dmd can't infer type even when type is given

Question

Here I want to lockstep iterate over two arrays of size_t

import std.stdio;
import std.range;
import std.exception;
import std.conv;

struct zip(R,Q)
if(isInputRange!(R) && isInputRange!(Q))
{
    R r;
    Q q;
    @property
    const auto front() {
        return tuple(r.front, q.front);
    }
    void popFront() {
        r.popFront();
        q.popFront();
    }
    @property
    const bool empty() {
        bool re = r.empty;
        enforce(re == q.empty);
        return re;
    }
}

void main() {
    size_t[] a = [0,1,2,3,4,5];
    size_t[] b = [2,3,4,5,6,7];
    foreach(size_t i, size_t j; zip!(size_t[],size_t[])(a,b)) {
        writeln(to!string(i) ~ " " ~ to!string(j));
    }
}

But this fails to compile with

src/Interpreter.d(30): Error: cannot infer argument types

However when I change the foreach line to use uint instead of size_t (I'm on a 32-bit laptop)

foreach(uint i, uint j; zip!(size_t[],size_t[])(a,b)) {

It compiles and runs just fine. What's going on?

Answer 1

It might be a bug. In v2.065.0 it doesn't work, but it does work in the latest git-head development version.