bjoernager/rust
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Also allow let chains in match guards

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This commit is contained in:
est31 2025-03-16 06:32:43 +01:00
parent eb1639bd33
commit d75f8cde2f
1 changed files with 20 additions and 11 deletions
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31
compiler/rustc_parse/src/parser/expr.rs
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@ -3431,15 +3431,15 @@ impl<'a> Parser<'a> {
fn parse_match_arm_guard(&mut self) -> PResult<'a, Option<P<Expr>>> {
// Used to check the `let_chains` and `if_let_guard` features mostly by scanning
// `&&` tokens.
fn check_let_expr(expr: &Expr) -> (bool, bool) {
fn has_let_expr(expr: &Expr) -> bool {
match &expr.kind {
ExprKind::Binary(BinOp { node: BinOpKind::And, .. }, lhs, rhs) => {
let lhs_rslt = check_let_expr(lhs);
let rhs_rslt = check_let_expr(rhs);
(lhs_rslt.0 || rhs_rslt.0, false)
let lhs_rslt = has_let_expr(lhs);
let rhs_rslt = has_let_expr(rhs);
lhs_rslt || rhs_rslt
}
ExprKind::Let(..) => (true, true),
_ => (false, true),
ExprKind::Let(..) => true,
_ => false,
}
}
if !self.eat_keyword(exp!(If)) {
@ -3452,12 +3452,21 @@ impl<'a> Parser<'a> {
CondChecker::new(self).visit_expr(&mut cond);
let (has_let_expr, does_not_have_bin_op) = check_let_expr(&cond);
if has_let_expr {
if does_not_have_bin_op {
// Remove the last feature gating of a `let` expression since it's stable.
self.psess.gated_spans.ungate_last(sym::let_chains, cond.span);
if has_let_expr(&cond) {
// Let chains are allowed in match guards, but only there
fn ungate_let_exprs(this: &mut Parser<'_>, expr: &Expr) {
match &expr.kind {
ExprKind::Binary(BinOp { node: BinOpKind::And, .. }, lhs, rhs) => {
ungate_let_exprs(this, rhs);
ungate_let_exprs(this, lhs);
}
ExprKind::Let(..) => {
this.psess.gated_spans.ungate_last(sym::let_chains, expr.span)
}
_ => (),
}
}
ungate_let_exprs(self, &cond);
let span = if_span.to(cond.span);
self.psess.gated_spans.gate(sym::if_let_guard, span);
}