Simple std::regex_search() code won't compile with Apple clang++ -std=c++14

Question

Here is the MCVE:

#include 
#include 

std::string s()
{
    return \"test\";
}

int main()
{
    static const std::regex regex(         


        

Answer 1

There was a change going from C++11 to C++14 where std::regex_search is no longer allowed to take a r-value

template< class STraits, class SAlloc,
          class Alloc, class CharT, class Traits >
bool regex_search( const std::basic_string&&,
                   std::match_results<
                       typename std::basic_string::const_iterator, 
                       Alloc>&,
                   const std::basic_regex&,
                   std::regex_constants::match_flag_type flags =
                       std::regex_constants::match_default ) = delete;

This was added as the overload that takes a const std::string&

is prohibited from accepting temporary strings, otherwise this function populates match_results m with string iterators that become invalid immediately.

So you can no longer pass a temporary to std::regex_search as of C++14

To fix your code we would simply store the return from s() into a variable in main and use that to call std::regex_search.

#include 
#include 

std::string s()
{
    return "test";
}

int main()
{
    static const std::regex regex(R"(\w)");
    std::smatch smatch;

    auto search = s();
    if (std::regex_search(search, smatch, regex)) {
        std::cout << smatch[0] << std::endl;
    }

    return 0;
}

Live Example