On Sun, Feb 08, 2026 at 06:52:26AM +0100, Jakub Jelinek wrote: > But sure, I can move the build_self_reference (); call to right > after TYPE_BEING_DEFINED (type) = 1; and in that case change > tree fields = NULL_TREE; to tree fields = TYPE_FIELDS (type); > too if you prefer. And in that case maybe also remove the > gcc_assert (!TYPE_FIELDS (type)).
Though, it clearly is cheaper to do it first when TYPE_FIELDS is NULL and so chainon doesn't have to walk all the FIELD_DECLs in the list. So I'm testing: 2026-02-08 Jakub Jelinek <[email protected]> PR c++/123984 * reflect.cc (eval_define_aggregate): Set TYPE_BEING_DEFINED on type after pushclass, call build_self_reference, remove assertion that TYPE_FIELDS (type) is NULL and instead set fields to TYPE_FIELDS (type). * g++.dg/reflect/define_aggregate6.C: New test. --- gcc/cp/reflect.cc.jj 2026-02-06 11:18:47.088640019 +0100 +++ gcc/cp/reflect.cc 2026-02-08 21:08:01.359261427 +0100 @@ -6080,8 +6080,9 @@ eval_define_aggregate (location_t loc, c if (!TYPE_BINFO (type)) xref_basetypes (type, NULL_TREE); pushclass (type); - gcc_assert (!TYPE_FIELDS (type)); - tree fields = NULL_TREE; + TYPE_BEING_DEFINED (type) = 1; + build_self_reference (); + tree fields = TYPE_FIELDS (type); for (int i = 0; i < TREE_VEC_LENGTH (rvec); ++i) { tree ra = TREE_VEC_ELT (rvec, i); --- gcc/testsuite/g++.dg/reflect/define_aggregate6.C.jj 2026-02-05 17:42:07.498427315 +0100 +++ gcc/testsuite/g++.dg/reflect/define_aggregate6.C 2026-02-05 17:41:55.461630714 +0100 @@ -0,0 +1,22 @@ +// PR c++/123984 +// { dg-do compile { target c++26 } } +// { dg-additional-options "-freflection" } + +#include <meta> + +struct A; +consteval +{ + define_aggregate (^^A, { data_member_spec (^^int, {.name{"_"}}) }); +} + +struct B : A {}; + +constexpr int +get (B &&d) +{ + constexpr auto ctx = std::meta::access_context::unchecked (); + return static_cast <A*> (&d)->[: nonstatic_data_members_of (^^A, ctx)[0] :]; +} + +static_assert (get (B { 123 }) == 123); Jakub
