ci: Add Windows cross-build and native test jobs

Sjors · Sjors · commit bbe64cff778a · 2026-04-21T20:58:55.000+02:00
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
@@ -127,6 +127,25 @@ jobs:
           export PATH="$(brew --prefix llvm)/bin:$PATH"
           CI_CONFIG="ci/configs/macos.bash" bash ci/scripts/ci.sh
 
+  test-windows-cross:
+    runs-on: windows-latest
+    name: test • windows cross
+    needs: build
+    # GitHub-hosted max, nix build is very slow without cache
+    timeout-minutes: 360
+
+    steps:
+      - uses: actions/checkout@v6
+
+      - name: Download Windows artifacts
+        uses: actions/download-artifact@v8
+        with:
+          name: windows-cross-ucrt-build
+          path: windows-cross-artifact
+
+      - name: Run Windows tests
+        shell: pwsh
+        run: ci/scripts/windows_native_test.ps1 -ArtifactRoot windows-cross-artifact
   build:
     runs-on: ubuntu-latest
 
@@ -142,7 +161,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        config: [default, llvm, gnu32, sanitize, olddeps]
+        config: [default, llvm, gnu32, sanitize, olddeps, windows]
 
     name: build • ${{ matrix.config }}
 
@@ -181,3 +200,18 @@ jobs:
         env:
           CI_CONFIG: ci/configs/${{ matrix.config }}.bash
         run: ci/scripts/run.sh
+
+      - name: Package Windows artifacts
+        if: matrix.config == 'windows'
+        env:
+          CI_CONFIG: ci/configs/${{ matrix.config }}.bash
+        run: |
+          source "$CI_CONFIG"
+          nix develop --ignore-environment --keep CI_CONFIG "${NIX_ARGS[@]+"${NIX_ARGS[@]}"}" -f shell.nix --command bash ci/scripts/windows_package.sh
+
+      - name: Upload Windows artifacts
+        if: matrix.config == 'windows'
+        uses: actions/upload-artifact@v7
+        with:
+          name: windows-cross-ucrt-build
+          path: windows-cross-artifact
diff --git a/ci/configs/windows.bash b/ci/configs/windows.bash
@@ -0,0 +1,53 @@
+CI_DESC="CI job cross-compiling to Windows (MinGW UCRT) and testing with Wine"
+CI_DIR=build-windows
+# Cache the cross-toolchain closure to avoid rebuilding mingw + wine every run.
+CI_CACHE_NIX_STORE=true
+
+# Wine needs a writable prefix and XDG_RUNTIME_DIR to talk to its services.
+# Pre-create the prefix outside of the nix shell so we can plumb it through
+# (the shell uses --ignore-environment).
+export WINEPREFIX="${WINEPREFIX:-$HOME/.wine-libmultiprocess}"
+export WINEARCH="${WINEARCH:-win64}"
+export XDG_RUNTIME_DIR="${XDG_RUNTIME_DIR:-/run/user/$(id -u)}"
+mkdir -p "$WINEPREFIX"
+# Silence wine's verbose warnings about missing Windows features during tests.
+export WINEDEBUG=-all
+
+NIX_ARGS=(
+  --arg minimal true
+  --arg enableWine true
+  --arg crossPkgs 'import <nixpkgs> { crossSystem = { config = "x86_64-w64-mingw32"; libc = "ucrt"; }; }'
+  # Wine stores its prefix under $HOME; preserve HOME so wineboot can initialize.
+  --keep HOME
+  --keep WINEPREFIX
+  --keep WINEARCH
+  --keep WINEDEBUG
+  --keep XDG_RUNTIME_DIR
+)
+export CXXFLAGS="-Werror -Wall -Wextra -Wpedantic -Wno-unused-parameter -Wa,-mbig-obj"
+
+# When sourced from inside the nix shell (during ci.sh), initialize wine and
+# pick up native capnp tools to use for build-time code generation. These
+# steps are no-ops when sourced from outside the shell (e.g. by run.sh).
+if command -v wineboot >/dev/null 2>&1; then
+  wineboot --init >/dev/null 2>&1 || true
+fi
+CAPNP_NATIVE=$(command -v capnp 2>/dev/null || true)
+CAPNPC_CXX_NATIVE=$(command -v capnpc-c++ 2>/dev/null || true)
+
+CMAKE_ARGS=(
+  -G Ninja
