Deprecation warnings about CMake < 3.5.

[1uc]

On cmake==3.27.7 I'm seeing the following warnings:

CMake Deprecation Warning at CMakeLists.txt:1 (cmake_minimum_required):
  Compatibility with CMake < 3.5 will be removed from a future version of
  CMake.

  Update the VERSION argument <min> value or use a ...<max> suffix to tell
  CMake that the project does not need compatibility with older versions.

CMake Deprecation Warning at CMakeLists.txt:2 (cmake_policy):
  Compatibility with CMake < 3.5 will be removed from a future version of
  CMake.

  Update the VERSION argument <min> value or use a ...<max> suffix to tell
  CMake that the project does not need compatibility with older versions.

These might be helpful when picking a default: https://cliutils.gitlab.io/modern-cmake/chapters/intro/dodonot.html (Section: Selecting a minimum in 2022) https://cliutils.gitlab.io/modern-cmake/chapters/intro/newcmake.html

[mgeplf]

@1uc do you happen to know what the plans are for HighFive?

I set the minimum in libsonata, but then I get this:

CMake Deprecation Warning at 3rdparty/HighFive/CMakeLists.txt:1 (cmake_minimum_required):
  Compatibility with CMake < 3.5 will be removed from a future version of
  CMake.

  Update the VERSION argument <min> value or use a ...<max> suffix to tell
  CMake that the project does not need compatibility with older versions.

[1uc]

Ah, that makes a lot of sense. Sorry, for not checking HighFive. The plan is to completely rewrite HighFive's CMake. The rewrite will change things. Hence, I only want to do it in a v3.0.0. Therefore, I'm collecting smaller issues so that if we make a breaking change we can discuss them all in one go; and then pick what we're willing to change/maintain. And that's why nothing is changing in HighFive's CMake.

I should probably try to find out what the effective minimum version for HighFive is and encode that value. Somehow I doubt it's cmake==3.0.0.

[mgeplf]

No worries; pybind is also emitting errors, and I think they'll be fixing it in the next version (at least there is work in progress on that front, from what I can tell). I can still proceed by cleaning up my own mess and setting a minimum version.

I should probably try to find out what the effective minimum version for HighFive is and encode that value. Somehow I doubt it's cmake==3.0.0.

Based on your cliutils link above (very handy, thanks) I settled on 3.16 as a starting point; at least then it's likely I'm not using very old constructs.

[mgeplf]

fixed in #321