Is it legal to pass a non-capturing lambda as a non-type template parameter to a function? Works in clang, not in gcc

In the code below, on the first form, gcc complains about having a lambda in a template parameter. In the second form, gcc complains about lambda_function_pointer not having external linkage. Clang compiles and runs the code just fine.

The + in front of the lambda is to coerce it to decay into a function pointer.

template<auto f>
void func() {
    f();
}
void g();
int main() {
    func<+[](){}>();  // gcc complains about lambda in template args

    constexpr auto lambda_function_pointer = +[](){};
    func<lambda_function_pointer>(); // gcc complains about not having external linkage

}

live: https://godbolt.org/g/VgYjCk

Any answers as to whether this should work or not as well as any workarounds are appreciated.

Thank you.