c++ - 使用Cmake构建PCL教程时如何处理 'Policy CMP0074 is not set'警告？

Question

我想完成这个基础教程: http://pointclouds.org/documentation/tutorials/writing_pcd.php#writing-pcd

非常简单。当我准备 CMakeLists.txt 和 .cpp 文件时，我使用 CMake GUI 运行它们并收到此警告。我安装了 PCL 1.9.1，所以我为 Visual Studio 2017 64x 构建了文件。

Selecting Windows SDK version 10.0.17134.0 to target Windows 10.0.17763.
The C compiler identification is MSVC 19.15.26726.0
The CXX compiler identification is MSVC 19.15.26726.0
Check for working C compiler: C:/Program Files (x86)/Microsoft Visual Studio/2017/Community/VC/Tools/MSVC/14.15.26726/bin/Hostx86/x64/cl.exe
Check for working C compiler: C:/Program Files (x86)/Microsoft Visual Studio/2017/Community/VC/Tools/MSVC/14.15.26726/bin/Hostx86/x64/cl.exe -- works
Detecting C compiler ABI info
Detecting C compiler ABI info - done
Detecting C compile features
Detecting C compile features - done
Check for working CXX compiler: C:/Program Files (x86)/Microsoft Visual Studio/2017/Community/VC/Tools/MSVC/14.15.26726/bin/Hostx86/x64/cl.exe
Check for working CXX compiler: C:/Program Files (x86)/Microsoft Visual Studio/2017/Community/VC/Tools/MSVC/14.15.26726/bin/Hostx86/x64/cl.exe -- works
Detecting CXX compiler ABI info
Detecting CXX compiler ABI info - done
Detecting CXX compile features
Detecting CXX compile features - done
CMake Warning (dev) at CMakeLists.txt:5(find_package):
  Policy CMP0074 is not set: find_package uses <PackageName>_ROOT variables.
  Run "cmake --help-policy CMP0074" for policy details.
  Use the cmake_policy command to set the policy and suppress this warning.

    Environment variable PCL_ROOT is set to:

      C:\libraries\PCL 1.9.1

   For compatibility, CMake is ignoring the variable. This warning is for project developers.  Use -Wno-dev to suppress it.

