diff -r -U3 flann-1.9.1.old/src/cpp/CMakeLists.txt flann-1.9.1/src/cpp/CMakeLists.txt
--- flann-1.9.1.old/src/cpp/CMakeLists.txt	2018-06-26 11:19:34.073015901 +0300
+++ flann-1.9.1/src/cpp/CMakeLists.txt	2018-06-26 22:21:11.516048223 +0300
@@ -28,8 +28,9 @@
     set_property(TARGET flann_cuda_s PROPERTY COMPILE_DEFINITIONS FLANN_STATIC)
 endif()
 
+file(WRITE "${CMAKE_CURRENT_BINARY_DIR}/empty.cpp")
 if(CMAKE_SYSTEM_NAME STREQUAL "Linux" AND CMAKE_COMPILER_IS_GNUCC)
-    add_library(flann_cpp SHARED "")
+    add_library(flann_cpp SHARED "${CMAKE_CURRENT_BINARY_DIR}/empty.cpp")
     set_target_properties(flann_cpp PROPERTIES LINKER_LANGUAGE CXX)
     target_link_libraries(flann_cpp -Wl,-whole-archive flann_cpp_s -Wl,-no-whole-archive)
 
@@ -83,7 +84,7 @@
     set_property(TARGET flann_s PROPERTY COMPILE_DEFINITIONS FLANN_STATIC)
 
     if(CMAKE_SYSTEM_NAME STREQUAL "Linux" AND CMAKE_COMPILER_IS_GNUCC)
-        add_library(flann SHARED "")
+        add_library(flann SHARED "${CMAKE_CURRENT_BINARY_DIR}/empty.cpp")
         set_target_properties(flann PROPERTIES LINKER_LANGUAGE CXX)
         target_link_libraries(flann -Wl,-whole-archive flann_s -Wl,-no-whole-archive)
     else()