[CMake] binary contains an unresolvable reference to symbol sym

[Mathieu Malaterre]

Dear all,

  I am trying to solve one remaining issue with one of my package in
debian [1]. The report says basically "binary  contains an
unresolvable reference to symbol sym". According to the documentation
[2]:

              The indicated symbol has not been found in the libraries  linked
              with the binary. The binary is most likely a plugin and the sym-
              bol is probably provided by the program that loads this  plugin.
              In  theory a plugin doesn't have any SONAME but this binary does
              have one and as such it could not be clearly identified as such.
              However  the  fact  that  the  binary  is stored in a non-public
              directory is a strong indication that's it's not a normal shared
              library.  If  the binary is really a plugin, then disregard this
              warning. But there's always the possibility  that  it's  a  real
              library  and  that  programs linking to it are using an RPATH so
              that the dynamic loader finds it. In that case, the  library  is
              broken and needs to be fixed.

The solution seems pretty straightforward: remove the -soname command
line switch when generating the python module. Looking at:
Modules/CMakeCInformation.cmake I can see:

...
IF(NOT CMAKE_C_CREATE_SHARED_MODULE)
  SET(CMAKE_C_CREATE_SHARED_MODULE ${CMAKE_C_CREATE_SHARED_LIBRARY})
ENDIF(NOT CMAKE_C_CREATE_SHARED_MODULE)
...

  So basically /module/ and /shared/ behave exactly the same on *nix
platform, correct ? If so how is someone supposed to remove the
explicit setting of CMAKE_SHARED_LIBRARY_SONAME_C_FLAG in such case ?

For example on my system I can see:

$ readelf -d /usr/lib/pyshared/python2.7/_gdcmswig.so | grep SONAME
 0x000000000000000e (SONAME)             Library soname: [_gdcmswig.so]

While in another package (using python distutils/setup.py):

$ readelf -d /usr/lib/python2.7/dist-packages/libtiff/tif_lzw.so  | grep SONAME
-> no output



Thanks much in advance,

[1] https://buildd.debian.org/~brlink/packages/g/gdcm.html
[2] http://man.he.net/man1/dpkg-shlibdeps
-- 
Mathieu