added isolated declarations flag.

src/compiler/commandLineParser.ts

@@ -795,6 +795,14 @@ const commandOptionsWithoutBuild: CommandLineOption[] = [
         description: Diagnostics.Do_not_transform_or_elide_any_imports_or_exports_not_marked_as_type_only_ensuring_they_are_written_in_the_output_file_s_format_based_on_the_module_setting,
         defaultValueDescription: false,
     },
+    {
+        name: "isolatedDeclarations",
+        type: "boolean",
+        category: Diagnostics.Interop_Constraints,
+        description: Diagnostics.Ensure_that_each_file_can_have_declaration_emit_generated_without_type_information,
+        transpileOptionValue: true,
+        defaultValueDescription: false,
+    },
 
     // Strict Type Checks
     {

src/compiler/diagnosticMessages.json

@@ -6067,6 +6067,11 @@
         "category": "Message",
         "code": 6718
     },
+    "Ensure that each file can have declaration emit generated without type information": {
+        "category": "Message",
+        "code": 6719
+    },
+
     "Default catch clause variables as 'unknown' instead of 'any'.": {
         "category": "Message",
         "code": 6803
@@ -6581,6 +6586,10 @@
         "category": "Error",
         "code": 9006
     },
+    "Declaration emit for this file requires type resolution. An explicit type annotation may unblock declaration emit.": {
+        "category": "Error",
+        "code": 9007
+    },
     "JSX attributes must only be assigned a non-empty 'expression'.": {
         "category": "Error",
         "code": 17000

src/compiler/transformers/declarations.ts

@@ -317,8 +317,15 @@ export function transformDeclarations(context: TransformationContext) {
     const resolver = context.getEmitResolver();
     const options = context.getCompilerOptions();
     const { noResolve, stripInternal } = options;
+    const isolatedDeclarations = false;
     return transformRoot;
 
+    function reportIsolatedDeclarationError(_node: Node) {
+        // context.addDiagnostic(createDiagnosticForNode(
+        //     node,
+        //     Diagnostics.Declaration_emit_for_this_file_requires_type_resolution_An_explicit_type_annotation_may_unblock_declaration_emit
+        // ));
+    }
     function recordTypeReferenceDirectivesIfNecessary(typeReferenceDirectives: readonly [specifier: string, mode: ResolutionMode][] | undefined): void {
         if (!typeReferenceDirectives) {
             return;
@@ -739,6 +746,7 @@ export function transformDeclarations(context: TransformationContext) {
     }
 
     function shouldPrintWithInitializer(node: Node) {
+        if (isolatedDeclarations) return false;
         return canHaveLiteralInitializer(node) && resolver.isLiteralConstDeclaration(getParseTreeNode(node) as CanHaveLiteralInitializer); // TODO: Make safe
     }
 
@@ -772,6 +780,13 @@ export function transformDeclarations(context: TransformationContext) {
             // Literal const declarations will have an initializer ensured rather than a type
             return;
         }
+        if (isolatedDeclarations) {
+            if (type == undefined) {
+                reportIsolatedDeclarationError(node);
+                return factory.createTypeReferenceNode("invalid");
+            }
+            return visitNode(type, visitDeclarationSubtree);
+        }
         const shouldUseResolverType = node.kind === SyntaxKind.Parameter &&
             (resolver.isRequiredInitializedParameter(node) ||
              resolver.isOptionalUninitializedParameterProperty(node));
@@ -1387,7 +1402,13 @@ export function transformDeclarations(context: TransformationContext) {
                         errorNode: input
                     });
                     errorFallbackNode = input;
-                    const varDecl = factory.createVariableDeclaration(newId, /*exclamationToken*/ undefined, resolver.createTypeOfExpression(input.expression, input, declarationEmitNodeBuilderFlags, symbolTracker), /*initializer*/ undefined);
+                    if (isolatedDeclarations) {
+                        reportIsolatedDeclarationError(input);
+                    }
+                    const type = isolatedDeclarations ? 
+                        factory.createTypeReferenceNode("invalud") :
+                        resolver.createTypeOfExpression(input.expression, input, declarationEmitNodeBuilderFlags, symbolTracker)
+                    const varDecl = factory.createVariableDeclaration(newId, /*exclamationToken*/ undefined, type, /*initializer*/ undefined);
                     errorFallbackNode = undefined;
                     const statement = factory.createVariableStatement(needsDeclare ? [factory.createModifier(SyntaxKind.DeclareKeyword)] : [], factory.createVariableDeclarationList([varDecl], NodeFlags.Const));
 
