On 2/5/2018 12:45 PM, H. S. Teoh wrote:
Sticking to C promotion rules is one of the scourges that continue to
plague D;
It's necessary. Working C expressions cannot be converted to D while introducing
subtle changes in behavior.
another example is char -> byte confusion no thanks to C
traditions:
int f(dchar ch) { return 1; }
int f(byte i) { return 2; }
void main() {
pragma(msg, f('a'));
pragma(msg, f(1));
}
Exercise for reader: guess compiler output.
'a' and 1 do not match dchar or byte exactly, and require implicit conversions.
D doesn't have the C++ notion of "better" implicit conversions for function
arguments, instead it uses the "leastAsSpecialized" C++ notion used for template
matching, which is better.
The idea is a byte can be implicitly converted to a dchar, but not the other way
around. Hence, f(byte) is selected as being the "most specialized" match.
