$NetBSD: patch-src_cpp_CMAkeLists.txt,v 1.1 2021/04/27 15:16:46 thor Exp $

See https://github.com/mariusmuja/flann/issues/443 .

--- src/cpp/CMakeLists.txt.orig	2016-08-05 01:20:50.000000000 +0200
+++ src/cpp/CMakeLists.txt	2020-04-15 21:19:33.106219724 +0200
@@ -29,7 +29,7 @@
 endif()
 
 if(CMAKE_SYSTEM_NAME STREQUAL "Linux" AND CMAKE_COMPILER_IS_GNUCC)
-    add_library(flann_cpp SHARED "")
+    add_library(flann_cpp SHARED "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 +83,7 @@
     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 "empty.cpp")
         set_target_properties(flann PROPERTIES LINKER_LANGUAGE CXX)
         target_link_libraries(flann -Wl,-whole-archive flann_s -Wl,-no-whole-archive)
     else()
--- src/cpp/empty.cpp	1970-01-01 01:00:00.000000000 +0100
+++ src/cpp/empty.cpp	2020-04-15 21:46:36.507084559 +0200
@@ -0,0 +1 @@
+// This is just a dummy to fix the build system.