Requesting a zero-size allocation is not allowed,
return a dangling pointer instead.

CC rust-lang#63291 (comment)

…size

Add a target setting to allow targets to specify whether the generated
`main` function should be passed `argc` and `argv` arguments. Set it
to false on wasm32-wasi, since WASI's `args::args()` calls into the
WASI APIs itself. This will allow the WASI toolchain to avoid linking
and running command-line argument initialization code when the arguments
aren't actually needed.

Instead of `as_str()`, which unnecessarily involves `LocalInternedString`.

Currently, `Symbol::Debug` and `Symbol::Display` produce the same
output; neither wraps the symbol in double quotes.

This commit changes `Symbol::Debug` so it wraps the symbol in quotes.
This change brings `Symbol`'s behaviour in line with `String` and
`InternedString`. The change requires a couple of trivial test output
adjustments.

They aren't used.

…efKey`.

They aren't used.

And make it more uniform with other macros.
By merging placeholders for future derives' outputs into the derive container's output fragment early.

The issue is rustdoc-specific because its root cause if the `everybody_loops` pass makes some def-ids to not have local hir-ids

Fix zero-size uninitialized boxes

Requesting a zero-size allocation is not allowed, return a dangling pointer instead.

CC rust-lang#63291 (comment)

…hewjasper

expand: Simplify expansion of derives

And make it more uniform with other macros.
This is done by merging placeholders for future derives' outputs into the derive container's output fragment early (addressing FIXMEs from rust-lang#63667).

Also, macros with names starting with `_` are no longer reported as unused, in accordance with the usual behavior of `unused` lints.

r? @matthewjasper or @mark-i-m

…match-ugliness, r=eddyb

Suppress ICE when validators disagree on `LiveDrop`s in presence of `&mut`

Resolves rust-lang#65394.

This hack disables the validator mismatch ICE in cases where a `MutBorrow` error has been emitted by both validators, but they don't agree on the number of `LiveDrop` errors.

The new validator is more conservative about whether a value is moved from in the presence of mutable borrows. For example, the new validator will emit a `LiveDrop` error on the following code.

```rust
const _: Vec<i32> = {
    let mut x = Vec::new();
    let px = &mut x as *mut _;
    let y = x;
    unsafe { ptr::write(px, Vec::new()); }
    y
};
```

This code is not UB AFAIK (it passes MIRI at least). The current validator does not emit a `LiveDrop` error for `x` upon exit from the initializer. `x` is not actually dropped, so I think this is correct? A proper fix for this would require a new `MaybeInitializedLocals` dataflow analysis or maybe a relaxation of the existing `IndirectlyMutableLocals` one.

r? @RalfJung

…tril

Refer to "associated functions" instead of "static methods"

Fix rust-lang#59782.

…=petrochenkov

More symbol cleanups

Some minor improvements, mostly aimed at reducing unimportant differences between `Symbol` and `InternedString`. Helps a little with rust-lang#60869.

r? @petrochenkov

…=alexcrichton

Don't add `argc` and `argv` arguments to `main` on WASI.

Add a target setting to allow targets to specify whether the generated
`main` function should be passed `argc` and `argv` arguments. Set it
to false on wasm32-wasi, since WASI's `args::args()` calls into the
WASI APIs itself. This will allow the WASI toolchain to avoid linking
and running command-line argument initialization code when the arguments
aren't actually needed.