Fixes rust-lang#120785

rust-lang#91913

Code changes in raw_vec require blessing UI tests every time

This commit:
- Moves the ICE file create/open outside the loop. (Redoing it on every
  loop iteration works, but is really weird.)
- Moves the explanatory note emission above the loop, which removes the
  need for the `enumerate` call.
- Introduces a `decorate` local.

This prevents a follow-up type error in a test, which seems fine.

- Put every literal in its own braces, rather than just some of them,
  for maximal error recovery.
- Add a blank line between every case, for readability.

This slightly changes error messages in `float-field.rs`, but nothing of
real importance.

… highlighting

…igations

Make `ReentrantLock` public

Implements the ACP rust-lang/libs-team#193.

`@rustbot` label +T-libs-api +S-waiting-on-ACP

…nieu

Vec::try_with_capacity

Related to rust-lang#91913

Implements try_with_capacity for `Vec`, `VecDeque`, and `String`. I can follow it up with more collections if desired.

`Vec::try_with_capacity()` is functionally equivalent to the current stable:

```rust
let mut v = Vec::new();
v.try_reserve_exact(n)?
```

However, `try_reserve` calls non-inlined `finish_grow`, which requires old and new `Layout`, and is designed to reallocate memory. There is benefit to using `try_with_capacity`, besides syntax convenience, because it generates much smaller code at the call site with a direct call to the allocator. There's codegen test included.

It's also a very desirable functionality for users of `no_global_oom_handling` (Rust-for-Linux), since it makes a very commonly used function available in that environment (`with_capacity` is used much more frequently than all `(try_)reserve(_exact)`).

…clauses-on-ty-aliases, r=compiler-errors

Detect empty leading where clauses on type aliases

1. commit: refactor the AST of type alias where clauses
   * I could no longer bear the look of `.0.1` and `.1.0`
   * Arguably moving `split` out of `TyAlias` into a substruct might not make that much sense from a semantic standpoint since it reprs an index into `TyAlias.predicates` but it's alright and it cleans up the usage sites of `TyAlias`
2. commit: fix an oversight: An empty leading where clause is still a leading where clause
   * semantically reject empty leading where clauses on lazy type aliases
     * e.g., on `#![feature(lazy_type_alias)] type X where = ();`
   * make empty leading where clauses on assoc types trigger lint `deprecated_where_clause_location`
     * e.g., `impl Trait for () { type X where = (); }`

…nethercote

Improve error messages for generics with default parameters

Fixes rust-lang#120785

Issue: Previously, all type parameters with default types were deliberately ignored to simplify error messages. For example, an error message for Box type would display `Box<T>` instead of `Box<T, _>`. But, this resulted in unclear error message when a concrete type was used instead of the default type.

Fix: This PR fixes it by checking if a concrete type is specified after a default type to display the entire type name or the simplified type name.

…g-whitespace, r=notriddle

[rustdoc] Prevent inclusion of whitespace character after macro_rules ident

Discovered this bug randomly when looking at:

![image](https://github.com/rust-lang/rust/assets/3050060/dca38047-9085-4377-bfac-f98890224be4)

We were too eagerly trying to merge tokens that shouldn't be merged together (for example if you have a code comment followed by a code comment, we merge them in one attribute to reduce the DOM size).

r? `@notriddle`

… r=oli-obk

Two diagnostic things

Two minor improvements to diagnostics-related things.

r? `@RalfJung`

…, r=fmease

Use `LitKind::Err` for malformed floats

rust-lang#121120 changed `StringReader::cook_lexer_literal` to return `LitKind::Err` for malformed integer literals. This commit does the same for float literals, for consistency.

r? `@fmease`

…r=compiler-errors

pattern analysis: Don't panic when encountering unexpected constructor

Tiny PR to fix rust-lang/rust-analyzer#16656

r? `@compiler-errors`

…resolve-regions, r=jackh726

Opportunistically resolve regions when processing region outlives obligations

Due to the matching in `TypeOutlives` being structural, we should attempt to opportunistically resolve regions before processing region obligations. Thanks `@lcnr` for finding this.

r? lcnr