bjoernager/rust
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And additionally enforce ? and async/const aren't mixed

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This commit is contained in:
Michael Goulet 2024-07-10 18:06:44 -04:00
parent 898ed2ffa6
commit de88bc5c89
10 changed files with 120 additions and 44 deletions
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29
compiler/rustc_parse/src/parser/ty.rs
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@ -930,6 +930,7 @@ impl<'a> Parser<'a> {
/// TRAIT_BOUND_MODIFIERS = [["~"] "const"] ["async"] ["?" | "!"]
/// ```
fn parse_trait_bound_modifiers(&mut self) -> PResult<'a, TraitBoundModifiers> {
let modifier_lo = self.token.span;
let constness = if self.eat(&token::Tilde) {
let tilde = self.prev_token.span;
self.expect_keyword(kw::Const)?;
@ -962,6 +963,7 @@ impl<'a> Parser<'a> {
} else {
BoundAsyncness::Normal
};
let modifier_hi = self.prev_token.span;
let polarity = if self.eat(&token::Question) {
BoundPolarity::Maybe(self.prev_token.span)
@ -972,6 +974,33 @@ impl<'a> Parser<'a> {
BoundPolarity::Positive
};
// Enforce the mutual-exclusivity of `const`/`async` and `?`/`!`.
match polarity {
BoundPolarity::Positive => {
// All trait bound modifiers allowed to combine with positive polarity
}
BoundPolarity::Maybe(polarity_span) | BoundPolarity::Negative(polarity_span) => {
match (asyncness, constness) {
(BoundAsyncness::Normal, BoundConstness::Never) => {
// Ok, no modifiers.
}
(_, _) => {
let constness = constness.as_str();
let asyncness = asyncness.as_str();
let glue =
if !constness.is_empty() && !asyncness.is_empty() { " " } else { "" };
let modifiers_concatenated = format!("{constness}{glue}{asyncness}");
self.dcx().emit_err(errors::PolarityAndModifiers {
polarity_span,
polarity: polarity.as_str(),
modifiers_span: modifier_lo.to(modifier_hi),
modifiers_concatenated,
});
}
}
}
}
Ok(TraitBoundModifiers { constness, asyncness, polarity })
}