Newer binutils 'ar' has added an option 'D' for
deterministic
builds, and at least on rawhide, this option is enabled by default.
But it conflicts with the 'u' optimization where the linker only
modifies libraries based on file timestamps, but can result in
different library ordering based on which files were touched last.
Thus, it results in some noisy compilation, for every CCLD line:
CCLD libvirt_driver_qemu_impl.la
ar: `u' modifier ignored since `D' is the default (see `U')
Upstream automake has decided that defaulting ARFLAGS to 'cru' is
no longer beneficial, and that switching the default to 'cr' will
both silence the noise and not penalize modern build systems.
https://lists.gnu.org/archive/html/automake-patches/2015-06/msg00000.html
But rather than wait for newer automake to propagate to all systems
that already have newer binutils, we might as well just use the new
default ourselves, even on older platforms.
Signed-off-by: Eric Blake <eblake(a)redhat.com>
---
This is bugging me even more now that Fedora 22 also suffers from
the same issue (we've been ignoring it in rawhide for several months
now). While it seems trivial, I'd like a review before pushing.
configure.ac | 4 ++++
1 file changed, 4 insertions(+)