Vite SSR doesn't overwrite `*` re-export by named export

[hi-ogawa]

Describe the bug

Example code

• dep.js

export const a = "dep-a"
export const b = "dep-b"
export const c = "dep-c"

• main.js

export const a = "main-a"
export * from "./dep.js"
export const c = "main-c"

expected

❯ node -e 'import("./src/main.js").then(console.log)'
[Module: null prototype] { a: 'main-a', c: 'main-c', b: 'dep-b' }

(Also rollup output on repl)

actual

# get "dep-a" instead of "main-a"
❯ node repro.js
{"a":"dep-a","b":"dep-b","c":"main-c"}

Side note: Current Vite SSR works if export const comes after export *. But, probably export hoisting PR #18983 currently breaks this pattern all the time. I think technically this is solvable if we gather local named export names first and then pass and exclude them from exportAll runtime function:

vite/packages/vite/src/module-runner/runner.ts

Line 407 in c0e3dba

[ssrExportAllKey]: (obj: any) => exportAll(exports, obj),

Reproduction

https://stackblitz.com/edit/vitejs-vite-kkt7njfs?file=src%2Fmain.js

Steps to reproduce

• Open stackblitz
• run node repro.js
• run node -e 'import("./src/main.js").then(console.log)'

System Info

System:
    OS: Linux 5.0 undefined
    CPU: (8) x64 Intel(R) Core(TM) i9-9880H CPU @ 2.30GHz
    Memory: 0 Bytes / 0 Bytes
    Shell: 1.0 - /bin/jsh
  Binaries:
    Node: 18.20.3 - /usr/local/bin/node
    Yarn: 1.22.19 - /usr/local/bin/yarn
    npm: 10.2.3 - /usr/local/bin/npm
    pnpm: 8.15.6 - /usr/local/bin/pnpm
  npmPackages:
    vite: ^6.2.0 => 6.2.0

Used Package Manager

npm

Logs

No response

Validations

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• The provided reproduction is a minimal reproducible example of the bug.

[Dunqing]

I got the output by ModuleRunnerTransform transforming main.js

const a = 'main-a';
Object.defineProperty(__vite_ssr_exports__, 'a', {
       enumerable: true,
       configurable: true,
       get() {
               return a;
       }
});
const __vite_ssr_import_0__ = await __vite_ssr_import__('./dep.js');
__vite_ssr_exportAll__(__vite_ssr_import_0__);
const c = 'main-c';
Object.defineProperty(__vite_ssr_exports__, 'c', {
       enumerable: true,
       configurable: true,
       get() {
               return c;
       }
});

I haven't looked into #18983, is this output correct? If not, does it need to be solved in the runtime runner?

[hi-ogawa]

On second thought, we probably don't need to change transform. Since Vite SSR cannot statically analyze export * ... beforehand, what we can do is to not overwrite the existing export, so we only need to fix __vite_ssr_exportAll__ runtime utility. I made a PR with this fix #19534.