diff options
Diffstat (limited to 'compiler/rustc_parse/src/parser/expr.rs')
| -rw-r--r-- | compiler/rustc_parse/src/parser/expr.rs | 31 |
1 files changed, 20 insertions, 11 deletions
diff --git a/compiler/rustc_parse/src/parser/expr.rs b/compiler/rustc_parse/src/parser/expr.rs index e60912d85b7..3bd7aaee78e 100644 --- a/compiler/rustc_parse/src/parser/expr.rs +++ b/compiler/rustc_parse/src/parser/expr.rs @@ -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); } |