Set cmake_minimum_required(VERSION 3.22) #175

1. 
   maflcko commented at 2:29 pm on May 15, 2025: contributor

   This PR is doing two different things:

   • It is switching on cmake policies CMP0076-CMP0128
   • It is triggering a fatal error if versions of cmake before 3.22 are used.

   This is a follow-up to the last bump in #164.

   It is unclear why effort should be made to try to support earlier cmake versions than the ones Bitcoin Core is using (https://github.com/bitcoin/bitcoin/blob/e486597f9a57903600656fb5106858941885852f/CMakeLists.txt#L10), because libmultiprocess is currently only used there.

   Moreover, old systems shipping with ancient cmake versions are likely already incompatible due to #205, if they lack the appropriate point release of capnproto.

   Once there is a need or use-case to derive from Bitcoin Core, the policy could be changed then.

   Bumping the minimum could also unlock simpler cmake code, see #163 (comment)

2. hebasto approved
3. 
   hebasto commented at 3:05 pm on May 15, 2025: member

   ACK 3f386cc3e31bd049eb0d069644a4d7188053b4bb.
4. 
   ryanofsky commented at 3:44 pm on May 15, 2025: collaborator

   Concept ~0 assuming #163 is merged first.

   This PR is doing two different things (see #163 (comment))

   1. It is switching on cmake policies CMP0076-CMP0128
   2. It is triggering a fatal error if versions of cmake before 3.22 are used.

   I think the first change is good. The second change seems a like it introduces misleading documentation and an inappropriate error message, but it is not very damaging and seems ok if we want to be paranoid about old versions of cmake doing bad things.

   I would like to see #163 merged first because it is only doing the first thing, not the second thing and I do think it is good to keep these things separate for clarity.

5. 
   maflcko commented at 4:16 pm on May 15, 2025: contributor

   This PR is doing two different things

   correct. Thanks for making it explicit. I like both things and I think it is the most simple and most practical way forward for now.

6. 
   DrahtBot commented at 11:21 am on June 23, 2025: none

   The following sections might be updated with supplementary metadata relevant to reviewers and maintainers.

   Reviews

   See the guideline for information on the review process.

   Type	Reviewers
   ACK	hebasto, fanquake

   If your review is incorrectly listed, please react with 👎 to this comment and the bot will ignore it on the next update.

   Conflicts

   Reviewers, this pull request conflicts with the following ones:

   • #212 (ci: add newdeps job testing newer versions of cmake and capnproto by ryanofsky)
   • #209 (cmake: Increase cmake policy version by ryanofsky)
   • #163 (build: set cmake policy version to 3.31 by purpleKarrot)

   If you consider this pull request important, please also help to review the conflicting pull requests. Ideally, start with the one that should be merged first.

7. 
   maflcko commented at 9:52 am on August 7, 2025: contributor

   For reference, the approach here is also taken by other software projects, like Google-OSS: https://github.com/google/crc32c/pull/68, https://opensource.google/documentation/policies/cplusplus-support
8. 
   fanquake commented at 1:47 pm on September 2, 2025: member

   ACK 3f386cc3e31bd049eb0d069644a4d7188053b4bb - just because it would now match what Core is setting, which seems reasonable.
9. maflcko force-pushed on Sep 22, 2025
10. Set cmake_minimum_required(VERSION 3.22) 34f48d1e8f
11. maflcko force-pushed on Sep 22, 2025
12. hebasto approved
13. 
    hebasto commented at 9:24 am on September 22, 2025: member

    ACK 34f48d1e8f85dcd471c16a14b0bae01c1f2d561d.
14. DrahtBot requested review from fanquake on Sep 22, 2025
15. 
    maflcko commented at 9:37 am on September 22, 2025: contributor

    (Rebased for silent merge conflict. Also, removed now unused ci code. Should be trivial to re-review.)
16. 
    fanquake commented at 8:31 pm on September 22, 2025: member

    ACK 34f48d1e8f85dcd471c16a14b0bae01c1f2d561d
17. 
    ryanofsky commented at 8:21 pm on October 2, 2025: collaborator

    I’m not sure what to do about this PR because I feel like it is not describing itself or the code accurately.

    From the PR description it sounds like it is only dropping support for old versions of cmake but this is not the case, since the changing poilcy version affects behavior of all versions of cmake including the newest ones. I don’t think there is a good reason to tie changes to the policy version and minimum version together, because they are separate concepts and have different effects.

    Writing cmake_minimum_required(VERSION 3.22) also seems misleading because it implies the cmake build requires features present in 3.22, which it doesn’t. This could be fixed by adding a comment, though.

18. 
    maflcko commented at 11:39 am on October 3, 2025: contributor

    thx, adjusted pull description (first section)

Contributors
maflcko hebasto ryanofsky DrahtBot fanquake

Review Requested
fanquake