[Bug c++/50810] c++0x-compat does not warn about narrowing conversions

["manu at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50810

Manuel LÃpez-IbÃÃez <manu at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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                 CC|                            |manu at gcc dot gnu.org

--- Comment #4 from Manuel LÃpez-IbÃÃez <manu at gcc dot gnu.org> 2011-10-22 01:15:14 UTC ---
(In reply to comment #3)
> (detail: not sure about the 'if (!warn_narrowing) return;' at the beginning of
> check_narrowing: probably we don't want -Wno-narrowing to suppress the warnings
> enabled of -Wc++0x-compat)

I think what you want is that -Wc++0x-compat enables -Wnarrowing independently
of -std=, but still -Wc++0x-compat -Wno-narrowing should disable it. See the
handling of Wlonglong in c-opts.c. So:

  if (!ok)
    {
      if (cxx_dialect != cxx98)
        pedwarn (input_location, OPT_Wnarrowing, "narrowing conversion of %qE "
            "from %qT to %qT inside { }", init, ftype, type);
      else
        warning_at (input_location, OPT_Wnarrowing, "narrowing conversion of
%qE "
            "from %qT to %qT inside { }", init, ftype, type);
    }

This approach also allows the user to specify -Wnarrowing to get the warnings
independently of -std=.