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    <p>Dear Rivet developers,</p>
    <p>Recently we got an e-mail from LHCb collaborations saying that
      they are experiencing some problem Rivet 2.5.4( and 2.5.3) from
      our LCG_91 release.</p>
    <p>The problem is the following. By some reason the  libRivet.so is
      linked with system libgsl.so.0 but not with libgsl.so.19 of GSL
      version explicitly specified with:<br>
    </p>
    <p>--with-gsl=/cvmfs/sft.cern.ch/lcg/releases/LCG_92/GSL/2.1/x86_64-slc6-gcc62-opt<br>
    </p>
    The source of the problem is that fastjet-config returns some flags
    pointing to system libraries and inside Rivet's src/Makefile.am<br>
    FASTJET flags are placed before GSL and therefore GSL library is
    taken from system...<br>
    <br>
    <b>/cvmfs/sft.cern.ch/lcg/releases/LCG_92/fastjet/3.3.0/x86_64-slc6-gcc62-opt/bin/fastjet-config
      --libs --shared=no --plugins<br>
      [ </b><b><b>fastjet-config is used by Rivet to get linking flags]</b></b><br>
    -lm
/cvmfs/sft.cern.ch/lcg/releases/fastjet/3.3.0-e4cac/x86_64-slc6-gcc62-opt/lib/libfastjettools.a
/cvmfs/sft.cern.ch/lcg/releases/fastjet/3.3.0-e4cac/x86_64-slc6-gcc62-opt/lib/libfastjet.a
/cvmfs/sft.cern.ch/lcg/releases/fastjet/3.3.0-e4cac/x86_64-slc6-gcc62-opt/lib/libfastjetplugins.a
/cvmfs/sft.cern.ch/lcg/releases/fastjet/3.3.0-e4cac/x86_64-slc6-gcc62-opt/lib/libsiscone.a
/cvmfs/sft.cern.ch/lcg/releases/fastjet/3.3.0-e4cac/x86_64-slc6-gcc62-opt/lib/libsiscone_spherical.a
-L/cvmfs/sft.cern.ch/lcg/contrib/gcc/6.2.0binutils/x86_64-slc6/bin/../lib/gcc/x86_64-pc-linux-gnu/6.2.0
-L/cvmfs/sft.cern.ch/lcg/contrib/gcc/6.2.0binutils/x86_64-slc6/bin/../lib/gcc
-L/cvmfs/sft.cern.ch/lcg/contrib/gcc/6.2.0binutils/x86_64-slc6/bin/../lib/gcc/x86_64-pc-linux-gnu/6.2.0/../../../../lib64
    <b>-L/lib/../lib64 -L/usr/lib/../lib64</b>
-L/cvmfs/sft.cern.ch/lcg/contrib/gcc/6.2.0binutils/x86_64-slc6/bin/../lib/gcc/x86_64-pc-linux-gnu/6.2.0/../../..
    -lgfortran -lm -lquadmath<br>
    <br>
    <b>Rivet Makefile.am content:</b><br>
    <br>
    SUBDIRS = Core Tools Projections<br>
    SUBDIRS += Analyses<br>
    ANA_LIBADD = Analyses/libRivetAnalysisTools.la<br>
    <br>
    lib_LTLIBRARIES = libRivet.la<br>
    libRivet_la_SOURCES =<br>
    libRivet_la_LDFLAGS = -export-dynamic -avoid-version
    -L$(YODALIBPATH) -L$(HEPMCLIBPATH)<br>
    libRivet_la_LIBADD = Core/libRivetCore.la
    Projections/libRivetProjections.la Tools/libRivetTools.la
    $(ANA_LIBADD) \<br>
      -lYODA -lHepMC -ldl -lm  <b>$(GSL_LDFLAGS) $(FASTJETCONFIGLIBADD)</b><br>
    src/Makefile.am (END) <br>
    <br>
    <br>
    Switching <b>$(GSL_LDFLAGS) $(FASTJETCONFIGLIBADD) can fix the
      problem.</b><br>
    <br>
    Please notу that LCG_92 is not affected and therefore I think that
    possible reason is that the latest release is built within docker
    container with more clean environment.<br>
    <br>
    Therefore there are two possible solution - 1) we are not touching
    anything and re-build Rivet within docker container or 2) we apply
    patch and rebuild.<br>
    <br>
    Cheers,<br>
       Dima for GENSER <br>
    <b></b><br>
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