Issue 90702 fix: Stop treating some crate loading failures as fatal errors

[mjptree]

Surface mulitple extern crate resolution errors at a time.

This is achieved by creating a dummy crate, instead of aborting directly after the resolution error. The ExternCrateError has been added to allow propagating the resolution error from rustc_metadata crate to the rustc_resolve with a minimal public surface. The import_extern_crate function is a block that was factored out from build_reduced_graph_for_item for better organization. The only added functionality made to it where the added error handling in the process_extern_crate call. The remaining bits in this function are the same as before.

Resolves #90702

r? @petrochenkov

[petrochenkov]

Two general comments:

• Could you move the extraction of fn build_reduced_graph_for_extern_crate to a separate commit that only moves code and doesn't do anything else? (It can actually be the very first commit.)
• ExternCrateError looks unnecessary, I'd keep the old scheme and report the error from fn resolve_crate.

[mjptree]

I restructered the PR into three commits grouped as thematically as possible incorporating all your suggestions. I hope this makes it easier to disambiguate.

EDIT: Wait, I messed up the commits. The first 2 commits were somehow squashed. I'll submit a new one.

[mjptree]

@rustbot label -S-waiting-on-author +S-waiting-on-review

[mjptree]

I'm aware the last commit currently fails 2 tests. But I'd like you to have a look at it whether these changes are what you had in mind.

Also, if you look at the two tests src/test/ui/crate-loading/invalid-rlib.rs and src/test/ui/rust-2018/uniform-paths/deadlock.rs it would be helpful if you have any suggestions how my changes caused these changes in error output. I'll also continue investigating further after work today.

@rustbot label -S-waiting-on-author +S-waiting-on-review

[petrochenkov]

Also, if you look at the two tests src/test/ui/crate-loading/invalid-rlib.rs and src/test/ui/rust-2018/uniform-paths/deadlock.rs it would be helpful if you have any suggestions how my changes caused these changes in error output.

IIRC, imports may attempt to load crates for the second time during import validation (which we now reach due to not producing a fatal error), this looks like the reason for the invalid-rlib.rs change.
The extra messages in deadlock.rs also look like an output from import validation.

You can attempt to avoid these extra messages for already erroneous imports (the relevant code should be somewhere inside fn finalize_imports), but it's a task for a separate PR.

[bors]

📌 Commit 2c9d9b4 has been approved by petrochenkov

[matthiaskrgr]

Mmh, this might cause this test failure here: #91405 (comment)
but I'm not 100% certain.
@bors rollup=iffy

[petrochenkov]

Yes, looks like this PR is the reason, ui/extern-flag/empty-extern-arg.rs has target-dependent output.

ui\panic-handler\weak-lang-item.rs is a similar test and it uses // needs-unwind to disable the test on targets producing different diagnostics.

[petrochenkov]

@bors r-

[mjptree]

ui\panic-handler\weak-lang-item.rs is a similar test and it uses // needs-unwind to disable the test on targets producing different diagnostics.

I'm trying the same fix then here, ignoring this particular test for panic=abort and emscripten targets.

@rustbot label -S-waiting-on-author +S-waiting-on-review

[petrochenkov]

@bors r+

[bors]

📌 Commit 2ca9333 has been approved by petrochenkov