Vite SSR doesn't fail when same name is declared via import

[hi-ogawa]

Describe the bug

Example code test.js

import { join } from "node:path";
import { join } from "node:path";

export default join("a", "b")

On Node:

❯ node src/test.js
SyntaxError: Identifier 'join' has already been declared (2:9)
    at ModuleLoader.moduleStrategy (https://kkvilbvzkqgithub-l0as.w-credentialless-staticblitz.com/builtins.8cb5228f.js:160:2071)
    at ModuleLoader.<anonymous> (https://kkvilbvzkqgithub-l0as.w-credentialless-staticblitz.com/builtins.8cb5228f.js:154:2546)
    at async https://kkvilbvzkqgithub-l0as.w-credentialless-staticblitz.com/builtins.8cb5228f.js:155:924

Node.js v18.20.3

On Vite SSR:

❯ node repro.js
[Module: null prototype] { default: 'a/b' }

---

I noticed this when testing oxc module runner transform in vitejs#85 where oxc rejected such code but current ssr tolerate the same code.

Reproduction

https://stackblitz.com/github/hi-ogawa/reproductions/tree/main/vite-ssr-import-name-already-declared?file=src%2Ftest.js

Steps to reproduce

Open stackblitz and run node repro.js and node src/test.js

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 => 6.2.1

Used Package Manager

npm

Logs

No response

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.

[sapphi-red]

This errors with Vite 4.5.9 (uses acorn):

Error: Parse failure: Identifier 'join' has already been declared (2:9)
At file: ./src/test.js
Contents of line 2: import { join } from "node:path";
    at ssrTransformScript (file:///home/projects/owainalwvo.github/node_modules/.pnpm/[email protected]/node_modules/vite/dist/node/chunks/dep-3936e161.js:55474:15)
    at ssrTransform (file:///home/projects/owainalwvo.github/node_modules/.pnpm/[email protected]/node_modules/vite/dist/node/chunks/dep-3936e161.js:55449:12)
    at Object.ssrTransform (file:///home/projects/owainalwvo.github/node_modules/.pnpm/[email protected]/node_modules/vite/dist/node/chunks/dep-3936e161.js:65323:20)
    at loadAndTransform (file:///home/projects/owainalwvo.github/node_modules/.pnpm/[email protected]/node_modules/vite/dist/node/chunks/dep-3936e161.js:55120:24)
    at async instantiateModule (file:///home/projects/owainalwvo.github/node_modules/.pnpm/[email protected]/node_modules/vite/dist/node/chunks/dep-3936e161.js:56006:10)

It's probably because acorn rejects these while SWC allows these.

[hi-ogawa]

By the similar token, this code doesn't fail on Vite SSR during module loading https://stackblitz.com/edit/github-tn8dri6l?file=src%2Ftest.js.

Example code

export { data }

On Node:

❯ node src/test.js
SyntaxError: Export 'data' is not defined (1:9)
    at ModuleLoader.moduleStrategy (https://owainalwvogithub-02gq.w-credentialless-staticblitz.com/builtins.8cb5228f.js:160:2071)
    at ModuleLoader.<anonymous> (https://owainalwvogithub-02gq.w-credentialless-staticblitz.com/builtins.8cb5228f.js:154:2546)
    at async https://owainalwvogithub-02gq.w-credentialless-staticblitz.com/builtins.8cb5228f.js:155:924

Node.js v18.20.3

On Vite SSR:

❯ node repro.js
[Module: null prototype] { data: [Getter] }

[sapphi-red]

It seems that one is also rejected by acorn but not by SWC.