Template function type inference with default arguments

[ixid via Digitalmars-d-learn]

Why don't templates take a type from the default argument if 
nothing else is supplied? It would be useful to be able to use an 
enum to set a default.

enum MAX = 1_000;
auto sieve(T)(T max = MAX) {
        import std.bitmanip : BitArray;
        BitArray n;
        n.length = max;
        T[] primes = [2];

        for(T i = 3; i < max; i += 2)
                if(n[i] == 0) {
                        primes ~= i;
                        for(T j = i + i; j < max; j += i)
                                n[j] = 1;
                }

        return primes;
}

Changing the type to T = typeof(MAX) works but feels 
unnecessarily clunky and out of step with how templates normally 
operate when supplied with an argument.