Make some non-diagnostic-affecting `QPath::LangItem` into regular `QPath`s
The rest of 'em affect diagnostics, so leave them alone... for now.
cc #115178
Make closures carry their own ClosureKind
Right now, we use the "`movability`" field of `hir::Closure` to distinguish a closure and a coroutine. This is paired together with the `CoroutineKind`, which is located not in the `hir::Closure`, but the `hir::Body`. This is strange and redundant.
This PR introduces `ClosureKind` with two variants -- `Closure` and `Coroutine`, which is put into `hir::Closure`. The `CoroutineKind` is thus removed from `hir::Body`, and `Option<Movability>` no longer needs to be a stand-in for "is this a closure or a coroutine".
r? eholk
remove dead inferred outlives testing code
The `test_inferred_outlives` function was never run, because the code that's actually used for the tests was part of the `inferred_outlives_of` query, which ran before `test_inferred_outlives` during type collecting. This PR separates the test code from the query and moves it inside the dedicated function.
Clairify `ast::PatKind::Struct` presese of `..` by using an enum instead of a bool
The bool is mainly used for when a `..` is present, but it is also set on recovery to avoid errors. The doc comment not describes both of these cases.
See cee794ee98/compiler/rustc_parse/src/parser/pat.rs (L890-L897) for the only place this is constructed.
r? ``@compiler-errors``
Split coroutine desugaring kind from source
What a coroutine is desugared from (gen/async gen/async) should be separate from where it comes (fn/block/closure).
Separate MIR lints from validation
Add a MIR lint pass, enabled with -Zlint-mir, which identifies undefined or
likely erroneous behaviour.
The initial implementation mostly migrates existing checks of this nature from
MIR validator, where they did not belong (those checks have false positives and
there is nothing inherently invalid about MIR with undefined behaviour).
Fixes#104736Fixes#104843Fixes#116079Fixes#116736Fixes#118990
There are only three. It's simpler to make the type
`DiagnosticBuilder<'_, ()>` from the start, no matter the level, than to
change the guarantee later.
Lots of vectors of messages called `message` or `msg`. This commit
pluralizes them.
Note that `emit_message_default` and `emit_messages_default` both
already existed, and both process a vector, so I renamed the former
`emit_messages_default_inner` because it's called by the latter.
Add support for `for await` loops
This adds support for `for await` loops. This includes parsing, desugaring in AST->HIR lowering, and adding some support functions to the library.
Given a loop like:
```rust
for await i in iter {
...
}
```
this is desugared to something like:
```rust
let mut iter = iter.into_async_iter();
while let Some(i) = loop {
match core::pin::Pin::new(&mut iter).poll_next(cx) {
Poll::Ready(i) => break i,
Poll::Pending => yield,
}
} {
...
}
```
This PR also adds a basic `IntoAsyncIterator` trait. This is partly for symmetry with the way `Iterator` and `IntoIterator` work. The other reason is that for async iterators it's helpful to have a place apart from the data structure being iterated over to store state. `IntoAsyncIterator` gives us a good place to do this.
I've gated this feature behind `async_for_loop` and opened #118898 as the feature tracking issue.
r? `@compiler-errors`
Refactor AST trait bound modifiers
Instead of having two types to represent trait bound modifiers in the parser / the AST (`parser::ty::BoundModifiers` & `ast::TraitBoundModifier`), only to map one to the other later, just use `parser::ty::BoundModifiers` (moved & renamed to `ast::TraitBoundModifiers`).
The struct type is more extensible and easier to deal with (see [here](https://github.com/rust-lang/rust/pull/119099/files#r1430749981) and [here](https://github.com/rust-lang/rust/pull/119099/files#r1430752116) for context) since it more closely models what it represents: A compound of two kinds of modifiers, constness and polarity. Modeling this as an enum (the now removed `ast::TraitBoundModifier`) meant one had to add a new variant per *combination* of modifier kind, which simply isn't scalable and which lead to a lot of explicit non-DRY matches.
NB: `hir::TraitBoundModifier` being an enum is fine since HIR doesn't need to worry representing invalid modifier kind combinations as those get rejected during AST validation thereby immensely cutting down the number of possibilities.
Give `VariantData::Struct` named fields, to clairfy `recovered`.
Implements https://github.com/rust-lang/rust/pull/119121#discussion_r1431467066. Supersedes #119121
This way, it's clear what the bool fields means, instead of having to find where it's generated. Changes both ast and hir.
r? `@compiler-errors`
do not allow ABI mismatches inside repr(C) types
In https://github.com/rust-lang/rust/pull/115476 we allowed ABI mismatches inside `repr(C)` types. This wasn't really discussed much; I added it because from how I understand calling conventions, this should actually be safe in practice. However I entirely forgot to actually allow this in Miri, and in the mean time I have learned that too much ABI compatibility can be a problem for CFI (it can reject fewer calls so that gives an attacker more room to play with).
So I propose we take back that part about ABI compatibility in `repr(C)`. It is anyway something that C and C++ do not allow, as far as I understand.
In the future we might want to introduce a class of ABI compatibilities where we say "this is a bug and it may lead to aborting the process, but it won't lead to arbitrary misbehavior -- worst case it'll just transmute the arguments from the caller type to the callee type". That would give CFI leeway to reject such calls without introducing the risk of arbitrary UB. (The UB can still happen if the transmute leads to bad results, of course, but it wouldn't be due to ABI weirdness.)
#115476 hasn't reached beta yet so if we land this before Dec 22nd we can just pretend this all never happened. ;) Otherwise we should do a beta backport (of the docs change at least).
Cc `@rust-lang/opsem` `@rust-lang/types`
Make exhaustiveness usable outside of rustc
With this PR, `rustc_pattern_analysis` compiles on stable (with the `stable` feature)! `rust-analyzer` will be able to use it to provide match-related diagnostics and refactors.
Two questions:
- Should I name the feature `nightly` instead of `rustc` for consistency with other crates? `rustc` makes more sense imo.
- `typed-arena` is an optional dependency but tidy made me add it to the allow-list anyway. Can I avoid that somehow?
r? `@compiler-errors`
