This lets us avoid the use of `DiagnosticBuilder::into_diagnostic` in
miri, when then means that `DiagnosticBuilder::into_diagnostic` can
become private, being now only used by `stash` and `buffer`.

Diagnostic API fixes

Some improvements to diagnostic APIs: improve some naming, use shortcuts in more places, and add a couple of missing methods.

r? `@compiler-errors`

`is_force_warn` is only possible for diagnostics with `Level::Warning`,
but it is currently stored in `Diagnostic::code`, which every diagnostic
has.

This commit:
- removes the boolean `DiagnosticId::Lint::is_force_warn` field;
- adds a `ForceWarning` variant to `Level`.

Benefits:
- The common `Level::Warning` case now has no arguments, replacing
  lots of `Warning(None)` occurrences.
- `rustc_session::lint::Level` and `rustc_errors::Level` are more
  similar, both having `ForceWarning` and `Warning`.

…iler-errors

Exhaustiveness: use an `Option` instead of allocating fictitious patterns

In the process of exhaustiveness checking, `Matrix` stores a 2D array of patterns. Those are subpatterns of the patterns we were provided as input, _except_ sometimes we allocate some extra wildcard patterns to fill a hole during specialization.

Morally though, we could store `Option<&'p DeconstructedPat>` in the matrix, where `None` signifies a wildcard. That way we'd only have "real" patterns in the matrix and we wouldn't need the arena to allocate these wildcards. This is what this PR does.

This is part of me splitting up rust-lang/rust#119581 for ease of review.

r? `@compiler-errors`

Use version-sorting for all sorting

Add a description of a version-sorting algorithm. (This algorithm does
not precisely match `strverscmp`; it's intentionally simpler in its
handling of leading zeroes, and produces a result easier for humans to
easily understand and do by hand.)

Change all references to sorting to use version-sorting.

Change all references to "ASCIIbetically" to instead say "sort
non-lowercase before lowercase".

Add some comments, add `can_define_opaque_ty` check to `try_normalize_ty_recur`

Follow-up from #117278, since I was recently re-reviewing this code.

Pass LLVM error message back to pass wrapper.

When rustc fails to load a plugin, it should provide more detailed error message. Before this PR, rustc prints:

```
error: failed to run LLVM passes: Failed to load pass pluginPLUGIN_NAME.so
```

This PR passes LLVM errors back to rustc. After this PR, rustc prints:

```
error: failed to run LLVM passes: Could not load library 'PLUGIN_NAME.so': PLUGIN_NAME.so: undefined symbol: _ZN4llvm9DebugFlagE
```

This PR only contains usability improvements and does not change any functionality. Thus, no new unit test is implemented.

…rrors

Exhaustiveness: abort on type error

This adds an error path to exhaustiveness checking so that we abort instead of ICEing when encountering a stray `ty::Error`.

Fixes rust-lang/rust#119493
Fixes rust-lang/rust#119778

r? `@compiler-errors`

Cleanup things in and around `Diagnostic`

These changes all arose when I was looking closely at how to simplify `DiagCtxtInner::emit_diagnostic`.

r? `@compiler-errors`

change function name in comments

fixes #119787 where I believe an incorrect function name is used in the comments

Fix all_trait* methods to return all traits available in StableMIR

Also provide a mechanism to retrieve traits and implementations for a given crate.

This fixes rust-lang/project-stable-mir#37

…ler-errors

Silence some follow-up errors [1/x]

this is one piece of the requested cleanups from rust-lang/rust#117449

When we use `-> impl SomeTrait<_>` as a return type, we are both using the "infer return type suggestion" code path, and the infer opaque type code path within the same function. That can lead to confusing diagnostics, so silence all opaque type diagnostics in that case.

Stabilize mutex_unpoison feature

Closes #96469

`@rustbot` +T-libs-api

…mpiler-errors

Meta: Add project const traits to triagebot config

r? compiler-errors or project-const-traits

Rollup of 11 pull requests

Successful merges:

 - #115046 (Use version-sorting for all sorting)
 - #118915 (Add some comments, add `can_define_opaque_ty` check to `try_normalize_ty_recur`)
 - #119006 (Fix is_global special address handling)
 - #119637 (Pass LLVM error message back to pass wrapper.)
 - #119715 (Exhaustiveness: abort on type error)
 - #119763 (Cleanup things in and around `Diagnostic`)
 - #119788 (change function name in comments)
 - #119790 (Fix all_trait* methods to return all traits available in StableMIR)
 - #119803 (Silence some follow-up errors [1/x])
 - #119804 (Stabilize mutex_unpoison feature)
 - #119832 (Meta: Add project const traits to triagebot config)

r? `@ghost`
`@rustbot` modify labels: rollup