Project to `TyKind::Error` when there are unconstrained non-lifetime (ty/const) impl params
It splits the `enforce_impl_params_are_constrained` function into lifetime/non-lifetime, and queryfies the latter. We can then use the result of the latter query (`Result<(), ErrorGuaranteed>`) to intercept projection and constrain the projected type to `TyKind::Error`, which ensures that we leak no ty or const vars to places that don't expect them, like `normalize_erasing_regions`.
The reason we split `enforce_impl_params_are_constrained` into two parts is because we only error for *lifetimes* if the lifetime ends up showing up in any of the associated types of the impl (e.g. we allow `impl<'a> Foo { type Assoc = (); }`). However, in order to compute the `type_of` query for the anonymous associated type of an RPITIT, we need to do trait solving (in `query collect_return_position_impl_trait_in_trait_tys`). That would induce cycles. Luckily, it turns out for lifetimes we don't even care about if they're unconstrained, since they're erased in all contexts that we are trying to fix ICEs. So it's sufficient to keep this check separated out of the query.
I think this is a bit less invasive of an approach compared to #127973. The major difference between this PR and that PR is that we queryify the check instead of merging it into the `explicit_predicates_of` query, and we use the result to taint just projection goals, rather than trait goals too. This doesn't require a lot of new tracking in `ItemCtxt` and `GenericPredicates`, and it also seems to not require any other changes to typeck like that PR did.
Fixes#123141Fixes#125874Fixes#126942Fixes#127804Fixes#130967
r? oli-obk
This is serves as a collection of crashes so that accidental ICE fixes are tracked.
This was formally done at https://github.com/rust-lang/glacier but doing it inside
the rustc testsuite is more convenient.
It is imperative that a test in the suite causes an internal compiler error/panic
or makes rustc crash in some other way.
A test will "pass" if rustc exits with something other than 1 or 0.
When adding crashes from https://github.com/rust-lang/rust/issues, the
issue number should be noted in the file name (12345.rs should suffice)
and also inside the file via //@ known-bug #4321 if possible.
If you happen to fix one of the crashes, please move it to a fitting
subdirectory in tests/ui and give it a meaningful name.
Also please add a doc comment at the top of the file explaining why
this test exists. :)
Adding
Fixes #NNNNN
Fixes #MMMMM
to the description of your pull request will ensure the
corresponding tickets will be closed automatically upon merge.
The ticket ids can be found in the file name or the known-bug annotation
inside the testfile.
Please do not re-report any crashes that you find here!
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