Allow setting JSON.parse return type

lib/lib.es5.d.ts

@@ -1056,7 +1056,7 @@ interface JSON {
      * @param reviver A function that transforms the results. This function is called for each member of the object.
      * If a member contains nested objects, the nested objects are transformed before the parent object is.
      */
-    parse(text: string, reviver?: (this: any, key: string, value: any) => any): any;
+    parse<T = any>(text: string, reviver?: (this: any, key: string, value: any) => any): T;
     /**
      * Converts a JavaScript value to a JavaScript Object Notation (JSON) string.
      * @param value A JavaScript value, usually an object or array, to be converted.

src/compiler/emitter.ts

@@ -620,7 +620,7 @@ namespace ts {
 
     /*@internal*/
     export function getBuildInfo(buildInfoText: string) {
-        return JSON.parse(buildInfoText) as BuildInfo;
+        return JSON.parse<BuildInfo>(buildInfoText);
     }
 
     /*@internal*/

src/harness/documentsUtil.ts

@@ -78,7 +78,7 @@ namespace documents {
         private _sourceLineMappings: Mapping[][][] = [];
 
         constructor(mapFile: string | undefined, data: string | RawSourceMap) {
-            this.raw = typeof data === "string" ? JSON.parse(data) as RawSourceMap : data;
+            this.raw = typeof data === "string" ? JSON.parse<RawSourceMap>(data) : data;
             this.mapFile = mapFile;
             this.version = this.raw.version;
             this.file = this.raw.file;
@@ -184,4 +184,4 @@ namespace documents {
             return vlq;
         }
     }
-}
+}

src/lib/es5.d.ts

@@ -1036,7 +1036,7 @@ interface JSON {
      * @param reviver A function that transforms the results. This function is called for each member of the object.
      * If a member contains nested objects, the nested objects are transformed before the parent object is.
      */
-    parse(text: string, reviver?: (this: any, key: string, value: any) => any): any;
+    parse<T = any>(text: string, reviver?: (this: any, key: string, value: any) => any): T;
     /**
      * Converts a JavaScript value to a JavaScript Object Notation (JSON) string.
      * @param value A JavaScript value, usually an object or array, to be converted.

src/server/session.ts

@@ -2756,7 +2756,7 @@ namespace ts.server {
             let request: protocol.Request | undefined;
             let relevantFile: protocol.FileRequestArgs | undefined;
             try {
-                request = <protocol.Request>JSON.parse(message);
+                request = JSON.parse<protocol.Request>(message);
                 relevantFile = request.arguments && (request as protocol.FileRequest).arguments.file ? (request as protocol.FileRequest).arguments : undefined;
 
                 perfLogger.logStartCommand("" + request.command, message.substring(0, 100));