+  # Tell CMake we're targeting Windows so FindThreads picks Win32 threads
+  # and other platform checks behave correctly.
+  -DCMAKE_SYSTEM_NAME=Windows
+  -DCMAKE_SYSTEM_PROCESSOR=x86_64
+  # Run target-arch executables (mpgen, capnpc, mptest) through wine64.
+  -DCMAKE_CROSSCOMPILING_EMULATOR=wine64
+  # Avoid pulling in libgcc_s_seh-1.dll and libstdc++-6.dll at runtime.
+  -DCMAKE_EXE_LINKER_FLAGS="-static-libgcc -static-libstdc++"
+  # Use native capnp/capnpc-c++ for build-time code generation so cmake
+  # doesn't try to exec target-arch .exe binaries directly.
+  ${CAPNP_NATIVE:+-DCAPNP_EXECUTABLE=$CAPNP_NATIVE}
+  ${CAPNPC_CXX_NATIVE:+-DCAPNPC_CXX_EXECUTABLE=$CAPNPC_CXX_NATIVE}
+)
+BUILD_ARGS=(-k 0)
diff --git a/ci/patches/capnproto-cidr-kj-async.patch b/ci/patches/capnproto-cidr-kj-async.patch
@@ -0,0 +1,42 @@
+From a2deb0511dba79f90373c3dc5d45983a574bccfa Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Bj=C3=B6rn=20Sch=C3=A4pers?= <bjoern@hazardy.de>
+Date: Sun, 27 Jul 2025 21:27:59 +0200
+Subject: [PATCH] KJ: Move cidr to kj-async
+
+This is where it belongs.
+
+Backported to v1.1.0 (CMake hunks only) so that on Windows the cidr.c++
+inet_pton/inet_ntop calls land in the kj-async DLL, which already links
+ws2_32. Without this fix, libkj.dll fails to link on mingw with
+"undefined reference to __imp_inet_pton".
+---
+ c++/src/kj/CMakeLists.txt | 3 +--
+ 1 file changed, 1 insertion(+), 2 deletions(-)
+
+diff --git a/c++/src/kj/CMakeLists.txt b/c++/src/kj/CMakeLists.txt
+--- a/c++/src/kj/CMakeLists.txt
++++ b/c++/src/kj/CMakeLists.txt
+@@ -3,7 +3,6 @@
+ 
+ set(kj_sources_lite
+   array.c++
+-  cidr.c++
+   list.c++
+   common.c++
+   debug.c++
+@@ -40,7 +39,6 @@ else()
+ endif()
+ 
+ set(kj_headers
+-  cidr.h
+   common.h
+   units.h
+   memory.h
+@@ -125,6 +123,7 @@ set(kj-async_sources
+   async-io-win32.c++
+   async-io.c++
+   async-io-unix.c++
++  cidr.c++
+   timer.c++
+ )
+ set(kj-async_headers
diff --git a/ci/patches/capnproto-wine-invalid-function.patch b/ci/patches/capnproto-wine-invalid-function.patch
@@ -0,0 +1,29 @@
+From: libmultiprocess CI <ci@invalid>
+Subject: [PATCH] kj: Treat ERROR_INVALID_FUNCTION from
+ GetFileInformationByHandleEx as non-fatal
+
+Newer Wine versions return ERROR_INVALID_FUNCTION (1) instead of
+ERROR_CALL_NOT_IMPLEMENTED (120) when an unsupported FileInfoClass is
+queried via NtQueryInformationFile. The existing fallback only matched
+ERROR_CALL_NOT_IMPLEMENTED, so cap'n proto's KJ filesystem layer
+threw an uncaught exception when running cross-compiled capnp.exe under
+recent Wine. Treat ERROR_INVALID_FUNCTION the same way: skip the sparse
+file space-usage query and continue.
+
+Forwarded: not-needed (CI-only build)
+---
+ c++/src/kj/filesystem-disk-win32.c++ | 3 +++
+ 1 file changed, 3 insertions(+)
+
+--- a/c++/src/kj/filesystem-disk-win32.c++
++++ b/c++/src/kj/filesystem-disk-win32.c++
+@@ -380,6 +380,9 @@
+       case ERROR_CALL_NOT_IMPLEMENTED:
+         // Probably WINE.
+       	break;
++      case ERROR_INVALID_FUNCTION:
++        // Probably newer WINE, which returns this instead of ERROR_CALL_NOT_IMPLEMENTED.
++        break;
+       case ERROR_INVALID_PARAMETER:
+         // Probably VeraCrypt. See https://github.com/capnproto/capnproto/issues/2176
+         break;
diff --git a/ci/scripts/windows_native_test.ps1 b/ci/scripts/windows_native_test.ps1
@@ -0,0 +1,39 @@
+param(
+    [Parameter(Mandatory = $true)]
+    [string]$ArtifactRoot
+)
+
+# Copyright (c) The Bitcoin Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or https://opensource.org/license/mit/.
