gcc struct/classes

gistfile1.txt

[davide@localhost bin]$ g++ blah.cpp -o blah
blah.cpp: In function ‘int main()’:
blah.cpp:10:9: error: ‘union’ tag used in naming ‘struct G<int>’ [-fpermissive]
   union G<int> foo;
         ^
blah.cpp:4:7: note: ‘struct G<int>’ was previously declared here
 class G {
       ^
[davide@localhost bin]$ cat blah.cpp
#include <stdio.h>

template <typename T>
class G {
public:
 G<T>() { puts("blah"); }
};

int main() {
  union G<int> foo;
  return (0);
}
[davide@localhost bin]$ g++ --version
g++ (GCC) 5.3.1 20151207 (Red Hat 5.3.1-2)
Copyright (C) 2015 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.