https://gcc.gnu.org/bugzilla/show_bug.cgi?id=17308
--- Comment #24 from Segher Boessenkool <segher at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #23)
> I also suspect many of these new warnings we are doing in recent years
> really should not be part of -Wall because of how many false positives we
> have. GCC has been getting a recent attention because of the false positives
> warnings too.
Current documentation says
'-Wall'
This enables all the warnings about constructions that some users
consider questionable, and that are easy to avoid (or modify to
prevent the warning), even in conjunction with macros.
and
'-Wextra'
This enables some extra warning flags that are not enabled by
'-Wall'.
We don't document at all what options should be enabled by -Wall, what
options should be enabled by -W, and which should be done by neither. The
current documentation for -Wall is very noncommittal.
It all is a tradeoff of course. IMO our documentation should make that clear
as well.
In my view, -Wall should enable all warnings that have few false positives
(less than 5% or 10%, say), and when they do this is easy to avoid, or perhaps
the warning points out very important (security) problems.
-W is the same but with higher tolerance for false positives. And the
warnings that are not so useful, or are hard to avoid, and have a high false
positive rate, should not be enabled by either.
(Oh, and please note that -Werror is not part of these considerations at all.
When -Werror makes things "break" this is just a learning opportunity for
whoever asked for it. Maybe we should document -Werror as an alias of
-Wself-flagellation).
