It used to work in 1.055 now it says

bug.d(6): Error: declaration _D3bug1A6__initZ forward declaration
bug.d(34): Error: template instance bug.Tuple!(_D3bug1A6__initZ) error instantiating
bug.d(38):        instantiated from here: InitsOf!(A)
bug.d(54):        instantiated from here: MinArgs!(func)


//////////////////////////
//////////////////////////
//////////////////////////

struct A {
}

//////////////////////////
//////////////////////////
//////////////////////////

template ParameterTupleOf( Fn )
{
    static if( is( Fn Params == function ) )
        alias Params ParameterTupleOf;
    else static if( is( Fn Params == delegate ) )
        alias ParameterTupleOf!(Params) ParameterTupleOf;
    else static if( is( Fn Params == Params* ) )
        alias ParameterTupleOf!(Params) ParameterTupleOf;
    else
        static assert( false, "Argument has no parameters." );
}

template Tuple( TList... )
{
    alias TList Tuple;
}

template InitsOf(T...) {
	static if(T.length == 0)
		alias Tuple!() InitsOf;
	else
		alias Tuple!(T[0].init, InitsOf!(T[1 .. $])) InitsOf;
}

template MinArgs(alias func) {
	const uint MinArgs = MinArgsImpl!(func, 0, InitsOf!(ParameterTupleOf!(typeof(&func))));
}

private template MinArgsImpl(alias func, int index, Args...) {
	static if(index >= Args.length)
		const uint MinArgsImpl = Args.length;
	else static if(is(typeof(func(Args[0 .. index]))))
		const uint MinArgsImpl = index;
	else
		const uint MinArgsImpl = MinArgsImpl!(func, index + 1, Args);
}	

void func(A) {
}

void main() {
	const a = MinArgs!(func);
}