Account for `for` lifetimes when constructing closure to see if dereferencing the return value would be valid.

Fix rust-lang#125634, fix rust-lang#124563.

`T: VaArgSafe` is relied on for soundness. Safe impls promise nothing.
Therefore this must be an unsafe trait. Slightly pedantic, as
only core can impl this, but we could choose to unseal the trait.
That would allow soundly (but unsafely) implementing this for e.g.
a `#[repr(C)] struct` that should be passable by varargs.

It was somewhat confusing that the old constructor would create a `FlatPat` in
a (possibly) non-simplified state, and then simplify its contents in-place.

So instead we now create its fields as local variables, perform simplification,
and then create the struct afterwards.

This doesn't affect correctness, but is less confusing.

…thBuf::_push`

…orms rust-lang#126333

…nkfelix

Mark assoc tys live only if the corresponding trait is live

r? `````@pnkfelix`````

Deny `use<>` for RPITITs

Precise capturing `use<>` syntax is currently a no-op on RPITITs, since GATs have no variance, so all captured lifetimes are captured invariantly.

We don't currently *need* to support `use<>` on RPITITs, since `use<>` is initially intended for migrating RPIT *overcaptures* from edition 2021->2024, but since RPITITs currently capture all in-scope lifetimes, we'll never need to write `use<>` on an RPITIT.

Eventually, though, it would be desirable to support precise capturing on RPITITs, since RPITITs overcapturing by default can be annoying to some folks. But let's separate that (which will likely require some delicate types team work for adding variances to GATs and adjusting the refinement rules) from the stabilization of the feature for edition 2024.

r? oli-obk cc ```@traviscross```

Tracking:

- rust-lang#123432

not use offset when there is not ends with brace

Fixes rust-lang#126764

Do not ICE when suggesting dereferencing closure arg

Account for `for` lifetimes when constructing closure to see if dereferencing the return value would be valid.

Fix rust-lang#125634, fix rust-lang#124563.

…ec, r=workingjubilee

Remove internal `PathBuf::as_mut_vec`

closes rust-lang#126333

Eliminate the distinction between PREC_POSTFIX and PREC_PAREN precedence level

I have been tangling with precedence as part of porting some pretty-printer improvements from syn back to rustc (related to parenthesization of closures, returns, and breaks by the AST pretty-printer).

As far as I have been able to tell, there is no difference between the 2 different precedence levels that rustc identifies as `PREC_POSTFIX` (field access, square bracket index, question mark, method call) and `PREC_PAREN` (loops, if, paths, literals).

There are a bunch of places that look at either `prec < PREC_POSTFIX` or `prec >= PREC_POSTFIX`. But there is nothing that needs to distinguish PREC_POSTFIX and PREC_PAREN from one another.

https://github.com/rust-lang/rust/blob/d49994b060684af423339b55769439b2f444a7b9/compiler/rustc_ast/src/util/parser.rs#L236-L237

https://github.com/rust-lang/rust/blob/d49994b060684af423339b55769439b2f444a7b9/compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs#L2829

https://github.com/rust-lang/rust/blob/d49994b060684af423339b55769439b2f444a7b9/compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs#L1290

In the interest of eliminating a distinction without a difference, this PR collapses these 2 levels down to 1.

There is exactly 1 case where an expression with PREC_POSTFIX precedence needs to be parenthesized in a location that an expression with PREC_PAREN would not, and that's when the receiver of ExprKind::MethodCall is ExprKind::Field. `x.f()` means a different thing than `(x.f)()`. But this does not justify having separate precedence levels because this special case in the grammar is not governed by precedence. Field access does not have "lower precedence than" method call syntax &mdash; you can tell because if it did, then `x.f[0].f()` wouldn't be able to have its unparenthesized field access in the receiver of a method call. Because this Field/MethodCall special case is not governed by precedence, it already requires special handling and is not affected by eliminating the PREC_POSTFIX precedence level.

https://github.com/rust-lang/rust/blob/d49994b060684af423339b55769439b2f444a7b9/compiler/rustc_ast_pretty/src/pprust/state/expr.rs#L217-L221

…r-errors

Don't suggest awaiting in closure patterns

Fixes rust-lang#126903.

