Create Imported Targets before or after find_package_handle_standard_args() call in Find modules?

[hwhsu1231 (Haowei Hsu)]

Hello, CMake Team.

Based on the statistical results, it appears that most of the CMake’s built-in Find modules create Imported Targets after the find_package_handle_standard_args() call in Find modules.

1. Before find_package_handle_standard_args() call:

   • CMake’s FindDoxygen.cmake
   • VTK’s FindFFMPEG.cmake

2. After find_package_handle_standard_args() call:

   • CMake’s FindGTest.cmake
   • CMake’s FindOpenGL.cmake
   • CMake’s FindGLEW.cmake
   • CMake’s FindGDAL.cmake
   • CMake’s FindOpenSSL.cmake
   • CMake’s FindZLIB.cmake
   • CMake’s FindGLUT.cmake
   • VTK’s FindEigen3.cmake
   • VTK’s Findutf8cpp.cmake

I’m curious about what are the benefits of this practice?

And is it generally recommended to create Imported Targets after the find_package_handle_standard_args() call in Find modules?

[ben.boeckel (Ben Boeckel (Kitware))]

It is better to make the targets only if the package is actually found as a whole. This avoids “FOUND is false, but I still have targets?”. I’ll fix at least VTK’s FFMPEG module. Thanks.

[ben.boeckel (Ben Boeckel (Kitware))]

Ah…FFMPEG is a bit special in that it has a lot wrapped up in functions. Splitting that out seems a bit more than a quick fix.