| /* 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; |
| } |