Directory in sourcemap is incorrect, impacting `vite serve` (but not Rollup)

Troubleshooting

1. Does tsc have the same output? If so, please explain why this is incorrect behavior

   No, due to this plugin changing outDir

2. Does your Rollup plugin order match this plugin’s compatibility? If not, please elaborate

   As far as I know - I have it configured as a pre plugin with vite

3. Can you create a minimal example that reproduces this behavior? Preferably, use this environment for your reproduction

   https://stackblitz.com/edit/vitejs-vite-rjjhlb?file=vite.config.js

What happens and why it is incorrect

When this plugin emits sourcemaps, the source map URL is incorrect, as the plugin configures typescript with a temporary output directory, and the sourcemap is generated relative to that. The sources property is modified in the .d.ts.map, but not similarly adjusted in the .js.map.

This works fine with Rollup itself, as when it merges sourcemaps it (from what I can tell) winds up only looking at the “root” sourcemap in the sourcemap chain. However, when using vite, it’s serve mode does not use rollup and instead uses @ampproject/remapping to combine sourcemaps, which relies on the sources URL being properly formed.

If you look at the script served by vite, you get:

sourceMappingURL=data:application/json;base64,eyJ2ZXJzaW9uIjozLCJtYXBwaW5ncyI6IkFBQUEsT0FBTztBQUNQLE9BQU8sb0JBQW9CO0FBQzNCLFNBQVMsb0JBQW9CO0FBRTdCLFNBQVMsY0FBOEIsTUFBTSxFQUFHLFlBQVk7QUFBQTtBQUFBO0FBQUE7QUFBQTtBQUFBO0FBQUEsa0JBTTFDO0FBQUE7QUFBQTtBQUFBO0FBQUE7QUFBQTtBQUFBO0FBQUE7QUFBQTtBQUFBO0FBQUE7QUFZbEIsYUFBYSxTQUFTLGNBQWlDLFVBQVUsQ0FBRSIsIm5hbWVzIjpbXSwic291cmNlcyI6WyIuLi8uLi8uLi8uLi9zcmMvbWFpbi50cyJdLCJmaWxlIjoiL2hvbWUvcHJvamVjdHMvdml0ZWpzLXZpdGUtcmpqaGxiL3NyYy9tYWluLnRzIiwic291cmNlc0NvbnRlbnQiOltudWxsXX0=

which decodes to:

{"version":3,"mappings":"AAAA,OAAO;AACP,OAAO,oBAAoB;AAC3B,SAAS,oBAAoB;AAE7B,SAAS,cAA8B,MAAM,EAAG,YAAY;AAAA;AAAA;AAAA;AAAA;AAAA;AAAA,kBAM1C;AAAA;AAAA;AAAA;AAAA;AAAA;AAAA;AAAA;AAAA;AAAA;AAAA;AAYlB,aAAa,SAAS,cAAiC,UAAU,CAAE","names":[],"sources":["../../../../src/main.ts"],"file":"/home/projects/vitejs-vite-rjjhlb/src/main.ts","sourcesContent":[null]}

The sources property should read ["../src/main.ts"]. Inserting log statements into this plugin confirms that this is what is being output from the plugin.

While technically this is a difference in behavior between vite and rollup and could arguably be a vite bug, my feeling was that this plugin should still expose accurate source URIs, especially since this is already handled for the .d.ts.map

Environment

Versions

System:
    OS: Linux 5.0 undefined
    CPU: (4) x64 Intel(R) Core(TM) i9-9880H CPU @ 2.30GHz
    Memory: 0 Bytes / 0 Bytes
    Shell: 1.0 - /bin/jsh
  Binaries:
    Node: 16.14.2 - /usr/local/bin/node
    Yarn: 1.22.10 - /bin/yarn
    npm: 7.17.0 - /bin/npm
  npmPackages:
    rollup-plugin-typescript2: ^0.32.1 => 0.32.1 
    typescript: ^4.6.4 => 4.7.4 
    vite: ^3.0.2 => 3.0.4

vite.config.js

:

import { defineConfig } from 'vite';
import typescriptPlugin from 'rollup-plugin-typescript2';

export default defineConfig({
  plugins: [
    {
      ...typescriptPlugin({}),
      enforce: 'pre',
    },
  ],
});

[luxaritas]

Ah, my apologies if my tone was too strict on that one!

No worries at all! Appreciate the additional context, just wanted to make sure we’re on the same page which it seems we are. Thanks again for taking the time to look into this.

[luxaritas]

I realized to get this working for now, I can pass:

tsconfigOverride: {
    compilerOptions: {
        sourceRoot: '../src'
    }
}

From what I understand, sourceRoot (or changes to the entries in sources itself) would always need to be resolved from the location of the output… which isn’t known during build hooks. Theoretically, you could specify an absolute path to the source files, but this would only work locally (e.g. fails when running on stackblitz). Does this mean Vite’s sourcemap merging approach would have to be changed to account for this, or is there some other way of reliably being able to determine how to resolve the source location?