Help using CMake on Windows

[Gold856]

I was trying to build allwpilib and robot code with CMake as an experiment, and while it mostly worked, there were some weird hiccups that I would like some help dealing with.
For reference, CMake is generating Visual Studio 17 2022 files and I'm building in Release mode and using the Configuration Manager to turn on installs. I'm also using default configs. I have the latest main checked out.
First, wpilibNewCommands doesn't want to play nice with CMake. When I tried installing allwpilib, I get this error:

CMake Error at wpilibNewCommands/cmake_install.cmake:40 (file):
  file INSTALL cannot find
  "C:/Users/gold/OneDrive/Documents/GitHub/allwpilib/wpilibNewCommands/wpilibNewCommands-config.cmake":
  No error.
Call Stack (most recent call first):
  cmake_install.cmake:57 (include)

Looking at wpilibNewCommands' cmake-install.cmake file, I see this not far down:

if(CMAKE_INSTALL_COMPONENT STREQUAL "Unspecified" OR NOT CMAKE_INSTALL_COMPONENT)
  file(INSTALL DESTINATION "${CMAKE_INSTALL_PREFIX}/share/wpilibNewCommands" TYPE FILE FILES "C:/Users/gold/OneDrive/Documents/GitHub/allwpilib/wpilibNewCommands/wpilibNewCommands-config.cmake")
endif()

Later on, I see a similar entry, but this time, it points to the build directory, not the source directory.

if(CMAKE_INSTALL_COMPONENT STREQUAL "Unspecified" OR NOT CMAKE_INSTALL_COMPONENT)
  file(INSTALL DESTINATION "${CMAKE_INSTALL_PREFIX}/share/wpilibNewCommands" TYPE FILE FILES "C:/Users/gold/OneDrive/Documents/GitHub/build/wpilibNewCommands-config.cmake")
endif()

Since wpilibNewCommands has a .cmake.in file, I suspected that was somehow related. So I looked into the cmake-install.cmake file for wpimath, which has a similar file. The only similar line is this:

if(CMAKE_INSTALL_COMPONENT STREQUAL "Unspecified" OR NOT CMAKE_INSTALL_COMPONENT)
  file(INSTALL DESTINATION "${CMAKE_INSTALL_PREFIX}/share/wpimath" TYPE FILE FILES "C:/Users/gold/OneDrive/Documents/GitHub/build/wpimath-config.cmake")
endif()

Which references the build directory, not the source directory. So that first snippet (the one that references the source directory) looks to be the problem. Something in wpilibNewCommands' CMake file is causing that rogue line which prevents an install. Note that when I'm not installing, and just building, there's no problem at all. I'm not familiar enough with CMake to figure out why wpilibNewCommands' cmake-install.cmake gets generated like that, and wpimath's is perfectly fine. My workaround was to drop the .in from the file name, which allows the install to finish.

The next thing I ran into was that it seems like some of the libraries can't be used from an external CMake project. If you use the CMakeLists.txt from README-CMake and try to add wpilibNewCommands as a library and include a file, Visual Studio will say it can't find the source file. I also tried it with apriltags and got the same result. I determined this was because it wasn't added as a dependency in the wpilib-config.cmake.in. So this is a question of what to include and what not to include (everything else? Apriltags and commands?)

Other than that, I love CMake builds! It builds so much faster than Gradle, so thanks!

[calcmogul]

Yea, I noticed a few days ago that the wpilibNewCommands install was broken on Linux. Idk how to fix it.

It doesn't seem to affect all of the targets though. wpiutil and wpimath install fine: https://aur.archlinux.org/cgit/aur.git/tree/PKGBUILD?h=wpimath

[Gold856]

I think I fixed it. When I disabled Java, it worked fine, and so I compared the install command in the Java section to the one outside of it. The Java one currently is install(FILES wpilibNewCommands-config.cmake DESTINATION ${wpilibNewCommands_config_dir}) while the other one is install(FILES ${WPILIB_BINARY_DIR}/wpilibNewCommands-config.cmake DESTINATION ${wpilibNewCommands_config_dir}). I copied the non-Java install command and replaced the Java one, and it built from scratch with no problems. Looks like we really were telling CMake to use the source directory instead of the build directory. It should now refer to the build directory.