depends, doc: Learn x86_64-w64-mingw32ucrt host and document it #33857

1. 
   hebasto commented at 5:48 pm on November 11, 2025: member

   This PR is part of the ongoing effort to migrate to the modern UCRT runtime for cross-compiled Windows binaries, including release builds.

   For more details about this migration, see:

   • #30210
   • #33593
   • #33764

   The changes in depends/hosts/mingw32.mk enable automatic detection of cross-compilers for Windows + UCRT, removing the need to specify them explicitly, as shown in the following example:https://github.com/bitcoin/bitcoin/blob/841206c149901fd4731ef28c5a8750f99850d33e/ci/test/00_setup_env_win64.sh#L12

   Can be tested on the following systems:

   • Debian Trixie (requires the g++-mingw-w64-ucrt64 package, as documented).
   • Fedora 42 or 43 (requires the ucrt64-gcc-c++ package).
2. depends, doc: Learn `x86_64-w64-mingw32ucrt` host and document it 483276078e
3. hebasto added the label Docs on Nov 11, 2025
4. hebasto added the label Windows on Nov 11, 2025
5. hebasto added the label Build system on Nov 11, 2025
6. 
   DrahtBot commented at 5:48 pm on November 11, 2025: contributor

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

   Code Coverage & Benchmarks

   For details see: https://corecheck.dev/bitcoin/bitcoin/pulls/33857.

   Reviews

   See the guideline for information on the review process. A summary of reviews will appear here.

   Conflicts

   Reviewers, this pull request conflicts with the following ones:

   • #32162 (depends: Switch from multilib to platform-specific toolchains by hebasto)

   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. 
   hebasto commented at 6:09 pm on November 11, 2025: member

   Can be tested on the following systems:

   • Fedora 42 or 43 (requires the ucrt64-gcc-c++ package).

   For example: https://github.com/hebasto/bitcoin-core-nightly/actions/runs/19274168370.

8. in depends/README.md:141 in 483276078e

   137@@ -137,16 +138,20 @@ The paths are automatically configured and no other options are needed.
   138 
   139 #### For macOS cross compilation
   140 
   141-    apt install clang lld llvm zip
   142+    sudo apt install clang lld llvm zip
   

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   ---

   

   fanquake commented at 9:47 am on November 12, 2025:

   Unrelated change? I don’t think we need to add more sudo usage.
9. in depends/README.md:125 in 483276078e

   121@@ -122,7 +122,8 @@ Common `host-platform-triplet`s for cross compilation are:
   122 
   123 - `i686-pc-linux-gnu` for Linux x86 32 bit
   124 - `x86_64-pc-linux-gnu` for Linux x86 64 bit
   125-- `x86_64-w64-mingw32` for Win64
   126+- `x86_64-w64-mingw32` for Windows using MSVCRT
   

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   fanquake commented at 9:49 am on November 12, 2025:

   How will someone know what to pick here? Should one be marked as deprecated/unsupported?
10. 
    fanquake commented at 3:43 pm on November 12, 2025: member

    If we are migrating, should we just do this at this same time as we actually migrate, then we don’t have to worry about both. Are we dropping support for the old runtime at the same time we switch to using the new ones in releases?

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