Default shared libs for cmake-build-system experiment

[Eric Bavier]

Hello Guix,

I recently explored the idea of adding "-DBUILD_SHARED_LIBS=TRUE" to 
cmake-build-system's default configure-flags.  This is just a summary of 
the experience for future reference.

At the time of testing, there were 124 packages that use 
cmake-build-system.  Of those, 7 already explicitly set 
BUILD_SHARED_LIBS=TRUE in their own #:configure-flags.  Removing these, 
and future, explicit uses was actually the motivator for this 
experiment.

Here's a summary of the results, store dir sizes in K:

            package current shared s/c
            ------- ------- ------ ---
            pugixml     372    336  .903226
               maim      96     96 1.000000
               slop      84     84 1.000000
            awesome    2144   2144 1.000000
          webkitgtk  110780 110780 1.000000
          rapidjson     552    552 1.000000
            libyajl     252    252 1.000000
      libwebsockets    3444   3444 1.000000
                vtk   98736  98724  .999878
                obs    9360   9360 1.000000
           avidemux   26248  26248 1.000000
            libgit2    1768   1768 1.000000
               pfff     656    800 1.219512
        taskwarrior    2848   2848 1.000000
            synergy    2920   2920 1.000000
             libssh     684    684 1.000000
               slim     540    540 1.000000
             cereal    6848   6852 1.000584
            scribus  109228 109232 1.000037
            clucene    5040   5040 1.000000
         qtkeychain     268    268 1.000000
       python2-tlsh     116    116 1.000000
        python-tlsh     116    116 1.000000
             gflags     404    404 1.000000
        polkit-qt-1     472    472 1.000000
          libpano13    1640   1640 1.000000
             podofo    8716   8716 1.000000
           keepassx    2524   2524 1.000000
          drumstick    3088   3088 1.000000
            yoshimi    9028   9028 1.000000
               vmpk    1860   1860 1.000000
           hydrogen   17408  17408 1.000000
        zynaddsubfx   52700  52700 1.000000
           portmidi      96     96 1.000000
             taglib    1940   1940 1.000000
          armadillo    4452   4456 1.000898
       ceres-solver    3448   3448 1.000000
             lapack    9656   9656 1.000000
             dealii  253640 253644 1.000016
                glm    2516   2516 1.000000
          armadillo    4452   4456 1.000898
              metis     700    700 1.000000
              flann   19740  19740 1.000000
  double-conversion     172    172 1.000000
               gmsh   22072  22072 1.000000
            superlu     572    572 1.000000
          scalapack    5704   5704 1.000000
       lxqt-session     712    712 1.000000
        lxqt-common    4808   4808 1.000000
           libqtxdg     516    516 1.000000
            liblxqt    1056   1056 1.000000
clang-runtime-3.7.1   11964  11964 1.000000
        clang-3.8.1  263760  50120  .190021
clang-runtime-3.8.1   13228  13228 1.000000
        clang-3.5.2  176304  42724  .242331
         llvm-3.5.2  297320  55024  .185067
clang-runtime-3.6.2   10584  10584 1.000000
        clang-3.7.1  241220  46428  .192472
         llvm-3.7.1  408884  67544  .165191
clang-runtime-3.5.2    8820   8820 1.000000
        clang-3.6.2  170680  44028  .257956
         llvm-3.8.1  492264  74696  .151740
         llvm-3.6.2  333604  59352  .177912
unionfs-fuse-static    1204   1204 1.000000
             pflask      84     84 1.000000
           thinkfan     164    164 1.000000
       unionfs-fuse     128    128 1.000000
            libftdi     204    204 1.000000
        snorenotify    1524   1524 1.000000
                qca    3328   3328 1.000000
extra-cmake-modules     416    416 1.000000
      kwindowsystem    2076   2076 1.000000
       oxygen-icons   47184  47256 1.001526
            quassel   20500  20500 1.000000
              vigra  158284 158284 1.000000
         openjpeg-1     536    536 1.000000
       openjpeg-2.1     536    596 1.111940
     perceptualdiff      80     80 1.000000
       openjpeg-2.0     648    648 1.000000
               cgal   38180  38196 1.000419
        openimageio   17828  17828 1.000000
           freeglut    1100   1100 1.000000
               mars   75384  75384 1.000000
           supertux  131656 131016  .995139
  emulation-station    4264   4264 1.000000
        allegro-5.2    2764   2764 1.000000
          allegro-4    4528   2764  .610424
             bullet    6392   4668  .730288
               sfml    1928   1928 1.000000
        allegro-5.0    2408   2408 1.000000
             physfs     564    564 1.000000
          graphite2     332    332 1.000000
              fcitx      60     60 1.000000
         stellarium  151712 151712 1.000000
            doxygen   15808  15808 1.000000
            mariadb  281328 281332 1.000014
              mysql  213112 213108  .999981
           cppcheck    3288   3288 1.000000
             cmocka     152    152 1.000000
             libcue      84     84 1.000000
            libical    2616   2616 1.000000
            diamond     832    832 1.000000
           bamtools    2864   2864 1.000000
            express    2532   2536 1.001580
            flexbar    1260   1260 1.000000
             openal     632    632 1.000000
             csound    5040   5040 1.000000
               soxr     324    324 1.000000
              eigen    3684   3684 1.000000
                dfc     168    168 1.000000
               glfw     344    344 1.000000

So it appears that many packages are not affected by the change; llvm 
and clang are most helped (with a small fix to the build phases), and 
pugixml, allegro-4, and bullet to a lesser absolute degree.  Many 
packages apparently build shared libraries by default.

What is not included in the above list, however, are the packages that 
FTBFS with BUILD_SHARED_LIBS=TRUE!  A summary of those packages and the 
issues:

blender => link error involving libjpeg.so version mismatches
ctl => validate-runpath failure
minetest => validate-runpath failure: libgmp.so cannot be found
aseprite => libbase-lib.so: undefined references to pthread_create, etc
conky => validate-runpath: bogus runpath entry, libtcp-portmem.so cannot 
be found
withershins => link error: invalid relocation against `bfd_errmsg', 
recompile with -fPIC

Based on this evidence, I think I'll just enable shared libraries in 
directly in the llvm and clang packages, and forget adding the default 
flag in cmake-build-system since its global impact would be minimal at 
this point and even in the future and fixing the fallout is non-trivial.

Happy Hacking,
--
`~Eric