Source maps containing `https://` urls get mangled

[lucacasonato]

When an input file has a sourcemap with a http: URL in the "sources" section, esbuild mangles it.

index.js

import "./foo/index.js";

foo/index.js

// index.js
throw new Error();
//# sourceMappingURL=data:application/json;base64,ewogICJ2ZXJzaW9uIjogMywKICAic291cmNlcyI6IFsiaHR0cHM6Ly9leGFtcGxlLmNvbS9pbmRleC5qcyJdLAogICJzb3VyY2VzQ29udGVudCI6IFsidGhyb3cgbmV3IEVycm9yKCk7Il0sCiAgIm1hcHBpbmdzIjogIjtBQUFBLE1BQU0sSUFBSTsiLAogICJuYW1lcyI6IFtdCn0K

The source map of the above file looks like this:

{
  "version": 3,
  "sources": ["https://example.com/index.js"],
  "sourcesContent": ["throw new Error();"],
  "mappings": ";AAAA,MAAM,IAAI;",
  "names": []
}

Then run:

esbuild --bundle --format=esm --sourcemap=inline index.js > index.dist.js

This generates the following file:

// foo/index.js
throw new Error();
//# sourceMappingURL=data:application/json;base64,ewogICJ2ZXJzaW9uIjogMywKICAic291cmNlcyI6IFsiZm9vL2h0dHBzOi9leGFtcGxlLmNvbS9pbmRleC5qcyJdLAogICJzb3VyY2VzQ29udGVudCI6IFsidGhyb3cgbmV3IEVycm9yKCk7Il0sCiAgIm1hcHBpbmdzIjogIjtBQUFBLE1BQU0sSUFBSSxNQUFBOyIsCiAgIm5hbWVzIjogW10KfQo=

This contains the following source map:

{
  "version": 3,
  "sources": ["foo/https:/example.com/index.js"],
  "sourcesContent": ["throw new Error();"],
  "mappings": ";AAAA,MAAM,IAAI,MAAA;",
  "names": []
}

You can see that the sources URL here is foo/https:/example.com/index.js even though it should be https://example.com/index.js.

Possibly related #1745

[evanw]

Closing as a duplicate.