For
```rust
async fn do_async() {}

fn main() {
    Some(do_async()).map(|()| {});
}
```
the error is now
```rust
error[E0308]: mismatched types
 --> src/main.rs:4:27
  |
4 |     Some(do_async()).map(|()| {});
  |                           ^^
  |                           |
  |                           expected future, found `()`
  |                           expected due to this
  |
  = note: expected opaque type `impl Future<Output = ()>`
               found unit type `()`
```

Ideally, if `main` were to be `async`, it should be
```rs
error[E0308]: mismatched types
 --> src/main.rs:4:27
  |
4 |     Some(do_async()).map(|()| {});
  |                           ^^
  |                           |
  |                           expected future, found `()`
  |                           expected due to this
  |
  = note: expected opaque type `impl Future<Output = ()>`
               found unit type `()`
help: consider `await`ing on the `Future`
  |
4 |     Some(do_async().await).map(|()| {});
  |                    ++++++
```
However, this would mean `FnCtx::check_pat_top` would have to be called with an `origin_expr` in `rustc_hir_typeck::check::check_fn`, and that expr would have to be somehow plumbed through `FnCtxt::check_expr_closure` and closure signature deduction. I'm willing to work on the plumbing but unsure how to start.

…specify-linker, r=Kobzol

Specify target specific linker for `riscv64gc-gnu` job

In rust-lang#125669 I updated the `riscv64gc-gnu` job to be more in line with other jobs, like the `armhf-gnu` one.

I missed something important, though! Since the `riscv64gc-unknown-linux-gnu` builds go through a cross compiler, invoking `cc` is not correct! That would invoke the `x86_64-unknown-linux-gnu` linker, instead of the `riscv64gc-unknown-linux-gnu` linker.

While developing rust-lang#125669 I assumed this line would have been sufficient, however it was not:

https://github.com/rust-lang/rust/blob/553a69030e5a086eb3841d020db8c9c463948c72/src/ci/docker/host-x86_64/disabled/riscv64gc-gnu/Dockerfile#L27-L28

Unfortunately, without the linker set, `cc` is invoked, and the following linker error occurs:

