https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114194
Bug ID: 114194 Summary: ICE when using std::unique_ptr with xtheadvector Product: gcc Version: 14.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: target Assignee: unassigned at gcc dot gnu.org Reporter: camel-cdr at protonmail dot com Target Milestone: --- Using std::unique_ptr with xtheadvector enabled causes an ICE: #include <memory> extern void use(std::unique_ptr<int> &x); void test(size_t n) { std::unique_ptr<int> x; use(x); } See also: https://godbolt.org/z/6nbhxKdfd I've managed to reduce the problem to the following set of templates, but I have no idea how this could cause the ICE. struct S1 { int x; }; struct S2 { constexpr S2() { } template<class T> S2(T&); }; struct S3 : S1, S2 { constexpr S3() : S1() { } S3(S3&); }; void f(S3 &) { S3 x; f(x); } See also: https://godbolt.org/z/5YxM6jd3s It's extremely brittle, the ICE goes away, if you remove constexpr, the reference, or any other part I could think of.