00218.c (1388B)
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 }