Signed-off-by: wcampbell <[email protected]>

Logically this first eliminates the innermost match by merging the patterns.
Then, in a second step, turns the newly innermost match into a `matches!` call.

Fix rust-lang#78507.

$ touch empty.rs
$ env RUSTC_LOG=debug rustc +stage1 --crate-type=lib empty.rs

Fails with a `BorrowMutError` because source map files are already
borrowed while `features_query` attempts to format a log message
containing a span.

Release the borrow before the query to avoid the issue.

And two small intra-doc link conversions in `std::{f32, f64}`.

Reorder benches const variable

Move LEN so it is is read in order.

…, r=jyn514

Simplify a nested bool match

Logically this first eliminates the innermost match by merging the patterns.
Then, in a second step, turns the newly innermost match into a `matches!` call.

…=jyn514

f64: Refactor collapsible_if

…ession, r=dtolnay

Revert invalid `fn` return type parsing change

Revert one of the changes in rust-lang#78379.

Fix rust-lang#78507.

…n1011

Avoid BorrowMutError with RUSTC_LOG=debug

```console
$ touch empty.rs
$ env RUSTC_LOG=debug rustc +stage1 --crate-type=lib empty.rs
```

Fails with a `BorrowMutError` because source map files are already
borrowed while `features_query` attempts to format a log message
containing a span.

Release the borrow before the query to avoid the issue.

Make anonymous binders start at 0

A few changes to some test outputs, but these actually look *more* correct to me.

…wording, r=jyn514

Improve wording of `core::ptr::drop_in_place` docs

And two small intra-doc link conversions in `std::{f32, f64}`.

Link to pass docs from NRVO module docs

It can be easy to miss that this is documented on the pass's struct if you are
looking at the module docs.

Cc https://rust-lang.zulipchat.com/#narrow/stream/189540-t-compiler.2Fwg-mir-opt/topic/what.20is.20NRVO.3F