[C++17] Recursive variadic template function with if constexpr to print a list of variables of any types to stdout | Equivalent function with fold expression

trace.hpp

#include <iostream>

template<typename First, typename... Rest>
void trace(First&& first, Rest&& ... rest) {
	if constexpr (sizeof...(rest) == 0) {
		std::cout << std::forward<First>(first) << '\n';
	} else {
		std::cout << std::forward<First>(first) << ' ';
		trace(std::forward<Rest>(rest)...);
	}
}

template<typename... Args>
void trace2(Args&& ... args) {
   std::cerr << "Error: ";
   ((std::cerr << args << ' '), ...) << '\n';
   // NOTE: unlike first version, there is an extra comma at the end
}

usage.cpp

#include "trace.hpp"

struct Foo {
	int bar = 0;
	std::string baz = "default";
};

std::ostream& operator<<(std::ostream& ostream, const Foo& foo) {
	return ostream << "Foo: {bar=" << foo.bar << " baz=" << foo.baz << '}';
}

int main() {
	int i = 42;
	double d = 89.6;
	std::string s = "hello, world";
	trace(i);
	trace(d);
	trace(s);

	Foo foo{42, "I ❤ C++17"};
	trace(foo);

	trace(s, i);
	trace(i, d, s);
	trace(i, foo, i, d, s);
}

usage_output.txt

42
89.6
hello, world
Foo: {bar=42 baz=I ❤ C++17}
hello, world 42
42 89.6 hello, world
42 Foo: {bar=42 baz=I ❤ C++17} 42 89.6 hello, world