Tracking issue for RFC 2282 - Cargo profile dependencies

[Manishearth]

This is a tracking issue for RFC 2282 (rust-lang/rfcs#2282).

Cargo issue: rust-lang/cargo#5298

Steps:

(cc @rust-lang/cargo for mentorship instructions)

• Implement the ability to override profiles via .cargo/config (Profile Overrides (RFC #2282 Part 1) cargo#5384)
• Implement the ability to override profile keys for specific dependencies (Config Profiles (RFC 2282 Part 2) cargo#5506)
• Adjust documentation (see instructions on forge)
• Stabilization PR (see instructions on forge)

Unresolved questions:

• We can bikeshed the names of the new keys that were introduces

[Boscop]

Any update on this? :)

[Manishearth]

Someone needs to implement it.

[ehuss]

If you're looking for someone to work on this I'd be happy to help!

[Manishearth]

Sure! I don't have the bandwidth to mentor this but feel free to try it out. Might want to file an issue on the cargo side to coordinate the implementation work.

[ehuss]

Some issues came up during implementation.

• @alexcrichton mentioned that the package name could support full-spec syntax (crates.io/foo, etc.). It looks like it should be easy to support, just let me know if you'd like me to add it! (Currently it just matches the name.)
• I briefly discussed with @matklad the possibility of having a dedicated profile used for scripts. It would be easy to add, and would remove "build-override" which is essentially a pseudo-profile (and seems a little confusing to me). It would also decouple building build scripts from the --release flag. Let me know if you want to consider this route!

[Manishearth]

Full spec sounds great.

The problem with having a dedicated profile for scripts is that you may wish them to be compiled differently in debug vs release. build-override lets you do both.

The original proposal (not the one we RFCd) allowed nesting of profiles which would have made this work well (you declare a new profile, and link it in as the build profile for an existing one)

[Manishearth]

(Also to me it seems like having a build profile just makes the whole profile vs workflow deal even messier -- we already are in a situation where the test/bench profiles are a bit weird)

[ehuss]

Yep! I was just meaning that it can probably be improved on without too much effort. I think there was some concern during the RFC process that shared dependencies would be a problem, but they shouldn't be. I think @matklad had more thoughts on the profile/workflow stuff, so I'll let him say more.