1/* Copyright 2002 Free Software Foundation, Inc. 2 3 Tests correct signedness of operations on bitfields; in particular 4 that integer promotions are done correctly, including the case when 5 casts are present. 6 7 The C front end was eliding the cast of an unsigned bitfield to 8 unsigned as a no-op, when in fact it forces a conversion to a 9 full-width unsigned int. (At the time of writing, the C++ front end 10 has a different bug; it erroneously promotes the uncast unsigned 11 bitfield to an unsigned int). 12 13 Source: Neil Booth, 25 Jan 2002, based on PR 3325 (and 3326, which 14 is a different manifestation of the same bug). 15*/ 16 17extern void abort (); 18 19int 20main(int argc, char *argv[]) 21{ 22 struct x { signed int i : 7; unsigned int u : 7; } bit; 23 24 unsigned int u; 25 int i; 26 unsigned int unsigned_result = -13U % 61; 27 int signed_result = -13 % 61; 28 29 bit.u = 61, u = 61; 30 bit.i = -13, i = -13; 31 32 if (i % u != unsigned_result) 33 abort (); 34 if (i % (unsigned int) u != unsigned_result) 35 abort (); 36 37 /* Somewhat counter-intuitively, bit.u is promoted to an int, making 38 the operands and result an int. */ 39 if (i % bit.u != signed_result) 40 abort (); 41 42 if (bit.i % bit.u != signed_result) 43 abort (); 44 45 /* But with a cast to unsigned int, the unsigned int is promoted to 46 itself as a no-op, and the operands and result are unsigned. */ 47 if (i % (unsigned int) bit.u != unsigned_result) 48 abort (); 49 50 if (bit.i % (unsigned int) bit.u != unsigned_result) 51 abort (); 52 53 return 0; 54} 55