`rootDirs` with `Node16`/`NodeNext` removes import extensions on file rename

[esdmr]

Bug Report

🔎 Search Terms

rootDirs, file extension, Node16, Node12, NodeNext, module, moduleResolution, Classic, importModuleSpecifierEnding, importModuleSpecifier, auto-import, file move.

🕗 Version & Regression Information

The last change was between version 3.5 and 3.6: decc3cd, later in 4.7 it started to affect the Node16/NodeNext module resolution.

⏯ Playground Link

Not replicable in TypeScript Playground, as it requires file rename. Here is a fourslash test for it:

/// <reference path="fourslash.ts"/>

// @Filename: /tsconfig.json
////{
////  "compilerOptions": {
////    "module": "Node16",
////    "rootDirs": ["src"]
////  }
////}

// @Filename: /src/person.ts
////export const name = "John Doe";

// @Filename: /src/index.ts
////import {name} from "./person.js";

verify.getEditsForFileRename({
	oldPath: '/src/person.ts',
	newPath: '/src/vip.ts',
	newFileContents: {
		'/src/index.ts': 'import {name} from "./vip.js";',
	},
});

💻 Code

1. Create a tsconfig.json setting moduleResolution to "Node16" and rootDirs to ["src"].
2. Create src/a.ts and src/b.ts.
3. Import './b.js' in src/a.ts.
4. Try renaming src/b.ts. (Make sure to enable automatic import updating in your editor)

🙁 Actual behavior

TypeScript updates the filename, removing the extension as a result. In ESM this would then err that “File may not be imported without an extension”. (Also, it seems that typescript.preferences.importModuleSpecifierEnding is ignored.)

🙂 Expected behavior

The file extension should not be removed by TypeScript since the original import had it.

[andrewbranch]

Related and possibly the same code path: #50710

Thanks for the fourslash test! ❤️