max() in phobos, and English logic operators

Sean Kelly sean at
Thu Nov 9 09:23:01 PST 2006

David Qualls wrote:
> == Quote from Bill Baxter (dnewsgroup at's article
>> But my point was just that the extra information is not
> necessary for
>> the macro version.  The intended meaning of max(x,0) is clear
> enough to
>> the reader, so the compiler should be able to handle it without
>> complaining, too.
>> --bb
> EXACTLY!  I also think you (mostly) nailed it with
>> About signed types, I think
>>     auto c = max(a,b)
>> should pick the same type for c that the compiler would pick for
>>     auto c = a+b;
> except I don't think max(10U , -1) should return -1 cast to an
> unsigned!

The addition promotion rules for integers are essentially as follows:

int + uint = uint
uint + long = long
(anything smaller than int) + (anything smaller than int) = int

It would be easy enough to simply use typeof(T.init + U.init) for 
concrete types and throw out a bunch of static ifs, but I'm not sure if 
integer promotion is desired here.  Suggestions?


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