------- Additional Comments From jakub at gcc dot gnu dot org 2005-03-04 00:29 ------- I'm not sure if it is actually a bug in the compiler that compiles macro.c or in libcpp.c. The code in question is: cpp_token *token = _cpp_temp_token (pfile); token->type = (*paste_flag)->type; token->val.str = (*paste_flag)->val.str; where val is a union of 2 pointers and struct cpp_string that has an uint, 4 bytes of padding and a pointer. The difference between non-working and working libcpp is (as shown e.g. in the assembly below) that the working one for the token->val.str = (*paste_flag)->val.str; assignment copies 16 bytes, i.e. len, 4 bytes of padding and text pointer, while the non-working one copies only 4 bytes of val.str.len and 8 bytes containing the val.str.text pointer, but not the padding.
Not sure why the uninitialized bits in the padding matter though, but apparently they do. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20282
