…inting

The Windows dist builders are the slowest builders right now, and the
distribution phase of them is enormously slow clocking in at around 20
minutes to build all the related installers. This commit starts to
optimize these by turning down the compression level in the `exe`
installers. These aren't super heavily used so there's no great need for
them to be so ultra-compressed, so let's dial back the compression
parameters to get closer to the rest of our xz archives. This brings the
installer in line with the gz tarball installer locally, and also brings
the compression settings on par with the rest of our xz installers.

This is the same as rust-lang#64615 except applied to our MSI installers. The
same fix is applied effectively bringing these installers in line with
the gz tarball installers, which are about 3x faster to produce locally
and likely much faster to produce on CI.

* Pass `/Q` to `iscc` on Windows to supress the thousands of lines of
  output about compressing documentation.
* Print out what's happening before long steps
* Use `timeit` to print out timing information for long-running
  installer assemblies.

Document From trait for LhsExpr in parser

Add doc for From trait for converting P<Expr> and Option<ThinVec<Attribute>> to LhsExpr

As part of issue rust-lang#51430 (cc @skade).

Both of these should just be moving an address and setting a discriminant in an enum. The main thing I'm not sure about is whether it's worth documenting the branch in the From<Option<ThinVec<Attribute>>. As far as I can tell it doesn't seem like it is optimized away (although if the discriminant happened to work out you could just copy the pointer and the discriminant which might be cheaper, but that's not guaranteed). So it seems like if it's being called often, it's doubling the number of possible branch mispredictions on this Option, which could be a significant cost.

Let me know if there's anything that needs fixing and I'll get to it as soon as possible!

factor out pluralisation remains after rust-lang#64280

there are two case that doesn't not match the original macro pattern at [here](https://github.com/rust-lang/rust/blob/master/src/librustc_lint/unused.rs#L146) and [here](https://github.com/rust-lang/rust/blob/master/src/libsyntax/parse/diagnostics.rs#L539) as the provided param is already a bool or the check condition is not `x != 1`, so I change the macro accept a boolean expr instead of number to fit all the cases.

@Centril  please review

Fixes rust-lang#64238.

…rkor

Fix redundant semicolon lint interaction with proc macro attributes

Fixes rust-lang#63967 and fixes rust-lang#63947, both of which were caused by the lint's changes to the parser interacting poorly with proc macro attributes and causing span information to be lost

r? @varkor

When possible point at argument causing item obligation failure

Fix rust-lang#41781, fix rust-lang#42855, fix rust-lang#46658, fix rust-lang#48099, fix rust-lang#63143.

…mulacrum

rustbuild: Turn down compression on exe installers

The Windows dist builders are the slowest builders right now, and the
distribution phase of them is enormously slow clocking in at around 20
minutes to build all the related installers. This commit starts to
optimize these by turning down the compression level in the `exe`
installers. These aren't super heavily used so there's no great need for
them to be so ultra-compressed, so let's dial back the compression
parameters to get closer to the rest of our xz archives. This brings the
installer in line with the gz tarball installer locally, and also brings
the compression settings on par with the rest of our xz installers.

…mulacrum

rustbuild: Turn down compression on msi installers

This is the same as rust-lang#64615 except applied to our MSI installers. The
same fix is applied effectively bringing these installers in line with
the gz tarball installers, which are about 3x faster to produce locally
and likely much faster to produce on CI.

…=Mark-Simulacrum

rustbuild: Improve output of `dist` step

* Pass `/Q` to `iscc` on Windows to supress the thousands of lines of
  output about compressing documentation.
* Print out what's happening before long steps
* Use `timeit` to print out timing information for long-running
  installer assemblies.
* Try to scope output of `Dist ...` to not also encompass actual build steps

Add Compatibility Notes to RELEASES.md for 1.38.0

### [Rendered](https://github.com/XAMPPRocky/rust/blob/relnotes/RELEASES.md)

r? @Mark-Simulacrum