Fixes #33868

Make sure that macros that didn't pass LHS checking are not expanded.

This avoid duplicate errors for things like invalid fragment specifiers, or
parsing errors for ambiguous macros.

Save metadata even with -Z no-trans (e.g. for multi-crate cargo check).

Removes the item symbol map in metadata, as we can now generate them in a deterministic manner.
The `-Z no-trans` change lets the LLVM passes and linking run, but with just metadata and no code.
It fails while trying to link a binary because there's no `main` function, which is correct but not good UX.

There's also no way to easily throw away all of the artifacts to rebuild with actual code generation.
We might want `cargo check` to do that using cargo-internal information and then it would just work.

cc @alexcrichton @nikomatsakis @Aatch @michaelwoerister

Don't suggest using fields in a static method

Fixes #33613.

cc @LeoTestard

Rollup of 7 pull requests

- Successful merges: #33692, #33759, #33779, #33781, #33797, #33810, #33832
- Failed merges:

Fixed link in Rust Book (no-stdlib)

Closes #33806

Changed toggle all sections key to `T`

Allows both `T` and `t`.

It had been [Shift]+[+] before.

In response to #33791.

cc @Manishearth
r? @GuillaumeGomez

Add new error code tests

r? @steveklabnik

Update repr_simd

r? @steveklabnik

Fix references links

There are duplicate link references in the article and just remove one of them.

Improve the long explanation of E0207.

The previous explanation does not seem to explain what it means for an
implementation parameter to be used or unused. The new explanation lists
the three ways specific ways by which an impl parameter becomes constrained
(taken from RFC 447).

This also adds a link to RFC 447.

The explanation has two different examples. The first is adapted from RFC 447,
and shows an instance of E0207 on a impl for a type. The second one is a trait
impl example adapted from issue #22834.

Closes #33650

cc #32777

r? @GuillaumeGomez

This avoids duplicate errors for things like invalid fragment specifiers, or
parsing errors for ambiguous macros. Fixes #29231.

Add --enable-local-rebuild to bootstrap from the current release

In Linux distributions, it is often necessary to rebuild packages for cases like applying new patches or linking against new system libraries.  In this scenario, the rustc in the distro build environment may already match the current release that we're trying to rebuild.  Thus we don't want to use the prior release's bootstrap key, nor `--cfg stage0` for the prior unstable features.

The new `configure --enable-local-rebuild` option specifies that we are rebuilding from the current release.  The current bootstrap key is used for the local rustc, and current stage1 features are also assumed.  Both the makefiles and rustbuild support this configuration.

Fixes #29556
r? @alexcrichton

Deprecate {f32,f64}::abs_sub.

The abs_sub name is misleading: the function actually computes the
positive difference (`fdim` in C), not the `(x - y).abs()` that *many* people expect
from the name.

This function can be replaced with just `(x - y).max(0.0)`, mirroring
the `abs` version, but this behaves differently with NAN: `NAN.max(0.0)
== 0.0`, while `NAN.positive_diff(0.0) == NAN`. People who absolutely
need that behaviour can use the C function directly and/or talk to the libs
team (we haven't encountered a concrete use-case for this functionality).

Closes #30315.

The previous explanation does not seem to explain what it means for an
implementation parameter to be used or unused. The new explanation lists
the three ways specific ways by which an impl parameter becomes constrained
(taken from RFC 447).

This also adds a link to RFC 447.

The explanation has two different examples. The first is adapted from RFC 447,
and shows an instance of E0207 on a impl for a type. The second one is a trait
impl example adapted from issue #22834.

Closes #33650

Allow `concat_idents!` in type positions as well as in expression positions

This allows the `concat_idents!` macro in type positions as well as in expression positions.
r? @nrc

Fix a broken link in the rust book.

Efficient trie lookup for boolean Unicode properties

Replace binary search of ranges with trie lookup using leaves of
64-bit bitmap chunks. Benchmarks suggest this is approximately 10x
faster than the bsearch approach.

Use libc::abort, not intrinsics::abort, in rtabort!

intrinsics::abort compiles down to an illegal instruction, which on
Unix-like platforms causes the process to be killed with SIGILL.  A more
appropriate way to kill the process would be SIGABRT; this indicates
better that the runtime has explicitly aborted, rather than some kind of
compiler bug or architecture mismatch that SIGILL might indicate.

For rtassert!, replace this with libc::abort.  libc::abort raises
SIGABRT, but is defined to do so in such a way that it will terminate
the process even if SIGABRT is currently masked or caught by a signal
handler that returns.

On non-Unix platforms, retain the existing behavior.  On Windows we
prefer to avoid depending on the C runtime, and we need a fallback for
any other platforms that may be defined.  An alternative on Windows
would be to call TerminateProcess, but this seems less essential than
switching to using SIGABRT on Unix-like platforms, where it is common
for the process-killing signal to be printed out or logged.

This is a [breaking-change] for any code that depends on the exact
signal raised to abort a process via rtabort!

cc #31273
cc #31333

intrinsics::abort compiles down to an illegal instruction, which on
Unix-like platforms causes the process to be killed with SIGILL.  A more
appropriate way to kill the process would be SIGABRT; this indicates
better that the runtime has explicitly aborted, rather than some kind of
compiler bug or architecture mismatch that SIGILL might indicate.

For rtassert!, replace this with libc::abort.  libc::abort raises
SIGABRT, but is defined to do so in such a way that it will terminate
the process even if SIGABRT is currently masked or caught by a signal
handler that returns.

On non-Unix platforms, retain the existing behavior.  On Windows we
prefer to avoid depending on the C runtime, and we need a fallback for
any other platforms that may be defined.  An alternative on Windows
would be to call TerminateProcess, but this seems less essential than
switching to using SIGABRT on Unix-like platforms, where it is common
for the process-killing signal to be printed out or logged.

This is a [breaking-change] for any code that depends on the exact
signal raised to abort a process via rtabort!

cc #31273
cc #31333

Realized browsers use [Ctrl]+[+=] for zoom, so using [Shift]+[+=] for
collapse/expand was not necessarily a conflict.

Also a bugfix.

Allows both `T` and `t`.

It had been [Shift]+[+] before.

The rustc for a local-rebuild is assumed to use the current bootstrap
key and already match the current stage1 features.