This D2 program compiles with no errors:

void delegate()[1] foo;
void main() {
    int n;
    foo[0] = { n++; };
}


But this one:

void delegate()[1] foo;
void main() {
    int n;
    foo[] = [{ n++; }];
}


With DMD 2.051:

test.d(4): Error: cannot implicitly convert expression ([delegate void()

{

n++;

}

]) of type void delegate()[] to const(void delegate()[])


It looks like a front-end bug.