[webkit-dev] Let's use -Werror on EWS?

[Michael Catanzaro]

Hi,

I'd like to suggest turning on -Werror on at least the GTK and WPE EWS, 
to reduce the amount of time I spend cleaning up newly-introduced build 
warnings. ;)

If we're worried about too many spurious build failures, let's at least 
build with a few flags to prevent the most common GCC warnings that 
developers using Clang will never notice: -Werror=return-type, 
-Werror=class-memaccess, and -Werror=pessimizing-move. These are simple 
to avoid if you see the warning from GCC, but very easy to miss if you 
develop with Clang. I guess these account for more than half of new GCC 
warnings introduced into WebKit.

I'd also like to see -Werror=unused, since it's easy to introduce these 
warnings for other ports when doing anything involving conditional 
compilation. That might require some CMake changes, though (as we don't 
want to break -Wno-unused-parameter, which we use when building 
Source/WebKit and several directories under Tools).

But really, rather than cherry-picking particular warning flags, using 
-Werror seems simplest to me. Problematic warnings should be disabled 
or suppressed.

I do *not* suggest using -Werror on any non-EWS bots, since that will 
make gardening harder for almost no benefit. We do not want to lose 
test results due to a missing UNUSED_PARAM() or 
RELEASE_ASSERT_NOT_REACHED() somewhere. I also certainly do not suggest 
using it by default in CMake, which would really annoy our 
distributors. I would only use it in the EWS bot config.

Michael