CMake: add .so-version

This is basically PR #2002, from Undef-a.

CMakeLists.txt

@@ -65,6 +65,11 @@ project(CALAMARES VERSION ${CALAMARES_VERSION_SHORT} LANGUAGES C CXX HOMEPAGE_UR
 if(NOT CALAMARES_RELEASE_MODE AND CMAKE_SOURCE_DIR STREQUAL CMAKE_BINARY_DIR)
     message(FATAL_ERROR "Do not build development versions in the source-directory.")
 endif()
+# Calamares in the 3.3 series promises ABI compatbility, so it sets a
+# .so-version equal to the series number. We use ci/abicheck.sh to
+# keep track of this. Note that the **alpha** releases also have
+# such an .so-version, but are not ABI-stable yet.
+set(CALAMARES_SOVERSION "${PROJECT_VERSION_MAJOR}.${PROJECT_VERSION_MINOR}")
 
 ### OPTIONS
 #

src/libcalamares/CMakeLists.txt

@@ -97,7 +97,7 @@ set_target_properties(
     calamares
     PROPERTIES
         VERSION ${CALAMARES_VERSION_SHORT}
-        SOVERSION ${CALAMARES_VERSION_SHORT}
+        SOVERSION ${CALAMARES_SOVERSION}
         INTERFACE_INCLUDE_DIRECTORIES ${CMAKE_INSTALL_FULL_INCLUDEDIR}/libcalamares
 )
 target_link_libraries(calamares LINK_PUBLIC yamlcpp::yamlcpp Qt5::Core KF5::CoreAddons)

src/libcalamaresui/CMakeLists.txt

@@ -53,6 +53,7 @@ calamares_add_library(calamaresui
     UI
         utils/ErrorDialog/ErrorDialog.ui
     VERSION ${CALAMARES_VERSION_SHORT}
+    SOVERSION ${CALAMARES_SOVERSION}
 )
 target_link_libraries(calamaresui PRIVATE yamlcpp::yamlcpp)
 if(KF5CoreAddons_FOUND AND KF5CoreAddons_VERSION VERSION_GREATER_EQUAL 5.58)