https://gcc.gnu.org/g:3058891d5c6f114d86a9a8c87fd52f202decff53
commit r16-8880-g3058891d5c6f114d86a9a8c87fd52f202decff53 Author: Marek Polacek <[email protected]> Date: Tue Apr 21 15:54:33 2026 -0400 c++/reflection: odr-used inline var of consteval-only type [PR124770] wrapup_namespace_globals gives errors for code like extern inline int i; int &r = i; // odr-used inline variable is not defined but because we mark consteval-only vars DECL_EXTERNAL, we also wrongly emit the error for: inline constexpr info value{}; static_assert(value == info{}); where value clearly is defined. This patch strenghtens the check to also check !DECL_INITIAL. We can't only check DECL_THIS_EXTERN because extern constexpr inline info v2{}; is OK. PR c++/124770 gcc/cp/ChangeLog: * decl.cc (wrapup_namespace_globals): Give the odr-used inline variable error only when !DECL_INITIAL. gcc/testsuite/ChangeLog: * g++.dg/reflect/init18.C: New test. Reviewed-by: Jason Merrill <[email protected]> (cherry picked from commit 6d035aa99c3d1197167e085302d8ce015b950b35) Diff: --- gcc/cp/decl.cc | 4 ++++ gcc/testsuite/g++.dg/reflect/init18.C | 14 ++++++++++++++ 2 files changed, 18 insertions(+) diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc index 679a8007ca6f..9924c0fc1725 100644 --- a/gcc/cp/decl.cc +++ b/gcc/cp/decl.cc @@ -1023,6 +1023,10 @@ wrapup_namespace_globals () if (VAR_P (decl) && DECL_EXTERNAL (decl) + /* We mark consteval-only variables DECL_EXTERNAL, but + extern constexpr inline std::meta::info i{}; + is a definition (the extern is redundant). */ + && !DECL_INITIAL (decl) && DECL_INLINE_VAR_P (decl) && DECL_ODR_USED (decl)) error_at (DECL_SOURCE_LOCATION (decl), diff --git a/gcc/testsuite/g++.dg/reflect/init18.C b/gcc/testsuite/g++.dg/reflect/init18.C new file mode 100644 index 000000000000..f13125be66e8 --- /dev/null +++ b/gcc/testsuite/g++.dg/reflect/init18.C @@ -0,0 +1,14 @@ +// PR c++/124770 +// { dg-do compile { target c++26 } } +// { dg-additional-options "-freflection" } + +using info = decltype(^^::); + +constexpr inline info v{}; +static_assert(v == info{}); +extern constexpr inline info v2{}; +static_assert(v2 == info{}); +constexpr inline info v3; +static_assert(v3 == info{}); + +extern constexpr inline info v4; // { dg-error "not a definition|consteval-only" }
