[Bug c++/84435] New: -Wliteral-suffix warns on a using-directive

[mferoldif at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84435

            Bug ID: 84435
           Summary: -Wliteral-suffix warns on a using-directive
           Product: gcc
           Version: 7.3.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: mferoldif at gmail dot com
  Target Milestone: ---

The following brief snippet wrongly triggers `-Wliteral-suffix`:

    #include <string>
    using std::string_literals::operator""s;

GCC 7.3.0's output:

    <source>:2:37: warning: literal operator suffixes not preceded by '_' are
reserved for future standardization [-Wliteral-suffix]
     using std::string_literals::operator""s;
                                         ^~~