Vite 6 change in behavior with noExternal & imports that share name with node builtins

[thebanjomatic]

Describe the bug

When using build.ssr: true and ssr.noExternal: true, and importing from a package with the same name as a node built-in, vite 6 appears to treat the package as external, but resolves the import path as if it was a package import.

This was happening in some nested dependencies of mine. readable_stream does require('string_decoder/') (presumably to force the import to use the package dependency over the node built-in).

From what I can guess, it seems like there is a mismatch between two bits of code in the resolution logic. One part sees the package name "string_decoder" and sees that it matches a node built-in and so it gets flagged as external, however, when the import is resolved, it sees the / at the end and resolves to the main export in the output.

Input:

import { StringDecoder } from 'string_decoder/';

Produces:

import { StringDecoder } from 'string_decoder/lib/string_decoder.js';

which is not a valid import from the node built-in, but also isn't bundled so this fails to execute at runtime if string_decoder is not present in node_modules.

In Vite 5, the string_decoder package dependency is bundled and included in the output of ./dist/index.js as expected.

Reproduction

https://stackblitz.com/edit/vitejs-vite-s9cz6r?file=src%2Findex.js&view=editor

Steps to reproduce

First, npm install followed by npm run build

Running npm run test will delete string_decoder from node_modules and then execute the output. The expectation is that string_decoder should have been bundled into the dist/index.js output, but that is not the case so running dist/index.js fails.

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: ^6.0.1 => 6.0.1 

Used Package Manager

npm

Logs

No response

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