Older llvm has the pre-C++17 restriction on success and failure memory
ordering, requiring the former to be at least as strong as the latter.
So, for llvm 12, this upgrades the success ordering to a stronger one if
necessary.

Of primary interest, this merges
rust-lang/rls@ece09b8 into rust-lang/rust,
which brings in the changes that fix RLS tests broken by rust-lang#97853. rust-lang#97853 already
introduced that commit's changes (under
27f4044df03d15c7c38a483c3e4635cf4f51807d) but without putting those changes on
rust-lang/rls as a branch, so we ended up with an orphan commit that caused
trouble when updating submodules in rust-lang/rust.

This commit, once merged into rust-lang/rust, should continue to let RLS tests
to pass on rust-lang/rust's side and move us back into a healthy state where tip
of the submodule points to a valid master commit in the rust-lang/rls
repository.

…ing, r=oli-obk

Fix printing `impl trait` under binders

Before, we would render `impl for<'a> Trait<'a>` like `impl Trait<for<'a> 'a>`, lol.

…rochenkov

Work around llvm 12's memory ordering restrictions.

Older llvm has the pre-C++17 restriction on success and failure memory ordering, requiring the former to be at least as strong as the latter. So, for llvm 12, this upgrades the success ordering to a stronger one if necessary.

See rust-lang#68464

x.py: Support systems with only `python3` not `python`

Fixes rust-lang#71818 without the pitfalls so far described in previous attempts.

…lbini

Bump RLS to latest master on rust-lang/rls

Of primary interest, this merges
rust-lang/rls@ece09b8 into rust-lang/rust,
which brings in the changes that fix RLS tests broken by rust-lang#97853. rust-lang#97853 already
introduced that commit's changes (under
rust-lang/rls@27f4044) but without putting those changes on
rust-lang/rls as a branch, so we ended up with an orphan commit that caused
trouble when updating submodules in rust-lang/rust.

This commit, once merged into rust-lang/rust, should continue to let RLS tests
to pass on rust-lang/rust's side and move us back into a healthy state where tip
of the submodule points to a valid master commit in the rust-lang/rls
repository.

cc rust-lang#98451, but not marking as fixed as I believe we need to add verification to prevent future oversights.

…abort, r=Dylan-DPC

Fix backtrace UI test when panic=abort is used

The function `contains_verbose_expected` is only used when the panic strategy is not abort, so it caused a warning when it was abort, which made the UI test failed on stderr comparison.

…, r=notriddle

Fix source sidebar hover in ayu theme

In the screenshot below, `rc.rs` should be orange:

![Screenshot from 2022-06-25 22-24-06](https://user-images.githubusercontent.com/3050060/175789532-99e8781d-2e62-43f7-bbd9-1b1151e1f8c1.png)

It's because the CSS selector was not precise enough and was "overloaded" with another one. This PR fixes it and adds a test for the colors in the source sidebar.

cc `@jsha`
r? `@notriddle`

…g, r=compiler-errors

diagnostics: consider parameter count when suggesting smart pointers

Fixes rust-lang#96834

…-Simulacrum

Fix LLVM rebuild with download-ci-llvm.

This fixes an issue where updating a local checkout that includes a change in `src/version` causes a linking failure.

The cause is that the `rustc_llvm` build script uses `rerun-if-changed` of `llvm-config` to know if it needs to rerun. Cargo only compares the timestamp of the last time the build script to the file. However, extracting the tar files retains the timestamps in the tarball which may be some time in the past. Since `src/version` is included in the LLVM `.so` filename, `rustc` attempts to load the wrong shared library since the `rustc_llvm` build script doesn't rerun.

rust-lang/cargo#10791 contains a more detailed explanation.

The solution here is a hack which updates the timestamp of `llvm-config` to the current time when it is extracted.

This is a bit of a hack, but seems to be the best solution I can think of until rust-lang/cargo#10791 is fixed. There are likely several other situations where this is a problem (such as using system LLVM), and this isn't really a complete fix.

Note that apple platforms are not directly affected by this problem because they don't have a version in the dylib filename.

How to test this:

1. On a linux host, enable download-ci-llvm
2. Check out 7036449 (the commit just before the last version bump)
3. `./x.py build library/std`
4. Check out 5f015a2 (the commit that bumped the version)
5. `./x.py build library/std`

Fixes rust-lang#98495