Re: [PATCH] c++: Reject std::initializer_list with bases [PR125647]

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
>