build: use UCRT runtime for Windows (release) binaries #30210

1. 
   fanquake commented at 8:56 am on May 31, 2024: member

   Switching to the modern runtime would be good, because the old runtime is missing features, which has meant writing workarounds for Windows in our code: i.e #29014/#29357.

   Mingw-w64 12.0.0 has been released, which now defaults to the UCRT runtime, over MSVCRT. See https://github.com/mingw-w64/mingw-w64/blob/master/mingw-w64-doc/howto-build/ucrt-vs-msvcrt.txt for more details. This makes using it somewhat easier, because we can just use 12.0.0 verbatim, rather than having to configure an older mingw-w64 for the newer runtime.

   • Upstream mingw-w64 12.0.0 into Guix: See https://git.savannah.gnu.org/cgit/guix.git/commit/?id=17188be0f723e00377b21b767f5447d7938a116e.
   • Update Guix time-machine here: #30452.
   • Add CI to cover new runtime.
   • Drop MSVCRT workarounds.
   • Any other documentation / Windows release build configuration updates.
   • A symbol-check that the new runtime is indeed being used.
2. fanquake added the label Windows on May 31, 2024
3. fanquake added the label Build system on May 31, 2024
4. 
   jeandudey commented at 10:32 am on July 4, 2024: none

   I’ve sent a patchset a while ago when working on cross-base updating MinGW to 12.0.0: https://issues.guix.gnu.org/71630.

   Using UCRT will likely need a new target triplet for Guix though like MSYS2 does, e.g. x86_64-w64-ucrt-mingw32.

5. fanquake referenced this in commit 156bf3630f on Jul 16, 2024
6. 
   fanquake commented at 11:04 am on July 16, 2024: member

   I’ve sent a patchset a while ago

   Thanks. That has now landed, so we’ll bump the time machine to get things started here. See #30452.

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12. 
    hebasto commented at 6:51 am on October 30, 2024: member

    Here is another reason to switch to UCRT.

    UPD. Switching to UCRT does not actually resolve the issue mentioned in the referenced comment.

13. 
    hebasto commented at 10:02 am on October 30, 2024: member

    FWIW, here is a way to cross-build UCRT-linked Windows binaries on Fedora 41:

    0$ sudo dnf install ucrt64-gcc-c++
    1$ make -C depends HOST=x86_64-w64-mingw32ucrt mingw32_CC=/usr/bin/x86_64-w64-mingw32ucrt-gcc mingw32_CXX=/usr/bin/x86_64-w64-mingw32ucrt-g++
    2$ cmake -B build --toolchain depends/x86_64-w64-mingw32ucrt/toolchain.cmake
    3$ cmake --build build
    

14. 
    fanquake commented at 2:07 pm on January 21, 2025: member

    Inconsistency in the binaries leading to more workarounds/disabling test code: #31410.
15. 
    hebasto commented at 8:54 pm on February 1, 2025: member

    • Add CI to cover new runtime.

    I’ve added a nightly build with UCRT to https://github.com/hebasto/bitcoin-core-nightly.

    Inconsistency in the binaries leading to more workarounds/disabling test code: #31410.

    It seems that the mentioned issue requires further investigation, as the fix is still needed.

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19. 
    hebasto commented at 8:33 am on May 28, 2025: member

    @jeandudey

    I’ve sent a patchset a while ago when working on cross-base updating MinGW to 12.0.0: https://issues.guix.gnu.org/71630.

    Using UCRT will likely need a new target triplet for Guix though like MSYS2 does, e.g. x86_64-w64-ucrt-mingw32.

    Trying to build mingw-w64 with the deleted --with-default-msvcrt=msvcrt configure option results in a linker error:

    0x86_64-w64-mingw32-ld: src/.libs/libwinpthread_la-thread.o: in function `pthread_create_wrapper':
    1/tmp/guix-build-mingw-w64-x86_64-winpthreads-12.0.0.drv-0/mingw-w64-v12.0.0/mingw-w64-libraries/winpthreads/src/thread.c:1544: undefined reference to `__intrinsic_setjmpex'
    2collect2: error: ld returned 1 exit status
    3make[4]: *** [Makefile:706: libwinpthread.la] Error 1
    

    Any ideas on how to resolve this?

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38. 
    hebasto commented at 6:13 pm on November 11, 2025: member

    • Any other documentation / Windows release build configuration updates.

    See: #33857.

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62. 
    hebasto commented at 11:57 am on November 29, 2025: member

    • Add CI to cover new runtime.

    Since bitcoin/bitcoin#33764 has been merged, this checkbox can now be ticked.

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72. 
    fanquake commented at 3:44 pm on December 3, 2025: member

    Since #33764 has been merged, this checkbox can now be ticked.

    As I mentioned in that PR, neither the headers, or the compiler version, match Guix, so its not exactly testing something similar to how we build releases. That will be improved by #33775.

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79. 
    maflcko commented at 2:17 pm on December 10, 2025: member

    I am seeing a bunch of CI failues in the ucrt task:

    • https://github.com/bitcoin/bitcoin/actions/runs/20090968443/job/57638966158?pr=32800#step:13:203
    • https://github.com/bitcoin/bitcoin/actions/runs/20098915295/job/57665466725#step:13:1494

    Haven’t looked, so not sure what they mean.

Contributors
fanquake jeandudey hebasto maflcko

Labels
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