[Bug c++/78031] New: Warning when a standard library UDL is brought to scope with a using-declaration

[ville.voutilainen at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78031

            Bug ID: 78031
           Summary: Warning when a standard library UDL is brought to
                    scope with a using-declaration
           Product: gcc
           Version: 7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: ville.voutilainen at gmail dot com
  Target Milestone: ---

#include <string>
#include <iostream>

int main() {
    using std::literals::operator""s;
    std::cout << "hello\n"s;
}

prog.cc: In function 'int main()':
prog.cc:5:34: warning: literal operator suffixes not preceded by '_' are
reserved for future standardization
     using std::literals::operator""s;
                                  ^~~

It's quite odd that gcc warns about code like that.