As `Rc/Arc::weak_count` returns 0 when having no strong counts, this
could be confusing and it's better to avoid using that completely.

Closes rust-lang#73840.

Add the rust-docs component to toolchain x86_64-unknown-linux-musl, which allows
people using rustup on their musl-based linux distribution to download the
rust-docs.

This commit updates the metadata location logic to ignore errors when
calling `fs::canonicalize`. Canonicalization was added historically so
multiple `-L` paths to the same directory don't print errors about
multiple candidates (since rustc can deduplicate same-named paths), but
canonicalization doesn't work on all filesystems. Cargo, for example,
always uses this sort of fallback where it will opportunitistically try
to canonicalize but fall back to using the input path if it otherwise
doesn't work.

If rustc is run on a filesystem that doesn't support canonicalization
then the effect of this change will be that `-L` paths which logically
point to the same directory will cause errors, but that's a rare enough
occurrence it shouldn't cause much issue in practice. Otherwise rustc
doesn't work at all today on those sorts of filesystem where
canonicalization isn't supported!

(cherry picked from commit 9e5fb40)

(cherry picked from commit 32166ab)

Clean up E0730 explanation

r? @Dylan-DPC

…lnay

Don't use "weak count" around Weak::from_raw_ptr

As `Rc/Arc::weak_count` returns 0 when having no strong counts, this
could be confusing and it's better to avoid using that completely.

Closes rust-lang#73840.

Clean up E0734 explanation

r? @Dylan-DPC

…crum

Enable docs on dist-x86_64-musl

Add the `rust-docs` component to toolchain `x86_64-unknown-linux-musl`, which allows people using rustup on their musl-based linux distribution to download the rust-docs.

`--disable-docs` is based on the assumption that `x86_64-unknown-linux-musl` is only a cross-compile target.

I have tested that the docs are built. I assume the build-system will automatically detect the docs and create a `rust-docs` component. I will [monitor](https://rust-lang.github.io/rustup-components-history/x86_64-unknown-linux-musl.html) the components and create a follow-up PR, if the docs aren't published.

See also rust-lang#70619, where we enabled `rust-lld` to enable the wasm-workflow on musl-based linux distributions.

Avoid bool-like naming

Lost in rust-lang#74127 (comment)

…kfire

Clean up E0740 explanation

r? @Dylan-DPC

…lize, r=Mark-Simulacrum

rustc: Ignore fs::canonicalize errors in metadata

This commit updates the metadata location logic to ignore errors when
calling `fs::canonicalize`. Canonicalization was added historically so
multiple `-L` paths to the same directory don't print errors about
multiple candidates (since rustc can deduplicate same-named paths), but
canonicalization doesn't work on all filesystems. Cargo, for example,
always uses this sort of fallback where it will opportunitistically try
to canonicalize but fall back to using the input path if it otherwise
doesn't work.

If rustc is run on a filesystem that doesn't support canonicalization
then the effect of this change will be that `-L` paths which logically
point to the same directory will cause errors, but that's a rare enough
occurrence it shouldn't cause much issue in practice. Otherwise rustc
doesn't work at all today on those sorts of filesystem where
canonicalization isn't supported!

Improve diagnostics when constant pattern is too generic

This PR is a follow-up to PR rust-lang#74538 and issue rust-lang#73976

When constants queries Layout, TypeId or type_name of a generic parameter, instead of emitting `could not evaluate constant pattern`, we will instead emit a more detailed message `constant pattern depends on a generic parameter`.

…hievink

Cherry-pick the release notes for 1.45.1