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

This not a bug, but expected behaviour. The reason is that s() returns a temporary string, regex_search makes use of regex_match and consequently if a temporary string was utilized match results would contain iterators to a string that no longer exists. This would have been undefined behaviour. Thus, the committee abolished this regex_search overload in C++14.

You can also confirm in the standard 28.4 Header synopsis [re.syn]:

template 
bool regex_search(const basic_string&&,
match_results<
typename basic_string::const_iterator,
Allocator>&,
const basic_regex&,
regex_constants::match_flag_type =
regex_constants::match_default) = delete;

As you can see the overload that takes a rvalue to a basic_string is marked deleted.