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Rollup merge of #132668 - ehuss:yield-gate-2024, r=davidtwco

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Feature gate yield expressions not in 2024

This changes it so that yield expressions are no longer allowed in the 2024 edition without a feature gate. We are currently only reserving the `gen` keyword in the 2024 edition, and not allowing anything else to be implicitly enabled by the edition.

In practice this doesn't have a significant difference since yield expressions can't really be used outside of coroutines or gen blocks, which have their own feature gates. However, it does affect what is accepted pre-expansion, and I would feel more comfortable not allowing yield expressions.

I believe the stabilization process for gen blocks or coroutines will not need to check the edition here, so this shouldn't ever be needed.
This commit is contained in:
Matthias Krüger 2024-11-12 08:07:16 +01:00 • committed by GitHub
commit 1dd975beb3
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3 changed files with 57 additions and 8 deletions
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15
compiler/rustc_ast_passes/src/feature_gate.rs
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@ -523,9 +523,18 @@ pub fn check_crate(krate: &ast::Crate, sess: &Session, features: &Features) {
"consider removing `for<...>`"
);
gate_all!(more_qualified_paths, "usage of qualified paths in this context is experimental");
for &span in spans.get(&sym::yield_expr).iter().copied().flatten() {
if !span.at_least_rust_2024() {
gate!(&visitor, coroutines, span, "yield syntax is experimental");
// yield can be enabled either by `coroutines` or `gen_blocks`
if let Some(spans) = spans.get(&sym::yield_expr) {
for span in spans {
if (!visitor.features.coroutines() && !span.allows_unstable(sym::coroutines))
&& (!visitor.features.gen_blocks() && !span.allows_unstable(sym::gen_blocks))
{
#[allow(rustc::untranslatable_diagnostic)]
// Don't know which of the two features to include in the
// error message, so I am arbitrarily picking one.
feature_err(&visitor.sess, sym::coroutines, *span, "yield syntax is experimental")
.emit();
}
}
}
gate_all!(gen_blocks, "gen blocks are experimental");