@@ -1494,9 +1515,15 @@ export function transformDeclarations(context: TransformationContext) {
                             return undefined; // TODO GH#33569: Handle element access expressions that created late bound names (rather than silently omitting them)
                         }
                         getSymbolAccessibilityDiagnostic = createGetSymbolAccessibilityDiagnosticForNode(p.valueDeclaration);
-                        const type = resolver.createTypeOfDeclaration(p.valueDeclaration, fakespace, declarationEmitNodeBuilderFlags, symbolTracker);
+                        let type = resolver.createTypeOfDeclaration(p.valueDeclaration, fakespace, declarationEmitNodeBuilderFlags, symbolTracker);
                         getSymbolAccessibilityDiagnostic = oldDiag;
                         const nameStr = unescapeLeadingUnderscores(p.escapedName);
+
+                        if(isolatedDeclarations) {
+                            reportIsolatedDeclarationError(p.valueDeclaration);
+                            type = factory.createTypeReferenceNode("invalid");
+                        }
+
                         const isNonContextualKeywordName = isStringANonContextualKeyword(nameStr);
                         const name = isNonContextualKeywordName ? factory.getGeneratedNameForNode(p.valueDeclaration) : factory.createIdentifier(nameStr);
                         if (isNonContextualKeywordName) {
@@ -1678,6 +1705,24 @@ export function transformDeclarations(context: TransformationContext) {
                 if (extendsClause && !isEntityNameExpression(extendsClause.expression) && extendsClause.expression.kind !== SyntaxKind.NullKeyword) {
                     // We must add a temporary declaration for the extends clause expression
 
+                    // Isolated declarations do not allow inferred type in the extends clause
+                    if(isolatedDeclarations) {
+                        reportIsolatedDeclarationError(extendsClause);
+                        return cleanup(factory.updateClassDeclaration(
+                            input,
+                            modifiers,
+                            input.name,
+                            typeParameters,
+                            factory.createNodeArray([factory.createHeritageClause(SyntaxKind.ExtendsKeyword, 
+                                [
+                                    factory.createExpressionWithTypeArguments(
+                                        factory.createIdentifier("invalid"),
+                                        /* typeArguments */undefined
+                                    )
+                                ])]),
+                            members
+                        ))
+                    }
                     const oldId = input.name ? unescapeLeadingUnderscores(input.name.escapedText) : "default";
                     const newId = factory.createUniqueName(`${oldId}_base`, GeneratedIdentifierFlags.Optimistic);
                     getSymbolAccessibilityDiagnostic = () => ({
@@ -1725,7 +1770,7 @@ export function transformDeclarations(context: TransformationContext) {
                 return cleanup(factory.updateEnumDeclaration(input, factory.createNodeArray(ensureModifiers(input)), input.name, factory.createNodeArray(mapDefined(input.members, m => {
                     if (shouldStripInternal(m)) return;
                     // Rewrite enum values to their constants, if available
-                    const constValue = resolver.getConstantValue(m);
+                    const constValue = isolatedDeclarations? undefined : resolver.getConstantValue(m);
                     return preserveJsDoc(factory.updateEnumMember(m, m.name, constValue !== undefined ? typeof constValue === "string" ? factory.createStringLiteral(constValue) : factory.createNumericLiteral(constValue) : undefined), m);
                 }))));
             }

src/compiler/types.ts

@@ -7071,6 +7071,7 @@ export interface CompilerOptions {
     inlineSourceMap?: boolean;
     inlineSources?: boolean;
     isolatedModules?: boolean;
+    isolatedDeclarations?: boolean;
     jsx?: JsxEmit;
     keyofStringsOnly?: boolean;
     lib?: string[];