src/services/shims.ts

@@ -346,7 +346,7 @@ namespace ts {
             // 'in' does not have this effect.
             if ("getModuleResolutionsForFile" in this.shimHost) {
                 this.resolveModuleNames = (moduleNames, containingFile) => {
-                    const resolutionsInFile = <MapLike<string>>JSON.parse(this.shimHost.getModuleResolutionsForFile!(containingFile)); // TODO: GH#18217
+                    const resolutionsInFile = JSON.parse<MapLike<string>>(this.shimHost.getModuleResolutionsForFile!(containingFile)); // TODO: GH#18217
                     return map(moduleNames, name => {
                         const result = getProperty(resolutionsInFile, name);
                         return result ? { resolvedFileName: result, extension: extensionFromPath(result), isExternalLibraryImport: false } : undefined;
@@ -358,7 +358,7 @@ namespace ts {
             }
             if ("getTypeReferenceDirectiveResolutionsForFile" in this.shimHost) {
                 this.resolveTypeReferenceDirectives = (typeDirectiveNames, containingFile) => {
-                    const typeDirectivesForFile = <MapLike<ResolvedTypeReferenceDirective>>JSON.parse(this.shimHost.getTypeReferenceDirectiveResolutionsForFile!(containingFile)); // TODO: GH#18217
+                    const typeDirectivesForFile = JSON.parse<MapLike<ResolvedTypeReferenceDirective>>(this.shimHost.getTypeReferenceDirectiveResolutionsForFile!(containingFile)); // TODO: GH#18217
                     return map(typeDirectiveNames, name => getProperty(typeDirectivesForFile, name));
                 };
             }
@@ -406,7 +406,7 @@ namespace ts {
             if (settingsJson === null || settingsJson === "") {
                 throw Error("LanguageServiceShimHostAdapter.getCompilationSettings: empty compilationSettings");
             }
-            const compilerOptions = <CompilerOptions>JSON.parse(settingsJson);
+            const compilerOptions = JSON.parse<CompilerOptions>(settingsJson);
             // permit language service to handle all files (filtering should be performed on the host side)
             compilerOptions.allowNonTsExtensions = true;
             return compilerOptions;
@@ -948,7 +948,7 @@ namespace ts {
             return this.forwardJSONCall(
                 `getCompletionEntryDetails('${fileName}', ${position}, '${entryName}')`,
                 () => {
-                    const localOptions: FormatCodeOptions = formatOptions === undefined ? undefined : JSON.parse(formatOptions);
+                    const localOptions: FormatCodeOptions | undefined = formatOptions === undefined ? undefined : JSON.parse(formatOptions);
                     return this.languageService.getCompletionEntryDetails(fileName, position, entryName, localOptions, source, preferences);
                 }
             );
@@ -1116,7 +1116,7 @@ namespace ts {
 
         public resolveModuleName(fileName: string, moduleName: string, compilerOptionsJson: string): string {
             return this.forwardJSONCall(`resolveModuleName('${fileName}')`, () => {
-                const compilerOptions = <CompilerOptions>JSON.parse(compilerOptionsJson);
+                const compilerOptions = JSON.parse<CompilerOptions>(compilerOptionsJson);
                 const result = resolveModuleName(moduleName, normalizeSlashes(fileName), compilerOptions, this.host);
                 let resolvedFileName = result.resolvedModule ? result.resolvedModule.resolvedFileName : undefined;
                 if (result.resolvedModule && result.resolvedModule.extension !== Extension.Ts && result.resolvedModule.extension !== Extension.Tsx && result.resolvedModule.extension !== Extension.Dts) {
@@ -1132,7 +1132,7 @@ namespace ts {
 
         public resolveTypeReferenceDirective(fileName: string, typeReferenceDirective: string, compilerOptionsJson: string): string {
             return this.forwardJSONCall(`resolveTypeReferenceDirective(${fileName})`, () => {
-                const compilerOptions = <CompilerOptions>JSON.parse(compilerOptionsJson);
+                const compilerOptions = JSON.parse<CompilerOptions>(compilerOptionsJson);
                 const result = resolveTypeReferenceDirective(typeReferenceDirective, normalizeSlashes(fileName), compilerOptions, this.host);
                 return {
                     resolvedFileName: result.resolvedTypeReferenceDirective ? result.resolvedTypeReferenceDirective.resolvedFileName : undefined,
@@ -1163,7 +1163,7 @@ namespace ts {
             return this.forwardJSONCall(
                 `getAutomaticTypeDirectiveNames('${compilerOptionsJson}')`,
                 () => {
-                    const compilerOptions = <CompilerOptions>JSON.parse(compilerOptionsJson);
+                    const compilerOptions = JSON.parse<CompilerOptions>(compilerOptionsJson);
                     return getAutomaticTypeDirectiveNames(compilerOptions, this.host);
                 }
             );
@@ -1212,7 +1212,7 @@ namespace ts {
         public discoverTypings(discoverTypingsJson: string): string {
             const getCanonicalFileName = createGetCanonicalFileName(/*useCaseSensitivefileNames:*/ false);
             return this.forwardJSONCall("discoverTypings()", () => {
-                const info = <DiscoverTypingsInfo>JSON.parse(discoverTypingsJson);
+                const info = JSON.parse<DiscoverTypingsInfo>(discoverTypingsJson);
                 if (this.safeList === undefined) {
                     this.safeList = JsTyping.loadSafeList(this.host, toPath(info.safeListPath, info.safeListPath, getCanonicalFileName));
                 }

