tests/tests2/92_enum_bitfield.c

   1 /* This checks if enums needing 8 bit but only having positive
   2    values are correctly zero extended (instead of sign extended)
   3    when stored into/loaded from a 8 bit bit-field of enum type (which
   4    itself is implementation defined, so isn't necessarily supported by all
   5    other compilers).  */
   6 enum tree_code {
   7   SOME_CODE = 148, /* has bit 7 set, and hence all further enum values as well */
   8   LAST_AND_UNUSED_TREE_CODE
   9 };
  10 typedef union tree_node *tree;
  11 struct tree_common
  12 {
  13   union tree_node *chain;
  14   union tree_node *type;
  15   enum tree_code code : 8;
  16   unsigned side_effects_flag : 1;
  17 };
  18 union tree_node
  19 {
  20   struct tree_common common;
  21  };
  22 enum c_tree_code {
  23   C_DUMMY_TREE_CODE = LAST_AND_UNUSED_TREE_CODE,
  24   STMT_EXPR,
  25   LAST_C_TREE_CODE
  26 };
  27 enum cplus_tree_code {
  28   CP_DUMMY_TREE_CODE = LAST_C_TREE_CODE,
  29   AMBIG_CONV,
  30   LAST_CPLUS_TREE_CODE
  31 };
  32
  33 extern int printf(const char *, ...);
  34 int blah(){return 0;}
  35
  36 int convert_like_real (tree convs)
  37 {
  38   switch (((enum tree_code) (convs)->common.code))
  39     {
  40     case AMBIG_CONV: /* This has bit 7 set, which must not be the sign
  41                         bit in tree_common.code, i.e. the bitfield must
  42                         be somehow marked unsigned.  */
  43       return blah();
  44     default:
  45       break;
  46     };
  47    printf("unsigned enum bit-fields broken\n");
  48 }
  49
  50 int main()
  51 {
  52   union tree_node convs;
  53
  54   convs.common.code = AMBIG_CONV;
  55   convert_like_real (&convs);
  56   return 0;
  57 }