[@rollup/plugin-tpescript] Rollup does not get `module` and `moduleResolution` settings from extended `tsconfig.json`

[floratmin]

• Rollup Plugin Name: @rollup/plugin-typescript
• Rollup Plugin Version: 11.1.6
• Rollup Version: 4.18.0
• Operating System (or Browser): Ubuntu 22.04.4 LTS
• Node Version: 22.2.0, but also not with 20.14.0
• Link to reproduction (⚠️ read below): rollup-tsconfig

Expected Behavior

Settings for module and moduleResolution in compilerOptions in tsconfig.base.json should be also used for tsconfig.lib.json and tsconfig.rollup.json.

Actual Behavior

If I do not specify 'moduleandmoduleResolutionintsconfig.rollup.json` I get the warning

(!) [plugin typescript] @rollup/plugin-typescript TS5110: Option 'module' must be set to 'Node16' when option 'moduleResolution' is set to 'Node16'.

The same warning appears when I do not specify these settings in the rollup.config.ts in the typescript plugin options or in the file tsconfig.lib.json.

Additional Information

[sam-mfb]

This looks like it is probably the same as this issue. That reporter provided a detailed explanation of the source.

[stale]

Hey folks. This issue hasn't received any traction for 60 days, so we're going to close this for housekeeping. If this is still an ongoing issue, please do consider contributing a Pull Request to resolve it. Further discussion is always welcome even with the issue closed. If anything actionable is posted in the comments, we'll consider reopening it. ⓘ

[newswim]

Hi — this is still reproducible on master (and @rollup/plugin-typescript@12.3.0) under TypeScript 5.x. The root cause is what #1583 described: parseTypescriptConfig in packages/typescript/src/options/tsconfig.ts spreads DEFAULT_COMPILER_OPTIONS ({ module: 'esnext', skipLibCheck: true }) into the leaf compilerOptions slot passed to ts.parseJsonConfigFileContent, which makes the plugin defaults win over anything inherited via extends. A base config setting module: nodenext / moduleResolution: nodenext ends up with module: esnext on the resolved options while moduleResolution: nodenext survives, and TypeScript reports TS5110.

I have a PR for this: #2004.

Approach: stop spreading DEFAULT_COMPILER_OPTIONS into the leaf slot; apply them after parseJsonConfigFileContent returns, only for keys the resolved config (extends chain included) left unset. Defaults are coerced via ts.convertCompilerOptionsFromJson so JSON strings like 'esnext' end up as ts.ModuleKind.ESNext on the parsed options.

Tests: a new extends-nodenext fixture plus a version-independent unit test on parseTypescriptConfig (red on master regardless of bundled TS version) and an end-to-end check that no TS5110 warning fires. Verified green against typescript@4.8.4 (current dev-dep) and typescript@5.9.3.

Happy to iterate on the approach.