Map RPITIT's opaque type bounds back from projections to opaques
An RPITIT in a program's AST is eventually translated into both a projection GAT and an opaque. The opaque is used for default trait methods, like:
```
trait Foo {
fn bar() -> impl Sized { 0i32 }
}
```
The item bounds for both the projection and opaque are identical, and both have a *projection* self ty. This is mostly okay, since we can normalize this projection within the default trait method body to the opaque, but it does two things:
1. it leads to bugs in places where we don't normalize item bounds, like `deduce_future_output_from_obligations`
2. it leads to extra match arms that are both suspicious looking and also easy to miss
This PR maps the opaque type bounds of the RPITIT's *opaque* back to the opaque's self type to avoid this quirk. Then we can fix the UI test for #108304 (1.) and also remove a bunch of match arms (2.).
Fixes#108304
r? `@spastorino`
Check lazy type aliases for well-formedness
Previously we didn't check if `T: Mul` holds given lazy `type Alias<T> = <T as Mul>::Output;`.
Now we do. It only makes sense.
`@rustbot` label F-lazy_type_alias
r? `@oli-obk`
This function has some shared code for the thin LTO and fat LTO cases,
but those cases have so little in common that it's actually clearer to
treat them fully separately.
PR #112946 tweaked the naming of LLVM threads, but messed things up
slightly, resulting in threads on Windows having names like `optimize
module {} regex.f10ba03eb5ec7975-cgu.0`.
This commit removes the extraneous `{} `.
The main loop has a *very* complex condition, which includes two
mentions of `codegen_state`. The body of the loop then immediately
switches on the `codegen_state`.
I find it easier to understand if it's a `loop` and we check for exit
conditions after switching on `codegen_state`. We end up with a tiny bit
of code duplication, but it's clear that (a) we never exit in the
`Ongoing` case, (b) we exit in the `Completed` state only if several
things are true (and there's interaction with LTO there), and (c) we
exit in the `Aborted` state if a couple of things are true. Also, the
exit conditions are all simple conjunctions.
This loop condition involves `codegen_state`, `work_items`, and
`running_with_own_token`. But the body of the loop cannot modify
`codegen_state`, so repeatedly checking it is unnecessary.
`CodegenContext` is immutable except for the `worker` field - we clone
`CodegenContext` in multiple places, changing the `worker` field each
time. It's simpler to move the `worker` field out of `CodegenContext`.
It took me some time to understand how the main thread can lend a
jobserver token to an LLVM thread. This commit renames a couple of
things to make it clearer.
- Rename the `LLVMing` variant as `Lending`, because that is a clearer
description of what is happening.
- Rename `running` as `running_with_own_token`, which makes it clearer
that there might be one additional LLVM thread running (with a loaned
token). Also add a comment to its definition.
And rename the `Compiled` variant as `Finished`, because that name makes
it clearer there is nothing left to do, contrasting nicely with the
`Needs*` variants.
Don't install default projection bound for return-position `impl Trait` in trait methods with no body
This ensures that we never try to project to an opaque type in a trait method that has no body to infer its hidden type, which means we never later call `type_of` on that opaque. This is because opaque types try to reveal their hidden type when proving auto traits.
I thought about this a lot, and I think this is a fix that's less likely to introduce other strange downstream ICEs than #113461.
Fixes#113434
r? `@spastorino`
Fix invalid suggestion for mismatched types in closure arguments
This PR fixes the invalid suggestion for mismatched types in closure arguments.
The invalid suggestion came from a wrongly created span in the parser for closure arguments that don't have a type specified. Specifically, the span in this case was the last token span, but in the case of tuples, the span represented the last parenthesis instead of the whole tuple, which is fixed by taking the more accurate span of the pattern.
There is one unfortunate downside of this fix, it worsens even more the diagnostic for mismatched types in closure args without an explicit type. This happens because there is no correct span for implied inferred type. I tried also fixing this but it's a rabbit hole.
Fixes https://github.com/rust-lang/rust/issues/114180
The invalid suggestion came from a wrongly created span in `rustc_parse'
for closure arguments that didn't have a type specified. Specifically,
the span in this case was the last token span, but in the case of
tuples, the span represented the last parenthesis instead of the whole
tuple, which is fixed by taking the more accurate span of the pattern.
[rustc][data_structures] Simplify binary_search_slice.
Instead of using `binary_search_by_key`, it's possible to use `partition_point` to find the lower bound. This avoids the need to locate the leftmost matching entry separately.
It's also possible to use `partition_point` to find the upper bound, so I plan to send a separate PR for your consideration.
