CMake on Linux: Only generate either the static or the dynamic library

In af72afb (Generate static library and fix compilation definitions
(#17) (#437), 2018-05-15) support was added for building a static
library next to the dynamic one.

As most users want to have only either library we use the newly
introduced option BUILD_SHARED_LIBS to build either one. This also
solves issues when cross-compiling where you might not have shared
libraries for the target architecture.

Author: t-b

CMakeLists.txt

@@ -33,7 +33,12 @@ add_subdirectory("log4tango")
 add_subdirectory("cppapi")
 
 if(BUILD_TESTING)
+  if(BUILD_SHARED_LIBS)
     add_subdirectory("cpp_test_suite")
+  else()
+    message(WARNING "Not building the tests, because that is currently supported only when BUILD_SHARED_LIBS is ON")
+    SET(BUILD_TESTING OFF)
+  endif()
 endif()
 
 if(WIN32)

INSTALL.md

@@ -28,6 +28,7 @@
 - `-DCMAKE_VERBOSE_MAKEFILE=true`
 - `-DTANGO_USE_USING_NAMESPACE=<ON|OFF>` choose `OFF` for modern builds
 - `-DBUILD_TESTING=<ON|OFF>` Build the test suite (`ON` by default)
+- `-DBUILD_SHARED_LIBS=<ON|OFF>` Build tango as shared library (`ON` by default)
 
 Typical output:
 

configure/CMakeLists.txt

@@ -214,3 +214,4 @@ include(GNUInstallDirs)
 include(configure/coveralls.cmake)
 
 option(TANGO_JPEG_MMX "Build MMX support" ON)
+option(BUILD_SHARED_LIBS "Build a shared library instead of static" ON)

configure/cmake_linux.cmake

@@ -1,35 +1,25 @@
 project(libtango)
 
-add_library(tango SHARED    $<TARGET_OBJECTS:log4tango_objects>
-                            $<TARGET_OBJECTS:client_objects>
-                            $<TARGET_OBJECTS:idl_objects>
-                            $<TARGET_OBJECTS:jpeg_objects>
-                            $<TARGET_OBJECTS:jpeg_mmx_objects>
-                            $<TARGET_OBJECTS:server_objects>)
+add_library(tango $<TARGET_OBJECTS:log4tango_objects>
+                  $<TARGET_OBJECTS:client_objects>
+                  $<TARGET_OBJECTS:idl_objects>
+                  $<TARGET_OBJECTS:jpeg_objects>
+                  $<TARGET_OBJECTS:jpeg_mmx_objects>
+                  $<TARGET_OBJECTS:server_objects>)
 target_link_libraries(tango PUBLIC ${ZMQ_PKG_LIBRARIES} ${OMNIORB_PKG_LIBRARIES} ${OMNICOS_PKG_LIBRARIES} ${OMNIDYN_PKG_LIBRARIES} ${CMAKE_DL_LIBS})
-target_compile_options(tango PRIVATE -fPIC)
 target_include_directories(tango PUBLIC ${ZMQ_PKG_INCLUDE_DIRS} ${OMNIORB_PKG_INCLUDE_DIRS} ${OMNIDYN_PKG_INCLUDE_DIRS})
-
 target_compile_options(tango PUBLIC ${ZMQ_PKG_CFLAGS_OTHER} ${OMNIORB_PKG_CFLAGS_OTHER} ${OMNICOS_PKG_CFLAGS_OTHER} ${OMNIDYN_PKG_CFLAGS_OTHER})
-target_compile_definitions(tango PUBLIC _REENTRANT)
-
-set_target_properties(tango PROPERTIES
-                      VERSION ${LIBRARY_VERSION}
-                      SOVERSION ${SO_VERSION})
-
-add_library(tango-static STATIC $<TARGET_OBJECTS:log4tango_objects>
-                                $<TARGET_OBJECTS:client_objects>
-                                $<TARGET_OBJECTS:idl_objects>
-                                $<TARGET_OBJECTS:jpeg_objects>
-                                $<TARGET_OBJECTS:jpeg_mmx_objects>
-                                $<TARGET_OBJECTS:server_objects>)
-target_link_libraries(tango-static PUBLIC ${ZMQ_PKG_LIBRARIES} ${OMNIORB_PKG_LIBRARIES} ${OMNICOS_PKG_LIBRARIES} ${OMNIDYN_PKG_LIBRARIES} ${CMAKE_DL_LIBS})
-target_include_directories(tango-static PUBLIC ${ZMQ_PKG_INCLUDE_DIRS} ${OMNIORB_PKG_INCLUDE_DIRS} ${OMNIDYN_PKG_INCLUDE_DIRS})
-target_compile_options(tango-static PUBLIC ${ZMQ_PKG_CFLAGS_OTHER} ${OMNIORB_PKG_CFLAGS_OTHER} ${OMNICOS_PKG_CFLAGS_OTHER} ${OMNIDYN_PKG_CFLAGS_OTHER})
-set_target_properties(tango-static PROPERTIES OUTPUT_NAME tango)
 
-install(TARGETS tango LIBRARY DESTINATION "${CMAKE_INSTALL_FULL_LIBDIR}")
-install(TARGETS tango-static ARCHIVE DESTINATION "${CMAKE_INSTALL_FULL_LIBDIR}")
+if(BUILD_SHARED_LIBS)
+  target_compile_options(tango PRIVATE -fPIC)
+  target_compile_definitions(tango PUBLIC _REENTRANT)
+  set_target_properties(tango PROPERTIES
+                        VERSION ${LIBRARY_VERSION}
+                        SOVERSION ${SO_VERSION})
+  install(TARGETS tango LIBRARY DESTINATION "${CMAKE_INSTALL_FULL_LIBDIR}")
+else()
+  install(TARGETS tango ARCHIVE DESTINATION "${CMAKE_INSTALL_FULL_LIBDIR}")
+endif()
 
 configure_file(tango.pc.cmake tango.pc @ONLY)
 install(FILES "${CMAKE_CURRENT_BINARY_DIR}/tango.pc"