RollupError: [type] is not exported by [file] - failure for relative imports of types

[donmccurdy]

Describe the bug

When running Vite in library mode, it fails to build if there are types imported from relative paths. The issue has previously been raised in a discussion, but I believe it's likely to be a bug and would like to report it for visibility here. Thanks!

Reproduction

https://github.com/donmccurdy/2024-06-20_vite_lib_ts

Steps to reproduce

// index.js
export { MyClass, MyType } from "./impl.js";

// impl.js
export class MyClass {}
export type MyType = string;

System Info

System:
    OS: macOS 14.5
    CPU: (10) arm64 Apple M2 Pro
    Memory: 296.55 MB / 16.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 20.11.0 - ~/.nvm/versions/node/v20.11.0/bin/node
    Yarn: 1.22.22 - ~/.nvm/versions/node/v20.11.0/bin/yarn
    npm: 10.2.4 - ~/.nvm/versions/node/v20.11.0/bin/npm
    pnpm: 9.4.0 - ~/.nvm/versions/node/v20.11.0/bin/pnpm
  Browsers:
    Chrome: 126.0.6478.62
    Edge: 126.0.2592.61
    Safari: 17.5
    Safari Technology Preview: 17.4
  npmPackages:
    vite: ^5.3.1 => 5.3.1

Used Package Manager

yarn

Logs

$ vite build --config vite.config.ts
vite v5.3.1 building for production...
✓ 2 modules transformed.
x Build failed in 16ms
error during build:
src/index.ts (1:18): "MyType" is not exported by "src/impl.ts", imported by "src/index.ts".
file: /Users/donmccurdy/Demos/2024-06-20_vite_lib_ts/src/index.ts:1:18

1: export { MyClass, MyType } from "./impl.js";
                     ^

    at getRollupError (file:///Users/donmccurdy/Demos/2024-06-20_vite_lib_ts/node_modules/rollup/dist/es/shared/parseAst.js:396:41)
    at error (file:///Users/donmccurdy/Demos/2024-06-20_vite_lib_ts/node_modules/rollup/dist/es/shared/parseAst.js:392:42)
    at Module.error (file:///Users/donmccurdy/Demos/2024-06-20_vite_lib_ts/node_modules/rollup/dist/es/shared/node-entry.js:13858:16)
    at Module.getVariableForExportName (file:///Users/donmccurdy/Demos/2024-06-20_vite_lib_ts/node_modules/rollup/dist/es/shared/node-entry.js:14022:29)
    at Module.includeAllExports (file:///Users/donmccurdy/Demos/2024-06-20_vite_lib_ts/node_modules/rollup/dist/es/shared/node-entry.js:14098:37)
    at Graph.includeStatements (file:///Users/donmccurdy/Demos/2024-06-20_vite_lib_ts/node_modules/rollup/dist/es/shared/node-entry.js:20033:36)
    at Graph.build (file:///Users/donmccurdy/Demos/2024-06-20_vite_lib_ts/node_modules/rollup/dist/es/shared/node-entry.js:19969:14)
    at async file:///Users/donmccurdy/Demos/2024-06-20_vite_lib_ts/node_modules/rollup/dist/es/shared/node-entry.js:20611:13
    at async catchUnfinishedHookActions (file:///Users/donmccurdy/Demos/2024-06-20_vite_lib_ts/node_modules/rollup/dist/es/shared/node-entry.js:20119:16)
    at async rollupInternal (file:///Users/donmccurdy/Demos/2024-06-20_vite_lib_ts/node_modules/rollup/dist/es/shared/node-entry.js:20606:5)
error Command failed with exit code 1.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.

Validations

• Follow our Code of Conduct
• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
• Make sure this is a Vite issue and not a framework-specific issue. For example, if it's a Vue SFC related bug, it should likely be reported to vuejs/core instead.
• Check that this is a concrete bug. For Q&A open a GitHub Discussion or join our Discord Chat Server.
• The provided reproduction is a minimal reproducible example of the bug.

[hi-ogawa]

I think this is working intended and Vite requires type import/export to be explicitly flagged as export { type MyType } since each ts file is transpiled independently.

Such invalid usage can be caught when enabling tsconfig's isolatedModules https://vitejs.dev/guide/features.html#isolatedmodules and typescript tells this error:

src/index.ts:1:19 - error TS1205: Re-exporting a type when 'isolatedModules' is enabled requires using 'export type'.

1 export { MyClass, MyType } from "./impl.js";
                    ~~~~~~

[donmccurdy]

Thanks @hi-ogawa! Indeed, that fixed the issue. I wasn't aware of the isolatedModules property.