…assembly

… format macro.

For example:
```rust
let s = "123";
println!({}, "sss", s);
```
Suggest:
`println!("{:?} {} {}", {}, "sss", s);`

fixes rust-lang#130170

…f_mut, r=dtolnay

Stabilize `Pin::as_deref_mut()`

Tracking issue: closes rust-lang#86918

Stabilizing the following API:

```rust
impl<Ptr: DerefMut> Pin<Ptr> {
    pub fn as_deref_mut(self: Pin<&mut Pin<Ptr>>) -> Pin<&mut Ptr::Target>;
}
```

I know that an FCP has not been started yet, but this isn't a very complex stabilization, and I'm hoping this can motivate an FCP to *get* started - this has been pending for a while and it's a very useful function when writing Future impls.

r? ``@jonhoo``

…nieu

Fix clobber_abi and disallow SVE-related registers in Arm64EC inline assembly

Currently `clobber_abi` in Arm64EC inline assembly is implemented using `InlineAsmClobberAbi::AArch64NoX18`, but broken since it attempts to clobber registers that cannot be used in Arm64EC: https://godbolt.org/z/r3PTrGz5r

```
error: cannot use register `x13`: x13, x14, x23, x24, x28, v16-v31 cannot be used for Arm64EC
 --> <source>:6:14
  |
6 |     asm!("", clobber_abi("C"), options(nostack, nomem, preserves_flags));
  |              ^^^^^^^^^^^^^^^^

error: cannot use register `x14`: x13, x14, x23, x24, x28, v16-v31 cannot be used for Arm64EC
 --> <source>:6:14
  |
6 |     asm!("", clobber_abi("C"), options(nostack, nomem, preserves_flags));
  |              ^^^^^^^^^^^^^^^^

<omitted the same errors for v16-v31>
```

Additionally, this disallows SVE-related registers per rust-lang#131332 (comment).

cc ``@dpaoliello``

r? ``@Amanieu``

``@rustbot`` label O-windows O-AArch64 +A-inline-assembly

…aheemdev

Update precondition tests (especially for zero-size access to null)

I don't much like the current way I've updated the precondition check helpers, but I couldn't come up with anything better. Ideas welcome.

I've organized `tests/ui/precondition-checks` mostly with one file per function that has `assert_unsafe_precondition` in it, with revisions that check each precondition. The important new test is `tests/ui/precondition-checks/zero-size-null.rs`.

Special treatment empty tuple when suggest adding a string literal in format macro.

For example:
```rust
let s = "123";
println!({}, "sss", s);
```
Suggest:
`println!("{:?} {} {}", {}, "sss", s);`

fixes rust-lang#130170

…astorino

Make some tweaks to extern block diagnostics

Self-explanatory. See the diagnostic changes; I hope they make them a bit more descriptive.

r? spastorino

…t, r=Amanieu

Fix AArch64InlineAsmReg::emit

Currently, this method uses `self as u32 - Self::x0 as u32` to get register index:
https://github.com/rust-lang/rust/blob/36780360b62320a61e2234b17ec600e8e4785509/compiler/rustc_target/src/asm/aarch64.rs#L204

However, this is incorrect for reasons explained in the following comment:
https://github.com/rust-lang/rust/blob/36780360b62320a61e2234b17ec600e8e4785509/compiler/rustc_codegen_llvm/src/asm.rs#L544-L549

r? ``@Amanieu``

``@rustbot`` label O-AArch64 +A-inline-assembly

compiletest: Document various parts of compiletest's `lib.rs`

This adds some much-needed comments to many of the items in compiletest's `lib.rs`, giving a better overview of how a compiletest invocation actually proceeds.

To make review easier I have refrained from renames or functional changes, though I couldn't resist getting rid of one obviously-redundant `Arc::clone` in `make_test_closure`.

…thar

Tag PRs affecting compiletest with `A-compiletest`