Difference between static and inline functions in C++

header.hpp

inline int f() {
    static int x = 0;
    return ++x;
}

static int g() {
    static int x = 0;
    return ++x;
}

main.cpp

#include "header.hpp"
#include <iostream>

void test();

int main() {
    std::cout << "From main:\n";
    std::cout << "f() = " << f() << ", g() = " << g() << '\n';

    std::cout << "From test:\n";
    test();
}

test.cpp

#include "header.hpp"
#include <iostream>

void test() {
    std::cout << "f() = " << f() << ", g() = " << g() << '\n';
}

Output:

From main:
f() = 1, g() = 1
From test:
f() = 2, g() = 1