Using C++ modules with GCC 12

main.cpp

import <iostream>;

int main() {
    std::cout << "Hello modules\n";
    return 0;
}

Makefile

.POSIX:

CXX = g++
CXXFLAGS = -std=c++20 -fmodules-ts

main: gcm.cache main.cpp
	$(CXX) $(CXXFLAGS) main.cpp -o main

gcm.cache:
	$(CXX) $(CXXFLAGS) -c -x c++-system-header iostream