Template Parameter Deduction

[John Colvin via Digitalmars-d-learn]

On Wednesday, 11 March 2015 at 22:44:12 UTC, Paul D Anderson 
wrote:
> This used to work in D2.065:
>
> given
>
> 1) public T mul(T)(in T x, in T y,
>     Context context = T.context) if (isDecimal!T)
>     // one template parameter for the two input values
>
> and
>
> 2) public T mul(T, U)(in T x, U n, Context context = T.context)
>     if (isDecimal!T && isIntegral!U)
>     // two different template parameters for the two input 
> values
>
> then
>
> 3) dec9 arg1 = dec9("1.20");
>    long arg2 = 3;
>    result = mul(arg1, arg2);
>    // correctly deduced function
>
> But now (D2.066.1) either 1) has to be changed to
>
> 1) public T mul(T, U)(in T x, U y, Context context = T.context)
>     if (isDecimal!T && isDecimal!U)
>     // two identical template parameters for the two input 
> values
>
> or 3) has to be changed to
>
> 3) dec9 arg1 = dec9("1.20");
>    long arg2 = 3;
>    result = mul!(dec9,long)(arg1, arg2);
>    // template parameters have to be made explicit
>
> Is this expecded behavior?
>
> Paul

This works with 2.066.1 and git HEAD

import std.stdio;
void mul(T)(in T x, in T y, long i = T.init)
if (is(T == int))
{
     writeln("same");
}

void mul(T, U)(in T x, U n, long i = T.init)
if (is(T == int) && is(U == ulong))
{
     writeln("different");
}

void main()
{
     mul(1,2);
     mul(1,2UL);
}


Perhaps there is something important in your incomplete example 
that I have missed out.