Fix server-only builds on older CMake versions (#11566)

closes #11564

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 9cb5678c4b15b10d0dda37e84614824a79bb5f14..7b266334186e33795ca9479196572c2eac0118b7 100644 (file)
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -71,8 +71,8 @@ if(EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/lib/irrlichtmt")
                endif()
        else()
                add_library(IrrlichtMt::IrrlichtMt INTERFACE IMPORTED)
-               target_include_directories(IrrlichtMt::IrrlichtMt INTERFACE
-                       "${CMAKE_CURRENT_SOURCE_DIR}/lib/irrlichtmt/include")
+               set_target_properties(IrrlichtMt::IrrlichtMt PROPERTIES
+                       INTERFACE_INCLUDE_DIRECTORIES "${CMAKE_CURRENT_SOURCE_DIR}/lib/irrlichtmt/include")
        endif()
 else()
        find_package(IrrlichtMt QUIET)
@@ -90,7 +90,9 @@ else()
                endif()
                message(STATUS "Found Irrlicht headers: ${IRRLICHT_INCLUDE_DIR}")
                add_library(IrrlichtMt::IrrlichtMt INTERFACE IMPORTED)
-               target_include_directories(IrrlichtMt::IrrlichtMt INTERFACE "${IRRLICHT_INCLUDE_DIR}")
+               # Note that we can't use target_include_directories() since that doesn't work for IMPORTED targets before CMake 3.11
+               set_target_properties(IrrlichtMt::IrrlichtMt PROPERTIES
+                       INTERFACE_INCLUDE_DIRECTORIES "${IRRLICHT_INCLUDE_DIR}")
        else()
                message(STATUS "Found IrrlichtMt ${IrrlichtMt_VERSION}")
        endif()