LibSass source maps don't return file system paths, correct?

[npetruzzelli]

This is a general question, which didn't seem to have specific guidelines in https://github.com/sass/libsass/blob/master/.github/CONTRIBUTING.md, I'll do my best to be thorough.

I originally asked this question in node-sass ( sass/node-sass#2393 ), but it sounds like that wasn't the appropriate place for it.

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My understanding is that source maps only work with URLs (though I have an issue open to confirm this), not file system paths, though I found the following comment in a popular node package

https://github.com/webpack-contrib/sass-loader/blob/2529c0716b1bca321c22d16636b1385682b1c730/lib/loader.js#L90-L94

            // node-sass returns POSIX paths, that's why we need to transform them back to native paths.
            // This fixes an error on windows where the source-map module cannot resolve the source maps.
            // @see https://github.com/webpack-contrib/sass-loader/issues/366#issuecomment-279460722
            result.map.sourceRoot = path.normalize(result.map.sourceRoot);
            result.map.sources = result.map.sources.map(path.normalize);

• Question 1: Can you confirm whether or not this comment is accurate?
• Question 2: Can you confirm whether or not libsass source maps aim to adhere to the Source Map Revision 3 Proposal? If not, can you point me to the documentation for the spec you are adhering to?

Thanks and regards

[mgreter]

If the sources are not absolute URLs after prepending of the “sourceRoot”, the sources are resolved relative to the SourceMap (like resolving script src in a html document).

This is what libsass does, so we do adhere to the v3 draft. Since they are relative they are also valid relative "posix" paths. Hth

[npetruzzelli]

Got it, thank you!

So if I were to explain it to someone else, then I'd be telling them that relative URLs only appear to be POSIX paths because:

• They both use . to represent the current directory
• They both use .. to represent the parent directory
• They both use / to represent a segment/directory separator

In the case of relative paths, there are not URI protocols, domains, or ports, so it otherwise is a valid POSIX filesystem path (assuming the relative path does not have a hash or a query string.)

Would it be too confusing to bring up symbolic links here?

And more information can be found:

• File System Paths
  • Windows Naming Files, Paths, and Namespaces
  • POSIX 4.13 Pathname Resolution
• URLs/URIs
  • Uniform Resource Identifier (URI): Generic Syntax
  • Keep in mind that there is more to URLs than what is in the URL Class

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Does that sound about right?