1*/
+    'text';

tests/cases/compiler/commentOnBinaryOperator2.ts

@@ -0,0 +1,13 @@
+// @removeComments: true
+var a = 'some'
+    // comment
+    + 'text';
+
+var b = 'some'
+    /* comment */
+    + 'text';
+
+var c = 'some'
+    /* comment */
+    + /*comment1*/
+    'text';

tests/cases/compiler/deferredLookupTypeResolution.ts

@@ -0,0 +1,28 @@
+// @strict: true
+// @declaration: true
+
+// Repro from #17456
+
+type StringContains<S extends string, L extends string> = (
+    { [K in S]:      'true' } &
+    { [key: string]: 'false' }
+  )[L]
+
+type ObjectHasKey<O, L extends string> = StringContains<keyof O, L>
+
+type First<T> = ObjectHasKey<T, '0'>;  // Should be deferred
+
+type T1 = ObjectHasKey<{ a: string }, 'a'>;  // 'true'
+type T2 = ObjectHasKey<{ a: string }, 'b'>;  // 'false'
+
+// Verify that mapped type isn't eagerly resolved in type-to-string operation
+
+declare function f1<A extends string, B extends string>(a: A, b: B): { [P in A | B]: any };
+
+function f2<A extends string>(a: A) {
+    return f1(a, 'x');
+}
+
+function f3(x: 'a' | 'b') {
+    return f2(x);
+}

tests/cases/compiler/deferredLookupTypeResolution2.ts

@@ -0,0 +1,24 @@
+// @strict: true
+// @declaration: true
+
+// Repro from #17456
+
+type StringContains<S extends string, L extends string> = ({ [K in S]: 'true' } & { [key: string]: 'false'})[L];
+
+type ObjectHasKey<O, L extends string> = StringContains<keyof O, L>;
+
+type A<T> = ObjectHasKey<T, '0'>;
+
+type B = ObjectHasKey<[string, number], '1'>;  // "true"
+type C = ObjectHasKey<[string, number], '2'>;  // "false"
+type D = A<[string]>;  // "true"
+
+// Error, "false" not handled
+type E<T> = { true: 'true' }[ObjectHasKey<T, '1'>];
+
+type Juxtapose<T> = ({ true: 'otherwise' } & { [k: string]: 'true' })[ObjectHasKey<T, '1'>];
+
+// Error, "otherwise" is missing
+type DeepError<T> = { true: 'true' }[Juxtapose<T>];
+
+type DeepOK<T> = { true: 'true', otherwise: 'false' }[Juxtapose<T>];

tests/cases/compiler/doNotInferUnrelatedTypes.ts

@@ -0,0 +1,6 @@
+// #16709
+declare function dearray<T>(ara: ReadonlyArray<T>): T;
+type LiteralType = "foo" | "bar";
+declare var alt: Array<LiteralType>;
+
+let foo: LiteralType = dearray(alt);

tests/cases/compiler/expressionTypeNodeShouldError.ts

@@ -0,0 +1,45 @@
+// @Filename: base.d.ts
+declare const x: "foo".charCodeAt(0);
+
+// @filename: string.ts
+interface String {
+    typeof<T>(x: T): T;
+}
+
+class C {
+    foo() {
+        const x: "".typeof(this.foo);
+    }
+}
+
+const nodes = document.getElementsByTagName("li");
+type ItemType = "".typeof(nodes.item(0));
+
+// @filename: number.ts
+interface Number {
+    typeof<T>(x: T): T;
+}
+
+class C2 {
+    foo() {
+        const x: 3.141592.typeof(this.foo);
+    }
+}
+
+const nodes2 = document.getElementsByTagName("li");
+type ItemType2 = 4..typeof(nodes.item(0));
+
+// @filename: boolean.ts
+interface Boolean {
+    typeof<T>(x: T): T;
+}
+
+class C3 {
+    foo() {
+        const x: false.typeof(this.foo);
+    }
+}
+
+const nodes3 = document.getElementsByTagName("li");
+type ItemType3 = true.typeof(nodes.item(0));
+

tests/cases/compiler/indexSignatureAndMappedType.ts

@@ -0,0 +1,35 @@
+// @strict: true
+// @declaration: true
+
+// A mapped type { [P in K]: X }, where K is a generic type, is related to
+// { [key: string]: Y } if X is related to Y.
+
+function f1<T, K extends string>(x: { [key: string]: T }, y: Record<K, T>) {
+    x = y;
+    y = x;  // Error
+}
+
+function f2<T>(x: { [key: string]: T }, y: Record<string, T>) {
+    x = y;
+    y = x;
+}
+
+function f3<T, U, K extends string>(x: { [key: string]: T }, y: Record<K, U>) {
+    x = y;  // Error
+    y = x;  // Error
+}
+
+// Repro from #14548
+
+type Dictionary = {
+    [key: string]: string;
+};
+
+interface IBaseEntity {
+    name: string;
+    properties: Dictionary;
+}
+
+interface IEntity<T extends string> extends IBaseEntity {
+    properties: Record<T, string>;
+}

tests/cases/compiler/signatureInstantiationWithRecursiveConstraints.ts

@@ -0,0 +1,13 @@
+// @strict: true
+
+// Repro from #17148
+
+class Foo {
+  myFunc<T extends Foo>(arg: T) {}
+}
+
+class Bar {
+  myFunc<T extends Bar>(arg: T) {}
+}
+
+const myVar: Foo = new Bar();

tests/cases/fourslash/completionListInObjectBindingPattern14.ts

@@ -0,0 +1,9 @@
+/// <reference path="fourslash.ts"/>
+
+////const { b/**/ } = new class {
+////    private ab;
+////    protected bc;
+////}
+
+goTo.marker();
+verify.completionListIsEmpty();