It has a single use. This makes the `let` handling case in
`parse_stmt_without_recovery` more similar to the statement path and
statement expression cases.

`parse_expr_assoc_with` has an awkward structure -- sometimes the lhs is
already parsed. This commit splits the post-lhs part into a new method
`parse_expr_assoc_rest_with`, which makes everything shorter and
simpler.

It can be done more concisely.

When collecting tokens there are two kinds of range:
- a range relative to the parser's full token stream (which we get when
  we are parsing);
- a range relative to a single AST node's token stream (which we use
  within `LazyAttrTokenStreamImpl` when replacing tokens).

These are currently both represented with `Range<u32>` and it's easy to
mix them up -- until now I hadn't properly understood the difference.

This commit introduces `ParserRange` and `NodeRange` to distinguish
them. This also requires splitting `ReplaceRange` in two, giving the new
types `ParserReplacement` and `NodeReplacement`. (These latter two names
reduce the overloading of the word "range".)

The commit also rewrites some comments to be clearer.

The end result is a little more verbose, but much clearer.

…3, r=petrochenkov"

This reverts commit 91b18a0, reversing
changes made to 9aedec9.

…nce, r=pnkfelix"

This reverts commit a70dc29, reversing
changes made to ceae371.

…nce-2, r=pnkfelix"

This reverts commit 31fe962, reversing
changes made to f203078.

…nce, r=pnkfelix"

This reverts commit 2724aea, reversing
changes made to d929a42.

…9, r=petrochenkov"

This reverts commit 977c5fd, reversing
changes made to 24c94f0.

…nce, r=pnkfelix"

This reverts commit 13314df, reversing
changes made to 6e534c7.

…hanges

Add the feature in `core/lib.rs`

The one use of it was guaranteed to be always true.

Added SHA512, SM3, SM4 target-features and `sha512_sm_x86` feature gate

This is an effort towards rust-lang#126624. This adds support for these 3 target-features and introduces the feature flag `sha512_sm_x86`, which would gate these target-features and the yet-to-be-implemented detection and intrinsics in stdarch.

…eyouxu

Migrate `reproducible-build-2` and `stable-symbol-names` `run-make` tests to rmake

Part of rust-lang#121876 and the associated [Google Summer of Code project](https://blog.rust-lang.org/2024/05/01/gsoc-2024-selected-projects.html).

Needs try-jobs.

try-job: x86_64-msvc
try-job: armhf-gnu
try-job: test-various
try-job: aarch64-apple
try-job: i686-msvc
try-job: x86_64-mingw

…ouxu

Migrate `raw-dylib-alt-calling-convention`, `raw-dylib-c` and `redundant-libs` `run-make` tests to rmake

Part of rust-lang#121876 and the associated [Google Summer of Code project](https://blog.rust-lang.org/2024/05/01/gsoc-2024-selected-projects.html).

Please try:

try-job: x86_64-msvc
try-job: x86_64-mingw

…riddle

nested aux-build in tests/rustdoc/ tests

* Fixes bug that prevented using nested aux-build in `tests/rustdoc/` tests. Before, `fn document` and the auxiliary builder disagreed about where to find the nested aux-build source file (`auxiliary/auxiliary/aux.rs` vs `auxiliary/aux.rs`), preventing them from building. Picked the latter in line with other builders in compiletest.
* Adds `//@ doc-flags` header, which forwards flags to rustdoc and not rustc.
* Adds `//@ unique-doc-out-dir` header, which sets the --out-dir for the rustdoc invocation to a unique directory: `<root out dir>/docs/<test name>/doc`
* Changes working directory of the rustdoc invocation to the root out directory (common among all aux-builds). Prior art: exec_compiled_test in runtest.rs
* Adds tests that use nested aux builds and new headers

These changes provide useful capabilities for writing rustdoc tests on their own. They are also needed to test the implementation for the [mergable-rustdoc-cross-crate-info](rust-lang/rfcs#3662) RFC.

try-job: x86_64-msvc

…ieyouxu

Migrate `cross-lang-lto-clang` and `cross-lang-lto-pgo-smoketest` `run-make` tests to rmake

Part of rust-lang#121876 and the associated [Google Summer of Code project](https://blog.rust-lang.org/2024/05/01/gsoc-2024-selected-projects.html).

This has the same problem outlined by rust-lang#126180, where the tests do not actually run as no test-running CI enviroment has `RUSTBUILD_FORCE_CLANG_BASED_TESTS` set.

However, I still find it interesting to turn the Makefiles into the rmake format until the Clang issue is fixed.

This should technically be tested on MSVC... if MSVC actually ran Clang tests.

try-job: x86_64-gnu-debug

…hanges, r=pnkfelix

Revert recent changes to dead code analysis

This is a revert to recent changes to dead code analysis, namely:
* efdf219 Rollup merge of rust-lang#128104 - mu001999-contrib:fix/128053, r=petrochenkov
* a70dc29 Rollup merge of rust-lang#127017 - mu001999-contrib:dead/enhance, r=pnkfelix
* 31fe962 Rollup merge of rust-lang#127107 - mu001999-contrib:dead/enhance-2, r=pnkfelix
* 2724aea Rollup merge of rust-lang#126618 - mu001999-contrib:dead/enhance, r=pnkfelix
* 977c5fd Rollup merge of rust-lang#126315 - mu001999-contrib:fix/126289, r=petrochenkov
* 13314df Rollup merge of rust-lang#125572 - mu001999-contrib:dead/enhance, r=pnkfelix

There is an additional change stacked on top, which suppresses false-negatives that were masked by this work. I believe the functions that are touched in that code are legitimately unused functions and the types are not reachable since this `AnonPipe` type is not publically reachable -- please correct me if I'm wrong cc ```@NobodyXu``` who added these in #rust-lang#127153.

Some of these reverts (rust-lang#126315 and rust-lang#126618) are only included because it makes the revert apply cleanly, and I think these changes were only done to fix follow-ups from the other PRs?

I apologize for the size of the PR and the churn that it has on the codebase (and for reverting ```@mu001999's``` work here), but I'm putting this PR up because I am concerned that we're making ad-hoc changes to fix bugs that are fallout of these PRs, and I'd like to see these changes reimplemented in a way that's more separable from the existing dead code pass. I am happy to review any code to reapply these changes in a more separable way.

cc ```@mu001999```
r? ```@pnkfelix```

Fixes rust-lang#128272
Fixes rust-lang#126169

…s, r=petrochenkov

Still more `cfg` cleanups

Found while looking closely at `cfg`/`cfg_attr` processing code.

r? ```````@petrochenkov```````

…e-this-cpuid-move-along, r=Amanieu

Finish removing `has_cpuid`

The one use of it was guaranteed to be always true.

try-job: test-various

chore: use shorthand initializer

Tiny readability improvement - don't use redundant initializer vars