On Sunday, 31 October 2021 at 05:04:33 UTC, Dom DiSc wrote:
On Friday, 29 October 2021 at 14:20:09 UTC, Ali Çehreli wrote:
Unsigned!T abs(T)(const(T) x) if(isIntegral!T)
{
static if(isSigned!T) if(x < 0) return cast(Unsigned!T)-x;
return x;
}
void main() {
int a = -5;
int b = -4;
writeln(a + abs(b)); // -5 + 4 == -1? (No!)
}
The program prints uint.max.
This should be no surprise. You need to know what the resulting
type of int + uint should be. And it is ...... uint! which is
one of the stupit integer-promotion rules inherited from C.
Then let's change the example to:
int b = -4;
writeln(-abs(b));
What would one normally expect to be printed here? Should the
unary minus operator also do some kind of implicit "unsigned ->
signed" type change magic to accommodate this modified version of
the abs function and make it behave in a non-surprising way?
