Process alias-relate obligations in CoerceUnsized loop
After #119106, we now emit `AliasRelate` goals when relating `?0` and `Alias<T, ..>` in the new solver. In the ad-hoc `CoerceUnsized` selection loop, we now may have `AliasRelate` goals which must be processed to constrain type variables which are mentioned in other goals.
---
For example, in the included test, we try to coerce `&<ManuallyDrop<T> as Deref>::Target` to `&dyn Foo`. This requires proving:
* 1 `&<ManuallyDrop<T> as Deref>::Target: CoerceUnsized<&dyn Foo>`
* 2 `<ManuallyDrop<T> as Deref>::Target alias-relate ?0`
* 3 `?0: Unsize<dyn Foo>`
* 4 `?0: Foo`
* 5 `?0: Sized`
If we don't process goal (2.) before processing goal (3.), then we hit ambiguity since `?0` is never constrained, and therefore we bail out, refusing to coerce the types. After processing (2.), we know `?0 := T`, and the rest of the goals can be processed normally.
Split rustc_type_ir to avoid rustc_ast from depending on it
unblocks #121576
and resolves a FIXME in `rustc_ast`'s `Cargo.toml`
The new crate is tiny, but it will get bigger in #121576
Adjust printing for RPITITs
1. Call RPITITs `{synthetic#N}` instead of `{opaque#N}`.
2. Fall back to printing the RPITIT like an opaque even when printed as an `AliasTy`, just like we do for `ty::Alias`.
You could argue that (2.) is misleading, but I believe it's more consistent than naming `{synthetic#N}`, which I assume approximately nobody knows where that def path name comes from.
r? lcnr
Fix link generation for foreign macro in jump to definition feature
The crate name is already added to the link so it shouldn't be added a second time for local foreign macros.
r? ``@notriddle``
Changing some attributes to only_local.
Modified according to https://github.com/rust-lang/compiler-team/issues/505.
By running test cases, I found that modifying the attribute's only_local tag sometimes causes some unintuitive error reports, so I tend to split it into multiple PRs and edit a small number of attributes each time to prevent too many changes at once. Prevent possible subsequent difficulties in locating problems.
r? ``@lcnr``
unix_sigpipe: Simple fixes and improvements in tests
In https://github.com/rust-lang/rust/pull/120832 I included 5 preparatory commits.
It will take a while before discussions there and in https://github.com/rust-lang/rust/issues/62569 is settled, so here is a PR that splits out 4 of the commits that are easy to review, to get them out of the way.
r? ``@davidtwco`` who already approved these commits in https://github.com/rust-lang/rust/pull/120832 (but I have tweaked them a bit and rebased them since then).
For the convenience of my reviewer, here are the full commit messages of the commits:
<details>
<summary>Click to expand</summary>
```
commit 948b1d68ab (HEAD -> unix_sigpipe-tests-fixes, origin/unix_sigpipe-tests-fixes)
Author: Martin Nordholts <martin.nordholts@codetale.se>
Date: Fri Feb 9 07:57:27 2024 +0100
tests: Add unix_sigpipe-different-duplicates.rs test variant
To make sure that
#[unix_sigpipe = "x"]
#[unix_sigpipe = "y"]
behaves like
#[unix_sigpipe = "x"]
#[unix_sigpipe = "x"]
commit d14f15862d
Author: Martin Nordholts <martin.nordholts@codetale.se>
Date: Fri Feb 9 08:47:47 2024 +0100
tests: Combine unix_sigpipe-not-used.rs and unix_sigpipe-only-feature.rs
The only difference between the files is the presence/absence of
#![feature(unix_sigpipe)]
attribute. Avoid duplication by using revisions instead.
commit a1cb3dba84
Author: Martin Nordholts <martin.nordholts@codetale.se>
Date: Fri Feb 9 06:44:56 2024 +0100
tests: Rename unix_sigpipe.rs to unix_sigpipe-bare.rs for clarity
The test is for the "bare" variant of the attribute that looks like this:
#[unix_sigpipe]
which is not allowed, because it must look like this:
#[unix_sigpipe = "sig_ign"]
commit e060274e55
Author: Martin Nordholts <martin.nordholts@codetale.se>
Date: Fri Feb 9 05:48:24 2024 +0100
tests: Fix typo unix_sigpipe-error.rs -> unix_sigpipe-sig_ign.rs
There is no error expected. It's simply the "regular" test for sig_ign.
So rename it.
```
</details>
Tracking issue: https://github.com/rust-lang/rust/issues/97889
Remove the `UntranslatableDiagnosticTrivial` lint.
It's a specialized form of the `UntranslatableDiagnostic` lint that is deny-by-default.
Now that `UntranslatableDiagnostic` has been changed from allow-by-default to deny-by-default, the trivial variant is no longer needed.
r? ``@davidtwco``
This new documentation tries to avoid to limit the impact of the
conceptual pitfall, that the if guard relaxes the constraint, when
really it tightens it. This is achieved by changing the text and
examples. The previous documentation also chose a rather weird and
non-representative example for the if guard, that made it needlessly
complicated to understand.
- Put every literal in its own braces, rather than just some of them,
for maximal error recovery.
- Add a blank line between every case, for readability.
It's a specialized form of the `UntranslatableDiagnostic` lint that is
deny-by-default.
Now that `UntranslatableDiagnostic` has been changed from
allow-by-default to deny-by-default, the trivial variant is no longer
needed.
