------- Comment #2 from amodra at gmail dot com 2010-05-26 13:22 ------- I think this testcase may invoke undefined behaviour. Section 6.5.2.2 of the ISO C spec says of function calls without a prototype that if "the types of the arguments after promotion are not compatible with those of the parameters after promotion, the behavior is undefined, except for the following cases" and the relevant case is "one promoted type is a signed integer type, the other promoted type is the corresponding unsigned integer type, and the value is representable in both types".
The value you are passing, (int)4294967259U, is a negative number so not representable as an unsigned int. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43249
