Waddress: warn about suspicious uses of memory addresses.

["Manuel López-Ibáñez" <lopezibanez at gmail dot com>]

This patch proposes a new option -Waddress to warn about suspicious
uses of memory addresses. A follow-up patch will add again
-Walways-true but this time actually warning for what its description
says it should warn.

This new option replaces 3 warnings: -Walways-true,
-Wstring-literal-comparison and an unconditional warning for a bare
reference to a function used in void context.

Replacing -Walways-true will prevent future confusion between the
original intent of -Walways-true and its name and description. This
has been explained in detail elsewhere [1].  The current mismatch is
leading to a situation similar to Wconversion, where the original
intent of the option is conflicting with the perceived meaning, but
worse in this case, since the perceived meaning is sanctioned by the
manual page but not by the implementation.

Even GCC developers are being confused by the current situation [2]. I
think we should fix this before a version of GCC with the current
-Walways-true is publicly released.

Also, there are other warnings that would be more suitable for
-Walways-true but they won't be for -Waddress [3]. This patch 'frees'
-Walways-true so it can be used for those warnings. Once this patch is
approved I will submit a follow-up for the new -Walways-true.

As for replacing -Wstrong-literal-comparison, its purpose matches
-Waddress and since it is a stated goal to avoid multiplication of
options as much as possible, I think it makes sense to integrate it
(and the name is shorter and nicer). But this is a secondary goal,
fixing -Walways-true is more important.

Lastly, the unconditional warning matched the original intent of
-Walways-true, however it didn't match its description. It matches
-Waddress, though.

Boostrapped and regression tested on i686-pc-linux-gnu.

[1] http://gcc.gnu.org/ml/gcc/2007-01/msg00480.html
[2] http://sourceware.org/ml/gdb-patches/2006-12/msg00351.html
[3] http://gcc.gnu.org/ml/gcc-patches/2007-01/msg01933.html


:ADDPATCH C/C++:

2007-02-16  Manuel Lopez-Ibanez  <manu@gcc.gnu.org>

 * c.opt (Waddress): New.
 * common.opt (Walways-true): Delete.
 (Wstring-literal-comparison): Delete.
 * doc/invoke.texi (Warning Options): Delete -Walways-true and
-Wstring-literal-comparison. Add -Waddress.
 (Waddress): New.
 (Walways-true): Delete.
 (Wstring-literal-comparison): Delete.
 * doc/extend.texi (#pragma GCC diagnostic): Use -Wformat
consistently instead of -Walways-true in example.
 * c-opts.c (c_common_handle_option): -Waddress is enabled by -Wall.
 * c-typeck.c (parser_build_binary_op): Replace
-Wstring-literal-comparison and -Walways-true with -Waddress.
 * c-common.c (c_common_truthvalue_conversion): Replace -Walways-true
with -Waddress.

cp/
 * typeck.c (build_binary_op): Replace -Wstring-literal-comparison
and -Walways-true with -Waddress.
 * cvt.c (convert_to_void): Replace unconditional warning with -Waddress.

testsuite/
 * gcc.dg/20031012-1.c: Replace -Walways-true with -Waddress.
 * gcc.dg/Walways-true-1.c: Likewise.
 * gcc.dg/weak/weak-3.c: Likewise.
 * gcc.dg/Werror-1.c: Likewise.
 * gcc.dg/Werror-3.c: Likewise.
 * gcc.dg/Werror-4.c: Likewise.
 * gcc.dg/Werror-5.c: Likewise.
 * gcc.dg/Werror-6.c: Likewise.
 * gcc.dg/Werror-7.c: Likewise.
 * gcc.dg/Werror-8.c: Likewise.
 * gcc.dg/Werror-10.c: Likewise.
 * gcc.dg/Werror-11.c: Likewise.
 * gcc.dg/Werror-12.c: Likewise.
 * g++.old-deja/g++.mike/warn8.C: Likewise.
 * g++.dg/warn/Walways-true-1.C: Likewise.
 * g++.dg/warn/Walways-true-2.C: Likewise.
 * g++.dg/warn/noeffect8.C: Warn only with -Waddress.
 * g++.dg/warn/Wstring-literal-comparison-1.C: Replace
-Wstring-literal-comparison with -Waddress.
 * gcc.dg/Wstring-literal-comparison-4.c: Replace
-Wno-string-literal-comparison with -Wno-address.

Attachment: waddress.diff
Description: Text document