Merge pull request PointCloudLibrary#5582 from mvieth/find_package_behaviour

Make sure that find_package(PCL) does not leak internals or overwrite variables

Author: mvieth

PCLConfig.cmake.in

@@ -268,7 +268,7 @@ endmacro()
 #                                       `--> component is induced ==> warn and remove it
 #                                                                     from the list
 
-macro(find_external_library _component _lib _is_optional)
+function(find_external_library _component _lib _is_optional)
   if("${_lib}" STREQUAL "boost")
     find_boost()
   elseif("${_lib}" STREQUAL "eigen")
@@ -299,13 +299,20 @@ macro(find_external_library _component _lib _is_optional)
     find_glew()
   elseif("${_lib}" STREQUAL "opengl")
     find_package(OpenGL)
+  elseif("${_lib}" STREQUAL "pcap")
+    find_package(Pcap)
+  elseif("${_lib}" STREQUAL "png")
+    find_package(PNG)
+  else()
+    message(WARNING "${_lib} is not handled by find_external_library")
   endif()
 
   string(TOUPPER "${_component}" COMPONENT)
   string(TOUPPER "${_lib}" LIB)
   string(REGEX REPLACE "[.-]" "_" LIB ${LIB})
   if(${LIB}_FOUND)
     list(APPEND PCL_${COMPONENT}_INCLUDE_DIRS ${${LIB}_INCLUDE_DIRS})
+    set(PCL_${COMPONENT}_INCLUDE_DIRS ${PCL_${COMPONENT}_INCLUDE_DIRS} PARENT_SCOPE)
 
     if(${LIB} MATCHES "VTK")
       if(${${LIB}_VERSION_MAJOR} GREATER_EQUAL 9)
@@ -317,12 +324,16 @@ macro(find_external_library _component _lib _is_optional)
       include(${${LIB}_USE_FILE})
     else()
       list(APPEND PCL_${COMPONENT}_LIBRARY_DIRS "${${LIB}_LIBRARY_DIRS}")
+      set(PCL_${COMPONENT}_LIBRARY_DIRS ${PCL_${COMPONENT}_LIBRARY_DIRS} PARENT_SCOPE)
     endif()
     if(${LIB}_LIBRARIES)
       list(APPEND PCL_${COMPONENT}_LINK_LIBRARIES "${${LIB}_LIBRARIES}")
+      set(PCL_${COMPONENT}_LINK_LIBRARIES ${PCL_${COMPONENT}_LINK_LIBRARIES} PARENT_SCOPE)
+      set(PCL_${LIB}_LIBRARIES ${${LIB}_LIBRARIES} PARENT_SCOPE) # Later appended to PCL_LIBRARIES
     endif()
     if(${LIB}_DEFINITIONS AND NOT ${LIB} STREQUAL "VTK")
       list(APPEND PCL_${COMPONENT}_DEFINITIONS ${${LIB}_DEFINITIONS})
+      set(PCL_${COMPONENT}_DEFINITIONS ${PCL_${COMPONENT}_DEFINITIONS} PARENT_SCOPE)
     endif()
   else()
     if("${_is_optional}" STREQUAL "OPTIONAL")
@@ -339,7 +350,7 @@ macro(find_external_library _component _lib _is_optional)
       endif()
     endif()
   endif()
-endmacro()
+endfunction()
 
 macro(pcl_check_external_dependency _component)
 endmacro()
@@ -658,7 +669,7 @@ endif()
 pcl_remove_duplicate_libraries(PCL_COMPONENTS PCL_LIBRARIES)
 
 # Add 3rd party libraries, as user code might include our .HPP implementations
-list(APPEND PCL_LIBRARIES ${BOOST_LIBRARIES} ${OPENNI_LIBRARIES} ${OPENNI2_LIBRARIES} ${ENSENSO_LIBRARIES} ${davidSDK_LIBRARIES} ${DSSDK_LIBRARIES} ${RSSDK_LIBRARIES} ${RSSDK2_LIBRARIES} ${VTK_LIBRARIES})
+list(APPEND PCL_LIBRARIES ${PCL_BOOST_LIBRARIES} ${PCL_OPENNI_LIBRARIES} ${PCL_OPENNI2_LIBRARIES} ${PCL_ENSENSO_LIBRARIES} ${PCL_davidSDK_LIBRARIES} ${PCL_DSSDK_LIBRARIES} ${PCL_RSSDK_LIBRARIES} ${PCL_RSSDK2_LIBRARIES} ${PCL_VTK_LIBRARIES})
 if (TARGET FLANN::FLANN)
   list(APPEND PCL_LIBRARIES FLANN::FLANN)
 endif()

cmake/Modules/FindFLANN.cmake

@@ -37,6 +37,7 @@
 # Early return if FLANN target is already defined. This makes it safe to run
 # this script multiple times.
 if(TARGET FLANN::FLANN)
+  set(FLANN_FOUND ON)
   return()
 endif()
 

cmake/Modules/Findlibusb.cmake

@@ -36,6 +36,8 @@
 # Early return if libusb target is already defined. This makes it safe to run
 # this script multiple times.
 if(TARGET libusb::libusb)
+  set(libusb_FOUND ON)
+  set(LIBUSB_FOUND ON)
   return()
 endif()
 
@@ -67,6 +69,7 @@ find_package_handle_standard_args(libusb DEFAULT_MSG libusb_LIBRARIES libusb_INC
 mark_as_advanced(libusb_INCLUDE_DIRS libusb_LIBRARIES)
 
 if(libusb_FOUND)
+  set(LIBUSB_FOUND ON)
   add_library(libusb::libusb UNKNOWN IMPORTED)
   set_target_properties(libusb::libusb PROPERTIES INTERFACE_INCLUDE_DIRECTORIES "${libusb_INCLUDE_DIR}")
   set_target_properties(libusb::libusb PROPERTIES IMPORTED_LOCATION "${libusb_LIBRARIES}")

doc/tutorials/content/sources/cmake_test/CMakeLists.txt

@@ -0,0 +1,15 @@
+cmake_minimum_required(VERSION 3.5 FATAL_ERROR)
+
+# This is not really a tutorial, but instead tests the behaviour of find_package(PCL) when built together with the other tutorials
+project(cmake_test)
+
+set(BOOST_LIBRARIES "boost_dont_overwrite")
+set(Boost_LIBRARIES "boost_dont_overwrite")
+find_package(PCL REQUIRED)
+
+if(NOT "${BOOST_LIBRARIES}" STREQUAL "boost_dont_overwrite")
+  message(FATAL_ERROR "find_package(PCL) changed the value of BOOST_LIBRARIES")
+endif()
+if(NOT "${Boost_LIBRARIES}" STREQUAL "boost_dont_overwrite")
+  message(FATAL_ERROR "find_package(PCL) changed the value of Boost_LIBRARIES")
+endif()