[Bug c/124305] btf_decl_tag and btf_type_tag attributes give compiler errors in C++ and with -Wwrite-strings in C

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=124305

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |easyhack

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
```
  /* Only narrow character strings are accepted.  */
  tree argtype = TREE_TYPE (TREE_TYPE (TREE_VALUE (args)));
  if (!(argtype == char_type_node
        || argtype == char8_type_node
        || argtype == signed_char_type_node
        || argtype == unsigned_char_type_node))
    {
      error ("unsupported wide string type argument in %qE attribute", name);
      return false;
    }
```

That is argtype should be `argtype = TYPE_MAIN_VARIANT (argtype);` before the
check.