src/testRunner/projectsRunner.ts

@@ -183,7 +183,7 @@ namespace project {
             }
 
             try {
-                testCase = <ProjectRunnerTestCase & ts.CompilerOptions>JSON.parse(testFileText!);
+                testCase = JSON.parse(testFileText!);
             }
             catch (e) {
                 throw assert(false, "Testcase: " + testCaseFileName + " does not contain valid json format: " + e.message);

src/testRunner/runner.ts

@@ -94,7 +94,7 @@ namespace Harness {
     export let globalTimeout: number;
     function handleTestConfig() {
         if (testConfigContent !== "") {
-            const testConfig = <TestConfig>JSON.parse(testConfigContent);
+            const testConfig = JSON.parse<TestConfig>(testConfigContent);
             if (testConfig.light) {
                 setLightMode(true);
             }
@@ -262,4 +262,4 @@ namespace Harness {
     }
 
     startTestEnvironment();
-}
+}

src/typingsInstaller/nodeTypingsInstaller.ts

@@ -54,7 +54,7 @@ namespace ts.server.typingsInstaller {
             return createMap<MapLike<string>>();
         }
         try {
-            const content = <TypesRegistryFile>JSON.parse(host.readFile(typesRegistryFilePath)!);
+            const content = JSON.parse<TypesRegistryFile>(host.readFile(typesRegistryFilePath)!);
             return createMapFromTemplate(content.entries);
         }
         catch (e) {

src/typingsInstallerCore/typingsInstaller.ts

@@ -215,8 +215,8 @@ namespace ts.server.typingsInstaller {
                 this.log.writeLine(`Trying to find '${packageJson}'...`);
             }
             if (this.installTypingHost.fileExists(packageJson) && this.installTypingHost.fileExists(packageLockJson)) {
-                const npmConfig = <NpmConfig>JSON.parse(this.installTypingHost.readFile(packageJson)!); // TODO: GH#18217
-                const npmLock = <NpmLock>JSON.parse(this.installTypingHost.readFile(packageLockJson)!); // TODO: GH#18217
+                const npmConfig = JSON.parse<NpmConfig>(this.installTypingHost.readFile(packageJson)!); // TODO: GH#18217
+                const npmLock = JSON.parse<NpmLock>(this.installTypingHost.readFile(packageLockJson)!); // TODO: GH#18217
                 if (this.log.isEnabled()) {
                     this.log.writeLine(`Loaded content of '${packageJson}': ${JSON.stringify(npmConfig)}`);
                     this.log.writeLine(`Loaded content of '${packageLockJson}'`);

