Fixed

SharedPtrCallsDestructorTwice.cpp

/* This crashes for me (line 19) */
#include <iostream>
#include <vector>
#include <thread>
#include <memory>
#include <chrono>
#include <mutex>
#include <assert.h>

struct mystruct_t {
	int32_t nInvocation = 0;
	~mystruct_t();
	mystruct_t() = default;
};
mystruct_t::~mystruct_t() {
	nInvocation++;
	int nInvoke = nInvocation;
	if (nInvoke > 1) {
		/* destructor was invoked twice */
		assert(0);
	}
	/* sleep is not necessary for crash */
	//std::this_thread::sleep_for(std::chrono::microseconds(525));
}
std::recursive_mutex mutex;
std::shared_ptr<mystruct_t> globalPtr;
void thread1() {
	for (;;) {
		std::this_thread::sleep_for(std::chrono::microseconds(1000));
		std::shared_ptr<mystruct_t> ptrNewInstance = std::make_shared<mystruct_t>();
		{
			std::lock_guard<std::recursive_mutex> lock(mutex);
			globalPtr = ptrNewInstance;
		}
	}
}
void thread2() {
	for (;;) {
		std::shared_ptr<mystruct_t> pointerCopy;
		{
			std::lock_guard<std::recursive_mutex> lock(mutex);
			pointerCopy = globalPtr;
		}
	}
}
int main()
{
	std::thread t1;
	t1 = std::thread([]() {
		thread1();
		});
	std::thread t2;
	t2 = std::thread([]() {
		thread2();
		});
	for (int i = 0;; ++i) {
		std::this_thread::sleep_for(std::chrono::microseconds(1000));
		std::shared_ptr<mystruct_t> pointerCopy;
		{
			std::lock_guard<std::recursive_mutex> lock(mutex);
			pointerCopy = globalPtr;
			globalPtr = nullptr;
		}
	}
	return 0;
}