Allow allowImportingTsExtensions to be set in any module resolution mode

src/compiler/commandLineParser.ts

@@ -1089,7 +1089,7 @@ const commandOptionsWithoutBuild: CommandLineOption[] = [
     {
         name: "allowImportingTsExtensions",
         type: "boolean",
-        affectsModuleResolution: true,
+        affectsSemanticDiagnostics: true,
         category: Diagnostics.Modules,
         description: Diagnostics.Allow_imports_to_include_TypeScript_file_extensions_Requires_moduleResolution_bundler_and_either_noEmit_or_emitDeclarationOnly_to_be_set,
         defaultValueDescription: false,

src/compiler/diagnosticMessages.json

@@ -4233,7 +4233,7 @@
         "category": "Error",
         "code": 5095
     },
-    "Option 'allowImportingTsExtensions' can only be used when 'moduleResolution' is set to 'bundler' and either 'noEmit' or 'emitDeclarationOnly' is set.": {
+    "Option 'allowImportingTsExtensions' can only be used when either 'noEmit' or 'emitDeclarationOnly' is set.": {
         "category": "Error",
         "code": 5096
     },

src/compiler/moduleNameResolver.ts

@@ -3033,9 +3033,7 @@ export function classicNameResolver(moduleName: string, containingFile: string,
 // Program errors validate that `noEmit` or `emitDeclarationOnly` is also set,
 // so this function doesn't check them to avoid propagating errors.
 export function shouldAllowImportingTsExtension(compilerOptions: CompilerOptions, fromFileName?: string) {
-    return getEmitModuleResolutionKind(compilerOptions) === ModuleResolutionKind.Bundler && (
-        !!compilerOptions.allowImportingTsExtensions ||
-        fromFileName && isDeclarationFileName(fromFileName));
+    return !!compilerOptions.allowImportingTsExtensions || fromFileName && isDeclarationFileName(fromFileName);
 }
 
 /**

src/compiler/program.ts

@@ -4213,7 +4213,7 @@ export function createProgram(rootNamesOrOptions: readonly string[] | CreateProg
         }
 
         if (options.allowImportingTsExtensions && !(options.noEmit || options.emitDeclarationOnly)) {
-            createOptionValueDiagnostic("allowImportingTsExtensions", Diagnostics.Option_allowImportingTsExtensions_can_only_be_used_when_moduleResolution_is_set_to_bundler_and_either_noEmit_or_emitDeclarationOnly_is_set);
+            createOptionValueDiagnostic("allowImportingTsExtensions", Diagnostics.Option_allowImportingTsExtensions_can_only_be_used_when_either_noEmit_or_emitDeclarationOnly_is_set);
         }
 
         const moduleResolution = getEmitModuleResolutionKind(options);

src/testRunner/unittests/tscWatch/programUpdates.ts

@@ -1957,4 +1957,42 @@ import { x } from "../b";`),
             },
         ]
     });
+
+    verifyTscWatch({
+        scenario,
+        subScenario: "when changing `allowImportingTsExtensions` of config file",
+        commandLineArgs: ["-w", "-p", ".", "--extendedDiagnostics"],
+        sys: () => {
+            const module1: File = {
+                path: `/user/username/projects/myproject/a.ts`,
+                content: ``
+            };
+            const module2: File = {
+                path: `/user/username/projects/myproject/b.ts`,
+                content: `import "./a.ts";`
+            };
+            const config: File = {
+                path: `/user/username/projects/myproject/tsconfig.json`,
+                content: JSON.stringify({
+                    compilerOptions: {
+                        noEmit: true,
+                        allowImportingTsExtensions: false
+                    }
+                }),
+            };
+            return createWatchedSystem([module1, module2, config, libFile], { currentDirectory: "/user/username/projects/myproject" });
+        },
+        edits: [
+            {
+                caption: "Change allowImportingTsExtensions to true",
+                edit: sys => sys.writeFile(`/user/username/projects/myproject/tsconfig.json`, JSON.stringify({
+                    compilerOptions: {
+                        noEmit: true,
+                        allowImportingTsExtensions: true
+                    }
+                })),
+                timeouts: sys => sys.checkTimeoutQueueLengthAndRun(1),
+            },
+        ]
+    });
 });

tests/baselines/reference/bundlerImportTsExtensions(allowimportingtsextensions=true,noemit=false).errors.txt

