modernc.org/cc@v1.0.1/testdata/gcc-6.3.0/gcc/testsuite/gcc.c-torture/compile/20020709-1.c (about)

     1  extern double atof (__const char *__nptr) __attribute__ ((__pure__));
     2  
     3  void bar (char *s)
     4  {
     5    union {double val; unsigned int a, b;} u;
     6    u.val = atof (s);
     7  }