Add soversion to library files to generate proper symlinks

As mentioned in https://github.com/TokTok/c-toxcore/issues/359#issuecomment-270710463
the current CMake build does not generate version symlinks for library .so files.
This is because the version is not specified for library targets.

See
- https://cmake.org/cmake/help/v3.0/prop_tgt/SOVERSION.html#prop_tgt:SOVERSION
- https://cmake.org/cmake/help/v3.0/prop_tgt/VERSION.html#prop_tgt:VERSION

Use PROJECT_VERSION_MAJOR and MINOR for SOVERSION because
api may break from 0.1 to 0.2 in the 0.x release cycle.

1 files changed, 7 insertions, 1 deletions

diff --git a/cmake/ModulePackage.cmake b/cmake/ModulePackage.cmake
index 613633ba..f6e7e31a 100644
--- a/cmake/ModulePackage.cmake
+++ b/cmake/ModulePackage.cmake
@@ -54,7 +54,13 @@ function(add_module lib)
 
   if(ENABLE_SHARED)
     add_library(${lib}_shared SHARED ${ARGN})
-    set_target_properties(${lib}_shared PROPERTIES OUTPUT_NAME ${lib})
+    set_target_properties(${lib}_shared PROPERTIES
+      OUTPUT_NAME ${lib}
+      VERSION ${PROJECT_VERSION}
+      # While on 0.x, the x behaves like the major version. 0.2 will be
+      # incompatible with 0.1. Change this, when releasing 1.0!
+      SOVERSION ${PROJECT_VERSION_MAJOR}.${PROJECT_VERSION_MINOR}
+    )
     install(TARGETS ${lib}_shared DESTINATION "lib")
   endif()
   if(ENABLE_STATIC)