c++17

I have a vector of vectors, and I want to check if all of them are empty. Using the standard library, I tried: #include <algorithm> #include <vector> int main() { std::vector<std::vector<int>> vv; std::all_of(std::begin(vv), std::end(vv), std::empty); } This result in the following error in clang 7.0: /usr/bin/../lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/c++/6.3.0/bits/stl_algo.h:508:5: note: candidate template ignored: couldn't infer template argument '_Predicate' I guess it's a standard behavior, due to the rules of type deduction. But anyway, what i the easiest way to workaround

Consider the following code: #include <iostream> struct Thing { Thing(void) {std::cout << __PRETTY_FUNCTION__ << std::endl;} Thing(Thing const &) = delete; Thing(Thing &&) = delete; Thing & operator =(Thing const &) = delete; Thing & operator =(Thing &&) = delete; }; int main() { Thing thing{Thing{}}; } I expect Thing thing{Thing{}}; statement to mean construction of temporary object of Thing class using default constructor and construction of thing object of Thing class using move constructor with just created temporary object as an argument. And I expect that this program to be considered

Trying to provide a solution to std::string_view and std::string in std::unordered_set , I'm playing around with replacing std::unordered_set<std::string> with std::unordered_map<std::string_view, std::unique_ptr<std::string>> (the value is std::unique_ptr<std::string> because the small string optimization would mean that the address of the string 's underlying data will not always be transferred as a result of std::move . My original test code, that seems to work, is (omitting headers): using namespace std::literals; int main(int argc, char **argv) { std::unordered_map<std::string_view, std: