On Saturday, 11 December 2021 at 22:50:45 UTC, apz28 wrote:
void foo2(T)(Unqual!T x) if(isUnsigned!T) {}
This means it treats foo2 as if it doesn't exist unless T is
unsigned...
onlineapp.d(15): Error: template `onlineapp.foo2` cannot deduce
function from argument types `!()(int)`
onlineapp.d(7): Candidate is: `foo2(T)(Unqual!T x)`
*/
And this is telling you it had a signed value - int - which means
it doesn't match.
For the other ones, the functions still exist, so it does
whatever conversion it needs. Whereas with the template that
constraint means the compiler acts like it doesn't exist at all
and thus doesn't even attempt an automatic conversion.
