libcxx/test/utilities/function.objects/func.wrap/func.wrap.func/func.wrap.func.con/nullptr_t_assign.pass.cpp

//===----------------------------------------------------------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

// <functional>

// class function<R(ArgTypes...)>

// function& operator=(nullptr_t);

#include <functional>
#include <new>
#include <cstdlib>
#include <cassert>

int new_called = 0;

void* operator new(std::size_t s) throw(std::bad_alloc)
{
    ++new_called;
    return std::malloc(s);
}

void  operator delete(void* p) throw()
{
    --new_called;
    std::free(p);
}

class A
{
    int data_[10];
public:
    static int count;

    A()
    {
        ++count;
        for (int i = 0; i < 10; ++i)
            data_[i] = i;
    }

    A(const A&) {++count;}

    ~A() {--count;}

    int operator()(int i) const
    {
        for (int j = 0; j < 10; ++j)
            i += data_[j];
        return i;
    }
};

int A::count = 0;

int g(int) {return 0;}

int main()
{
    assert(new_called == 0);
    {
    std::function<int(int)> f = A();
    assert(A::count == 1);
    assert(new_called == 1);
    assert(f.target<A>());
    f = nullptr;
    assert(A::count == 0);
    assert(new_called == 0);
    assert(f.target<A>() == 0);
    }
    {
    std::function<int(int)> f = g;
    assert(new_called == 0);
    assert(f.target<int(*)(int)>());
    assert(f.target<A>() == 0);
    f = nullptr;
    assert(new_called == 0);
    assert(f.target<int(*)(int)>() == 0);
    }
}