+
+$ErrorActionPreference = "Stop"
+# Prevent PowerShell 7 from turning native-command stderr into a terminating
+# error before we get a chance to see it.
+$PSNativeCommandUseErrorActionPreference = $false
+
+$artifactPath = (Resolve-Path $ArtifactRoot).Path
+$env:PATH = "$artifactPath;$env:PATH"
+
+$mptest = Join-Path $artifactPath "test\mptest.exe"
+& $mptest 2>&1 | ForEach-Object { "$_" }
+$code = $LASTEXITCODE
+Write-Host ("mptest exit code: {0} (0x{0:X8})" -f $code)
+if ($code -ne 0) {
+    exit $code
+}
+
+$exampleDir = Join-Path $artifactPath "example"
+Push-Location $exampleDir
+try {
+    $output = "2+2`nexit`n" | & ".\mpexample.exe" 2>&1 | Out-String
+    Write-Host $output
+    if ($LASTEXITCODE -ne 0) {
+        exit $LASTEXITCODE
+    }
+    if ($output -notmatch "mpprinter:" -or $output -notmatch "Bye!") {
+        throw "Unexpected mpexample output."
+    }
+} finally {
+    Pop-Location
+}
diff --git a/ci/scripts/windows_package.sh b/ci/scripts/windows_package.sh
@@ -0,0 +1,75 @@
+#!/usr/bin/env bash
+#
+# Copyright (c) The Bitcoin Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or https://opensource.org/license/mit/.
+#
+# Package cross-compiled Windows binaries + runtime DLLs into a directory
+# suitable for uploading as a workflow artifact. Must be run inside the
+# nix shell produced by `ci/configs/windows.bash` so the mingw toolchain
+# (objdump, g++) is on PATH.
+
+export LC_ALL=C.UTF-8
+
+set -o errexit -o nounset -o pipefail -o xtrace
+
+readonly SCRIPT_DIR="$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)"
+readonly REPO_DIR="$(cd -- "${SCRIPT_DIR}/../.." && pwd)"
+
+[ "${CI_CONFIG+x}" ] && source "$CI_CONFIG"
+: "${CI_DIR:=build-windows}"
+
+readonly BUILD_DIR="${REPO_DIR}/${CI_DIR}"
+readonly ARTIFACT_DIR="${REPO_DIR}/windows-cross-artifact"
+
+# Nix's cross stdenv exports these; fall back to the canonical names if not.
+: "${CXX:=x86_64-w64-mingw32-g++}"
+: "${OBJDUMP:=x86_64-w64-mingw32-objdump}"
+
+copy_artifact_file() {
+  install -D -m 0755 "$1" "${ARTIFACT_DIR}/$2"
+}
+
+copy_runtime_dlls() {
+  local exe="$1"
+  local dll dll_path
+  while read -r dll; do
+    [[ -n "${dll}" ]] || continue
+    # Skip DLLs that ship with Windows / Wine.
+    case "${dll}" in
+      ADVAPI32.dll|COMBASE.dll|COMCTL32.dll|GDI32.dll|KERNEL32.dll|OLE32.dll|OLEAUT32.dll|RPCRT4.dll|SHELL32.dll|UCRTBASE.dll|USER32.dll|WS2_32.dll)
+        continue
+        ;;
+    esac
+    dll_path="$(${CXX} -print-file-name="${dll}")"
+    if [[ "${dll_path}" == "${dll}" || ! -f "${dll_path}" ]]; then
+      case "${dll}" in
+        lib*.dll)
+          echo "Could not locate runtime DLL ${dll}." >&2
+          exit 1
+          ;;
+        *)
+          continue
+          ;;
+      esac
+    fi
+    install -D -m 0755 "${dll_path}" "${ARTIFACT_DIR}/${dll}"
+  done < <(${OBJDUMP} -p "${exe}" | awk '/DLL Name: / {print $3}' | sort -u)
+}
+
+rm -rf "${ARTIFACT_DIR}"
+
+readonly EXES=(
+  test/mptest.exe
+  example/mpexample.exe
+  example/mpcalculator.exe
+  example/mpprinter.exe
+)
+
+for exe in "${EXES[@]}"; do
+  copy_artifact_file "${BUILD_DIR}/${exe}" "${exe}"
+done
+
+for exe in "${EXES[@]}"; do
+  copy_runtime_dlls "${BUILD_DIR}/${exe}"
+done
diff --git a/shell.nix b/shell.nix
@@ -6,6 +6,7 @@
 , capnprotoSanitizers ? null # Optional sanitizers to build cap'n proto with
 , cmakeVersion ? null
 , libcxxSanitizers ? null # Optional LLVM_USE_SANITIZER value to use for libc++, see https://llvm.org/docs/CMake.html
+, enableWine ? false # Whether to add wine64 for running cross-compiled Windows binaries
 }:
 
