source: https://git.alpinelinux.org/cgit/aports/tree/testing/flann/cmake.patch?id=fe5137a340af202cefe6b67601af0133b6b660bd
reason: cmake 3.11 fails without it

diff --git a/src/cpp/CMakeLists.txt b/src/cpp/CMakeLists.txt
index 49c53f0..9f19406 100644
--- a/src/cpp/CMakeLists.txt
+++ b/src/cpp/CMakeLists.txt
@@ -28,25 +28,25 @@ if (BUILD_CUDA_LIB)
     set_property(TARGET flann_cuda_s PROPERTY COMPILE_DEFINITIONS FLANN_STATIC)
 endif()
 
-if(CMAKE_SYSTEM_NAME STREQUAL "Linux" AND CMAKE_COMPILER_IS_GNUCC)
-    add_library(flann_cpp SHARED "")
-    set_target_properties(flann_cpp PROPERTIES LINKER_LANGUAGE CXX)
-    target_link_libraries(flann_cpp -Wl,-whole-archive flann_cpp_s -Wl,-no-whole-archive)
-
-    if (BUILD_CUDA_LIB)
-	    cuda_add_library(flann_cuda SHARED "")
-        set_target_properties(flann_cuda PROPERTIES LINKER_LANGUAGE CXX)
-        target_link_libraries(flann_cuda -Wl,-whole-archive flann_cuda_s -Wl,-no-whole-archive)
-        set_property(TARGET flann_cpp_s PROPERTY COMPILE_DEFINITIONS FLANN_USE_CUDA)
-    # 	target_link_libraries(flann_cuda cudpp_x86_64)
-    endif()
-else()
+#if(CMAKE_SYSTEM_NAME STREQUAL "Linux" AND CMAKE_COMPILER_IS_GNUCC)
+#    add_library(flann_cpp SHARED "")
+#    set_target_properties(flann_cpp PROPERTIES LINKER_LANGUAGE CXX)
+#    target_link_libraries(flann_cpp -Wl,-whole-archive flann_cpp_s -Wl,-no-whole-archive)
+#
+#    if (BUILD_CUDA_LIB)
+#	    cuda_add_library(flann_cuda SHARED "")
+#        set_target_properties(flann_cuda PROPERTIES LINKER_LANGUAGE CXX)
+#        target_link_libraries(flann_cuda -Wl,-whole-archive flann_cuda_s -Wl,-no-whole-archive)
+#        set_property(TARGET flann_cpp_s PROPERTY COMPILE_DEFINITIONS FLANN_USE_CUDA)
+#    # 	target_link_libraries(flann_cuda cudpp_x86_64)
+#    endif()
+#else()
     add_library(flann_cpp SHARED ${CPP_SOURCES})
     if (BUILD_CUDA_LIB)
 		cuda_add_library(flann_cuda SHARED ${CPP_SOURCES})
         set_property(TARGET flann_cpp PROPERTY COMPILE_DEFINITIONS FLANN_USE_CUDA)
     endif()
-endif()
+#endif()
 
 set_target_properties(flann_cpp PROPERTIES
    VERSION ${FLANN_VERSION}
@@ -82,17 +82,17 @@ if (BUILD_C_BINDINGS)
     endif()
     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 "")
-        set_target_properties(flann PROPERTIES LINKER_LANGUAGE CXX)
-        target_link_libraries(flann -Wl,-whole-archive flann_s -Wl,-no-whole-archive)
-    else()
+    #if(CMAKE_SYSTEM_NAME STREQUAL "Linux" AND CMAKE_COMPILER_IS_GNUCC)
+    #    add_library(flann SHARED "")
+    #    set_target_properties(flann PROPERTIES LINKER_LANGUAGE CXX)
+    #    target_link_libraries(flann -Wl,-whole-archive flann_s -Wl,-no-whole-archive)
+    #else()
         add_library(flann SHARED ${C_SOURCES})
 
         if(MINGW AND OPENMP_FOUND)
           target_link_libraries(flann gomp)
         endif()
-    endif()
+    #endif()
 
     set_target_properties(flann PROPERTIES
        VERSION ${FLANN_VERSION}

