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rustc_expand: ensure stack in InvocationCollector::visit_expr
In Fedora, when we built rustc with PGO on ppc64le, we started failing the test `issue-74564-if-expr-stack-overflow.rs`. This could also be reproduced on other arches by setting a smaller `RUST_MIN_STACK`, so it's probably just unlucky that ppc64le PGO created a large stack frame somewhere in this recursion path. Adding an `ensure_sufficient_stack` solves the stack overflow. Historically, that test and its fix were added in rust-lang#74708, which was also an `ensure_sufficient_stack` in this area of code at the time. However, the refactor in rust-lang#92573 basically left that to the general `MutVisitor`, and then rust-lang#142240 removed even that ensure call. It may be luck that our tier-1 tested targets did not regress the original issue across those refactors.
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compiler/rustc_expand/src/expand.rs

Lines changed: 2 additions & 1 deletion
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@@ -14,6 +14,7 @@ use rustc_ast::{
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use rustc_ast_pretty::pprust;
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use rustc_attr_parsing::{EvalConfigResult, ShouldEmit};
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use rustc_data_structures::flat_map_in_place::FlatMapInPlace;
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use rustc_data_structures::stack::ensure_sufficient_stack;
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use rustc_errors::PResult;
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use rustc_feature::Features;
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use rustc_parse::parser::{
@@ -2437,7 +2438,7 @@ impl<'a, 'b> MutVisitor for InvocationCollector<'a, 'b> {
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if let Some(attr) = node.attrs.first() {
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self.cfg().maybe_emit_expr_attr_err(attr);
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}
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self.visit_node(node)
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ensure_sufficient_stack(|| self.visit_node(node))
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}
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fn visit_method_receiver_expr(&mut self, node: &mut ast::Expr) {

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