Cannot declare generic struct with zero type parameters

[mlbrooks]

Wishing for:

forall ( | {void fun();} ) {

    struct thing {};

    void ?{}( thing & this ) {
        fun();
    }
}

void fun() {
    printf("this is fun\n");
}

int main() {
   thing x;
}

That is, the forall is used only to declare an assertion.

Expect: compile succeeds; run prints

this is fun

Actual: compiler error

Too few type arguments in generic type instance of struct thing with body 1

Workaround is to treat the generic type as if it had one type parameter, i.e.

forall ( dtype T | {void fun();} ) {

    struct thing ...

This workaround is

forall ( | {void fun();} ) {

    struct thing {};

    void ?{}( thing(float) & this ) {
        fun();
    }
}

void fun() {
    printf("this is fun\n");
}

int main() {
   thing(float) x;
}

Workaround Expected: compiler error

Too many type arguments in generic type instance of struct thing...

Workaround Actual: compile succeeds; run prints

this is fun