1  /* PR middle-end/84108 - incorrect -Wattributes warning for packed/aligned
       2     conflict on struct members
       3     { dg-do compile }
       4     { dg-options "-Wall -Wattributes" } */
       5  
       6  #define ATTR(list) __attribute__ (list)
       7  #define ASSERT(e) _Static_assert (e, #e)
       8  
       9  /* GCC is inconsistent in how it treats attribute aligned between
      10     variable and member declarations.  Attribute aligned alone is
      11     sufficient to reduce a variable's alignment requirement but
      12     the attribute must be paired with packed to have the same
      13     effect on a member.  Worse, declaring a variable both aligned
      14     and packed emits a warning.  */
      15  
      16  /* Avoid exercising this since emitting a warning for these given
      17     the requirement for members seems like a misfeature:
      18     int a ATTR ((packed, aligned (2)));   // -Wattributes
      19     int b ATTR ((aligned (2), packed));   // -Wattributes
      20     ASSERT (_Alignof (a) == 2);
      21     ASSERT (_Alignof (b) == 2);  */
      22  
      23  int c ATTR ((aligned (2)));           // okay (reduces alignment)
      24  ASSERT (_Alignof (c) == 2);
      25  
      26  struct {
      27    int a ATTR ((packed, aligned (2)));   /* { dg-bogus "\\\[-Wattributes" "" { target { ! default_packed } } } */
      28    /* { dg-warning "attribute ignored" "" { target { default_packed } } .-1 } */
      29    int b ATTR ((aligned (2), packed));   /* { dg-bogus "\\\[-Wattributes" "" { target { ! default_packed } } } */
      30    /* { dg-warning "attribute ignored" "" { target { default_packed } } .-1 } */
      31  
      32    /* Avoid exercising this since the attribute has no effect yet
      33       there is no warning.
      34       int c ATTR ((aligned (2)));           // missing warning?  */
      35  } s;
      36  
      37  ASSERT (_Alignof (s.a) == 2);
      38  ASSERT (_Alignof (s.b) == 2);
      39  
      40  /* ASSERT (_Alignof (s.c) == 4); */