<details>

<summary>Long output</summary>

```
2024-06-21T14:37:54.4786899Z === HAYSTACK ===
2024-06-21T14:37:54.4787240Z error: linking with `cc` failed: exit status: 1
2024-06-21T14:37:54.4787589Z   |
2024-06-21T14:37:54.4806781Z   = note: LC_ALL="C" PATH="/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib/rustlib/x86_64-unknown-linux-gnu/bin:/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib/rustlib/x86_64-unknown-linux-gnu/bin:/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib/rustlib/x86_64-unknown-linux-gnu/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin" VSLANG="1033" "cc" "/tmp/rustc7Ju6va/symbols.o" "inaccessible/tmp/program.program.45572bc5f2b14090-cgu.0.rcgu.o" "inaccessible/tmp/program.dv9uftjrq86w5xa7l2eo7g9l7.rcgu.o" "-Wl,--as-needed" "-L" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/run-make/inaccessible-temp-dir/inaccessible-temp-dir/rmake_out" "-L" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib/rustlib/riscv64gc-unknown-linux-gnu/lib" "-Wl,-Bstatic" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib/rustlib/riscv64gc-unknown-linux-gnu/lib/libstd-bb9ed017b7d70437.rlib" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib/rustlib/riscv64gc-unknown-linux-gnu/lib/libpanic_unwind-5b34ef68c22a7b9b.rlib" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib/rustlib/riscv64gc-unknown-linux-gnu/lib/libobject-4b9224407e296f51.rlib" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib/rustlib/riscv64gc-unknown-linux-gnu/lib/libmemchr-1eaaa8d74bbe0b36.rlib" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib/rustlib/riscv64gc-unknown-linux-gnu/lib/libaddr2line-b34292f7086867e9.rlib" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib/rustlib/riscv64gc-unknown-linux-gnu/lib/libgimli-1927540c5dff6690.rlib" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib/rustlib/riscv64gc-unknown-linux-gnu/lib/librustc_demangle-ab493befe3742702.rlib" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib/rustlib/riscv64gc-unknown-linux-gnu/lib/libstd_detect-41195694489636c4.rlib" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib/rustlib/riscv64gc-unknown-linux-gnu/lib/libhashbrown-6905da49c8a1542a.rlib" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib/rustlib/riscv64gc-unknown-linux-gnu/lib/librustc_std_workspace_alloc-bbc6290f03f92349.rlib" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib/rustlib/riscv64gc-unknown-linux-gnu/lib/libminiz_oxide-7a4683d4a82cf47c.rlib" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib/rustlib/riscv64gc-unknown-linux-gnu/lib/libadler-071583516cdbce90.rlib" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib/rustlib/riscv64gc-unknown-linux-gnu/lib/libunwind-d84b176d2f4c1334.rlib" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib/rustlib/riscv64gc-unknown-linux-gnu/lib/libcfg_if-92b7de0160f87442.rlib" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib/rustlib/riscv64gc-unknown-linux-gnu/lib/liblibc-cff1533ea7c26263.rlib" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib/rustlib/riscv64gc-unknown-linux-gnu/lib/liballoc-49e374c13f9e6132.rlib" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib/rustlib/riscv64gc-unknown-linux-gnu/lib/librustc_std_workspace_core-9389dcc15b2f7f7b.rlib" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib/rustlib/riscv64gc-unknown-linux-gnu/lib/libcore-46f0fa14905fdc5c.rlib" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib/rustlib/riscv64gc-unknown-linux-gnu/lib/libcompiler_builtins-20e1af401f90cd1c.rlib" "-Wl,-Bdynamic" "-lgcc_s" "-lutil" "-lrt" "-lpthread" "-lm" "-ldl" "-lc" "-Wl,--eh-frame-hdr" "-Wl,-z,noexecstack" "-L" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib/rustlib/riscv64gc-unknown-linux-gnu/lib" "-o" "program" "-Wl,--gc-sections" "-pie" "-Wl,-z,relro,-z,now" "-nodefaultlibs"
2024-06-21T14:37:54.4823900Z   = note: /usr/bin/ld: inaccessible/tmp/program.program.45572bc5f2b14090-cgu.0.rcgu.o: Relocations in generic ELF (EM: 243)
2024-06-21T14:37:54.4825032Z           /usr/bin/ld: inaccessible/tmp/program.program.45572bc5f2b14090-cgu.0.rcgu.o: Relocations in generic ELF (EM: 243)
2024-06-21T14:37:54.4826130Z           /usr/bin/ld: inaccessible/tmp/program.program.45572bc5f2b14090-cgu.0.rcgu.o: Relocations in generic ELF (EM: 243)
2024-06-21T14:37:54.4827200Z           /usr/bin/ld: inaccessible/tmp/program.program.45572bc5f2b14090-cgu.0.rcgu.o: Relocations in generic ELF (EM: 243)
2024-06-21T14:37:54.4828279Z           /usr/bin/ld: inaccessible/tmp/program.program.45572bc5f2b14090-cgu.0.rcgu.o: Relocations in generic ELF (EM: 243)
2024-06-21T14:37:54.4829365Z           /usr/bin/ld: inaccessible/tmp/program.program.45572bc5f2b14090-cgu.0.rcgu.o: Relocations in generic ELF (EM: 243)
2024-06-21T14:37:54.4830474Z           /usr/bin/ld: inaccessible/tmp/program.program.45572bc5f2b14090-cgu.0.rcgu.o: Relocations in generic ELF (EM: 243)
2024-06-21T14:37:54.4831554Z           /usr/bin/ld: inaccessible/tmp/program.program.45572bc5f2b14090-cgu.0.rcgu.o: Relocations in generic ELF (EM: 243)
2024-06-21T14:37:54.4833002Z           /usr/bin/ld: inaccessible/tmp/program.program.45572bc5f2b14090-cgu.0.rcgu.o: Relocations in generic ELF (EM: 243)
2024-06-21T14:37:54.4834116Z           /usr/bin/ld: inaccessible/tmp/program.program.45572bc5f2b14090-cgu.0.rcgu.o: Relocations in generic ELF (EM: 243)
2024-06-21T14:37:54.4835237Z           /usr/bin/ld: inaccessible/tmp/program.program.45572bc5f2b14090-cgu.0.rcgu.o: error adding symbols: file in wrong format
2024-06-21T14:37:54.4835971Z           collect2: error: ld returned 1 exit status
2024-06-21T14:37:54.4836449Z
2024-06-21T14:37:54.4836584Z
2024-06-21T14:37:54.4836744Z error: aborting due to 1 previous error
2024-06-21T14:37:54.4836983Z
2024-06-21T14:37:54.4836990Z
2024-06-21T14:37:54.4837083Z === NEEDLE ===
2024-06-21T14:37:54.4837518Z failed to find or create the directory specified by `--temps-dir`
2024-06-21T14:37:54.4838250Z thread 'main' panicked at /checkout/tests/run-make/inaccessible-temp-dir/rmake.rs:35:14:
2024-06-21T14:37:54.4838801Z needle was not found in haystack
2024-06-21T14:37:54.4839270Z note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
2024-06-21T14:37:54.4840125Z thread 'main' panicked at /checkout/tests/run-make/inaccessible-temp-dir/rmake.rs:27:5:
2024-06-21T14:37:54.4840759Z called `Result::unwrap()` on an `Err` value: Any { .. }
2024-06-21T14:37:54.4841194Z ------------------------------------------
```

