[tor-bugs] #27309 [Core Tor/Tor]: Deterministic builds / ar warns about u modifier

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#27309: Deterministic builds / ar warns about u modifier
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     Reporter:  traumschule   |      Owner:  (none)
         Type:  defect        |     Status:  new
     Priority:  Medium        |  Milestone:
    Component:  Core Tor/Tor  |    Version:
     Severity:  Normal        |   Keywords:
Actual Points:                |  Parent ID:
       Points:                |   Reviewer:
      Sponsor:                |
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 Building Tor from source brings up this warning several times:

 > "ar: `u' modifier ignored since `D' is the default (see `U')" a lot.

 The fix is to change the according line in Makefile.in to
 {{{ARFLAGS=crD}}}.

 (easy to find with {{{grep -n "ARFLAGS =" Makefile.in}}})

 Since Makefile.in is created by the {{{./configure}}} script, the
 [https://www.gnu.org/software/automake/manual/automake.html#A-Library
 default flags need to be changed]:
 > "ARFLAGS will default to cru; you can override this variable by setting
 it in your Makefile.am or by AC_SUBSTing it from your configure.ac."

 Before distributing Tor with it, we need to check if any platform build
 breaks. For example versions before
 [https://bugzilla.redhat.com/show_bug.cgi?id=1124342#c4 binutils v2.24-20]
 / [https://savannah.gnu.org/forum/forum.php?forum_id=7749 GNU Make 4]
 (2013-10-09). I did not check for OSX and BSD yet.

 The options -D / -U
 [https://bugzilla.redhat.com/show_bug.cgi?id=1195883#c3 were introduced]
 in [https://lists.gnu.org/archive/html/info-gnu/2003-12/msg00001.html
 January 2013]. For debian see [https://bugs.debian.org/cgi-
 bin/bugreport.cgi?bug=798913 Bug 798913] (and the
 [https://salsa.debian.org/srivasta/make-dfsg/blob/master/debian/changelog
 Debian changelog]):
 > binutils upstream provides a configure option '--enable-deterministic-
 archives', which makes this behaviour the default, though it can still be
 disabled at runtime via the 'u' switch, in case someone wants to use ar to
 pack non-library files in an archive and cares about the metadata.

 References
 * https://www.mail-archive.com/bug-automake@gnu.org/msg04226.html

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/27309>
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