See:

- rust-lang#80996
- rust-lang#80996 (comment)

Previously we were just using the parent node as the scope for a
temporary value, but it turns out this is too narrow. For example, in
an expression like

    Foo {
        b: &42,
        a: async { 0 }.await,
    }

the scope for the &42 was set to the ExprField node for `b: &42`, when
we actually want to use the Foo struct expression.

We fix this by recursively searching through parent nodes until we find
a Node::Expr. It may be that we don't find one, and if so that's okay,
we will just fall back on the enclosing temporary scope which is always
sufficient.

revealed by tests, manually add a panic to test for dead code

…ossible...

- ... when creating diagnostics in rustc_metadata
-  use the error_code! macro
- pass macro output to diag.code()
- use fluent from within manual implementation of SessionDiagnostic
- emit the untested errors in case they occur in the wild
- stop panicking in the probably-not-dead code, add fixme to write test

Also briefly document the history of `sys/windows/rand.rs` as they may be relevant to any future changes.

Fuchsia .manifest files do not support a `#` comment syntax. Because of this, if you copy and paste the current example code for this file, and then remove the line you don't need, you still see an error. To make this a bit easier to follow, split this into two code blocks, one for rustc, and one for cargo.

…partial-stabilization-bounds-as-ref, r=dtolnay

Partially stabilize `bound_as_ref` by stabilizing `Bound::as_ref`

Stabilizing `Bound::as_ref` will simplify the implementation for `RangeBounds<usize>` for custom range types:

```rust
impl RangeBounds<usize> for Region {
    fn start_bound(&self) -> Bound<&usize> {
        // TODO: Use `self.start.as_ref()` when upstream `std` stabilizes:
        // rust-lang#80996
        match self.start {
            Bound::Included(ref bound) => Bound::Included(bound),
            Bound::Excluded(ref bound) => Bound::Excluded(bound),
            Bound::Unbounded => Bound::Unbounded,
        }
    }

    fn end_bound(&self) -> Bound<&usize> {
        // TODO: Use `self.end.as_ref()` when upstream `std` stabilizes:
        // rust-lang#80996
        match self.end {
            Bound::Included(ref bound) => Bound::Included(bound),
            Bound::Excluded(ref bound) => Bound::Excluded(bound),
            Bound::Unbounded => Bound::Unbounded,
        }
    }
}
```

See:

- rust-lang#80996
- rust-lang#80996 (comment)

cc `@yaahc` who suggested partial stabilization.

…s, r=davidtwco

Migrate rustc_metadata to SessionDiagnostics

Migrate rustc_metadata to SessionDiagnostics.

Part of rust-lang#100717

[drop tracking] Use parent expression for scope, not parent node

Previously we were just using the parent node as the scope for a temporary value, but it turns out this is too narrow. For example, in an expression like

    Foo {
        b: &42,
        a: async { 0 }.await,
    }

the scope for the &42 was set to the ExprField node for `b: &42`, when we actually want to use the Foo struct expression.

We fix this by recursively searching through parent nodes until we find a Node::Expr. It may be that we don't find one, and if so that's okay, we will just fall back on the enclosing temporary scope which is always sufficient.

Helps with rust-lang#97331

r? ``@jyn514``

… r=thomcc

Windows RNG: Use `BCRYPT_RNG_ALG_HANDLE` by default

This only changes a small amount of actual code, the rest is documentation outlining the history of this module as I feel it will be relevant to any future issues that might crop up.

The code change is to use the `BCRYPT_RNG_ALG_HANDLE` [pseudo-handle](https://docs.microsoft.com/en-us/windows/win32/seccng/cng-algorithm-pseudo-handles) by default, which simply uses the default RNG. Previously we used `BCRYPT_USE_SYSTEM_PREFERRED_RNG` which has to load the system configuration and then find and load that RNG. I suspect this was the cause of failures on some systems (e.g. due to corrupted config). However, this is admittedly speculation as I can't reproduce the issue myself (and it does seem quite rare even in the wild). Still, removing a possible point of failure is likely worthwhile in any case.

r? libs

…n514

Fix `std::collections::HashSet::drain` documentation

Hi!

`std::collections::HashSet::drain` contains small typo in the docstring.

I didn't read too much about the model of contributing to Rust, so merge this PR or close and fix the typo the right way :)

Thanks for Rust!

Fix unsupported syntax in .manifest file

Fuchsia .manifest files do not support a `#` comment syntax. Because of this, if you copy and paste the current example code for this file, and then remove the line you don't need, you still see an error. To make this a bit easier to follow, split this into two code blocks, one for rustc, and one for cargo.

…r=notriddle

Cleanup css theme

Follow-up of rust-lang#100494.

The change for the border color of the search input in the dark mode was actually a weird case: the search input border was unique, it didn't share the same variable with other items with borders. This weird case being unique to the dark theme, I removed it, hence the modification in the GUI test.

Live demo is [here](https://rustdoc.crud.net/imperio/cleanup-css-theme/std/index.html).

cc `@jsha`
r? `@notriddle`