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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.