Wfutile-unsigned-comparison (PR7651 Define -Wextra strictly in terms of other warning flags)

["Manuel LÃpez-IbÃÃez" <lopezibanez at gmail dot com>]

:ADDPATCH middle-end:

This patch continues the effort to fix PR7651 [1].

It adds a new option -Wfutile-unsigned-comparison that takes over the
function of warning  about comparison of unsigned variables against
zero with < or >=. The new option is enabled by -Wextra, so we keep
the current behaviour but add the ability to enable/disable this
individual warning.

Bootstrapped and regression tested with --enable-languages=all on
i686-pc-linux-gnu.

OK for mainline?

[1] http://gcc.gnu.org/ml/gcc-patches/2006-12/msg01103.html


2006-12-23  Manuel Lopez-Ibanez  <manu@gcc.gnu.org>

   PR middle-end/7651
   * c.opt (Wfutile-unsigned-comparison): New.
   * doc/invoke.texi (Wfutile-unsigned-comparison): Document it.
   (Wextra): Enabled by -Wextra.
   * c-opts.c (c_common_post_options): Enabled by -Wextra.
   * c-common.c (shorten_compare): Replace Wextra with
   Wfutile-unsigned-comparison.

testsuite/
2006-12-23  Manuel Lopez-Ibanez  <manu@gcc.gnu.org>

   PR middle-end/7651
   * gcc.dg/Wfutile-unsigned-comparison.c: New.
   * gcc.dg/Wfutile-unsigned-comparison-Wextra.c: New.
   * gcc.dg/Wfutile-unsigned-comparison-no.c: New.
   * g++.dg/warn/Wfutile-unsigned-comparison.C: New.
   * g++.dg/warn/Wfutile-unsigned-comparison-Wextra.C: New.
   * g++.dg/warn/Wfutile-unsigned-comparison-no.C: New.

Attachment: wfutile-unsigned-comparison.diff
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