build: Bump g++ minimum supported version to 12 #33842

1. 
   maflcko commented at 3:03 PM on November 10, 2025: member

   All supported operating systems that previously came with at least g++-11, also come with at least g++-12, so bumping the minimum should be fine.

   For reference:

   • https://packages.ubuntu.com/jammy/g++-12
   • https://packages.ubuntu.com/noble/g++ (g++-13)
   • https://packages.debian.org/bookworm/g++ (g++-12)
   • FreeBSD Ports ship a recent GCC
   • RHEL-based 8, and 9 ship with g++-14 via appstream (dnf install gcc-toolset-14 -> /opt/rh/gcc-toolset-14/)
   • RHEL-based 10 ships with g++ (14 by default)
   • OpenSuse Leap and Tumbleweed ship with g++ 15 https://software.opensuse.org/package/gcc15-c++

   Obviously, downloading pre-compiled releases or compiling previous release branches is unaffected by this change.

2. 
   hebasto commented at 3:33 PM on November 10, 2025: member

   Such a change might also require updating the build guides. For instance, the following commands on Ubuntu 22.04 would use GCC 11:

   sudo apt-get install build-essential ...
   cmake --build build
   

3. maflcko force-pushed on Nov 10, 2025
4. 
   maflcko commented at 3:59 PM on November 10, 2025: member

   Such a change might also require updating the build guides. For instance, the following commands on Ubuntu 22.04 would use GCC 11:

   I am happy to add a general note that the latest stable or LTS is recommended and that earlier releases may need the user to install the required minimum dependencies.

5. maflcko force-pushed on Nov 10, 2025
6. build: Bump g++ minimum supported version to 12 fa807f78ae
7. maflcko force-pushed on Nov 11, 2025
8. TheCharlatan approved
9. 
   TheCharlatan commented at 10:45 AM on November 11, 2025: contributor

   ACK fabf8e51083120883162399293c620f2afc0c5e2

10. hebasto approved
11. 
    hebasto commented at 11:39 AM on November 11, 2025: member

    ACK fabf8e51083120883162399293c620f2afc0c5e2.

12. 
    DrahtBot commented at 11:39 AM on November 11, 2025: contributor

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    Code Coverage & Benchmarks

    For details see: https://corecheck.dev/bitcoin/bitcoin/pulls/33842.

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    Conflicts

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    • #32748 (fees: prevent redundant estimates flushes by ismaelsadeeq)

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13. 
    janb84 commented at 11:41 AM on November 11, 2025: contributor

    lgtm ACK fabf8e51083120883162399293c620f2afc0c5e2

    With the note added I can't think of a reason not to bump the g++ version to version 12.

14. 
    fanquake commented at 12:02 PM on November 11, 2025: member

    Are we keeping gccbug_90348 (for -fstack-reuse bugs), even though it will no-longer reproduce with our supported versions of GCC?

15. fanquake added the label Needs release note on Nov 11, 2025
16. maflcko removed the label Needs release note on Nov 11, 2025
17. DrahtBot added the label Build system on Nov 11, 2025
18. DrahtBot added the label CI failed on Nov 11, 2025
19. util: [refactor] Remove unused create_directories workaround

    This was added in commit 1f46b6e46e1454b91ff7ceb31853bc440952f8eb, but
    is no longer needed after g++-12 is the minimum required.

    fa9dacdbde
20. test: Remove unused fs::create_directories test

    The test was added in commit ddb75c2e87a60ed24065bdf0c3bfabf4e058cef1.
    After the create_directories wrapper removal, the test is redundant with
    the unit test in the upstream stdlib. Also, there is a Bitcoin Core
    functional test that covers this behavior in
    test/functional/feature_dirsymlinks.py
    
    So remove this unit test.
    
    Finally, I could not find a real system that still ships a buggy stdlib
    (v11.2) in their package manager. A stand-alone test is also available
    in compiler-explorer under https://godbolt.org/z/aeMKraYrT.

    fa3854e432
21. maflcko force-pushed on Nov 11, 2025
22. test: Remove gccbug_90348 test case

    The test case no longer detects this specific issue for GCC versions
    12.1+, as explained in the
    https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90348 thread and in this
    compiler-explorer playground:
    https://godbolt.org/z/Y48osrjM8
    
    So remove the test case and update the -fstack-reuse=none cmake
    docstring with the underlying affected GCC versions, and the bug URL.

    fabce97b30
23. ci: Enable experimental kernel stuff in G++-12 task (previous releases)

    Base the task on --preset=dev-mode to ensure maximal coverage and add
    the following:
    
       bitcoin-chainstate (experimental) ... ON
       libbitcoinkernel (experimental) ..... ON
       kernel-test (experimental) .......... ON
    
    Also, shorten the name, for a less cluttered web view.

    faa8be75c9
24. doc: Add GCC-12 min release notes fa1711ee0d
25. doc: Recommend latest Debian stable or Ubuntu LTS fa9f29a4a7
26. maflcko force-pushed on Nov 11, 2025
27. DrahtBot removed the label CI failed on Nov 11, 2025
28. TheCharlatan approved
29. 
    TheCharlatan commented at 8:23 AM on November 12, 2025: contributor

    Re-ACK fa9f29a4a79944f6ffbb58eab0ac41e243fbeb97

30. DrahtBot requested review from hebasto on Nov 12, 2025
31. DrahtBot requested review from janb84 on Nov 12, 2025
32. 
    janb84 commented at 9:13 AM on November 12, 2025: contributor

    re-ACK fa9f29a4a79944f6ffbb58eab0ac41e243fbeb97

33. hebasto approved
34. 
    hebasto commented at 10:10 AM on November 12, 2025: member

    ACK fa9f29a4a79944f6ffbb58eab0ac41e243fbeb97.

35. fanquake merged this on Nov 12, 2025
36. fanquake closed this on Nov 12, 2025

    ---

37. maflcko deleted the branch on Nov 12, 2025
38. in src/test/fs_tests.cpp:165 in fa9f29a4a7

     160 | -
     161 | -    fs::remove(symlink);
     162 | -    fs::remove(dir);
     163 | -}
     164 | -#endif // __MINGW64__
     165 | -
    

    ---

    ---

    

    hebasto commented at 1:17 PM on November 12, 2025:

    Good to see this test gone, as it was annoying to set SeCreateSymbolicLinkPrivilege to make it pass when building natively on Windows.

Review Requested
janb84