build: Bump clang minimum supported version to 19 #36036

1. 
   maflcko commented at 1:47 PM on August 20, 2026: member

   Most supported operating systems ship with clang-19 (or later), so bump the minimum to that and allow new code to drop workarounds for previous clang bugs.

   (For this bump, only C++20 CTAD will become available.)

   This patch will only be released in version 33.x, next year (2027).

   For reference:

   • https://packages.debian.org/bookworm/clang-22
   • https://packages.ubuntu.com/noble/clang-20
   • CentOS-like 8/9/10 ship clang-21 via Stream
   • Free/Open/Net*BSD ship clang-19
   • OpenSuse Tumbleweed ships with https://software.opensuse.org/package/clang (clang22); leap:latest with clang-19
   • macOS 14: depends/release cross-builds are unaffected and use clang-19
   • macOS 14: Native builds use llvm-19-ish via XCode CLT 26.3 since #36287

   On operating systems where the minimum Clang version is not shipped by default, the user would have to use GCC, or install Clang in a different way. For example:

   • https://packages.debian.org/bookworm/g++ (g++-12)
   • https://packages.ubuntu.com/jammy/g++-12
   • https://apt.llvm.org/, brew, nix, guix, or compile clang from source, ...
2. DrahtBot added the label Build system on Aug 20, 2026
3. 
   DrahtBot commented at 1:47 PM on August 20, 2026: contributor

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   External sites

   • Code coverage & benchmarks: https://corecheck.dev/bitcoin/bitcoin/pulls/36036
   • Ralph review <img src=https://review.fish.foo/assets/bitcoin/bitcoin/36036.png alt="Ralph review status"> https://git.fish.foo/bitcoin/bitcoin/pulls/36036#author-ralph

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   Reviews

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   Type	Reviewers
   ACK	hebasto
   Concept ACK	l0rinc, winterrdog

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   Conflicts

   Reviewers, this pull request conflicts with the following ones:

   • #36042 _{<img src="https://drahtbot.space/ack_count/bitcoin/bitcoin/36042.svg">} (build: Bump g++ minimum supported version to 13 by maflcko)

   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.

   <!--5faf32d7da4f0f540f40219e4f7537a3-->

4. maflcko marked this as a draft on Aug 20, 2026
5. maflcko added this to the milestone 33.0 on Aug 20, 2026
6. maflcko force-pushed on Aug 20, 2026
7. DrahtBot added the label CI failed on Aug 20, 2026
8. maflcko force-pushed on Aug 20, 2026
9. maflcko removed the label CI failed on Aug 20, 2026
10. DrahtBot added the label CI failed on Aug 20, 2026
11. maflcko removed the label CI failed on Aug 20, 2026
12. DrahtBot added the label CI failed on Aug 20, 2026
13. maflcko removed the label CI failed on Aug 20, 2026
14. DrahtBot added the label CI failed on Aug 20, 2026
15. DrahtBot removed the label CI failed on Sep 17, 2026
16. DrahtBot added the label Needs rebase on Oct 8, 2026
17. maflcko force-pushed on Oct 8, 2026
18. DrahtBot removed the label Needs rebase on Oct 8, 2026
19. DrahtBot added the label CI failed on Oct 9, 2026
20. maflcko removed this from the milestone 33.0 on Oct 12, 2026
21. 
    hebasto commented at 11:25 AM on October 20, 2026: member

    Concept ACK.

22. 
    l0rinc commented at 11:47 AM on October 20, 2026: contributor

    Concept ACK, please check if Ralph's objections are valid. Will review properly after it's out of draft - unless you want a detailed review now.

23. maflcko force-pushed on Oct 20, 2026
24. in .github/workflows/ci.yml:32 in d70ec1737b

      28 | @@ -29,7 +29,7 @@ defaults:
      29 |  jobs:
      30 |    test-each-commit:
      31 |      name: 'test ancestor commits'
      32 | -    runs-on: ${{ github.repository == 'bitcoin/bitcoin' && 'warp-ubuntu-latest-x64-8x' || 'ubuntu-latest' }}
      33 | +    runs-on: ${{ github.repository == 'bitcoin/bitcoin' && 'warp-ubuntu-2604-x64-8x' || 'ubuntu-latest' }}
    

    ---

    ---

    

    maflcko commented at 12:07 PM on October 20, 2026:

    re Ralph: Was hoping they change the image in September, like last time (https://github.blog/changelog/2024-09-25-actions-new-images-and-ubuntu-latest-changes/), but I guess not anymore

    ---

    

    maflcko commented at 8:34 AM on October 22, 2026:

    fixed in the last commit

25. maflcko marked this as ready for review on Oct 22, 2026
26. maflcko force-pushed on Oct 22, 2026
27. 
    fanquake commented at 9:38 AM on October 22, 2026: member

    Update https://github.com/bitcoin/bitcoin/blob/2034d3078ee1df99cdbfab738b1f2b54c30bd022/src/test/fuzz/vecdeque.cpp#L459 while here?

28. DrahtBot removed the label CI failed on Oct 22, 2026
29. maflcko force-pushed on Oct 22, 2026
30. DrahtBot added the label CI failed on Oct 22, 2026
31. hebasto approved
32. 
    hebasto commented at 10:24 AM on October 22, 2026: member

    ACK fae84b611f0b209387e7ab25348bb5594d052432.

    nit: Maybe squash the 1st and 3rd commits?

33. DrahtBot requested review from l0rinc on Oct 22, 2026
34. maflcko force-pushed on Oct 22, 2026
35. 
    maflcko commented at 10:46 AM on October 22, 2026: member

    nit: Maybe squash the 1st and 3rd commits?

    I think it is fine to keep the removals separate from the bump. Force pushed to fix a Ralph nit

36. 
    hebasto commented at 11:02 AM on October 22, 2026: member

    re-ACK fa70b1cc63a7762a62bc90e0cdd2950706d456fc.

    nit: Maybe squash the 1st and 3rd commits?

    I think it is fine to keep the removals separate from the bump.

    Not sure I follow which "removals" are referred to here.

37. build: Bump clang minimum supported version to 19

    Also, in ci: test-each-commit: Bump to Ubuntu 26.04
    for clang-18 -> clang-21

    fa0427654f
38. clang-format: Use Standard: Latest

    It should mostly be irrelevant and generally be fine to format any C++
    code with the latest standard version. So set that here, but it can be
    changed in the future, if there is ever a reason.

    fa699076d2
39. refactor: Drop unused libc++-16 workarounds

    Also, drop redundant Clang version requirement mentions.

    faa98fadbc
40. maflcko force-pushed on Oct 22, 2026
41. 
    maflcko commented at 11:27 AM on October 22, 2026: member

    thx, I can't count to 3, squashed now with empty diff

42. DrahtBot removed the label CI failed on Oct 22, 2026
43. hebasto approved
44. 
    hebasto commented at 1:32 PM on October 22, 2026: member

    re-ACK faa98fadbcd2149ce31c0464a7b5e4a600bac5d2.

45. 
    maflcko commented at 11:43 AM on October 27, 2026: member

    cc @winterrdog I see you used Clang 18 in #36160#pullrequestreview-5116887377. Would this change be a problem for you?

46. 
    winterrdog commented at 5:38 PM on October 27, 2026: contributor

    concept ACK

    ---

    re: #36036 (comment)

    Would this change be a problem for you?

    not at all. i can easily switch to clang 20 since i have it installed already

Contributors

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Review Requested
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