Re: [PATCH 01/13] btrfs-progs: turn on more compiler warnings and use -Wall

[David Sterba <dsterba@suse.cz>]

On Tue, Mar 08, 2022 at 05:51:26PM +0100, David Sterba wrote:
> On Tue, Feb 22, 2022 at 05:26:11PM -0500, Josef Bacik wrote:
> > In converting some of our helpers to take new args I would miss some
> > locations because we don't stop on any warning, and I would miss the
> > warning in the scrollback.  Fix this by stopping compiling on any error
> > and turn on the fancy compiler checks.
> > 
> > Signed-off-by: Josef Bacik <josef@toxicpanda.com>
> > ---
> >  Makefile | 3 +++
> >  1 file changed, 3 insertions(+)
> > 
> > diff --git a/Makefile b/Makefile
> > index af4908f9..e0921ca3 100644
> > --- a/Makefile
> > +++ b/Makefile
> > @@ -93,6 +93,9 @@ CFLAGS = $(SUBST_CFLAGS) \
> >  	 -D_XOPEN_SOURCE=700  \
> >  	 -fno-strict-aliasing \
> >  	 -fPIC \
> > +	 -Wall \
> > +	 -Wunused-but-set-parameter \
> > +	 -Werror \
> 
> That's in the default flags and based on the recent experience in kernel
> defaulting to Werror it creates more problems than not. The build is
> clean enough that new warnings are quite obvious and get fixed right
> away.
> 
> You can always use the EXTRA_CFLAG=-Werror when developing or you can
> also set CFLAGS=-Werror at configure time, as they get stored in the
> generated Makefile.inc into SUBST_CFLAGS.

And actually there's make parameter W=1 like in kernel, that enables
more warnings though the W=1 build is not clean. I'd rather not clutter
the default flags by random warnings at all as the build is supposed to
work on various LTS distros and compilers so that would probably fail
build.