* c-common.c (c_common_truthvalue_conversion): Generalise warning
for addresses converted to booleans; not just function addresses.
* c-typeck.c (build_binary_op): Warn for address comparisons which
can never be NULL (eg. func == NULL or &var == NULL).
* common.opt (Walways-true): New option.
* c-opts.c (c_common_handle_option): Set it with -Wall.
* doc/invoke.texi: Document it.
testsuite/
* gcc.dg/warn-addr-cmp.c: New test.
git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@108489
138bc75d-0d04-0410-961f-
82ee72b054a4