`enzyme::autodiff` compile error when a callable struct is passed

[jeffpollock9]

Hi, if I try the following code:

Enzyme Explorer link

#include <enzyme/enzyme>
#include <cstdio>

struct objective {
  double operator()(double x) { return x * 10;  }
};

int main() {
    // ok
    // auto y = enzyme::autodiff<enzyme::Reverse>(objective{}, enzyme::Active<double>(3.1));

    // not ok
    objective fn;
    auto y = enzyme::autodiff<enzyme::Reverse>(fn, enzyme::Active<double>(3.1));
    
    auto y1 = enzyme::get<0>(enzyme::get<0>(y));
    std::printf("dmul %f\n", y1);
}

It results in a compiler error:

error: 'f' declared as a pointer to a reference of type 'objective &'

I believe this could (hopefully) be fixed by changing to something like:

        template<typename function, typename RT, typename ...T>
        struct templated_call<function, RT(T...)> {
            static RT wrap(std::remove_reference_t<function>* __restrict__ f, T... args) {
                return (*f)(args...);
            }
        };

in this:

Enzyme/enzyme/include/enzyme/utils

Lines 330 to 335 in 1961293

	template<typename function, typename RT, typename ...T>
	struct templated_call<function, RT(T...)> {
	static RT wrap(function* __restrict__ f, T... args) {
	return (*f)(args...);
	}
	};

I guess in the tests only the // ok part of the code is tested, see e.g.

Enzyme/enzyme/test/Integration/ReverseMode/sugar.cpp

Line 92 in 1961293

auto y = enzyme::autodiff<enzyme::Reverse>(overload{}, enzyme::Active<double>(3.1));

I can set up a pull request, or if someone who knows a better fix or is more familiar with the code (I am not really familiar at all) perhaps they could fix accordingly and I would be very happy :)

Thank you.