Use cmake 3.22.1 features in Ionic

[scpeters]

Desired behavior

The next major release of gz-cmake will be supported on newer distributions with newer versions of cmake than version 3.10.2 that is currently used in gz-cmake3. We should identify which version of cmake we can target in order to use those new features.

Alternatives considered

Continue using cmake 3.10.2.

Implementation suggestion

Look into updating the following places where it is suggested that a new version of cmake will allow changes:

• GzFindPackage.cmake:286-328
• Find python directly in downstream packages so that GzPython.cmake can be deprecated
  • Find python directly instead of using GzPython gz-math#588
  • Find python directly instead of using GzPython gz-physics#625
  • Find python directly instead of using GzPython gz-rendering#990
• Deprecate GzPython.cmake #431
• gz-config.cmake.in:86-88
• FindSQLite3.cmake (see FindSQLite3.cmake shadows a module with the same name in upstream CMake with differnt target name #312 (comment) and traversaro@a61bfc5)
• In downstream packages with python bindings, there are checks for cmake version >= 3.12 like in gz-math
  • Enable 24.04 CI, remove distutils dependency gz-math#587
  • Enable 24.04 CI, remove distutils dependency sdformat#1408
  • Enable 24.04 CI, require cmake 3.22.1 gz-transport#504
  • Enable 24.04 CI, require cmake 3.22.1 gz-sim#2420
• Require cmake 3.22.1 in all Ionic packages
  • gz-cmake4 Require cmake version 3.22.1 #396
  • gz-utils3
  • gz-math8 Enable 24.04 CI, remove distutils dependency gz-math#587
  • sdformat15 Enable 24.04 CI, remove distutils dependency sdformat#1408
  • gz-plugin3 Enable 24.04 CI, require cmake 3.22.1 gz-plugin#146
  • gz-common6
  • gz-rendering9
  • gz-physics8
  • gz-msgs11 Enable 24.04 CI, require cmake 3.22.1 gz-msgs#444
  • gz-transport13 Enable 24.04 CI, require cmake 3.22.1 gz-transport#504
  • gz-fuel-tools10
  • gz-gui9
  • gz-sensors9
  • gz-sim9 Enable 24.04 CI, require cmake 3.22.1 gz-sim#2420
  • gz-launch8

Additional context

[scpeters]

For reference:

• Ubuntu 20.04 includes cmake 3.16.3
• Ubuntu 22.04 includes cmake 3.22.1

[Bi0T1N]

A brief summary of additions can be found here. Simpler than checking all the release notes.

Here is an initial list:

• FindPython (CMake 3.12 but got enhancements in almost each new release)
• More support for generator expressions (CMake 3.16)
• FindCUDAToolkit (CMake 3.17) (maybe more important for downstream AI projects or if the waves in gz-rendering are ported from OpenGL Shading Language)
• Support for C++20 (CMake 3.12) and C++23 (CMake 3.20)
• Colored messages based on message type (CMake 3.21)

[scpeters]

since Harmonic has already dropped support for 20.04, I think we can target cmake 3.22.1 since that is in 22.04

[scpeters]

bumping the required cmake version in gz-cmake4 to 3.22.1 in #396

we can start using new features in follow-up pull requests

[scpeters]

having worked with some of the find_package(Python3) logic, I think we should just deprecate GzPython

[mjcarroll]

having worked with some of the find_package(Python3) logic, I think we should just deprecate GzPython

I'm always in favor of less code!

[mjcarroll]

Just a note that cmake_path can be used for path manipulation in 3.20+ and may tidy up code: https://cmake.org/cmake/help/latest/command/cmake_path.html

[scpeters]

If we decide not to support Ubuntu 22.04 with Ionic, we could increase the required cmake version to 3.28.3:

• https://packages.ubuntu.com/noble/cmake

[scpeters]

I just noticed from What's new in cmake that the create_symlink command can now be used on Windows as of version 3.13:

• https://cmake.org/cmake/help/latest/release/3.13.html#command-line