extends generates wrong sourcemap

[hardfist]

I try to use @parcel/source-map to implement remapping like https://github.com/ampproject/remapping for efficiency, but it seems that It generates wrong sourcemap.
You can see the demo https://github.com/hardfist/remap here

[binyamin]

@hardfist Can you give us an example? What's "wrong" with your source-map?

[ArrayZoneYour]

I run the demo before, @ampproject/remapping can get correct remapping result and @parcel/sourcemap extends result is different.

@ampproject/remapping

@parcel/sourcemap