 let
@@ -42,7 +43,24 @@ let
   } // (lib.optionalAttrs (lib.versionOlder capnprotoVersion "0.10") {
     env = { }; # Drop -std=c++20 flag forced by nixpkgs
   }));
-  capnproto = (capnprotoBase.overrideAttrs (old: lib.optionalAttrs (capnprotoSanitizers != null) {
+  # capnproto v1.1.0 puts cidr.c++ in libkj, but it calls inet_pton/inet_ntop
+  # which require ws2_32 on Windows -- only kj-async links ws2_32. Apply the
+  # upstream fix that moves cidr.c++ into kj-async (capnproto@a2deb05).
+  # mingw with mcf thread model also requires _WIN32_WINNT to be defined
+  # before any libstdc++ thread headers are included.
+  capnprotoPatched = capnprotoBase.overrideAttrs (old: lib.optionalAttrs crossPkgs.stdenv.hostPlatform.isMinGW {
+    patches = (old.patches or []) ++ [
+      ./ci/patches/capnproto-cidr-kj-async.patch
+      ./ci/patches/capnproto-wine-invalid-function.patch
+    ];
+    env = (old.env or { }) // {
+      NIX_CFLAGS_COMPILE = lib.concatStringsSep " " [
+        (old.env.NIX_CFLAGS_COMPILE or "")
+        "-D_WIN32_WINNT=0x0601"
+      ];
+    };
+  });
+  capnproto = (capnprotoPatched.overrideAttrs (old: lib.optionalAttrs (capnprotoSanitizers != null) {
     env = (old.env or { }) // {
       CXXFLAGS =
         lib.concatStringsSep " " [
@@ -52,7 +70,14 @@ let
           "-g"
         ];
     };
-  })).override (lib.optionalAttrs enableLibcxx { clangStdenv = llvm.libcxxStdenv; });
+  })).override (
+    if enableLibcxx then { clangStdenv = llvm.libcxxStdenv; }
+    # nixpkgs forces capnproto to be built with clangStdenv, but the mingw
+    # clang wrapper auto-adds `-lgcc_s` to the link line, which doesn't exist
+    # in the mingw GCC runtime layout (see nixpkgs#177129). Fall back to the
+    # GCC cross stdenv when cross-compiling to mingw.
+    else if crossPkgs.stdenv.hostPlatform.isMinGW then { clangStdenv = crossPkgs.stdenv; }
+    else { });
   clang = if enableLibcxx then llvm.libcxxClang else llvm.clang;
   clang-tools = llvm.clang-tools.override { inherit enableLibcxx; };
   cmakeHashes = {
@@ -66,7 +91,7 @@ let
     };
     patches = [];
   })).override { isMinimalBuild = true; };
-in crossPkgs.mkShell {
+in crossPkgs.mkShell ({
   buildInputs = [
     capnproto
   ];
@@ -77,8 +102,29 @@ in crossPkgs.mkShell {
   ] ++ lib.optionals (!minimal) [
     clang
     clang-tools
-  ];
+  ] ++ lib.optional enableWine pkgs.wineWowPackages.stable
+    # When cross-compiling, also expose a native capnp/capnpc-c++ on PATH so
+    # build-time code generators (capnp_generate_cpp) can run on the build host
+    # instead of trying to execute target-arch binaries directly.
+    ++ lib.optional (crossPkgs.stdenv.hostPlatform != crossPkgs.stdenv.buildPlatform) pkgs.capnproto;
 
   # Tell IWYU where its libc++ mapping lives
   IWYU_MAPPING_FILE = if enableLibcxx then "${llvm.libcxx.dev}/include/c++/v1/libcxx.imp" else null;
-}
+} // lib.optionalAttrs (enableWine && crossPkgs.stdenv.hostPlatform.isMinGW) {
+  # Cross-compiled .exe files run under wine64 need the capnproto and mingw
+  # thread runtime DLLs at startup. Wine searches the .exe directory and the
+  # Windows system directory for PE imports, so symlink the required DLLs
+  # into $WINEPREFIX/drive_c/windows/system32 when entering the shell.
+  shellHook = ''
+    if [ -n "''${WINEPREFIX-}" ]; then
+      _mp_sys32="$WINEPREFIX/drive_c/windows/system32"
+      mkdir -p "$_mp_sys32"
+      for _d in ${capnproto}/bin ${crossPkgs.windows.mcfgthreads}/bin; do
+        for _dll in "$_d"/*.dll; do
+          [ -e "$_dll" ] && ln -sf "$_dll" "$_mp_sys32/"
+        done
+      done
+      unset _mp_sys32 _d _dll
+    fi
+  '';
+})
