emplace calls copy constructor.

[philippecp]

The following code doesn't compile with sparse_hash_map but works fine with std::unordered_map;

int main()
{
	using StringPtr = std::unique_ptr<std::string>;
#if 1
	using StringPtrContainer = spp::sparse_hash_map<StringPtr, StringPtr>;
#else
	using StringPtrContainer = unordered_map<StringPtr, StringPtr>;
#endif
	StringPtrContainer c;

	c.emplace(std::piecewise_construct, std::forward_as_tuple(new string{ "key" }), std::forward_as_tuple(new string{ "value" }));
}

[greg7mdp]

I believe that the last version of spp.h fixes the issue. Please let me know if you still have problems.