By creating an unnamed thread handle when the actual one has already been destroyed, synchronization primitives using thread parking can be used even outside the Rust runtime.

This also fixes an inefficiency in the queue-based `RwLock`: if `thread::current` was not initialized yet, it will create a new handle on every parking attempt without initializing `thread::current`. The private `current_or_unnamed` function introduced here fixes this.

This is explicitly mentioned for std::fs::remove_file's documentation,
but not in the aforementioned function.

It is more likely for a slightly lazy programmer to believe that
removing a file would work and that they do not have to distinguish
between directories (with contents) and files themself, because of the
function's recursive nature and how it distinguishes between files and
directories when removing them.

std: allow after-main use of synchronization primitives

By creating an unnamed thread handle when the actual one has already been destroyed, synchronization primitives using thread parking can be used even outside the Rust runtime.

This also fixes an inefficiency in the queue-based `RwLock`: if `thread::current` was not initialized yet, it will create a new handle on every parking attempt without initializing `thread::current`. The private `current_or_unnamed` function introduced here fixes this.

only store valid proc macro item for doc link

Fixes rust-lang#132743

The definition item can be detected if it is exported in the doc, so store these items rather than skipping.

r? `@petrochenkov`

Constify the `Deref`/`DerefMut` traits, too

One more constification. Rebased on that one commit that makes it so we don't need to provide stability on const impls.

r? fee1-dead

Remove legacy bitcode for iOS

Follow rust-lang#117364.

…hs, r=Noratrieb

Mention that std::fs::remove_dir_all fails on files

This is explicitly mentioned for std::fs::remove_file.

It is more likely for a slightly lazy programmer to believe that removing a file would work and that they do not have to distinguish between directories (with contents) and files themself, because of the function's recursive nature and how it distinguishes between files and directories when removing them.

Follow-up for rust-lang#133183.

…=jieyouxu

add a test for target-feature-ABI warnings in closures and when calling extern fn

Also update the comment regarding the inheritance of target features into closures, to make it more clear that we really shouldn't do this right now.