@@ -1,6 +1,6 @@
 error TS5056: Cannot write file 'out/b.js' because it would be overwritten by multiple input files.
 error TS5056: Cannot write file 'out/c.js' because it would be overwritten by multiple input files.
-error TS5096: Option 'allowImportingTsExtensions' can only be used when 'moduleResolution' is set to 'bundler' and either 'noEmit' or 'emitDeclarationOnly' is set.
+error TS5096: Option 'allowImportingTsExtensions' can only be used when either 'noEmit' or 'emitDeclarationOnly' is set.
 error TS6054: File '/project/e.txt' has an unsupported extension. The only supported extensions are '.ts', '.tsx', '.d.ts', '.js', '.jsx', '.cts', '.d.cts', '.cjs', '.mts', '.d.mts', '.mjs'.
   The file is in the program because:
     Root file specified for compilation
@@ -11,7 +11,7 @@ error TS6054: File '/project/e.txt' has an unsupported extension. The only suppo
 
 !!! error TS5056: Cannot write file 'out/b.js' because it would be overwritten by multiple input files.
 !!! error TS5056: Cannot write file 'out/c.js' because it would be overwritten by multiple input files.
-!!! error TS5096: Option 'allowImportingTsExtensions' can only be used when 'moduleResolution' is set to 'bundler' and either 'noEmit' or 'emitDeclarationOnly' is set.
+!!! error TS5096: Option 'allowImportingTsExtensions' can only be used when either 'noEmit' or 'emitDeclarationOnly' is set.
 !!! error TS6054: File '/project/e.txt' has an unsupported extension. The only supported extensions are '.ts', '.tsx', '.d.ts', '.js', '.jsx', '.cts', '.d.cts', '.cjs', '.mts', '.d.mts', '.mjs'.
 !!! error TS6054:   The file is in the program because:
 !!! error TS6054:     Root file specified for compilation

tests/baselines/reference/tscWatch/programUpdates/when-changing-`allowImportingTsExtensions`-of-config-file.js

