Rollup merge of #127054 - compiler-errors:bound-ordering, r=fmease

Reorder trait bound modifiers *after* `for<...>` binder in trait bounds

This PR suggests changing the grammar of trait bounds from:

```
[CONSTNESS] [ASYNCNESS] [?] [BINDER] [TRAIT_PATH]

const async ? for<'a> Sized
```

to

```
([BINDER] [CONSTNESS] [ASYNCNESS] | [?]) [TRAIT_PATH]
```

i.e., either

```
? Sized
```

or

```
for<'a> const async Sized
```

(but not both)

### Why?

I think it's strange that the binder applies "more tightly" than the `?` trait polarity. This becomes even weirder when considering that we (or at least, I) want to have `async` trait bounds expressed like:

```
where T: for<'a> async Fn(&'a ()) -> i32,
```

and not:

```
where T: async for<'a> Fn(&'a ()) -> i32,
```

### Fallout

No crates on crater use this syntax, presumably because it's literally useless. This will require modifying the reference grammar, though.

### Alternatives

If this is not desirable, then we can alternatively keep parsing `for<'a>` after the `?` but deprecate it with either an FCW (or an immediate hard error), and begin parsing `for<'a>` *before* the `?`.

4 files changed, 1 insertions, 11 deletions

diff --git a/src/tools/rustfmt/tests/source/type.rs b/src/tools/rustfmt/tests/source/type.rs
index 61ef73a3cab..7a232f85198 100644
--- a/src/tools/rustfmt/tests/source/type.rs
+++ b/src/tools/rustfmt/tests/source/type.rs
@@ -146,8 +146,6 @@ trait T: ~   const  Super {}
 
 const fn not_quite_const<S: ~  const    T>() -> i32 { <S as T>::CONST }
 
-struct S<T:~  const   ?  Sized>(std::marker::PhantomData<T>);
-
 impl ~    const T {}
 
 fn apit(_: impl ~   const T) {}
diff --git a/src/tools/rustfmt/tests/target/negative-bounds.rs b/src/tools/rustfmt/tests/target/negative-bounds.rs
index 4fb35cccf66..9fcb86ef4a4 100644
--- a/src/tools/rustfmt/tests/target/negative-bounds.rs
+++ b/src/tools/rustfmt/tests/target/negative-bounds.rs
@@ -3,9 +3,3 @@ where
     i32: !Copy,
 {
 }
-
-fn maybe_const_negative()
-where
-    i32: ~const !Copy,
-{
-}
diff --git a/src/tools/rustfmt/tests/target/type.rs b/src/tools/rustfmt/tests/target/type.rs
index c789ecb055a..325adb52f3f 100644
--- a/src/tools/rustfmt/tests/target/type.rs
+++ b/src/tools/rustfmt/tests/target/type.rs
@@ -153,8 +153,6 @@ const fn not_quite_const<S: ~const T>() -> i32 {
     <S as T>::CONST
 }
 
-struct S<T: ~const ?Sized>(std::marker::PhantomData<T>);
-
 impl ~const T {}
 
 fn apit(_: impl ~const T) {}
diff --git a/src/tools/tidy/src/ui_tests.rs b/src/tools/tidy/src/ui_tests.rs
index 5e6992038e3..0ae0356b2c4 100644
--- a/src/tools/tidy/src/ui_tests.rs
+++ b/src/tools/tidy/src/ui_tests.rs
@@ -16,7 +16,7 @@ use std::path::{Path, PathBuf};
 const ENTRY_LIMIT: u32 = 901;
 // FIXME: The following limits should be reduced eventually.
 
-const ISSUES_ENTRY_LIMIT: u32 = 1672;
+const ISSUES_ENTRY_LIMIT: u32 = 1673;
 
 const EXPECTED_TEST_FILE_EXTENSIONS: &[&str] = &[
     "rs",     // test source files