It's about whether you can put stack allocated VLAs into temporary structs: keno@anubis:~$ cat test2.c void bar(int *); int foo(int n) { struct

It's about whether you can put stack allocated VLAs into temporary structs: keno@anubis:~$ cat test2.c void bar(int *); int foo(int n) { struct { int non_terminal_val[n]; int some_other_member; } val; bar(val.non_terminal_val); return val.some_other_member; } keno@anubis:~$ gcc -c test2.c keno@anubis:~$ clang test2.c test2.c:4:13: error: fields must have a constant size: 'variable length array in structure' extension will never be supported int non_terminal_val[n]; ^ 1 error generated.