Implements `IntoDiagnosticArg` for `char` using its `Debug`
implementation and introduces a macro for those types which just
delegate the implementation to `ToString`.

Signed-off-by: David Wood <david.wood@huawei.com>

Apply the `#[rustc_lint_diagnostics]` attribute to
`LintDiagnosticBuilder::build` so that diagnostic migration lints will
trigger for it.

Signed-off-by: David Wood <david.wood@huawei.com>

Add support for `MultiSpan` with any of the attributes that work on a
`Span` - requires that diagnostic logic generated for these attributes
are emitted in the by-move block rather than the by-ref block that they
would normally have been generated in.

Signed-off-by: David Wood <david.wood@huawei.com>

Both diagnostic and subdiagnostic derives were missing the ability to
add warnings to diagnostics - this is made more difficult by the `warn`
attribute already existing, so this name being unavailable for the
derives to use. `#[warn_]` is used instead, which requires
special-casing so that `{span_,}warn` is called instead of
`{span_,}warn_`.

Signed-off-by: David Wood <david.wood@huawei.com>

Migrate half of the `rustc_passes::check_attr` diagnostics to using
diagnostic derives and being translatable.

…site

…it ever happened

…aque types

This reverts commit 0813525.

We check that there's a single level of block nesting to ensure always
correct suggestions. If we don't, then we only provide a free-form
message to avoid misleading users in cases like
`src/test/ui/nll/borrowed-temporary-error.rs`.

We could expand the analysis to suggest hoising all of the relevant
parts of the users' code to make the code compile, but that could be
too much.

… format

…r=estebank

Allow destructuring opaque types in their defining scopes

fixes rust-lang#96572

Before this PR, the following code snippet failed with an incomprehensible error, and similar code just ICEd in mir borrowck.

```rust
    type T = impl Copy;
    let foo: T = (1u32, 2u32);
    let (a, b) = foo;
```

The problem was that the last line created MIR projections of the form `foo.0` and `foo.1`, but `foo`'s type is `T`, which doesn't have fields (only its hidden type does). But the pattern supplies enough type information (a tuple of two different inference types) to bind a hidden type.

…s, r=compiler-errors

migrate some of `rustc_passes::check_attr`'s diagnostics and derive improvements

- Implements `IntoDiagnosticArg` for `char` using its `Debug` implementation and introduces a macro for those types which just delegate the implementation to `ToString`.
- Apply the `#[rustc_lint_diagnostics]` attribute to `LintDiagnosticBuilder::build` so that diagnostic migration lints will trigger for it - some diagnostics in `rustc_privacy` need updated after this since the lints apply to that crate.
- Add support for `MultiSpan` with any of the attributes that work on a `Span` in the diagnostic derive (`SessionDiagnostic` + `LintDiagnostic`). Requires that diagnostic logic generated for these attributes are emitted in the by-move block rather than the by-ref block that they would normally have been generated in.
- Both diagnostic and subdiagnostic derives were missing the ability to add warnings to diagnostics - this is made more difficult by the `warn` attribute already existing, so this name being unavailable for the derives to use. `#[warn_]` is used instead, which requires special-casing so that `{span_,}warn` is called instead of `{span_,}warn_`.
- Migrate half of the `rustc_passes::check_attr` diagnostics to using diagnostic derives and being translatable. I got tired after a while. I modified some diagnostic output for consistency while doing this, nothing too crazy.

r? `@compiler-errors`

Provide structured suggestion for dropped temp value

interpret/visitor: support visiting with a PlaceTy

Finally we can visit a `PlaceTy` in a way that will only do `force_allocation` when needed ti visit a field. :)

r? `@oli-obk`

…export, r=notriddle

[rustdoc-json] JSON no longer inlines

Fixes rust-lang#98007.
Fixes rust-lang#96161.
Fixes rust-lang#83057.
Fixes rust-lang#83720.

I took over rust-lang#93518 and applied the comments and added more tests.

There was one thing missing (which is in the second commit): if a non-exported item was used in a public API but not reexported, it was still missing.

cc `@CraftSpider` `@Urgau` `@Enselic`

r? `@notriddle`

Revert "Highlight conflicting param-env candidates"

This reverts rust-lang#98794, commit 0813525.

Seems to have caused an incremental compilation bug. The root cause of the incr comp bug is somewhat unrelated but is triggered by this PR, so I don't feel comfortable with having this PR in the codebase until it can be investigated further. Fixes rust-lang#99233.

docs: add missing word

…r=Mark-Simulacrum

Borrow Vec<T, A> as [T]

Hello all,

When `Vec` was parametrized with `A`, the `Borrow` impls were omitted and currently `Vec<T, A>` can't be borrowed as `[T]`. This PR fixes that.

This was probably missed, because the `Borrow` impls are in a different file - `src/alloc/slice.rs`.

We briefly discussed this here: rust-lang/wg-allocators#96 and I was told to go ahead and make a PR :)

I tested this by building the toolchain and building my code that needed the `Borrow` impl against it, but let me know if I should add any tests to this PR.

…an-DPC

Fix flakyness of GUI tests

Fixes rust-lang#98163.

All flaky tests seemed to be linked to the search. Since the search JS is loaded when we focus the search input, I think it's possible that we enter faster than the JS is actually loaded. The solution for that would be to do it in two steps: first we write into the search input (`browser-ui-test` adds a small sleep time after such commands) and then we press enter to be sure that it wasn't missed.

cc `@JohnTitor`
r? `@Dylan-DPC`

…ersions, r=compiler-errors

Avoid some `Symbol` to `String` conversions

This patch removes some Symbol to String conversions.