用于进行gcc测试

				/* { dg-do compile } */				/* { dg-options "-O2 -Wstrict-aliasing -fstrict-aliasing" } */												union U {				  int i;				  float f;				};								float foo () {				  union U u;				  float* f = &u.f;  /* { dg-bogus "unions are holy in GCC" } */				  u.i = 2;				  return *f;				}