Can not use target<> to check if two std::function are equal

[czs108]

GleeBug/GleeBug/Debugger.Thread.cpp

Lines 42 to 56 in cd01d22

	void Thread::StepInto(const StepCallback & cbStep)
	{
	StepInto();
	auto target = cbStep.target<void()>();
	for (const auto & cb : stepCallbacks)
	{
	if (target == cb.target<void()>())
	{
	puts("duplicate StepInto callback detected!");
	return;
	}
	}
	stepCallbacks.push_back(cbStep);
	}

I run a test with following code, taget<void()> always return nullptr. So I can't use this to check if two std::function are equal.

#include <vector>
#include <functional>

typedef std::function<void()> StepCallback;

std::vector<StepCallback> stepCallbacks;

void StepInto(const StepCallback& cbStep)
{
	auto target = cbStep.target<void()>();
	for (const auto& cb : stepCallbacks)
	{
                // always get null
		if (target == cb.target<void()>())
		{
			puts("duplicate StepInto callback detected!");
			return;
		}
	}
	stepCallbacks.push_back(cbStep);
}

void fun1() {}

void fun2() {}

int main()
{
	StepInto(fun1);
	StepInto(fun1);
	StepInto(fun2);
	StepInto([]() {});
	StepInto(std::bind([]() {}));
	return 0;
}

output:

duplicate StepInto callback detected!
duplicate StepInto callback detected!
duplicate StepInto callback detected!
duplicate StepInto callback detected!

According to cppreference, the template type of target<> seems very strict. Or there is something wrong with my test?

[mrexodia]

It works correctly. Doing debugger.StepInto doesn’t magically wait until the step finishes, so there are 5 callbacks registered.

…

On Wed, 8 May 2019 at 13:07, Chenzs108 ***@***.***> wrote: https://github.com/x64dbg/GleeBug/blob/cd01d22686028a1d23735a24771aac533390f1e2/GleeBug/Debugger.Thread.cpp#L42-L56 I run a test with following code, taget<void()> always return nullptr. So I can't use this to check if two std::function are equal. #include <vector> #include <functional> typedef std::function<void()> StepCallback; std::vector<StepCallback> stepCallbacks; void StepInto(const StepCallback& cbStep) { auto target = cbStep.target<void()>(); for (const auto& cb : stepCallbacks) { // always get null if (target == cb.target<void()>()) { puts("duplicate StepInto callback detected!"); return; } } stepCallbacks.push_back(cbStep); } void fun1() {} void fun2() {} int main() { StepInto(fun1); StepInto(fun1); StepInto(fun2); StepInto([]() {}); StepInto(std::bind([]() {})); return 0; } output: duplicate StepInto callback detected! duplicate StepInto callback detected! duplicate StepInto callback detected! duplicate StepInto callback detected! According to cppreference <https://en.cppreference.com/w/cpp/utility/functional/function/target>, the template type of target<> seems very strict. Or there is something wrong with my test? — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#49>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AASYFGK2WMIUUXXE4QOWLKDPUKX5ZANCNFSM4HLQWFMA> .

[czs108]

But if target<> always return nullptr, how can if (target == cb.target<void()>()) check if I push_back the same callback function twice? It is if (nullptr == nullptr) actually.

[mrexodia]

Probably when this was written for Visual Studio 2013 the standard wasn't followed and everything was working... If you know some other way to check if two std::functions call the same function it would be appreciated.