rewriteRelativeImportExtensions: tsc doesn't rewrite extensions in emitted declaration files

🔎 Search Terms

"rewriteRelativeImportExtensions", "extensions", "declaration", ".d.ts"

🕗 Version & Regression Information

• This is the behavior in every version I tried (even in the next 5.8.0), and I reviewed the FAQ for entries about "rewriteRelativeImportExtensions"

⏯ Playground Link

No response

💻 Code

In an index.ts file:

export * from './file.ts';

then build it with tsc and "rewriteRelativeImportExtensions": true & "declaration": true in the compilerOptions of your tsconfig.json

🙁 Actual behavior

Built files content: In the JS file, index.js, the extension is rewritten to .js:

export * from './file.js';

In the declaration file, index.d.ts, the extension is not rewritten to .js:

export * from './file.ts';

🙂 Expected behavior

In the declaration file, the extension should be rewritten to .js too:

export * from './file.js';

Additional information about the issue

It occurs in the current TS 5.7.3 and in the next version (5.8.0-dev.20250123 at this time). Even if TS correctly interprets .d.ts files with .ts extensions in import/export, it's not the case of the IDE I use, PhpStorm. It can't provide a real code assistance with these declaration files. In fact, I don't really know if it's a feature, a bug or an oversight in tsc, or if rewriteRelativeImportExtensions is just too new to be completely supported by all IDEs! Let me know!