Need allowJs to be true to use the json module resolution

src/compiler/checker.ts

@@ -2084,7 +2084,7 @@ namespace ts {
             }
 
             // May be an untyped module. If so, ignore resolutionDiagnostic.
-            if (resolvedModule && !resolutionExtensionIsTypeScriptOrJson(resolvedModule.extension) && resolutionDiagnostic === undefined || resolutionDiagnostic === Diagnostics.Could_not_find_a_declaration_file_for_module_0_1_implicitly_has_an_any_type) {
+            if (resolvedModule && !extensionIsTypeScript(resolvedModule.extension) && resolutionDiagnostic === undefined || resolutionDiagnostic === Diagnostics.Could_not_find_a_declaration_file_for_module_0_1_implicitly_has_an_any_type) {
                 if (isForAugmentation) {
                     const diag = Diagnostics.Invalid_module_name_in_augmentation_Module_0_resolves_to_an_untyped_module_at_1_which_cannot_be_augmented;
                     error(errorNode, diag, moduleReference, resolvedModule.resolvedFileName);

src/compiler/commandLineParser.ts

@@ -2037,7 +2037,8 @@ namespace ts {
 
         // Rather than requery this for each file and filespec, we query the supported extensions
         // once and store it on the expansion context.
-        const supportedExtensions = getSupportedExtensions(options, extraFileExtensions);
+        // When computing file names, do not include json files. Use only module resolution or explicit includes for them
+        const supportedExtensions = getSupportedExtensions(options, extraFileExtensions, /*excludeJson*/ true);
 
         // Literal files are always included verbatim. An "include" or "exclude" specification cannot
         // remove a literal file.

src/compiler/core.ts

@@ -2674,14 +2674,21 @@ namespace ts {
     export const supportedTypescriptExtensionsForExtractExtension: ReadonlyArray<Extension> = [Extension.Dts, Extension.Ts, Extension.Tsx];
     export const supportedJavascriptExtensions: ReadonlyArray<Extension> = [Extension.Js, Extension.Jsx];
     const allSupportedExtensions: ReadonlyArray<Extension> = [...supportedTypeScriptExtensions, ...supportedJavascriptExtensions];
+    let allSupportedExtensionsIncludingJson: ReadonlyArray<Extension> | undefined;
+    function getAllSupportedExtensionsIncludingJson() {
+        return allSupportedExtensionsIncludingJson || (allSupportedExtensionsIncludingJson = [...allSupportedExtensions, Extension.Json]);
+    }
 
-    export function getSupportedExtensions(options?: CompilerOptions, extraFileExtensions?: ReadonlyArray<JsFileExtensionInfo>): ReadonlyArray<string> {
+    export function getSupportedExtensions(options?: CompilerOptions, extraFileExtensions?: ReadonlyArray<JsFileExtensionInfo>, excludeJson?: boolean): ReadonlyArray<string> {
         const needAllExtensions = options && options.allowJs;
+        const useJsonExtension = needAllExtensions && !excludeJson && getEmitModuleResolutionKind(options) === ModuleResolutionKind.NodeJs;
         if (!extraFileExtensions || extraFileExtensions.length === 0 || !needAllExtensions) {
-            return needAllExtensions ? allSupportedExtensions : supportedTypeScriptExtensions;
+            return useJsonExtension ?
+                getAllSupportedExtensionsIncludingJson() :
+                needAllExtensions ? allSupportedExtensions : supportedTypeScriptExtensions;
         }
         return deduplicate(
-            [...allSupportedExtensions, ...extraFileExtensions.map(e => e.extension)],
+            [...(useJsonExtension ? getAllSupportedExtensionsIncludingJson() : allSupportedExtensions), ...extraFileExtensions.map(e => e.extension)],
             equateStringsCaseSensitive,
             compareStringsCaseSensitive
         );
@@ -2691,6 +2698,10 @@ namespace ts {
         return forEach(supportedJavascriptExtensions, extension => fileExtensionIs(fileName, extension));
     }
 
