The existing documentation felt a little unhelpfully concise, so this
change tries to improve it by using longer sentences, each of which
specifies which kinds of types it applies to as early as possible. In
particular, the third item starts with “Structs ...” instead of
saying “Foo is a struct” later.

Also, the previous list items “Only the last field has a type
involving `T`” and “`T` is not part of the type of any other
fields” are, as far as I see, redundant with each other, so I removed
the latter.

Commit 95e096d changed a bunch of size checks already, but more have
been added, so this fixes the new ones the same way: the various size
checks that are conditional on target_arch = "x86_64" were not intended
to apply to x86_64-unknown-linux-gnux32, so add
target_pointer_width = "64" to the conditions.

Rustdoc doesn't require the build artifacts to generate the docs, and
especially in the case of rustc, it greatly increases the time needed to
run the build.

Local variables can never be exported.

Reword description of automatic impls of `Unsize`.

The existing documentation felt a little unhelpfully concise, so this change tries to improve it by using longer sentences, each of which specifies which kinds of types it applies to as early as possible. In particular, the third item starts with “Structs ...” instead of saying “Foo is a struct” later.

Also, the previous list items “Only the last field has a type involving `T`” and “`T` is not part of the type of any other fields” are, as far as I see, redundant with each other, so I removed the latter.

I have no particular knowledge of `Unsize`; I have attempted to leave the meaning entirely unchanged but may have missed a nuance.

Markdown preview of the edited documentation:

> All implementations of `Unsize` are provided automatically by the compiler.
> Those implementations are:
>
> - Arrays `[T; N]` implement `Unsize<[T]>`.
> - Types implementing a trait `Trait` also implement `Unsize<dyn Trait>`.
> - Structs `Foo<..., T, ...>` implement `Unsize<Foo<..., U, ...>>` if all of these conditions
>   are met:
>   - `T: Unsize<U>`.
>   - Only the last field of `Foo` has a type involving `T`.
>   - `Bar<T>: Unsize<Bar<U>>`, where `Bar<T>` stands for the actual type of that last field.

Fix non-capturing closure return type coercion

Fixes rust-lang#88097. For the example given there:
```rust
fn peculiar() -> impl Fn(u8) -> u8 {
    return |x| x + 1
}
```
which incorrectly reports an error, I noticed something weird in the debug log:
```
DEBUG rustc_typeck::check::coercion coercion::try_find_coercion_lub([[email protected]:2:12: 2:21], [[email protected]:2:12: 2:21], exprs=1 exprs)
```
Apparently, `try_find_coercion_lub()` thinks that the LUB for two closure types always has to be a function pointer (which explains the `expected closure, found fn pointer` error in rust-lang#88097). There is one corner case where that isn't true, though — namely, when the two closure types are equal, in which case the trivial LUB is the type itself. This PR fixes this by inserting an explicit check for type equality in `try_find_coercion_lub()`.

Improve error message when _ is used for in/inout asm operands

As suggested by ``@Commeownist`` in rust-lang#72016 (comment).

…ports, r=Amanieu

Remove `cfg(doc)` from std::os module reexports to fix rustdoc linking issues

Fixes rust-lang#88304.

I tested it based on rust-lang#88292.

Not sure if it's the best approach, but at least it makes thing a bit simpler.

cc ``@jyn514``

Change more x64 size checks to not apply to x32.

Commit 95e096d changed a bunch of size checks already, but more have
been added, so this fixes the new ones the same way: the various size
checks that are conditional on target_arch = "x86_64" were not intended
to apply to x86_64-unknown-linux-gnux32, so add
target_pointer_width = "64" to the conditions.

Don't build the compiler and standard library before documenting them

Rustdoc doesn't require the build artifacts to generate the docs, and
especially in the case of rustc, it greatly increases the time needed to
run the build.

r? ``@Mark-Simulacrum`` cc ``@steffahn``

rustc: Remove local variable IDs from `Export`s

Local variables can never be exported.

generic_const_exprs: use thir for abstract consts instead of mir

not sure if this is handling some of the weirder `thir::ExprKind` correctly in `recurse_build` (it probably isnt)

r? ``@lcnr``

Use more accurate spans for "unused delimiter" lint

Add help for E0463

Fixes rust-lang#87871.

r? ``@estebank``

…chenkov

don't clone types that are Copy (clippy::clone_on_copy)