/* Copyright 2002 Free Software Foundation, Inc. Tests correct signedness of operations on bitfields; in particular that integer promotions are done correctly, including the case when casts are present. The C front end was eliding the cast of an unsigned bitfield to unsigned as a no-op, when in fact it forces a conversion to a full-width unsigned int. (At the time of writing, the C++ front end has a different bug; it erroneously promotes the uncast unsigned bitfield to an unsigned int). Source: Neil Booth, 25 Jan 2002, based on PR 3325 (and 3326, which is a different manifestation of the same bug). */ extern void abort (); int main(int argc, char *argv[]) { struct x { signed int i : 7; unsigned int u : 7; } bit; unsigned int u; int i; unsigned int unsigned_result = -13U % 61; int signed_result = -13 % 61; bit.u = 61, u = 61; bit.i = -13, i = -13; if (i % u != unsigned_result) abort (); if (i % (unsigned int) u != unsigned_result) abort (); /* Somewhat counter-intuitively, bit.u is promoted to an int, making the operands and result an int. */ if (i % bit.u != signed_result) abort (); if (bit.i % bit.u != signed_result) abort (); /* But with a cast to unsigned int, the unsigned int is promoted to itself as a no-op, and the operands and result are unsigned. */ if (i % (unsigned int) bit.u != unsigned_result) abort (); if (bit.i % (unsigned int) bit.u != unsigned_result) abort (); return 0; }