The support for runtime multi-threading was removed from LLVM. Calls to
`LLVMStartMultithreaded` became no-ops equivalent to checking if LLVM
was compiled with support for threads http://reviews.llvm.org/D4216.

The const qualification was so far performed before the promotion and
the implementation assumed that it will never encounter a promoted.

With `const_precise_live_drops` feature, checking for live drops is
delayed until after drop elaboration, which in turn runs after
promotion. so the assumption is no longer true. When evaluating
`NeedsNonConstDrop` it is now possible to encounter promoteds.

Use type base qualification for the promoted. It is a sound
approximation in general, and in the specific case of promoteds and
`NeedsNonConstDrop` it is precise.

Now explicitly says negative value.

rustbot doesn't allow unauthenticated users to set `I-nominated`; apply
the same permissions to the new `I-*nominated` labels.

Previously, it wasn't clear whether "This could include" was referring
to logic errors, or undefined behaviour. Tweak wording to clarify this
sentence does not relate to UB.

…rk-Simulacrum

Clarify undefined behaviour in binary heap, btree and hashset docs

Previously, it wasn't clear whether "This could include" was referring to logic errors, or undefined behaviour. Tweak wording to clarify this sentence does not relate to UB.

Cleanup LLVM multi-threading checks

The support for runtime multi-threading was removed from LLVM. Calls to
`LLVMStartMultithreaded` became no-ops equivalent to checking if LLVM
was compiled with support for threads http://reviews.llvm.org/D4216.

Change `Duration::[try_]from_secs_{f32, f64}` underflow error

The error message now says that it was a negative value.

Fixes rust-lang#89913.

…=spastorino

Reject closures in patterns

Fixes rust-lang#90013.

…piler, r=Mark-Simulacrum

Make new symbol mangling scheme default for compiler itself.

As suggest in rust-lang#89917 (comment), this PR enables the new symbol mangling scheme for the compiler itself. The standard library is still compiled using the legacy mangling scheme so that the new symbol format does not show up in user code (yet).

r? `@Mark-Simulacrum`

…i-obk

Fix const qualification when executed after promotion

The const qualification was so far performed before the promotion and
the implementation assumed that it will never encounter a promoted.

With `const_precise_live_drops` feature, checking for live drops is
delayed until after drop elaboration, which in turn runs after
promotion. so the assumption is no longer true. When evaluating
`NeedsNonConstDrop` it is now possible to encounter promoteds.

Use type base qualification for the promoted. It is a sound
approximation in general, and in the specific case of promoteds and
`NeedsNonConstDrop` it is precise.

Fixes rust-lang#89938.

…crum

Add a regression test for issue-83479

Add a regression test for rust-lang#83479 (comment), but not close the issue, see rust-lang#83479 (comment).

Add some tests for const_generics_defaults

I think this covers some of the stuff required for stabilisation report, some of these tests are probably covering stuff we already have but it can't hurt to have more :)

r? `@lcnr`

Add test for issue rust-lang#78561

Adds test for and closes rust-lang#78561 which previously crashed compiler.

…k-Simulacrum

CI: make docker cache download attempt time out after 10 minutes

Might help to prevent timeouts we have been seeing:
* https://github.com/rust-lang-ci/rust/runs/3946294286?check_suite_focus=true#step:25:23
* https://github.com/rust-lang-ci/rust/runs/3956799200?check_suite_focus=true#step:25:22

…=Mark-Simulacrum

triagebot: Treat `I-*nominated` like `I-nominated`

rustbot doesn't allow unauthenticated users to set `I-nominated`; apply the same permissions to the new `I-*nominated` labels.