Subject: How to force using ARFLAGS = cr instead of "cru" to overcome the warning : ar: `u' modifier ignored since `D' is the default (see `U')

From: . <[email-masked]>
Date: Sun, 14 Jan 2018 22:04:21 -0500

*The environment:*

 host-triplet:   x86_64-pc-linux-gnu
       shell:          /bin/bash
       compiler:       gcc
       compiler flags: -g -O2 -fstack-protector-strong -Wformat
-Werror=format-security
       linker:         /usr/bin/ld -m elf_x86_64 (gnu? yes)
       version:        libtool (GNU libtool) 2.4.6
       automake:       automake (GNU automake) 1.15
       autoconf:       autoconf (GNU Autoconf) 2.69

*The Project being built:*

https://github.com/dogecoin/dogecoin.git

*The Error:*

ar: `u' modifier ignored since `D' is the default (see `U')

*The temporary solution:*

So I've basically come to the point that to make this work you have to
modify two files and change "cru" to "cr" in them :

/usr/share/aclocal/libtool.m4

and

/usr/share/libtool/configure

then rerun ./autogen.sh and ./configure

Additionally add to make command line::

make ARFLAGS="cr" AR_FLAGS="cr"

====================
This affectively suppresses the warning from appearing, but it's not a
clean way to make this work. Could you please assist with this matter thank
you. Also I've looked into the libtool repository :  git://
git.savannah.gnu.org/libtool.git  and saw a NEWS file stating:

* New features:

  - Libtool script now supports (configure-time and runtime) ARFLAGS
    variable, which obsoletes AR_FLAGS.  This is due to naming conventions
    among other *FLAGS and to be consistent with Automake's ARFLAGS.

  - Gnulib testsuite is enabled and run during 'make check'.

** Important incompatible changes:

  - Libtool changed ARFLAGS/AR_FLAGS default from 'cru' to 'cr'.

However, it's unclear how the configure-time and runtime ARFLAGS var should
be set. Various options have been tried in the configure.ac and Makefile.am
files, but nothing worked.

Hope to hear from you soon on a viable option here. Thank you in advance
for your attention to this matter.

Regards,

[email-masked]

P.S. This is something many crypto projects have in their code base that is
throwing this warning including Bitcoin itself. Would be nice to make this
a permanent fix.