Re: [PATCH] Revert "spec: Simplify setting features off by default"
On Tue, 2020-10-27 at 14:05 +0100, Andrea Bolognani wrote:
I'm not convinced reverting this was the right call.
The way RPM conditional macros work is that, if you have
%{!?macro:value}
that will expand to 'value' if 'macro' is *not* defined, and to
nothing otherwise. So if you have for example
%define with_fuse 0%{!?_without_fuse:0}
that means that, if you pass
--define '_without_fuse 1'
to rpmbuild the line will expand to
%define with_fuse 0
and if you don't pass the extra option to rpmbuild it will instead
expand to
%define with_fuse 00
The two are clearly equivalent, so there is no point in keeping the
conditional macro - it merely obfuscates the logic.
Of course things would be different if you had
%define with_fuse 0%{!?_without_fuse:1}
instead: in this case, the line would expand to
%define with_fuse 0
and
%define with_fuse 01
respectively, which means the feature would be enabled by default but
could optionally be disabled by passing the correct argument to
rpmbuild, as expected. We have plenty similar macros in libvirt.spec,
and since they work just as intended 31d687a3218c didn't touch them.
Note that in this case I've removed
# fuse is used to provide virtualized /proc for LXC
%if %{with_lxc}
%define with_fuse 0%{!?_without_fuse:1}
%endif
from the spec to make sure that the value for the 'fuse' option
passed to Meson depended solely on the value of the _without_fuse
macro, and then checked the rpmbuild output to compare.
Also note that I'm aware you want to eventually push for adoption of
the standard bcond macros, and I fully stand behind that desire! If
this patch had been the first in a series that introduced bcond
support and was clearing the path for that, I would have zero
problems with it. As it is, however, you're simply reintroducing some
of the obfuscation we had recently managed to get rid of, without
getting anything in return.
--
Andrea Bolognani / Red Hat / Virtualization