On 6/10/26 2:15 AM, Jakub Jelinek wrote:
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?
OK.
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