+    export function hasJavaScriptOrJsonFileExtension(fileName: string) {
+        return hasJavaScriptFileExtension(fileName) || fileExtensionIs(fileName, Extension.Json);
+    }
+
     export function hasTypeScriptFileExtension(fileName: string) {
         return forEach(supportedTypeScriptExtensions, extension => fileExtensionIs(fileName, extension));
     }
@@ -3091,10 +3102,6 @@ namespace ts {
         return ext === Extension.Ts || ext === Extension.Tsx || ext === Extension.Dts;
     }
 
-    export function resolutionExtensionIsTypeScriptOrJson(ext: Extension) {
-        return extensionIsTypeScript(ext) || ext === Extension.Json;
-    }
-
     /**
      * Gets the extension from a path.
      * Path must have a valid extension.
@@ -3112,7 +3119,9 @@ namespace ts {
     }
 
     export function tryGetExtensionFromPath(path: string): Extension | undefined {
-        return find<Extension>(supportedTypescriptExtensionsForExtractExtension, e => fileExtensionIs(path, e)) || find(supportedJavascriptExtensions, e => fileExtensionIs(path, e));
+        return find<Extension>(supportedTypescriptExtensionsForExtractExtension, e => fileExtensionIs(path, e)) ||
+            find(supportedJavascriptExtensions, e => fileExtensionIs(path, e)) ||
+            (fileExtensionIs(path, Extension.Json) ? Extension.Json : undefined);
     }
 
     // Retrieves any string from the final "." onwards from a base file name.

src/compiler/moduleNameResolver.ts

@@ -890,7 +890,7 @@ namespace ts {
 
         // If that didn't work, try stripping a ".js" or ".jsx" extension and replacing it with a TypeScript one;
         // e.g. "./foo.js" can be matched by "./foo.ts" or "./foo.d.ts"
-        if (hasJavaScriptFileExtension(candidate) || fileExtensionIs(candidate, Extension.Json)) {
+        if (hasJavaScriptOrJsonFileExtension(candidate)) {
             const extensionless = removeFileExtension(candidate);
             if (state.traceEnabled) {
                 const extension = candidate.substring(extensionless.length);

src/compiler/program.ts

@@ -1975,7 +1975,7 @@ namespace ts {
                     }
 
                     const isFromNodeModulesSearch = resolution.isExternalLibraryImport;
-                    const isJsFile = !resolutionExtensionIsTypeScriptOrJson(resolution.extension);
+                    const isJsFile = !extensionIsTypeScript(resolution.extension);
                     const isJsFileFromNodeModules = isFromNodeModulesSearch && isJsFile;
                     const resolvedFileName = resolution.resolvedFileName;
 
@@ -2404,7 +2404,6 @@ namespace ts {
         switch (extension) {
             case Extension.Ts:
             case Extension.Dts:
-            case Extension.Json:
                 // These are always allowed.
                 return undefined;
             case Extension.Tsx:
@@ -2412,6 +2411,7 @@ namespace ts {
             case Extension.Jsx:
                 return needJsx() || needAllowJs();
             case Extension.Js:
+            case Extension.Json:
                 return needAllowJs();
         }
 

src/harness/fourslash.ts

@@ -511,8 +511,9 @@ namespace FourSlash {
         }
 
         private getAllDiagnostics(): ts.Diagnostic[] {
+            const options = this.languageService.getProgram().getCompilerOptions();
             return ts.flatMap(this.languageServiceAdapterHost.getFilenames(), fileName =>
-                ts.isAnySupportedFileExtension(fileName) ? this.getDiagnostics(fileName) : []);
+                ts.fileExtensionIsOneOf(fileName, ts.getSupportedExtensions(options)) ? this.getDiagnostics(fileName) : []);
         }
 
         public verifyErrorExistsAfterMarker(markerName: string, shouldExist: boolean, after: boolean) {