@@ -0,0 +1,146 @@
+Input::
+//// [/user/username/projects/myproject/a.ts]
+
+
+//// [/user/username/projects/myproject/b.ts]
+import "./a.ts";
+
+//// [/user/username/projects/myproject/tsconfig.json]
+{"compilerOptions":{"noEmit":true,"allowImportingTsExtensions":false}}
+
+//// [/a/lib/lib.d.ts]
+/// <reference no-default-lib="true"/>
+interface Boolean {}
+interface Function {}
+interface CallableFunction {}
+interface NewableFunction {}
+interface IArguments {}
+interface Number { toExponential: any; }
+interface Object {}
+interface RegExp {}
+interface String { charAt: any; }
+interface Array<T> { length: number; [n: number]: T; }
+
+
+/a/lib/tsc.js -w -p . --extendedDiagnostics
+Output::
+[12:00:23 AM] Starting compilation in watch mode...
+
+Current directory: /user/username/projects/myproject CaseSensitiveFileNames: false
+FileWatcher:: Added:: WatchInfo: /user/username/projects/myproject/tsconfig.json 2000 undefined Config file
+Synchronizing program
+CreatingProgramWith::
+  roots: ["/user/username/projects/myproject/a.ts","/user/username/projects/myproject/b.ts"]
+  options: {"noEmit":true,"allowImportingTsExtensions":false,"watch":true,"project":"/user/username/projects/myproject","extendedDiagnostics":true,"configFilePath":"/user/username/projects/myproject/tsconfig.json"}
+FileWatcher:: Added:: WatchInfo: /user/username/projects/myproject/a.ts 250 undefined Source file
+FileWatcher:: Added:: WatchInfo: /user/username/projects/myproject/b.ts 250 undefined Source file
+FileWatcher:: Added:: WatchInfo: /a/lib/lib.d.ts 250 undefined Source file
+DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject/node_modules/@types 1 undefined Type roots
+Elapsed:: *ms DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject/node_modules/@types 1 undefined Type roots
+b.ts:1:8 - error TS5097: An import path can only end with a '.ts' extension when 'allowImportingTsExtensions' is enabled.
+
+1 import "./a.ts";
+         ~~~~~~~~
+
+[12:00:24 AM] Found 1 error. Watching for file changes.
+
+DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject 1 undefined Wild card directory
+Elapsed:: *ms DirectoryWatcher:: Added:: WatchInfo: /user/username/projects/myproject 1 undefined Wild card directory
+
+
+Program root files: ["/user/username/projects/myproject/a.ts","/user/username/projects/myproject/b.ts"]
+Program options: {"noEmit":true,"allowImportingTsExtensions":false,"watch":true,"project":"/user/username/projects/myproject","extendedDiagnostics":true,"configFilePath":"/user/username/projects/myproject/tsconfig.json"}
+Program structureReused: Not
+Program files::
+/a/lib/lib.d.ts
+/user/username/projects/myproject/a.ts
+/user/username/projects/myproject/b.ts
+
+Semantic diagnostics in builder refreshed for::
+/a/lib/lib.d.ts
+/user/username/projects/myproject/a.ts
+/user/username/projects/myproject/b.ts
+
+Shape signatures in builder refreshed for::
+/a/lib/lib.d.ts (used version)
+/user/username/projects/myproject/a.ts (used version)
+/user/username/projects/myproject/b.ts (used version)
+
+PolledWatches::
+/user/username/projects/myproject/node_modules/@types:
+  {"pollingInterval":500}
+
+FsWatches::
+/user/username/projects/myproject/tsconfig.json:
+  {}
+/user/username/projects/myproject/a.ts:
+  {}
+/user/username/projects/myproject/b.ts:
+  {}
+/a/lib/lib.d.ts:
+  {}
+
+FsWatchesRecursive::
+/user/username/projects/myproject:
+  {}
+
+exitCode:: ExitStatus.undefined
+
+
+Change:: Change allowImportingTsExtensions to true
+
+Input::
+//// [/user/username/projects/myproject/tsconfig.json]
+{"compilerOptions":{"noEmit":true,"allowImportingTsExtensions":true}}
+
+
+Output::
+FileWatcher:: Triggered with /user/username/projects/myproject/tsconfig.json 1:: WatchInfo: /user/username/projects/myproject/tsconfig.json 2000 undefined Config file
+Scheduling update
+Elapsed:: *ms FileWatcher:: Triggered with /user/username/projects/myproject/tsconfig.json 1:: WatchInfo: /user/username/projects/myproject/tsconfig.json 2000 undefined Config file
+Reloading config file: /user/username/projects/myproject/tsconfig.json
+Synchronizing program
+[12:00:28 AM] File change detected. Starting incremental compilation...
+
+CreatingProgramWith::
+  roots: ["/user/username/projects/myproject/a.ts","/user/username/projects/myproject/b.ts"]
+  options: {"noEmit":true,"allowImportingTsExtensions":true,"watch":true,"project":"/user/username/projects/myproject","extendedDiagnostics":true,"configFilePath":"/user/username/projects/myproject/tsconfig.json"}
+[12:00:29 AM] Found 0 errors. Watching for file changes.
+
+
+
+Program root files: ["/user/username/projects/myproject/a.ts","/user/username/projects/myproject/b.ts"]
+Program options: {"noEmit":true,"allowImportingTsExtensions":true,"watch":true,"project":"/user/username/projects/myproject","extendedDiagnostics":true,"configFilePath":"/user/username/projects/myproject/tsconfig.json"}
+Program structureReused: Completely
+Program files::
+/a/lib/lib.d.ts
+/user/username/projects/myproject/a.ts
+/user/username/projects/myproject/b.ts
+
+Semantic diagnostics in builder refreshed for::
+/a/lib/lib.d.ts
+/user/username/projects/myproject/a.ts
+/user/username/projects/myproject/b.ts
+
+No shapes updated in the builder::
+
+PolledWatches::
+/user/username/projects/myproject/node_modules/@types:
+  {"pollingInterval":500}
+
+FsWatches::
+/user/username/projects/myproject/tsconfig.json:
+  {}
+/user/username/projects/myproject/a.ts:
+  {}
+/user/username/projects/myproject/b.ts:
+  {}
+/a/lib/lib.d.ts:
+  {}
+
+FsWatchesRecursive::
+/user/username/projects/myproject:
+  {}
+
+exitCode:: ExitStatus.undefined
+

tests/cases/conformance/moduleResolution/allowImportingTsExtensions.ts

@@ -0,0 +1,29 @@
+// @allowImportingTsExtensions: true
+// @noEmit: true
+// @moduleResolution: classic,node10,node16,nodenext,bundler
+// @jsx: preserve
+// @noTypesAndSymbols: true
+
+// @Filename: /ts.ts
+export {};
+
+// @Filename: /tsx.tsx
+export {};
+
+// @Filename: /dts.d.ts
+export {};
+
+// @Filename: /b.ts
+import {} from "./ts.js";
+import {} from "./ts.ts";
+import type {} from "./ts.d.ts";
+
+import {} from "./tsx.js";
+import {} from "./tsx.jsx";
+import {} from "./tsx.ts";
+import {} from "./tsx.tsx";
+import type {} from "./tsx.d.ts";
+
+import {} from "./dts.js";
+import {} from "./dts.ts";
+import type {} from "./dts.d.ts";