Support diffing against the original repo

[epage]

The information is usually present.

For context for the use case, see https://rust-lang.zulipchat.com/#narrow/stream/318791-t-crates-io/topic/Link.20to.20where.20the.20sources.20of.20a.20crate.20are.20located.20in.20git/near/429819690

[xfbs]

I can look into this, it sounds like something that could be useful.

Just for my understanding: do you mean that diff.rs should diff a released version of a crate with the commit in git?

One idea I had was to be able to diff a released version of a crate vs a specific branch. As in: compare v0.3.1 vs master. But that sounds like a slightly different use-case to the one that you are describing.

[epage]

Just for my understanding: do you mean that diff.rs should diff a released version of a crate with the commit in git?

Yes, particularly the commit used when publishing. On publish, cargo records

• commit hash
• path within repo

So long as the user set their repo in the metadata, we can diff against that commit. Diffing against tags and branches could also be nice; I just don't have as concrete of use cases for doing so.

[xfbs]

So, one way to get this done is:

• parse the Cargo.toml in the diff version (left)
• check if repository is in the metadata
• in the right version dropdown, show an entry for git
• if selected, attempt to fetch an archive of the commit (like https://github.com/$user/$repo/archive/aef66c462abe817e33aad91d97aa782a1e2ad2c7.tar.gz)
• when doing the diff, have to account for the fact that the crate might live in a subfolder in the repo (in case of a cargo workspace)

[epage]

Yes and for

when doing the diff, have to account for the fact that the crate might live in a subfolder in the repo (in case of a cargo workspace)

the vcs info contains that path