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

@@ -7083,6 +7083,7 @@ declare namespace ts {
         inlineSourceMap?: boolean;
         inlineSources?: boolean;
         isolatedModules?: boolean;
+        isolatedDeclarations?: boolean;
         jsx?: JsxEmit;
         keyofStringsOnly?: boolean;
         lib?: string[];

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

@@ -3140,6 +3140,7 @@ declare namespace ts {
         inlineSourceMap?: boolean;
         inlineSources?: boolean;
         isolatedModules?: boolean;
+        isolatedDeclarations?: boolean;
         jsx?: JsxEmit;
         keyofStringsOnly?: boolean;
         lib?: string[];

tests/baselines/reference/config/initTSConfig/Default initialized TSConfig/tsconfig.json

@@ -76,6 +76,7 @@
     /* Interop Constraints */
     // "isolatedModules": true,                          /* Ensure that each file can be safely transpiled without relying on other imports. */
     // "verbatimModuleSyntax": true,                     /* Do not transform or elide any imports or exports not marked as type-only, ensuring they are written in the output file's format based on the 'module' setting. */
+    // "isolatedDeclarations": true,                     /* Ensure that each file can have declaration emit generated without type information */
     // "allowSyntheticDefaultImports": true,             /* Allow 'import x from y' when a module doesn't have a default export. */
     "esModuleInterop": true,                             /* Emit additional JavaScript to ease support for importing CommonJS modules. This enables 'allowSyntheticDefaultImports' for type compatibility. */
     // "preserveSymlinks": true,                         /* Disable resolving symlinks to their realpath. This correlates to the same flag in node. */

tests/baselines/reference/config/initTSConfig/Initialized TSConfig with --help/tsconfig.json

@@ -76,6 +76,7 @@
     /* Interop Constraints */
     // "isolatedModules": true,                          /* Ensure that each file can be safely transpiled without relying on other imports. */
     // "verbatimModuleSyntax": true,                     /* Do not transform or elide any imports or exports not marked as type-only, ensuring they are written in the output file's format based on the 'module' setting. */
+    // "isolatedDeclarations": true,                     /* Ensure that each file can have declaration emit generated without type information */
     // "allowSyntheticDefaultImports": true,             /* Allow 'import x from y' when a module doesn't have a default export. */
     "esModuleInterop": true,                             /* Emit additional JavaScript to ease support for importing CommonJS modules. This enables 'allowSyntheticDefaultImports' for type compatibility. */
     // "preserveSymlinks": true,                         /* Disable resolving symlinks to their realpath. This correlates to the same flag in node. */

tests/baselines/reference/config/initTSConfig/Initialized TSConfig with --watch/tsconfig.json

@@ -76,6 +76,7 @@
     /* Interop Constraints */
     // "isolatedModules": true,                          /* Ensure that each file can be safely transpiled without relying on other imports. */
     // "verbatimModuleSyntax": true,                     /* Do not transform or elide any imports or exports not marked as type-only, ensuring they are written in the output file's format based on the 'module' setting. */
+    // "isolatedDeclarations": true,                     /* Ensure that each file can have declaration emit generated without type information */
     // "allowSyntheticDefaultImports": true,             /* Allow 'import x from y' when a module doesn't have a default export. */
     "esModuleInterop": true,                             /* Emit additional JavaScript to ease support for importing CommonJS modules. This enables 'allowSyntheticDefaultImports' for type compatibility. */
     // "preserveSymlinks": true,                         /* Disable resolving symlinks to their realpath. This correlates to the same flag in node. */

tests/baselines/reference/config/initTSConfig/Initialized TSConfig with advanced options/tsconfig.json

