Source maps sources are relative to root instead of to .map file

[jsedlacek]

Describe the bug

Source map sources are related to root instead of to .map file.

I have source (Typescript) files inside the src folder and generate (javascript) into the build folder using:

yarn swc src -d build -s true

The build/index.js.map contains:

{
  "version": 3,
  "sources": [
    "src/index.ts"
  ],
...

When compiled via tsc, the result is:

{
  "version": 3,
  "file": "index.js",
  "sourceRoot": "",
  "sources": [
    "../src/index.ts"
  ],
  ...

Input code

src/index.ts:

console.log('Hello');

Config

{}

Expected behavior

The source reference is relative to the .map file.

Version

The version of @swc/core: 1.2.40

Additional context

Because of this, the VS Code is not able to add a breakpoint in the .ts file when debugging.

[jsedlacek]

@kdy1 Is this fixed in version 1.2.47? I just tried it, and the bug seems to be present there.

[kdy1]

@jsedlacek Hmm... I thought I fixed it, but maybe I made a mistake.

[kherock]

This is due to a combination of #1388 and the CLI package not using the cwd option when an output directory is specified. I'm working on a PR fixing this in the CLI, but I haven't learned Rust yet and probably can't fix #1388 on my own.

[kdy1]

I found that being relative to the output source file requires knowing the destination path of sourcemap.
But it has some problems.

• For inline sourcemaps, destination path may not exist at all.

tsc is a bit different, as it always emit to file.

• For .map files, we need to pass down some parts of cli options to transform and print so that the swc crate can know the destination path.

This seems like a bad design. The function named print accepting the destination path without printing to the path is strange.

I'll postpone this issue to think about it more.

[pbadenski]

@kdy1 Apologies for being a bit impatient... Any updates on this, any way I could help? This is the remaining big reason we're holding off to move our project over from babel to swc :(

[kdy1]

@pbadenski
I'll look into this. This seems a bit complex, though.

[kdy1]

This will be fixed as of v1.2.64
I need to patch cli to detect the version of swc core and pass some more options for v1.2.64+

[pbadenski]

Is there anything special I need to have this work with @swc/register? I just tried on @swc/core#v1.2.70 and debugging still doesn't work in my WebStorm (where it works fine with babel).

I tried both sourceMaps: true and sourceMaps: "inline" in my .swcrc.

The difference seems to be that source map in babel is:

...
"sourceRoot": "/Users/pbadenski/workspace/ui/tests/unit/formula/engine/",
"sources": [
    "evaluatorV1.spec.ts"
  ],
...

and in swc it's:

...
"sources": [ "/Users/pbadenski/workspace/ui/tests/unit/formula/engine/evaluatorV1.spec.ts"
  ],
...

[kdy1]

I think it's an issue of @swc/register. I'll take a look when current task is finished.

[pbadenski]

Correction - it looks like this works now, but lines aren't correct in the source maps, I'll submit a separate issue for that.

[swc-bot]

This closed issue has been automatically locked because it had no new activity for a month. If you are running into a similar issue, please create a new issue with the steps to reproduce. Thank you.