Convert errors in libcore’s try! macro too.

[SimonSapin]

It is still a separate definition from libstd’s so that $crate expands to std:: in the latter, not core::.

See discussion at #27701. There is an expectation that core::foo is the same as std::foo. We should not have two things with the same name but subtly different behavior.

r? @aturon

[rust-highfive]

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @aturon (or someone else) soon.

If any changes to this PR are deemed necessary, please add them as extra commits. This ensures that the reviewer can see what has changed since they last reviewed the code. The way Github handles out-of-date commits, this should also make it reasonably obvious what issues have or haven't been addressed. Large or tricky changes may require several passes of review and changes.

Please see the contribution instructions for more information.

[briansmith]

If the macro in libcore is defined identically to the macro in libstd, then why are there two definitions? It will be problematic to keep them in sync if they are separate.

[SimonSapin]

As mentioned, if the macro was only defined in core and re-exported in std, $crate would always expand to core::, which wouldn’t work in crates that don’t have extern crate core;. Having two macros allows having $crate expand to either core:: or std:: depending on which one you use.

[alexcrichton]

@SimonSapin I think that $crate actually expands to the crate-of-origin so it should actually work to be just "vanilla reexported" from core in std. I just ran a build locally with the reexport and it seems to be going along ok at least!

Perhaps we could try that out?

[SimonSapin]

Uh. It sounds like I made incorrect assumptions, but now I’m confused as to how $crate works. I’m not sure how to do the reexport. If you already have it locally, could you make a PR with it?

[alexcrichton]

Ah you should just be able to move the try macro as-is from the standard library into libcore and then update this list to have try as well, and that should do the trick!

[bors]

☔ The latest upstream changes (presumably #30187) made this pull request unmergeable. Please resolve the merge conflicts.

[alexcrichton]

Ah I landed this in #30187 basically

[SimonSapin]

Thanks for taking care of it!