[Bug c/79881] New: -Wc++-compat should warn about sizeof character literals

[max at maxbruckner dot de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79881

            Bug ID: 79881
           Summary: -Wc++-compat should warn about sizeof character
                    literals
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: max at maxbruckner dot de
  Target Milestone: ---

The c++-compat warning should warn about uses of sizeof when used with
character literals, because in C++ sizeof(' ') is the same as sizeof(char)
whereas it is sizeof(int) in C, therefore this is not part of the common subset
between C and C++ and should be warned about.