From f68bcb376da2a34b6809ba76dad20ca400bd9966 Mon Sep 17 00:00:00 2001 From: Josh Stone Date: Thu, 14 Aug 2025 16:02:31 -0700 Subject: [PATCH] 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/rust#74708, which was also an `ensure_sufficient_stack` in this area of code at the time. However, the refactor in rust-lang/rust#92573 basically left that to the general `MutVisitor`, and then rust-lang/rust#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. --- compiler/rustc_expand/src/expand.rs | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/compiler/rustc_expand/src/expand.rs b/compiler/rustc_expand/src/expand.rs index 670f5c91bb93a..4cacc0bf4781a 100644 --- a/compiler/rustc_expand/src/expand.rs +++ b/compiler/rustc_expand/src/expand.rs @@ -14,6 +14,7 @@ use rustc_ast::{ use rustc_ast_pretty::pprust; use rustc_attr_parsing::{EvalConfigResult, ShouldEmit}; use rustc_data_structures::flat_map_in_place::FlatMapInPlace; +use rustc_data_structures::stack::ensure_sufficient_stack; use rustc_errors::PResult; use rustc_feature::Features; use rustc_parse::parser::{ @@ -2437,7 +2438,7 @@ impl<'a, 'b> MutVisitor for InvocationCollector<'a, 'b> { if let Some(attr) = node.attrs.first() { self.cfg().maybe_emit_expr_attr_err(attr); } - self.visit_node(node) + ensure_sufficient_stack(|| self.visit_node(node)) } fn visit_method_receiver_expr(&mut self, node: &mut ast::Expr) {