1  /* Test of <stddef.h> substitute.
       2     Copyright (C) 2009-2023 Free Software Foundation, Inc.
       3  
       4     This program is free software: you can redistribute it and/or modify
       5     it under the terms of the GNU General Public License as published by
       6     the Free Software Foundation, either version 3 of the License, or
       7     (at your option) any later version.
       8  
       9     This program is distributed in the hope that it will be useful,
      10     but WITHOUT ANY WARRANTY; without even the implied warranty of
      11     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      12     GNU General Public License for more details.
      13  
      14     You should have received a copy of the GNU General Public License
      15     along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
      16  
      17  /* Written by Eric Blake <ebb9@byu.net>, 2009.  */
      18  
      19  #include <config.h>
      20  
      21  #include <stddef.h>
      22  
      23  /* Check that appropriate types are defined.  */
      24  wchar_t a = 'c';
      25  ptrdiff_t b = 1;
      26  size_t c = 2;
      27  max_align_t mat;
      28  
      29  /* Check that NULL can be passed through varargs as a pointer type,
      30     per POSIX 2008.  */
      31  static_assert (sizeof NULL == sizeof (void *));
      32  
      33  /* Check that offsetof produces integer constants with correct type.  */
      34  struct d
      35  {
      36    char e;
      37    char f;
      38  };
      39  /* Solaris 10 has a bug where offsetof is under-parenthesized, and
      40     cannot be used as an arbitrary expression.  However, since it is
      41     unlikely to bite real code, we ignore that short-coming.  */
      42  /* static_assert (sizeof offsetof (struct d, e) == sizeof (size_t)); */
      43  static_assert (sizeof (offsetof (struct d, e)) == sizeof (size_t));
      44  static_assert (offsetof (struct d, f) == 1);
      45  
      46  /* Check max_align_t's alignment.  */
      47  static_assert (alignof (double) <= alignof (max_align_t));
      48  static_assert (alignof (int) <= alignof (max_align_t));
      49  static_assert (alignof (long double) <= alignof (max_align_t));
      50  static_assert (alignof (long int) <= alignof (max_align_t));
      51  static_assert (alignof (ptrdiff_t) <= alignof (max_align_t));
      52  static_assert (alignof (size_t) <= alignof (max_align_t));
      53  static_assert (alignof (wchar_t) <= alignof (max_align_t));
      54  static_assert (alignof (struct d) <= alignof (max_align_t));
      55  #if defined __GNUC__ || defined __clang__ || defined __IBM__ALIGNOF__
      56  static_assert (__alignof__ (double) <= __alignof__ (max_align_t));
      57  static_assert (__alignof__ (int) <= __alignof__ (max_align_t));
      58  static_assert (__alignof__ (long double) <= __alignof__ (max_align_t));
      59  static_assert (__alignof__ (long int) <= __alignof__ (max_align_t));
      60  static_assert (__alignof__ (ptrdiff_t) <= __alignof__ (max_align_t));
      61  static_assert (__alignof__ (size_t) <= __alignof__ (max_align_t));
      62  static_assert (__alignof__ (wchar_t) <= __alignof__ (max_align_t));
      63  static_assert (__alignof__ (struct d) <= __alignof__ (max_align_t));
      64  #endif
      65  
      66  int test_unreachable_optimization (int x);
      67  _Noreturn void test_unreachable_noreturn (void);
      68  
      69  int
      70  test_unreachable_optimization (int x)
      71  {
      72    /* Check that the compiler uses 'unreachable' for optimization.
      73       This function, when compiled with optimization, should have code
      74       equivalent to
      75         return x + 3;
      76       Use 'objdump --disassemble test-stddef.o' to verify this.  */
      77    if (x < 4)
      78      unreachable ();
      79    return (x > 1 ? x + 3 : 2 * x + 10);
      80  }
      81  
      82  _Noreturn void
      83  test_unreachable_noreturn (void)
      84  {
      85    /* Check that the compiler's data-flow analysis recognizes 'unreachable ()'.
      86       This function should not elicit a warning.  */
      87    unreachable ();
      88  }
      89  
      90  #include <limits.h> /* INT_MAX */
      91  
      92  /* offsetof promotes to an unsigned integer if and only if sizes do
      93     not fit in int.  */
      94  static_assert ((offsetof (struct d, e) < -1) == (INT_MAX < (size_t) -1));
      95  
      96  int
      97  main (void)
      98  {
      99    return 0;
     100  }