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Rollup merge of #124099 - voidc:disallow-ambiguous-expr-attrs, r=davidtwco

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Disallow ambiguous attributes on expressions

This implements the suggestion in [#15701](https://github.com/rust-lang/rust/issues/15701#issuecomment-2033124217) to disallow ambiguous outer attributes on expressions. This should resolve one of the concerns blocking the stabilization of `stmt_expr_attributes`.
This commit is contained in:
Matthias Krüger 2024-04-23 12:10:26 +02:00 • committed by GitHub
commit 57dad1d75e
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15 changed files with 141 additions and 49 deletions
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9
compiler/rustc_parse/src/errors.rs
View file

@ -495,6 +495,15 @@ pub(crate) struct OuterAttributeNotAllowedOnIfElse {
pub attributes: Span,
}
#[derive(Diagnostic)]
#[diag(parse_outer_attr_ambiguous)]
pub(crate) struct AmbiguousOuterAttributes {
#[primary_span]
pub span: Span,
#[subdiagnostic]
pub sugg: WrapInParentheses,
}
#[derive(Diagnostic)]
#[diag(parse_missing_in_in_for_loop)]
pub(crate) struct MissingInInForLoop {

32
compiler/rustc_parse/src/parser/expr.rs
View file

@ -327,7 +327,9 @@ impl<'a> Parser<'a> {
this.parse_expr_assoc_with(prec + prec_adjustment, LhsExpr::NotYetParsed)
})?;
let span = self.mk_expr_sp(&lhs, lhs_span, rhs.span);
self.error_ambiguous_outer_attrs(&lhs, lhs_span, rhs.span);
let span = lhs_span.to(rhs.span);
lhs = match op {
AssocOp::Add
| AssocOp::Subtract
@ -426,6 +428,18 @@ impl<'a> Parser<'a> {
});
}
fn error_ambiguous_outer_attrs(&self, lhs: &P<Expr>, lhs_span: Span, rhs_span: Span) {
if let Some(attr) = lhs.attrs.iter().find(|a| a.style == AttrStyle::Outer) {
self.dcx().emit_err(errors::AmbiguousOuterAttributes {
span: attr.span.to(rhs_span),
sugg: errors::WrapInParentheses::Expression {
left: attr.span.shrink_to_lo(),
right: lhs_span.shrink_to_hi(),
},
});
}
}
/// Possibly translate the current token to an associative operator.
/// The method does not advance the current token.
///
@ -506,7 +520,8 @@ impl<'a> Parser<'a> {
None
};
let rhs_span = rhs.as_ref().map_or(cur_op_span, |x| x.span);
let span = self.mk_expr_sp(&lhs, lhs.span, rhs_span);
self.error_ambiguous_outer_attrs(&lhs, lhs.span, rhs_span);
let span = lhs.span.to(rhs_span);
let limits =
if op == AssocOp::DotDot { RangeLimits::HalfOpen } else { RangeLimits::Closed };
let range = self.mk_range(Some(lhs), rhs, limits);
@ -722,7 +737,8 @@ impl<'a> Parser<'a> {
expr_kind: fn(P<Expr>, P<Ty>) -> ExprKind,
) -> PResult<'a, P<Expr>> {
let mk_expr = |this: &mut Self, lhs: P<Expr>, rhs: P<Ty>| {
this.mk_expr(this.mk_expr_sp(&lhs, lhs_span, rhs.span), expr_kind(lhs, rhs))
this.error_ambiguous_outer_attrs(&lhs, lhs_span, rhs.span);
this.mk_expr(lhs_span.to(rhs.span), expr_kind(lhs, rhs))
};
// Save the state of the parser before parsing type normally, in case there is a
@ -3813,16 +3829,6 @@ impl<'a> Parser<'a> {
self.mk_expr(span, ExprKind::Err(guar))
}
/// Create expression span ensuring the span of the parent node
/// is larger than the span of lhs and rhs, including the attributes.
fn mk_expr_sp(&self, lhs: &P<Expr>, lhs_span: Span, rhs_span: Span) -> Span {
lhs.attrs
.iter()
.find(|a| a.style == AttrStyle::Outer)
.map_or(lhs_span, |a| a.span)
.to(rhs_span)
}
fn collect_tokens_for_expr(
&mut self,
attrs: AttrWrapper,