[CMake] Set the minimum required version to 3.23

[ferdymercury]

This version of CMake was released in March 2022
https://github.com/Kitware/CMake/releases/tag/v3.23.0

This version is required to use FILE_SETs, which could help towards #16327 and #18419.

[guitargeek]

Unfortunately, we still have older CMake versions on the platforms that we still support:

• ubuntu2204 - cmake version 3.22.1 (end of life April 2027)
• debian125 - cmake version 3.25.1 (end of life 30 Jun 2028)
• alma8 - cmake version 3.26.5
• ubuntu2404 - cmake version 3.28.3
• macOS 14 - cmake version 3.29.5

On Windows, I don't know.

So I think in practice, that means we can only require CMake 3.23+ when Ubuntu 22.04 is end-of-life in two years 🙁

By the way, so far our strategy has been to just use the same minimum CMake version as LLVM.

[ferdymercury]

@dannf @roehling
Is there any remote plan / chance to bump Ubuntu's 22.04 cmake version from 3.22 to 3.23 ?

[github-actions]

Test Results

     9 files       9 suites   1d 2h 57m 39s ⏱️
 3 739 tests  3 739 ✅ 0 💤 0 ❌
33 330 runs  33 330 ✅ 0 💤 0 ❌

Results for commit 10f29c1.

♻️ This comment has been updated with latest results.

[ferdymercury]

So I think in practice, that means we can only require CMake 3.23+ when Ubuntu 22.04 is end-of-life in two years

Question: wouldn't it be an option to ask those users to install cmake from snap or from the official cmake PPA in that corner case?

[ferdymercury]

Thanks, but it seems cmake is not found in the Ubu22 image

[bellenot]

AFAIK, we never force users to take another version of CMake than the one installed by default on the distros. That's what defines the minimal version of CMake. At least it was like this so far. @dpiparo can correct me if I'm wrong

[guitargeek]

Thanks, but it seems cmake is not found in the Ubu22 image

That's just an effect of the incremental build I guess

AFAIK, we never force users to take another version of CMake than the one installed by default on the distros. That's what defines the minimal version of CMake. At least it was like this so far. @dpiparo can correct me if I'm wrong

Yes, that's what we have done so far, but maybe at some point we should discuss if we should keep it like that when Ubuntu doesn't update it's CMake version in 5 years at all. Even RedHat does that.

The only thing that I changed now was to install a newer CMake version on the Ubuntu 22.04 CI image, which is independent of what we require from our users.

[guitargeek]

@ferdymercury, you have any idea what is going on with all these failures? Maybe it would help to rebase the commit on master and push again to this PR branch?

[ferdymercury]

Force-pushing didn't help.

It might be the underlying call to cmake_policy(3.23) causes issues.?

I checked in https://man.archlinux.org/man/cmake-policies.7.en#Policies_Introduced_by_CMake_3.23
but didn't see anything obvious.

Not sure if we need to change anything else in our CMakeLists around these lines:

set(policy_new CMP0072 CMP0076 CMP0077 CMP0079
    CMP0156 CMP0179 #deduplicate static libraries when linker supports it
)
set(policy_old CMP0116 CMP0135 CMP0144)