https://gcc.gnu.org/g:94010a2af914ade3cfd791ac72c25df79efe299b
commit r16-6334-g94010a2af914ade3cfd791ac72c25df79efe299b Author: Yuao Ma <[email protected]> Date: Tue Dec 23 00:40:54 2025 +0800 c++: fix function body cloning when using implicit constexpr When using implicit constexpr, we should not discard the function body, as it can result in ICE during constant evaluation. PR c++/123261 gcc/cp/ChangeLog: * semantics.cc (expand_or_defer_fn_1): Use maybe_constexpr_fn. gcc/testsuite/ChangeLog: * g++.dg/ext/fimplicit-constexpr2.C: New test. Diff: --- gcc/cp/semantics.cc | 2 +- gcc/testsuite/g++.dg/ext/fimplicit-constexpr2.C | 18 ++++++++++++++++++ 2 files changed, 19 insertions(+), 1 deletion(-) diff --git a/gcc/cp/semantics.cc b/gcc/cp/semantics.cc index a2d655a60c1d..e598632d85bc 100644 --- a/gcc/cp/semantics.cc +++ b/gcc/cp/semantics.cc @@ -5578,7 +5578,7 @@ expand_or_defer_fn_1 (tree fn) the maybe-in-charge cdtor and regenerate the clones from it on demand, so we also need to keep the body. Otherwise we don't need it anymore. */ - if (!DECL_DECLARED_CONSTEXPR_P (fn) + if (!maybe_constexpr_fn (fn) && !(module_maybe_has_cmi_p () && vague_linkage_p (fn))) DECL_SAVED_TREE (fn) = void_node; return false; diff --git a/gcc/testsuite/g++.dg/ext/fimplicit-constexpr2.C b/gcc/testsuite/g++.dg/ext/fimplicit-constexpr2.C new file mode 100644 index 000000000000..f72323ee8312 --- /dev/null +++ b/gcc/testsuite/g++.dg/ext/fimplicit-constexpr2.C @@ -0,0 +1,18 @@ +// { dg-additional-options -fimplicit-constexpr } +// { dg-do compile { target c++23 } } + +class A +{ +public: + A () { asm volatile (""); } // { dg-error {inline assembly is not a constant expression} } + ~A () {} +}; + +constexpr bool +test () +{ + A a; // { dg-error {'A::A\(\)' called in a constant expression} } + return true; +} + +static_assert (test ()); // { dg-error {non-constant condition for static assertion} }
