Support generation of working Xcode project for signature purposes on MacOS (#15303)

irr/src/CMakeLists.txt

@@ -313,21 +313,6 @@ add_library(IRRMESHOBJ OBJECT
 
 target_link_libraries(IRRMESHOBJ PUBLIC tiniergltf::tiniergltf)
 
-add_library(IRROBJ OBJECT
-	CBillboardSceneNode.cpp
-	CCameraSceneNode.cpp
-	CDummyTransformationSceneNode.cpp
-	CEmptySceneNode.cpp
-	CMeshManipulator.cpp
-	CSceneCollisionManager.cpp
-	CSceneManager.cpp
-	CMeshCache.cpp
-)
-
-# Make sure IRROBJ gets the transitive include directories for
-# tiniergltf from IRRMESHOBJ.
-target_link_libraries(IRROBJ PRIVATE IRRMESHOBJ)
-
 set(IRRDRVROBJ
 	CNullDriver.cpp
 	CGLXManager.cpp
@@ -460,14 +445,29 @@ add_library(IRRGUIOBJ OBJECT
 
 # Library
 
-add_library(IrrlichtMt STATIC)
+# There have to be some sources in IrrlichtMt to workaround Cmake Xcode generator bug
+add_library(IrrlichtMt STATIC
+	CBillboardSceneNode.cpp
+	CCameraSceneNode.cpp
+	CDummyTransformationSceneNode.cpp
+	CEmptySceneNode.cpp
+	CMeshManipulator.cpp
+	CSceneCollisionManager.cpp
+	CSceneManager.cpp
+	CMeshCache.cpp
+)
 foreach(object_lib
-	IRRMESHOBJ IRROBJ IRRVIDEOOBJ
+	IRRMESHOBJ IRRVIDEOOBJ
 	IRRIOOBJ IRROTHEROBJ IRRGUIOBJ)
 	# Set include directories for object library compilation
 	target_include_directories(${object_lib} PRIVATE ${link_includes})
-	# Add objects from object library to main library
-	target_sources(IrrlichtMt PRIVATE $<TARGET_OBJECTS:${object_lib}>)
+	if(CMAKE_GENERATOR STREQUAL "Xcode")
+		# Workaround for Cmake Xcode project generator
+		target_link_libraries(IrrlichtMt PRIVATE ${object_lib})
+	else()
+		# Add objects from object library to main library
+		target_sources(IrrlichtMt PRIVATE $<TARGET_OBJECTS:${object_lib}>)
+	endif()
 
 	if(BUILD_WITH_TRACY)
 		target_link_libraries(${object_lib} PRIVATE Tracy::TracyClient)