Found Eigen: C:/libraries/PCL 1.9.1/3rdParty/Eigen/eigen3
Eigen found (include: C:/libraries/PCL 1.9.1/3rdParty/Eigen/eigen3, version: 3.3.5)
Looking for pthread.h
Looking for pthread.h - not found
Found Threads: TRUE
Found Boost: C:/libraries/PCL 1.9.1/3rdParty/Boost/include/boost-1_68 (found suitable version "1.68.0", minimum required is "1.40.0") found components: system filesystem thread date_time iostreams serialization chrono atomic regex
Found FLANN: C:/libraries/PCL 1.9.1/3rdParty/FLANN/lib/flann_cpp_s.lib   FLANN found (include: C:/libraries/PCL 1.9.1/3rdParty/FLANN/include, lib: optimized;C:/libraries/PCL 1.9.1/3rdParty/FLANN/lib/flann_cpp_s.lib;debug;C:/libraries/PCL 1.9.1/3rdParty/FLANN/lib/flann_cpp_s-gd.lib)
FLANN found (include: C:/libraries/PCL 1.9.1/3rdParty/FLANN/include, lib: optimized;C:/libraries/PCL 1.9.1/3rdParty/FLANN/lib/flann_cpp_s.lib;debug;C:/libraries/PCL 1.9.1/3rdParty/FLANN/lib/flann_cpp_s-gd.lib)
Found OpenNI2: C:/libraries/OpenNI2/Lib/OpenNI2.lib
OpenNI2 found (include: C:/libraries/OpenNI2/Include, lib: C:/libraries/OpenNI2/Lib/OpenNI2.lib)
OpenNI2 found (include: C:/libraries/OpenNI2/Include, lib: C:/libraries/OpenNI2/Lib/OpenNI2.lib)
Found Qhull: optimized;C:/libraries/PCL 1.9.1/3rdParty/Qhull/lib/qhullstatic.lib;debug;C:/libraries/PCL 1.9.1/3rdParty/Qhull/lib/qhullstatic_d.lib
QHULL found (include: C:/libraries/PCL 1.9.1/3rdParty/Qhull/include, lib: optimized;C:/libraries/PCL 1.9.1/3rdParty/Qhull/lib/qhullstatic.lib;debug;C:/libraries/PCL 1.9.1/3rdParty/Qhull/lib/qhullstatic_d.lib)
looking for PCL_COMMON
Found PCL_COMMON: C:/libraries/PCL 1.9.1/lib/pcl_common_release.lib  
looking for PCL_KDTREE
Found PCL_KDTREE: C:/libraries/PCL 1.9.1/lib/pcl_kdtree_release.lib   looking for PCL_OCTREE
Found PCL_OCTREE: C:/libraries/PCL 1.9.1/lib/pcl_octree_release.lib  
looking for PCL_SEARCH
Found PCL_SEARCH: C:/libraries/PCL 1.9.1/lib/pcl_search_release.lib
looking for PCL_SAMPLE_CONSENSUS
Found PCL_SAMPLE_CONSENSUS: C:/libraries/PCL 1.9.1/lib/pcl_sample_consensus_release.lib
looking for PCL_FILTERS
Found PCL_FILTERS: C:/libraries/PCL 1.9.1/lib/pcl_filters_release.lib 
looking for PCL_2D
Found PCL_2D: C:/libraries/PCL 1.9.1/include/pcl-1.9
looking for PCL_GEOMETRY
Found PCL_GEOMETRY: C:/libraries/PCL 1.9.1/include/pcl-1.9
looking for PCL_IO
Found PCL_IO: C:/libraries/PCL 1.9.1/lib/pcl_io_release.lib
looking for PCL_FEATURES
Found PCL_FEATURES: C:/libraries/PCL 1.9.1/lib/pcl_features_release.lib   looking for PCL_ML
Found PCL_ML: C:/libraries/PCL 1.9.1/lib/pcl_ml_release.lib
looking for PCL_SEGMENTATION
Found PCL_SEGMENTATION: C:/libraries/PCL 1.9.1/lib/pcl_segmentation_release.lib
looking for PCL_VISUALIZATION
Found PCL_VISUALIZATION: C:/libraries/PCL 1.9.1/lib/pcl_visualization_release.lib
looking for PCL_SURFACE
Found PCL_SURFACE: C:/libraries/PCL 1.9.1/lib/pcl_surface_release.lib 