src/services/jsTyping.ts

@@ -98,7 +98,7 @@ namespace ts.JsTyping {
         // Only infer typings for .js and .jsx files
         fileNames = mapDefined(fileNames, fileName => {
             const path = normalizePath(fileName);
-            if (hasJavaScriptFileExtension(path)) {
+            if (hasJavaScriptOrJsonFileExtension(path)) {
                 return path;
             }
         });
@@ -193,7 +193,7 @@ namespace ts.JsTyping {
          */
         function getTypingNamesFromSourceFileNames(fileNames: string[]) {
             const fromFileNames = mapDefined(fileNames, j => {
-                if (!hasJavaScriptFileExtension(j)) return undefined;
+                if (!hasJavaScriptOrJsonFileExtension(j)) return undefined;
 
                 const inferredTypingName = removeFileExtension(getBaseFileName(j.toLowerCase()));
                 const cleanedTypingName = removeMinAndVersionNumbers(inferredTypingName);

tests/baselines/reference/jsFileCompilationWithMapFileAsJs.errors.txt

@@ -1,11 +1,11 @@
 error TS5055: Cannot write file 'tests/cases/compiler/b.js' because it would overwrite input file.
   Adding a tsconfig.json file will help organize projects that contain both TypeScript and JavaScript files. Learn more at https://aka.ms/tsconfig.
-error TS6054: File 'tests/cases/compiler/b.js.map' has unsupported extension. The only supported extensions are '.ts', '.tsx', '.d.ts', '.js', '.jsx'.
+error TS6054: File 'tests/cases/compiler/b.js.map' has unsupported extension. The only supported extensions are '.ts', '.tsx', '.d.ts', '.js', '.jsx', '.json'.
 
 
 !!! error TS5055: Cannot write file 'tests/cases/compiler/b.js' because it would overwrite input file.
 !!! error TS5055:   Adding a tsconfig.json file will help organize projects that contain both TypeScript and JavaScript files. Learn more at https://aka.ms/tsconfig.
-!!! error TS6054: File 'tests/cases/compiler/b.js.map' has unsupported extension. The only supported extensions are '.ts', '.tsx', '.d.ts', '.js', '.jsx'.
+!!! error TS6054: File 'tests/cases/compiler/b.js.map' has unsupported extension. The only supported extensions are '.ts', '.tsx', '.d.ts', '.js', '.jsx', '.json'.
 ==== tests/cases/compiler/a.ts (0 errors) ====
     class c {
     }

tests/baselines/reference/jsFileCompilationWithMapFileAsJsWithInlineSourceMap.errors.txt

@@ -1,11 +1,11 @@
 error TS5055: Cannot write file 'tests/cases/compiler/b.js' because it would overwrite input file.
   Adding a tsconfig.json file will help organize projects that contain both TypeScript and JavaScript files. Learn more at https://aka.ms/tsconfig.
-error TS6054: File 'tests/cases/compiler/b.js.map' has unsupported extension. The only supported extensions are '.ts', '.tsx', '.d.ts', '.js', '.jsx'.
+error TS6054: File 'tests/cases/compiler/b.js.map' has unsupported extension. The only supported extensions are '.ts', '.tsx', '.d.ts', '.js', '.jsx', '.json'.
 
 
 !!! error TS5055: Cannot write file 'tests/cases/compiler/b.js' because it would overwrite input file.
 !!! error TS5055:   Adding a tsconfig.json file will help organize projects that contain both TypeScript and JavaScript files. Learn more at https://aka.ms/tsconfig.
-!!! error TS6054: File 'tests/cases/compiler/b.js.map' has unsupported extension. The only supported extensions are '.ts', '.tsx', '.d.ts', '.js', '.jsx'.
+!!! error TS6054: File 'tests/cases/compiler/b.js.map' has unsupported extension. The only supported extensions are '.ts', '.tsx', '.d.ts', '.js', '.jsx', '.json'.
 ==== tests/cases/compiler/a.ts (0 errors) ====
     class c {
     }

