Hi! The following testcase shows that declaring std::initializer_list<T> with bases can lead to ICEs, right now we were just testing that it is a class template, not a union, and contains one pointer member and one size_t member.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk? 2026-06-09 Jakub Jelinek <[email protected]> PR c++/125647 * class.cc (finish_struct): Reject std::initializer_list template with bases. * g++.dg/cpp0x/initlist134.C: New test. --- gcc/cp/class.cc.jj 2026-06-02 08:15:04.582141780 +0200 +++ gcc/cp/class.cc 2026-06-09 12:09:17.352024884 +0200 @@ -8370,6 +8370,8 @@ finish_struct (tree t, tree attributes) } /* It also cannot be a union. */ ok &= NON_UNION_CLASS_TYPE_P (t); + if (BINFO_N_BASE_BINFOS (TYPE_BINFO (t))) + ok = false; if (!ok) fatal_error (input_location, "definition of %qD does not match " "%<#include <initializer_list>%>", TYPE_NAME (t)); --- gcc/testsuite/g++.dg/cpp0x/initlist134.C.jj 2026-06-09 12:14:39.307861068 +0200 +++ gcc/testsuite/g++.dg/cpp0x/initlist134.C 2026-06-09 12:19:58.905734199 +0200 @@ -0,0 +1,18 @@ +// PR c++/125647 +// { dg-do compile { target c++11 } } + +struct A { int a; }; +namespace std { + template <class T> + class initializer_list : A { T *d; decltype (sizeof 0) s; }; // { dg-error "definition of 'class std::initializer_list<T>' does not match '#include <initializer_list>'" } +} + +void foo (std::initializer_list <int>); + +void +bar () +{ + foo ({ 1, 2, 3 }); +} + +// { dg-prune-output "compilation terminated" } Jakub