looking for PCL_REGISTRATION
Found PCL_REGISTRATION: C:/libraries/PCL 1.9.1/lib/pcl_registration_release.lib
looking for PCL_KEYPOINTS
Found PCL_KEYPOINTS: C:/libraries/PCL 1.9.1/lib/pcl_keypoints_release.lib
looking for PCL_TRACKING
Found PCL_TRACKING: C:/libraries/PCL 1.9.1/lib/pcl_tracking_release.lib  
looking for PCL_RECOGNITION
Found PCL_RECOGNITION: C:/libraries/PCL 1.9.1/lib/pcl_recognition_release.lib
looking for PCL_STEREO
Found PCL_STEREO: C:/libraries/PCL 1.9.1/lib/pcl_stereo_release.lib  
looking for PCL_OUTOFCORE
Found PCL_OUTOFCORE: C:/libraries/PCL 1.9.1/lib/pcl_outofcore_release.lib
looking for PCL_PEOPLE
Found PCL_PEOPLE: C:/libraries/PCL 1.9.1/lib/pcl_people_release.lib
Found PCL: pcl_common;pcl_kdtree;pcl_octree;pcl_search;pcl_sample_consensus;pcl_filters;pcl_io;pcl_features;pcl_ml;pcl_segmentation;pcl_visualization;pcl_surface;pcl_registration;pcl_keypoints;pcl_tracking;pcl_recognition;pcl_stereo;pcl_outofcore;pcl_people;optimized;C:/libraries/PCL 1.9.1/3rdParty/Boost/lib/libboost_system-vc141-mt-x64-1_68.lib;debug;C:/libraries/PCL 1.9.1/3rdParty/Boost/lib/libboost_system-vc141-mt-gd-x64-1_68.lib;optimized;C:/libraries/PCL 1.9.1/3rdParty/Boost/lib/libboost_filesystem-vc141-mt-x64-1_68.lib;debug;C:/libraries/PCL 1.9.1/3rdParty/Boost/lib/libboost_filesystem-vc141-mt-gd-x64-1_68.lib;optimized;C:/libraries/PCL 1.9.1/3rdParty/Boost/lib/libboost_thread-vc141-mt-x64-1_68.lib;debug;C:/libraries/PCL 1.9.1/3rdParty/Boost/lib/libboost_thread-vc141-mt-gd-x64-1_68.lib;optimized;C:/libraries/PCL 1.9.1/3rdParty/Boost/lib/libboost_date_time-vc141-mt-x64-1_68.lib;debug;C:/libraries/PCL 1.9.1/3rdParty/Boost/lib/libboost_date_time-vc141-mt-gd-x64-1_68.lib;optimized;C:/libraries/PCL 1.9.1/3rdParty/Boost/lib/libboost_iostreams-vc141-mt-x64-1_68.lib;debug;C:/libraries/PCL 1.9.1/3rdParty/Boost/lib/libboost_iostreams-vc141-mt-gd-x64-1_68.lib;optimized;C:/libraries/PCL 1.9.1/3rdParty/Boost/lib/libboost_serialization-vc141-mt-x64-1_68.lib;debug;C:/libraries/PCL 1.9.1/3rdParty/Boost/lib/libboost_serialization-vc141-mt-gd-x64-1_68.lib;optimized;C:/libraries/PCL 1.9.1/3rdParty/Boost/lib/libboost_chrono-vc141-mt-x64-1_68.lib;debug;C:/libraries/PCL 1.9.1/3rdParty/Boost/lib/libboost_chrono-vc141-mt-gd-x64-1_68.lib;optimized;C:/libraries/PCL 1.9.1/3rdParty/Boost/lib/libboost_atomic-vc141-mt-x64-1_68.lib;debug;C:/libraries/PCL 1.9.1/3rdParty/Boost/lib/libboost_atomic-vc141-mt-gd-x64-1_68.lib;optimized;C:/libraries/PCL 1.9.1/3rdParty/Boost/lib/libboost_regex-vc141-mt-x64-1_68.lib;debug;C:/libraries/PCL 1.9.1/3rdParty/Boost/lib/libboost_regex-vc141-mt-gd-x64-1_68.lib;optimized;C:/libraries/PCL 1.9.1/3rdParty/Qhull/lib/qhullstatic.lib;debug;C:/libraries/PCL 1.9.1/3rdParty/Qhull/lib/qhullstatic_d.lib;C:/libraries/OpenNI2/Lib/OpenNI2.lib;optimized;C:/libraries/PCL 