In DMD 2.058head the compiler accepts a function template as argument for the foo() function:

void foo(int function(int x) g) {}
void main() {
    foo((x) => 0); // OK
}


So I think it should accept an assignment too:

void main() {
    int function(int x) f;
    f = (x) => 0; // Error
}


Currently it gives:
test.d(3): Error: __lambda4 has no value