On 04/05/2016 12:39 AM, Lars Magne Ingebrigtsen wrote:
> warnings should be enabled by default (on Linux), but
> they shouldn't be treated as errors.

It's good at times to not treat them as errors, so I installed the 
attached patch to add that capability more clearly, with a new 
configure-time option --enable-gcc-warnings=warn-only. The attached 
patch makes this new option the default if you have a Git checkout of 
Emacs and GCC 5.3 or later. This shouldn't affect Eli any time soon, 
since he uses an old compiler.

If this patch causes trouble by generating too many warnings on some 
platforms, we can dial it back by suppressing warnings on those 
platforms. But the latest GNU/Linux platforms running the latest GTK 
should be warnings-free.

As others have noted in this thread, -Wall generates too many warnings. 
The --enable-gcc-warnings option suppresses GCC warnings that are false 
alarms for Emacs. It also enables some warnings that -Wall does not, but 
which work well with Emacs.