PR c++/64767
* c.opt (Wpointer-compare): New option.
* c-parser.c (c_parser_postfix_expression): Mark zero character
constants by setting original_type in c_expr.
* c-typeck.c (parser_build_binary_op): Warn when a pointer is compared
with a zero character constant.
(char_type_p): New function.
* typeck.c (cp_build_binary_op): Warn when a pointer is compared with
a zero character literal.
* doc/invoke.texi: Document -Wpointer-compare.
* c-c++-common/Wpointer-compare-1.c: New test.
From-SVN: r244076