tests/baselines/reference/1.0lib-noErrors.js

@@ -1,4 +1,4 @@
-//// [1.0lib-noErrors.ts]
+//// [1.0lib-noErrors.ts]
 /* *****************************************************************************
 Copyright (c) Microsoft Corporation. All rights reserved. 
 Licensed under the Apache License, Version 2.0 (the "License"); you may not use
@@ -936,7 +936,7 @@ interface JSON {
       * @param reviver A function that transforms the results. This function is called for each member of the object. 
       * If a member contains nested objects, the nested objects are transformed before the parent object is. 
       */
-    parse(text: string, reviver?: (key: any, value: any) => any): any;
+    Wparse<T = any>(text: string, reviver?: (this: any, key: string, value: any) => any): T;
     /**
       * Converts a JavaScript value to a JavaScript Object Notation (JSON) string.
       * @param value A JavaScript value, usually an object or array, to be converted.
@@ -1141,21 +1141,22 @@ declare var Array: {
     <T>(...items: T[]): T[];
     isArray(arg: any): boolean;
     prototype: Array<any>;
-}
-
-//// [1.0lib-noErrors.js]
-/* *****************************************************************************
-Copyright (c) Microsoft Corporation. All rights reserved.
-Licensed under the Apache License, Version 2.0 (the "License"); you may not use
-this file except in compliance with the License. You may obtain a copy of the
-License at http://www.apache.org/licenses/LICENSE-2.0
-
-THIS CODE IS PROVIDED ON AN *AS IS* BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
-KIND, EITHER EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION ANY IMPLIED
-WARRANTIES OR CONDITIONS OF TITLE, FITNESS FOR A PARTICULAR PURPOSE,
-MERCHANTABLITY OR NON-INFRINGEMENT.
-
-See the Apache Version 2.0 License for specific language governing permissions
-and limitations under the License.
-***************************************************************************** */
-/// <reference no-default-lib="true"/>
+}
+
+
+//// [1.0lib-noErrors.js]
+/* *****************************************************************************
+Copyright (c) Microsoft Corporation. All rights reserved.
+Licensed under the Apache License, Version 2.0 (the "License"); you may not use
+this file except in compliance with the License. You may obtain a copy of the
+License at http://www.apache.org/licenses/LICENSE-2.0
+
+THIS CODE IS PROVIDED ON AN *AS IS* BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+KIND, EITHER EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION ANY IMPLIED
+WARRANTIES OR CONDITIONS OF TITLE, FITNESS FOR A PARTICULAR PURPOSE,
+MERCHANTABLITY OR NON-INFRINGEMENT.
+
+See the Apache Version 2.0 License for specific language governing permissions
+and limitations under the License.
+***************************************************************************** */
+/// <reference no-default-lib="true"/>

tests/baselines/reference/controlFlowIfStatement.types

@@ -100,10 +100,10 @@ function c<T>(data: string | T): T {
 >'string' : "string"
 
         return JSON.parse(data);
->JSON.parse(data) : any
->JSON.parse : (text: string, reviver?: (this: any, key: string, value: any) => any) => any
+>JSON.parse(data) : T
+>JSON.parse : <T = any>(text: string, reviver?: (this: any, key: string, value: any) => any) => T
 >JSON : JSON
->parse : (text: string, reviver?: (this: any, key: string, value: any) => any) => any
+>parse : <T = any>(text: string, reviver?: (this: any, key: string, value: any) => any) => T
 >data : string | (T & string)
     }
     else {

tests/cases/conformance/decorators/1.0lib-noErrors.ts

@@ -936,7 +936,7 @@ interface JSON {
       * @param reviver A function that transforms the results. This function is called for each member of the object. 
       * If a member contains nested objects, the nested objects are transformed before the parent object is. 
       */
-    parse(text: string, reviver?: (key: any, value: any) => any): any;
+    parse<T = any>(text: string, reviver?: (this: any, key: string, value: any) => any): T;
     /**
       * Converts a JavaScript value to a JavaScript Object Notation (JSON) string.
       * @param value A JavaScript value, usually an object or array, to be converted.
@@ -1141,4 +1141,4 @@ declare var Array: {
     <T>(...items: T[]): T[];
     isArray(arg: any): boolean;
     prototype: Array<any>;
-}
+}

tests/lib/lib.d.ts

@@ -974,7 +974,7 @@ interface JSON {
       * @param reviver A function that transforms the results. This function is called for each member of the object.
       * If a member contains nested objects, the nested objects are transformed before the parent object is.
       */
-    parse(text: string, reviver?: (key: any, value: any) => any): any;
+    parse<T = any>(text: string, reviver?: (this: any, key: string, value: any) => any): T;
     /**
       * Converts a JavaScript value to a JavaScript Object Notation (JSON) string.
       * @param value A JavaScript value, usually an object or array, to be converted.