https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126922
--- Comment #6 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Jakub Jelinek <[email protected]>: https://gcc.gnu.org/g:7c459132de478dbede44e323e195073e8d2bca55 commit r17-3784-g7c459132de478dbede44e323e195073e8d2bca55 Author: Jakub Jelinek <[email protected]> Date: Mon Aug 31 09:38:43 2026 +0200 c++: Fix mangling of aggregates containing std::meta::info [PR126922] We ICE during mangling on the following testcase. There are two problems on it. One is the use of build_zero_cst for skipped members when using designated initializers. build_zero_cst is a gcc/tree.cc function, so it doesn't know about META_TYPE and how to create a zero constant for it. We could call probably build_zero_init instead, but it does significantly more work and apparently (from what I've been playing with e.g. using pointer-to-data-member types etc.) it isn't needed except for the reflection case, so this patch just calls get_null_reflection () for reflections and keeps using build_zero_cst for everything else. Another problem is that we mangle A { .a = {}, .b = {} } vs. A { .a = {} } differently, although both have the same value. If a and b fields have pointer-to-data-member type instead (or int), the zero initialized members are skipped from the tl value list, and this patch changes zero_init_expr_p so that it handles null reflections the same way (before P4101 mangling is probably the only way to observe whether null reflection is all zeros or not). 2026-08-31 Jakub Jelinek <[email protected]> PR c++/126922 * mangle.cc (write_expression): For CONSTRUCTOR skipped member of std::meta::info type, call write_expression on get_null_reflection rather than build_zero_cst. * tree.cc (zero_init_expr_p): If type is std::meta::info, return true iff t is null reflection. * g++.dg/reflect/mangle10.C: New test. Reviewed-by: Jason Merrill <[email protected]>
