Allocate HIR on an arena 1/4
This PR is the first in a series of 4, aiming at allocating the HIR on an arena, as a memory optimisation.
1. This first PR lays the groundwork and migrates some low-hanging fruits.
2. The second PR will migrate `hir::Expr`, `hir::Pat` and related.
3. The third PR will migrate `hir::Ty` and related.
4. The final PR will be dedicated to eventual cleanups.
In order to make the transition as gradual as possible, some lowering routines receive `Box`-allocated data and move it into the arena. This is a bit wasteful, but hopefully temporary.
Nonetheless, special care should be taken to avoid double arena allocations.
Work mentored by @Zoxc.
Require issue = "none" over issue = "0" in unstable attributes
These changes make the use of `issue = "none"` required in unstable attributes throughout the compiler.
Notes:
- #66299 is now in beta so `issue = "none"` is accepted.
- The `tidy` tool now fails on `issue = "0"`.
- Tests that used `issue = "0"` were changed to use `issue = "none"`, except for _one_ that asserts `issue = "0"` can still be used.
- The compiler still allows `issue = "0"` because some submodules require it, this could be disallowed once these are updated.
Resolves#41260
r? @varkor
Cleanup `lower_pattern_unadjusted` & Improve slice pat typeck
Following up on https://github.com/rust-lang/rust/pull/67318, in this PR, the HAIR lowering of patterns (`lower_pattern_unadjusted`) is cleaned up with a focus on slice patterns (in particular, some dead code is removed). Moreover, `check_pat_slice` is refactored some more.
r? @matthewjasper
Refactor type & bounds parsing thoroughly
PR is based on https://github.com/rust-lang/rust/pull/67131 with first one from this PR being ` extract parse_ty_tuple_or_parens`.
Also fixes#67146.
r? @estebank
Revamp `// run-fail` wrt. `--pass` & support `// build-fail` & `// check-fail`
Revamp how `// run-fail` tests work internally by having a separate `FailMode` that does not interfere with `PassMode`. In particular, `--pass check` will now have no effect on `// *-fail` tests. Moreover, new test annotations `// check-fail` (the default) and `// build-fail` are added. The latter is useful to distinguish post-monomorphization failures from pre-monomorphization failures as seen throughout the PR. Finally, ensure that non-`Ui` tests do not listen to `--pass check` such that the flag can be used with e.g. `./x.py test --pass check` directly.
Fixes#66929.
Fixes#67128.
r? @petrochenkov
cc @RalfJung @ninjasource
