Proposal: Always allow type-only imports to reference .ts extensions (#54746)

tests/cases/conformance/externalModules/typeOnly/allowsImportingTsExtension.ts

@@ -0,0 +1,23 @@
+// @allowImportingTsExtensions: false
+// @target: esnext
+// @module: esnext
+
+// @Filename: a.ts
+export class A {}
+
+// @Filename: a.d.ts
+export class A {}
+
+// @Filename: b.ts
+import type { A } from "./a.ts"; // ok
+import {} from "./a.ts"; // error
+import { type A as _A } from "./a.ts"; // error
+type __A = import("./a.ts").A; // ok
+const aPromise = import("./a.ts"); // error
+
+// @Filename: c.ts
+import type { A } from "./a.d.ts"; // ok
+import {} from "./a.d.ts"; // error
+import { type A as _A } from "./a.d.ts"; // error
+type __A = import("./a.d.ts").A; // ok
+const aPromise = import("./a.d.ts"); // error

tests/cases/fourslash/completionsImport_promoteTypeOnly6.ts

@@ -0,0 +1,34 @@
+/// <reference path="fourslash.ts" />
+// @module: nodenext
+// @allowImportingTsExtensions: false
+
+// @Filename: /exports.ts
+//// export interface SomeInterface {}
+//// export class SomePig {}
+
+// @Filename: /a.ts
+//// import type { SomePig } from "./exports.ts";
+//// new SomePig/**/
+
+verify.completions({
+  marker: "",
+  includes: [{
+    name: "SomePig",
+    source: completion.CompletionSource.TypeOnlyAlias,
+    hasAction: true,
+  }]
+});
+
+verify.applyCodeActionFromCompletion("", {
+  name: "SomePig",
+  source: completion.CompletionSource.TypeOnlyAlias,
+  description: `Remove 'type' from import declaration from "./exports.ts"`,
+  newFileContent:
+`import { SomePig } from "./exports.js";
+new SomePig`,
+  preferences: {
+    includeCompletionsForModuleExports: true,
+    allowIncompleteCompletions: true,
+    includeInsertTextCompletions: true,
+  },
+});

tests/cases/fourslash/completionsImport_promoteTypeOnly7.ts

@@ -0,0 +1,34 @@
+/// <reference path="fourslash.ts" />
+// @module: nodenext
+// @allowImportingTsExtensions: true
+
+// @Filename: /exports.ts
+//// export interface SomeInterface {}
+//// export class SomePig {}
+
+// @Filename: /a.ts
+//// import type { SomePig } from "./exports.ts";
+//// new SomePig/**/
+
+verify.completions({
+  marker: "",
+  includes: [{
+    name: "SomePig",
+    source: completion.CompletionSource.TypeOnlyAlias,
+    hasAction: true,
+  }]
+});
+
+verify.applyCodeActionFromCompletion("", {
+  name: "SomePig",
+  source: completion.CompletionSource.TypeOnlyAlias,
+  description: `Remove 'type' from import declaration from "./exports.ts"`,
+  newFileContent:
+`import { SomePig } from "./exports.ts";
+new SomePig`,
+  preferences: {
+    includeCompletionsForModuleExports: true,
+    allowIncompleteCompletions: true,
+    includeInsertTextCompletions: true,
+  },
+});