https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69425
Bug ID: 69425
Summary: __atomic_load should diagnose const output parameter
Product: gcc
Version: 6.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: eric at efcs dot ca
Target Milestone: ---
The __atomic_load builtin takes a pointer to an output parameter. Obviously the
output parameter cannot point to a const object. Unfortunatly GCC doesn't
diagnose this case at compile time and this makes it much harder for users to
find their bug.
The reproducer is contrived, but I ran into this while writing generic code.
#include <assert.h>
int main() {
const int source = 4;
const int dest = 0;
__atomic_load(&source, &dest, __ATOMIC_RELAXED); // Should emit
-Wdiscards-qualifiers
assert(dest == 4); // FAILS! 'dest' is still 0.
}
