While in theory I like the idea of compiler warnings always being
fatal. In practice this causes problems when small harmless errors
cause build failures for end users. To handle this I've updated
the build system such that -Werror is only used when --enable-debug
is passed to configure. This is how I always build when developing
so I'll catch all build warnings and end users will not get stuck
by minor issues.
The cleanest way to do this is to set AM_LIBTOOLFLAGS = --silent. However,
AM_LIBTOOLFLAGS is not honored by automake-1.9.6-2.1 which is what I have
been using. To cleanly handle this I am updating to automake-1.11-3 which
is why it looks like there is a lot of churn in the Makefiles.
We need dependent packages to be able to include zfs_config.h to
build properly. This was partially solved previously be using
AH_BOTTOM to #undef common #defines (PACKAGE, VERSION, etc) which
autoconf always adds and cannot be easily removed. This solution
works as long as the zfs_config.h is included before your projects
config.h. That turns out to be easier said than done. In particular,
this is a problem when your package includes its config.h using the
-include gcc option which ensures the first thing included is your
config.h.
To handle all cases cleanly I have removed the AH_BOTTOM hack and
replaced it with an AC_CONFIG_HEADERS command. This command runs
immediately after zfs_config.h is written and with a little awk-foo
it strips the offending #defines from the file. This eliminates
the problem entirely and makes header safe for inclusion.
All these errors are now either addressed in a gcc-* topic branch, or
in whatever branch the original warning was introduced by (i.e. I fixed
the bug which just went unnoticed until now due to the compiler flags)
Brian Behlendorf