1.9.1/3rdParty/FLANN/lib/flann_cpp_s.lib;debug;C:/libraries/PCL 1.9.1/3rdParty/FLANN/lib/flann_cpp_s-gd.lib;vtksys;vtkCommonCore;vtkCommonMath;vtkCommonMisc;vtkCommonSystem;vtkCommonTransforms;vtkCommonDataModel;vtkCommonColor;vtkCommonExecutionModel;vtkCommonComputationalGeometry;vtkFiltersCore;vtkFiltersGeneral;vtkImagingCore;vtkImagingFourier;vtkalglib;vtkFiltersStatistics;vtkFiltersExtraction;vtkInfovisCore;vtkFiltersGeometry;vtkFiltersSources;vtkRenderingCore;vtkzlib;vtkfreetype;vtkRenderingFreeType;vtkRenderingContext2D;vtkChartsCore;vtkDICOMParser;vtklz4;vtkIOCore;vtkIOLegacy;vtkexpat;vtkIOXMLParser;vtkDomainsChemistry;vtkIOXML;vtkParallelCore;vtkFiltersAMR;vtkFiltersFlowPaths;vtkFiltersGeneric;vtkImagingSources;vtkFiltersHybrid;vtkFiltersHyperTree;vtkImagingGeneral;vtkFiltersImaging;vtkFiltersModeling;vtkFiltersParallel;vtkFiltersParallelImaging;vtkFiltersPoints;vtkFiltersProgrammable;vtkFiltersSMP;vtkFiltersSelection;vtkFiltersTexture;vtkFiltersTopology;verdict;vtkFiltersVerdict;vtkmetaio;vtkjpeg;vtkpng;vtktiff;vtkIOImage;vtkImagingHybrid;vtkInfovisLayout;vtkInteractionStyle;vtkImagingColor;vtkRenderingAnnotation;vtkRenderingVolume;vtkInteractionWidgets;vtkViewsCore;vtkproj4;vtkGeovisCore;vtkhdf5_hl;vtkhdf5;vtkIOAMR;vtkIOEnSight;vtkNetCDF;vtkexoIIc;vtkIOExodus;vtkRenderingOpenGL;vtkRenderingContextOpenGL;vtkgl2ps;vtkRenderingGL2PS;vtklibharu;vtkIOExport;vtkRenderingLabel;vtkIOExportOpenGL;vtkIOGeometry;vtkIOImport;vtklibxml2;vtkIOInfovis;vtkIOLSDyna;vtkIOMINC;vtkoggtheora;vtkIOMovie;vtknetcdfcpp;vtkIONetCDF;vtkIOPLY;vtkjsoncpp;vtkIOParallel;vtkIOParallelXML;vtksqlite;vtkIOSQL;vtkIOTecplotTable;vtkIOVideo;vtkImagingMath;vtkImagingMorphological;vtkImagingStatistics;vtkImagingStencil;vtkInteractionImage;vtkRenderingImage;vtkRenderingLIC;vtkRenderingLOD;vtkRenderingVolumeOpenGL;vtkViewsContext2D;vtkViewsInfovis (Required is at least version "1.2")
Configuring done
Generating done

构建后，当我单击打开项目并运行它时，出现此错误。

有什么解决办法吗？

Answer 1

CMP0074 警告并不是您作为用户真正需要担心的问题。这是对 CMakeLists.txt 开发人员的警告，表明 CMake 中的行为已更改。

https://cmake.org/cmake/help/latest/policy/CMP0074.html

In CMake 3.12 and above the find_package() command now searches prefixes specified by the _ROOT CMake variable and the ROOT environment variable. Package roots are maintained as a stack so nested calls to all find* commands inside find modules also search the roots as prefixes. This policy provides compatibility with projects that have not been updated to avoid using _ROOT variables for other purposes.

The OLD behavior for this policy is to ignore _ROOT variables. The NEW behavior for this policy is to use _ROOT variables.

基本上，警告是 CMakeLists.txt 的开发人员尚未设置启用新行为或保留旧行为的策略，但是定义了 PCL_ROOT . CMake 不会自动使用它，因为未启用新行为。

ALL_BUILD 错误消息是因为 ALL_BUILD 目标/项目不是可执行目标。它的目的是强制构建解决方案中的所有项目。要修复该部分，您需要右键单击 Solution Explorer 中的可执行项目/目标，然后单击“将此项目设置为启动项目”