@@ -76,6 +76,7 @@
     /* Interop Constraints */
     // "isolatedModules": true,                          /* Ensure that each file can be safely transpiled without relying on other imports. */
     // "verbatimModuleSyntax": true,                     /* Do not transform or elide any imports or exports not marked as type-only, ensuring they are written in the output file's format based on the 'module' setting. */
+    // "isolatedDeclarations": true,                     /* Ensure that each file can have declaration emit generated without type information */
     // "allowSyntheticDefaultImports": true,             /* Allow 'import x from y' when a module doesn't have a default export. */
     "esModuleInterop": true,                             /* Emit additional JavaScript to ease support for importing CommonJS modules. This enables 'allowSyntheticDefaultImports' for type compatibility. */
     // "preserveSymlinks": true,                         /* Disable resolving symlinks to their realpath. This correlates to the same flag in node. */

tests/baselines/reference/config/initTSConfig/Initialized TSConfig with boolean value compiler options/tsconfig.json

@@ -76,6 +76,7 @@
     /* Interop Constraints */
     // "isolatedModules": true,                          /* Ensure that each file can be safely transpiled without relying on other imports. */
     // "verbatimModuleSyntax": true,                     /* Do not transform or elide any imports or exports not marked as type-only, ensuring they are written in the output file's format based on the 'module' setting. */
+    // "isolatedDeclarations": true,                     /* Ensure that each file can have declaration emit generated without type information */
     // "allowSyntheticDefaultImports": true,             /* Allow 'import x from y' when a module doesn't have a default export. */
     "esModuleInterop": true,                             /* Emit additional JavaScript to ease support for importing CommonJS modules. This enables 'allowSyntheticDefaultImports' for type compatibility. */
     // "preserveSymlinks": true,                         /* Disable resolving symlinks to their realpath. This correlates to the same flag in node. */

tests/baselines/reference/config/initTSConfig/Initialized TSConfig with enum value compiler options/tsconfig.json

@@ -76,6 +76,7 @@
     /* Interop Constraints */
     // "isolatedModules": true,                          /* Ensure that each file can be safely transpiled without relying on other imports. */
     // "verbatimModuleSyntax": true,                     /* Do not transform or elide any imports or exports not marked as type-only, ensuring they are written in the output file's format based on the 'module' setting. */
+    // "isolatedDeclarations": true,                     /* Ensure that each file can have declaration emit generated without type information */
     // "allowSyntheticDefaultImports": true,             /* Allow 'import x from y' when a module doesn't have a default export. */
     "esModuleInterop": true,                             /* Emit additional JavaScript to ease support for importing CommonJS modules. This enables 'allowSyntheticDefaultImports' for type compatibility. */
     // "preserveSymlinks": true,                         /* Disable resolving symlinks to their realpath. This correlates to the same flag in node. */

tests/baselines/reference/config/initTSConfig/Initialized TSConfig with files options/tsconfig.json

@@ -76,6 +76,7 @@
     /* Interop Constraints */
     // "isolatedModules": true,                          /* Ensure that each file can be safely transpiled without relying on other imports. */
     // "verbatimModuleSyntax": true,                     /* Do not transform or elide any imports or exports not marked as type-only, ensuring they are written in the output file's format based on the 'module' setting. */
+    // "isolatedDeclarations": true,                     /* Ensure that each file can have declaration emit generated without type information */
     // "allowSyntheticDefaultImports": true,             /* Allow 'import x from y' when a module doesn't have a default export. */
     "esModuleInterop": true,                             /* Emit additional JavaScript to ease support for importing CommonJS modules. This enables 'allowSyntheticDefaultImports' for type compatibility. */
     // "preserveSymlinks": true,                         /* Disable resolving symlinks to their realpath. This correlates to the same flag in node. */

tests/baselines/reference/config/initTSConfig/Initialized TSConfig with incorrect compiler option value/tsconfig.json

