cmake: only create target obj lib on new enough cmakes

Edward Thomson · Edward Thomson · commit db16c5e7587a · 2017-02-04T18:45:39.000+01:00
diff --git a/CMakeLists.txt b/CMakeLists.txt
@@ -602,20 +602,27 @@ ENDIF()
 
 SET(SRC_LIBGIT2 ${SRC_GIT2} ${SRC_OS} ${SRC_ZLIB} ${SRC_HTTP} ${SRC_REGEX} ${SRC_SSH} ${SRC_SHA1})
 
-# Compile the objects that make up our library; we will create an actual
-# shared/static library with them later.
-ADD_LIBRARY(git2_src OBJECT ${SRC_LIBGIT2})
-IDE_SPLIT_SOURCES(git2_src)
+# On a sufficiently new cmake, we can compile the objects that make up our
+# library as a separate target (without needing to link a library or an
+# executable).  This will satisfy the dependency for our tests, and saves
+# us from having to recompile them.
+IF (${CMAKE_VERSION} VERSION_GREATER 2.8.7)
+	ADD_LIBRARY(git2_src OBJECT ${SRC_LIBGIT2})
+	IDE_SPLIT_SOURCES(git2_src)
+
+	SET(SRC_LIBGIT2 $<TARGET_OBJECTS:git2_src>)
+ENDIF()
 
 # Compile and link libgit2
-ADD_LIBRARY(git2 $<TARGET_OBJECTS:git2_src> ${WIN_RC})
+ADD_LIBRARY(git2 ${SRC_LIBGIT2} ${WIN_RC})
 TARGET_LINK_LIBRARIES(git2 ${SECURITY_DIRS})
 TARGET_LINK_LIBRARIES(git2 ${COREFOUNDATION_DIRS})
 TARGET_LINK_LIBRARIES(git2 ${SSL_LIBRARIES})
 TARGET_LINK_LIBRARIES(git2 ${SSH_LIBRARIES})
 TARGET_LINK_LIBRARIES(git2 ${GSSAPI_LIBRARIES})
 TARGET_LINK_LIBRARIES(git2 ${ICONV_LIBRARIES})
 TARGET_OS_LIBRARIES(git2)
+IDE_SPLIT_SOURCES(git2)
 
 # Workaround for Cmake bug #0011240 (see http://public.kitware.com/Bug/view.php?id=11240)
 # Win64+MSVC+static libs = linker error
@@ -685,7 +692,7 @@ IF (BUILD_CLAR)
 		${CLAR_PATH}/clar.c
 		PROPERTIES OBJECT_DEPENDS ${CLAR_PATH}/clar.suite)
 
-	ADD_EXECUTABLE(git2_tests ${SRC_CLAR} ${SRC_TEST} $<TARGET_OBJECTS:git2_src>)
+	ADD_EXECUTABLE(git2_tests ${SRC_CLAR} ${SRC_TEST} ${SRC_LIBGIT2})
 
 	TARGET_LINK_LIBRARIES(git2_tests ${COREFOUNDATION_DIRS})
 	TARGET_LINK_LIBRARIES(git2_tests ${SECURITY_DIRS})
