I have created a simple program using two C++ threads:
```
#include <iostream>
#include <mutex>
#include <thread>

int num = 0;
std::mutex mut{};

void func() {
	for (int i = 0; i < 10000; ++i) {
		std::lock_guard lock(mut)
		++num;
	}
}

int main() {
	std::thread thread1 = std::thread(func);
	std::thread thread2 = std::thread(func);

	thread2.join();
	thread1.join();

	printf("%d\n", num);

	return 0;
}
```

Compiling this with `g++13 -static -O3 -pthread main.cpp` and running `./a.out` generates a core dump: 
```
zsh: abort (core dumped)  ./a.out
```

I've tried linking with `-lthr` and `-static-libstdc++` and `-static-libgcc` but those should be implied by `g++ -static` anyways.

I'm working on a project where this issue occures aswell when using the pthread.h header instead of C++ threads.

Clang's static and dynammic output works as expected as well as gcc's dynamic executable.