</details>

By setting `--set target.riscv64gc-unknown-linux-gnu.linker=riscv64-linux-gnu-gcc` the correct linker is invoked.

## Testing

> [!NOTE]
> `riscv64gc-unknown-linux-gnu` is a [**Tier 2 with Host Tools** platform](https://doc.rust-lang.org/beta/rustc/platform-support.html), all tests may not necessarily pass! This change should only make fix existing broken tests (like `inaccessible-temp-dir`) while introducing no new breakage.

You can test out the job locally:

```sh
mv src/ci/docker/host-x86_64/disabled/riscv64gc-gnu src/ci/docker/host-x86_64/riscv64gc-gnu
DEPLOY=1 ./src/ci/docker/run.sh riscv64gc-gnu
```

…ieril

Tweak a confusing comment in `create_match_candidates`

This comment was accurate at the time it was written, but various later changes reshuffled things in ways that caused the existing comment to become confusing.

I've therefore tried to clarify that *these* candidates are 1:1 with match arms, while also warning that that isn't the case in general.

…, r=joboet

core: VaArgSafe is an unsafe trait

`T: VaArgSafe` is relied on for soundness. Safe impls promise nothing. Therefore this must be an unsafe trait. Slightly pedantic, as only core can impl this, but we *could* choose to unseal the trait. That would allow soundly (but unsafely) implementing this for e.g. a `#[repr(C)] struct` that should be passable by varargs.

Relates to rust-lang#44930

Tweak `FlatPat::new` to avoid a temporarily-invalid state

It was somewhat confusing that the old constructor would create a `FlatPat` in a (possibly) non-simplified state, and then simplify its contents in-place.

So instead we now create its fields as local variables, perform simplification, and then create the struct afterwards.

This doesn't affect correctness, but is less confusing.

---

I've also included some semi-related comments that I made while trying to navigate this code.

…vm-ident, r=Kobzol

Migrate `run-make/llvm-ident` to `rmake.rs`

Part of rust-lang#121876.

r? `@Kobzol`

Add missing slash in `const_eval_select` doc comment

In the middle of the doc comment, one line has only two slashes instead of three and isn't included in the [rendered documentation](https://doc.rust-lang.org/std/intrinsics/fn.const_eval_select.html#stability-concerns). This PR adds the missing slash.

…ctoring, r=petrochenkov

Delegation: ast lowering refactor

refactoring changes for rust-lang#126699

r? ``@petrochenkov``