@@ -76,6 +76,7 @@
     /* Interop Constraints */
     // "isolatedModules": true,                          /* Ensure that each file can be safely transpiled without relying on other imports. */
     // "verbatimModuleSyntax": true,                     /* Do not transform or elide any imports or exports not marked as type-only, ensuring they are written in the output file's format based on the 'module' setting. */
+    // "isolatedDeclarations": true,                     /* Ensure that each file can have declaration emit generated without type information */
     // "allowSyntheticDefaultImports": true,             /* Allow 'import x from y' when a module doesn't have a default export. */
     "esModuleInterop": true,                             /* Emit additional JavaScript to ease support for importing CommonJS modules. This enables 'allowSyntheticDefaultImports' for type compatibility. */
     // "preserveSymlinks": true,                         /* Disable resolving symlinks to their realpath. This correlates to the same flag in node. */

tests/baselines/reference/config/initTSConfig/Initialized TSConfig with incorrect compiler option/tsconfig.json

@@ -76,6 +76,7 @@
     /* Interop Constraints */
     // "isolatedModules": true,                          /* Ensure that each file can be safely transpiled without relying on other imports. */
     // "verbatimModuleSyntax": true,                     /* Do not transform or elide any imports or exports not marked as type-only, ensuring they are written in the output file's format based on the 'module' setting. */
+    // "isolatedDeclarations": true,                     /* Ensure that each file can have declaration emit generated without type information */
     // "allowSyntheticDefaultImports": true,             /* Allow 'import x from y' when a module doesn't have a default export. */
     "esModuleInterop": true,                             /* Emit additional JavaScript to ease support for importing CommonJS modules. This enables 'allowSyntheticDefaultImports' for type compatibility. */
     // "preserveSymlinks": true,                         /* Disable resolving symlinks to their realpath. This correlates to the same flag in node. */

tests/baselines/reference/config/initTSConfig/Initialized TSConfig with list compiler options with enum value/tsconfig.json

@@ -76,6 +76,7 @@
     /* Interop Constraints */
     // "isolatedModules": true,                          /* Ensure that each file can be safely transpiled without relying on other imports. */
     // "verbatimModuleSyntax": true,                     /* Do not transform or elide any imports or exports not marked as type-only, ensuring they are written in the output file's format based on the 'module' setting. */
+    // "isolatedDeclarations": true,                     /* Ensure that each file can have declaration emit generated without type information */
     // "allowSyntheticDefaultImports": true,             /* Allow 'import x from y' when a module doesn't have a default export. */
     "esModuleInterop": true,                             /* Emit additional JavaScript to ease support for importing CommonJS modules. This enables 'allowSyntheticDefaultImports' for type compatibility. */
     // "preserveSymlinks": true,                         /* Disable resolving symlinks to their realpath. This correlates to the same flag in node. */

tests/baselines/reference/config/initTSConfig/Initialized TSConfig with list compiler options/tsconfig.json

@@ -76,6 +76,7 @@
     /* Interop Constraints */
     // "isolatedModules": true,                          /* Ensure that each file can be safely transpiled without relying on other imports. */
     // "verbatimModuleSyntax": true,                     /* Do not transform or elide any imports or exports not marked as type-only, ensuring they are written in the output file's format based on the 'module' setting. */
+    // "isolatedDeclarations": true,                     /* Ensure that each file can have declaration emit generated without type information */
     // "allowSyntheticDefaultImports": true,             /* Allow 'import x from y' when a module doesn't have a default export. */
     "esModuleInterop": true,                             /* Emit additional JavaScript to ease support for importing CommonJS modules. This enables 'allowSyntheticDefaultImports' for type compatibility. */
     // "preserveSymlinks": true,                         /* Disable resolving symlinks to their realpath. This correlates to the same flag in node. */

tests/baselines/reference/config/showConfig/Shows tsconfig for single option/isolatedDeclarations/tsconfig.json

@@ -0,0 +1,5 @@
+{
+    "compilerOptions": {
+        "isolatedDeclarations": true
+    }
+}