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Auto merge of #116447 - oli-obk:gen_fn, r=compiler-errors

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Implement `gen` blocks in the 2024 edition

Coroutines tracking issue https://github.com/rust-lang/rust/issues/43122
`gen` block tracking issue https://github.com/rust-lang/rust/issues/117078

This PR implements `gen` blocks that implement `Iterator`. Most of the logic with `async` blocks is shared, and thus I renamed various types that were referring to `async` specifically.

An example usage of `gen` blocks is

```rust
fn foo() -> impl Iterator<Item = i32> {
    gen {
        yield 42;
        for i in 5..18 {
            if i.is_even() { continue }
            yield i * 2;
        }
    }
}
```

The limitations (to be resolved) of the implementation are listed in the tracking issue
This commit is contained in:
bors 2023-10-29 00:03:52 +00:00
commit 2cad938a81
75 changed files with 1096 additions and 148 deletions
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3
compiler/rustc_borrowck/src/borrowck_errors.rs
View file

@ -373,11 +373,12 @@ impl<'cx, 'tcx> crate::MirBorrowckCtxt<'cx, 'tcx> {
span: Span,
yield_span: Span,
) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
let coroutine_kind = self.body.coroutine.as_ref().unwrap().coroutine_kind;
let mut err = struct_span_err!(
self,
span,
E0626,
"borrow may still be in use when coroutine yields",
"borrow may still be in use when {coroutine_kind:#} yields",
);
err.span_label(yield_span, "possible yield occurs here");
err

21
compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs
View file

@ -2491,11 +2491,17 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
let (sugg_span, suggestion) = match tcx.sess.source_map().span_to_snippet(args_span) {
Ok(string) => {
if string.starts_with("async ") {
let pos = args_span.lo() + BytePos(6);
(args_span.with_lo(pos).with_hi(pos), "move ")
} else if string.starts_with("async|") {
let pos = args_span.lo() + BytePos(5);
let coro_prefix = if string.starts_with("async") {
// `async` is 5 chars long. Not using `.len()` to avoid the cast from `usize` to `u32`
Some(5)
} else if string.starts_with("gen") {
// `gen` is 3 chars long
Some(3)
} else {
None
};
if let Some(n) = coro_prefix {
let pos = args_span.lo() + BytePos(n);
(args_span.with_lo(pos).with_hi(pos), " move")
} else {
(args_span.shrink_to_lo(), "move ")
@ -2505,6 +2511,11 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
};
let kind = match use_span.coroutine_kind() {
Some(coroutine_kind) => match coroutine_kind {
CoroutineKind::Gen(kind) => match kind {
CoroutineSource::Block => "gen block",
CoroutineSource::Closure => "gen closure",
_ => bug!("gen block/closure expected, but gen function found."),
},
CoroutineKind::Async(async_kind) => match async_kind {
CoroutineSource::Block => "async block",
CoroutineSource::Closure => "async closure",

14
compiler/rustc_borrowck/src/diagnostics/region_name.rs
View file

@ -698,6 +698,20 @@ impl<'tcx> MirBorrowckCtxt<'_, 'tcx> {
" of async function"
}
},
Some(hir::CoroutineKind::Gen(gen)) => match gen {
hir::CoroutineSource::Block => " of gen block",
hir::CoroutineSource::Closure => " of gen closure",
hir::CoroutineSource::Fn => {
let parent_item =
hir.get_by_def_id(hir.get_parent_item(mir_hir_id).def_id);
let output = &parent_item
.fn_decl()
.expect("coroutine lowered from gen fn should be in fn")
.output;
span = output.span();
" of gen function"
}
},
Some(hir::CoroutineKind::Coroutine) => " of coroutine",
None => " of closure",
};