handle dynamic imports on windows

[edivados]

Added two failing tests using server functions to reproduce the issue with dynamic imports on Windows.

Descirption

An absolute file path like C:/users/edivados/index.js does not work with dyamic imports in Vite (dev) and Node (runtime).

Production

File urls should be used instead of absolute paths.

Development

If the path does not start with . or / vite uses nodeImport which fails on absolute paths.
https://github.com/vitejs/vite/blob/385d580a7df67570b8014318a607f62fe15eaef9/packages/vite/src/node/ssr/ssrModuleLoader.ts#L158-L164

Based on what ssrImport does this works.

• import(posix.resolve(/@fs, path))
• import(posix.resolve('/', path))
• import(decodeURIComponent(pathToFileURL(path).pathname))

Not using pathe because it does not add the leading slash on Windows.

Static and Dynamic import behavior on Windows

Static import

✔️ Posix style path

This is ok because the import is processed by vite or rollup and node never sees this.

import "C:/users/edivados/index.js";
await import("C:/users/edivados/index.js");

	resolver	mode	sees	comment
✔️	vite	dev	/@fs/C:/users/edivados/index.js	/@fs/ gets added by vite. vite:resolve plugin removes /@fs/ and normalizes to slash. /@fs/ skips checking if the file exists.
✔️	rollup	build	?	valid Windows path
✔️	node	runtime	bundler output

✔️ Windows style path

This is ok because the import is processed by vite or rollup and node never sees this.

import "C:\\users\\edivados\\index.js";
await import("C:\\users\\edivados\\index.js");

	resolver	mode	sees	comment
✔️	vite	dev	/@fs/C:/users/edivados/index.js	/@fs/ gets added by vite + normalization. vite:resolve plugin removes /@fs/ and normalizes to slash. /@fs/ skips checking if the file exists.
✔️	rollup	build	?	valid Windows path
✔️	node	runtime	bundler output

✔️ Leading slash (Posix style path)

import "/C:/users/edivados/index.js";
await import("/C:/users/edivados/index.js");

	resolver	mode	sees	comment
✔️	vite	dev	/@fs/C:/users/edivados/index.js
✔️	rollup	build	?	valid Windows path
✔️	node	runtime	bundler output

Dynamic import

✔️ Conditional

// path = C:/users/edivados/index.js
if (import.meta.env.DEV) path = posix.resolve("/@fs", path);
else path = pathToFileURL(path).href;

await import(path)

	resolver	mode	sees	comment
✔️	vite	dev	/@fs/C:/users/edivados/index.js	vite:resolve plugin removes /@fs/ and normalizes to slash. /@fs/ skips checking if the file exists.
✔️	rollup	build		noop
✔️	node	runtime	file:///C:/users/edivados/index.js

✔️ Leading slash (Posix style path)

// path = C:/users/edivados/index.js
path = posix.resolve("/", path);
await import(path);

	resolver	mode	sees	comment
✔️	vite	dev	/C:/users/edivados/index.js	vite:resolve plugin removes the leading slash, calls resolve(root, path) and also checks if the file exists.
✔️	rollup	build		noop
✔️	node	runtime	file:///C:/users/edivados/index.js	ok?

❌ Posix style path

// path = C:/users/edivados/index.js
await import(path)

	resolver	mode	sees	comment
❌	vite	dev	C:/users/edivados/index.js	uses nodeImport and fails
✔️	rollup	build		noop
❌	node	runtime	C:/users/edivados/index.js	has to be a file url

❌ Windows style path

// path = C:\\users\\edivados\\index.js
await import(path)

	resolver	mode	sees	comment
❌	vite	dev	C:\users\edivados\index.js	uses nodeImport and fails
✔️	rollup	build		noop
❌	node	runtime	C:\users\edivados\index.js	has to be a file url

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[nksaraf]

Thanks for the test!! Its going to be very helpful. I have been meaning to add more tests for things like this.

Do you have a fix for this? Open to anything. I am usually out of my league with this mac/windows file path stuff.