tests/baselines/reference/requireOfJsonFileWithoutAllowJs.js

@@ -0,0 +1,27 @@
+//// [tests/cases/compiler/requireOfJsonFileWithoutAllowJs.ts] ////
+
+//// [file1.ts]
+import b1 = require('./b');
+let x = b1.a;
+import b2 = require('./b.json');
+if (x) {
+    let b = b2.b;
+    x = (b1.b === b);
+}
+
+//// [b.json]
+{
+    "a": true,
+    "b": "hello"
+}
+
+//// [file1.js]
+"use strict";
+exports.__esModule = true;
+var b1 = require("./b");
+var x = b1.a;
+var b2 = require("./b.json");
+if (x) {
+    var b = b2.b;
+    x = (b1.b === b);
+}

tests/baselines/reference/requireOfJsonFileWithoutAllowJs.symbols

@@ -0,0 +1,24 @@
+=== tests/cases/compiler/file1.ts ===
+import b1 = require('./b');
+>b1 : Symbol(b1, Decl(file1.ts, 0, 0))
+
+let x = b1.a;
+>x : Symbol(x, Decl(file1.ts, 1, 3))
+>b1 : Symbol(b1, Decl(file1.ts, 0, 0))
+
+import b2 = require('./b.json');
+>b2 : Symbol(b2, Decl(file1.ts, 1, 13))
+
+if (x) {
+>x : Symbol(x, Decl(file1.ts, 1, 3))
+
+    let b = b2.b;
+>b : Symbol(b, Decl(file1.ts, 4, 7))
+>b2 : Symbol(b2, Decl(file1.ts, 1, 13))
+
+    x = (b1.b === b);
+>x : Symbol(x, Decl(file1.ts, 1, 3))
+>b1 : Symbol(b1, Decl(file1.ts, 0, 0))
+>b : Symbol(b, Decl(file1.ts, 4, 7))
+}
+

tests/baselines/reference/requireOfJsonFileWithoutAllowJs.types

@@ -0,0 +1,33 @@
+=== tests/cases/compiler/file1.ts ===
+import b1 = require('./b');
+>b1 : any
+
+let x = b1.a;
+>x : any
+>b1.a : any
+>b1 : any
+>a : any
+
+import b2 = require('./b.json');
+>b2 : any
+
+if (x) {
+>x : any
+
+    let b = b2.b;
+>b : any
+>b2.b : any
+>b2 : any
+>b : any
+
+    x = (b1.b === b);
+>x = (b1.b === b) : boolean
+>x : any
+>(b1.b === b) : boolean
+>b1.b === b : boolean
+>b1.b : any
+>b1 : any
+>b : any
+>b : any
+}
+

tests/cases/compiler/requireOfJsonFile.ts

@@ -1,5 +1,6 @@
 // @module: commonjs
 // @outdir: out/
+// @allowJs: true
 
 // @Filename: file1.ts
 import b1 = require('./b');

tests/cases/compiler/requireOfJsonFileWithAmd.ts

@@ -1,5 +1,6 @@
 // @module: amd
 // @outdir: out/
+// @allowJs: true
 
 // @Filename: file1.ts
 import b1 = require('./b');

tests/cases/compiler/requireOfJsonFileWithEmptyObject.ts

@@ -1,5 +1,6 @@
 // @module: commonjs
 // @outdir: out/
+// @allowJs: true
 
 // @Filename: file1.ts
 import b1 = require('./b');

tests/cases/compiler/requireOfJsonFileWithEmptyObjectWithErrors.ts

@@ -1,5 +1,6 @@
 // @module: commonjs
 // @outdir: out/
+// @allowJs: true
 
 // @Filename: file1.ts
 import b1 = require('./b');

tests/cases/compiler/requireOfJsonFileWithNoContent.ts

@@ -1,5 +1,6 @@
 // @module: commonjs
 // @outdir: out/
+// @allowJs: true
 
 // @Filename: file1.ts
 import b1 = require('./b');

tests/cases/compiler/requireOfJsonFileWithoutAllowJs.ts

@@ -0,0 +1,17 @@
+// @module: commonjs
+// @outdir: out/
+
+// @Filename: file1.ts
+import b1 = require('./b');
+let x = b1.a;
+import b2 = require('./b.json');
+if (x) {
+    let b = b2.b;
+    x = (b1.b === b);
+}
+
+// @Filename: b.json
+{
+    "a": true,
+    "b": "hello"
+}