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From: "luigighiron at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c/114723] New: ICE when checking for type compatibility with
 structure that contains flexible array member
Date: Mon, 15 Apr 2024 15:33:07 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: new
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X-Bugzilla-Product: gcc
X-Bugzilla-Component: c
X-Bugzilla-Version: 14.0
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: normal
X-Bugzilla-Who: luigighiron at gmail dot com
X-Bugzilla-Status: UNCONFIRMED
X-Bugzilla-Resolution: 
X-Bugzilla-Priority: P3
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D114723

            Bug ID: 114723
           Summary: ICE when checking for type compatibility with
                    structure that contains flexible array member
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: luigighiron at gmail dot com
  Target Milestone: ---

The following code causes an internal compiler error on GCC 14:

#include<stdio.h>
struct S{int x,y[1];}*a;
int main(void){
        struct S{int x,y[];};
        puts(_Generic(
                a,
                struct S*:"compatible",
                default:"incompatible"
        ));
}

If I understand the type compatibility rules, these types should be compati=
ble?
The types "int[1]" and "int[]" are compatible and everything else seems to
match exactly. Interestingly, it seems to also crash when checking if the t=
ype
of a is compatible with struct S (instead of struct S*).=