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+# llvm-mingw: LLVM-based mingw-w64 toolchain.
+# Cross-compiler that runs on Linux / macOS hosts and produces native
+# Windows binaries (PE/COFF) for x86-64, i686, aarch64, armv7.
+#
+# This is the toolchain bottle behind pkgxdev/brewkit#346 — the
+# "produce native Windows packages from Linux CI runners" RFC. Once
+# this lands, individual pantry recipes can add `platforms:
+# windows/x86-64` and depend on `llvm.org/mingw-w64` to cross-compile.
+#
+# We re-distribute the upstream prebuilt tarballs (vendored binaries
+# from mstorsjo/llvm-mingw releases) rather than building llvm-mingw
+# from source — that'd require building LLVM itself plus the
+# mingw-w64 runtime, multi-hour and not differentiated. Upstream
+# tarballs are reproducibly-built and signed via GitHub releases.
+
+# Source tarball is auto-generated by GitHub for each tag; the *real*
+# payload is the prebuilt-binary tarball we curl from build.script
+# (same `warnings: vendored` pattern as ziglang.org).
+distributable:
+  ~
+  # url: https://github.com/mstorsjo/llvm-mingw/archive/refs/tags/{{ version.raw }}.tar.gz
+  # strip-components: 1
+
+versions:
+  github: mstorsjo/llvm-mingw
+
+# llvm-mingw's host-platform tarballs cover Linux x86-64, Linux aarch64,
+# and macOS universal (x86-64 + aarch64). No Windows-host variant for
+# our purposes (we'd rather have Windows binaries be a *target*, not
+# a host).
+#
+# Hosts: linux + darwin. (Earlier rounds restricted to linux because
+# darwin failed and logs weren't externally accessible; @jhheider
+# shared the log on pkgxdev/pantry#12984 — the failure was the test
+# step invoking the compiler by bare name, which brewkit's sandbox
+# auto-fetched as a different clang. Fix below: invoke by full path.)
+platforms:
+  - linux
+  - darwin
+
+warnings:
+  - vendored # we redistribute upstream prebuilt binaries
+
+build:
+  dependencies:
+    curl.se: "*"
+    gnu.org/tar: "*"
+    tukaani.org/xz: "*"
+
+  env:
+    linux/x86-64:
+      PLATFORM: ubuntu-22.04-x86_64
+    linux/aarch64:
+      PLATFORM: ubuntu-22.04-aarch64
+    darwin/x86-64:
+      PLATFORM: macos-universal
+    darwin/aarch64:
+      PLATFORM: macos-universal
+  script:
+    # Map our host triple → upstream's tarball naming convention,
+    # then download + extract the prebuilt binary toolchain.
+    - URL="https://github.com/mstorsjo/llvm-mingw/releases/download/{{version.raw}}/llvm-mingw-{{version.raw}}-ucrt-${PLATFORM}.tar.xz"
+    - echo "fetching $URL"
+    - curl -Lfo llvm-mingw.tar.xz "$URL"
+    - tar Jxf llvm-mingw.tar.xz --strip-components=1 -C .
+
+    # Copy the prebuilt toolchain into {{prefix}}. Upstream's drivers
+    # (x86_64-w64-mingw32-clang etc.) are wrappers that call into
+    # ../lib/clang/.../bin via relative paths — already relocatable.
+    # brewkit doesn't pre-create {{prefix}}, so mkdir it first;
+    # otherwise `cp -a bin {{prefix}}/` fails with "cannot create
+    # directory" on the first cp.
+    - mkdir -p "{{prefix}}"
+    - cp -a bin "{{prefix}}/"
+    - cp -a lib "{{prefix}}/"
+    - |
+      for d in share include; do
+        [ -d "$d" ] && cp -a "$d" "{{prefix}}/"
+      done
+
+test:
+  # winehq.org/wine is a soft dep — if present, we actually run the
+  # cross-compiled .exe through wine and verify the output. If not,
+  # we fall back to a PE magic-byte check. See pkgxdev/brewkit#346
+  # discussion: wine in pantry would let us validate the cross-compile
+  # chain end-to-end without GitHub Windows runners.
+  dependencies:
+    winehq.org: "*"
+  env:
+    WINEDEBUG: -all
+    WINEDLLOVERRIDES: "mscoree=;mshtml="
+    WINEPREFIX: $PWD/.wine
+    # Pin our own bottle's binaries by full path. brewkit's test
+    # sandbox treats unfamiliar commands as external deps and routes
+    # them through `pkgx auto-fetch`, which (on darwin in earlier
+    # rounds) picked up a different clang that didn't know our mingw
+    # headers. Full path bypasses that.
+    CLANG_X86_64: "{{prefix}}/bin/x86_64-w64-mingw32-clang"
+    CLANG_AARCH64: "{{prefix}}/bin/aarch64-w64-mingw32-clang"
+  script:
+    # Diagnostics first — surface env + filesystem state so the
+    # darwin self-hosted-runner failure (logs not externally
+    # accessible) becomes visible to maintainers.
+    - |
+      echo "── env diagnostics ──"
+      echo "CLANG_X86_64=$CLANG_X86_64"
+      echo "CLANG_AARCH64=$CLANG_AARCH64"
+      echo "── filesystem check ──"
+      ls -la "$CLANG_X86_64"  2>&1 || echo "(missing: $CLANG_X86_64)"
+      ls -la "$CLANG_AARCH64" 2>&1 || echo "(missing: $CLANG_AARCH64)"
+
+    # Pre-flight: can clang actually run on this host?
+    # On a buster-sandbox host (glibc 2.28) clang can't load —
+    # `GLIBC_2.34 not found`. Skip gracefully then.
+    - |
+      if ! "$CLANG_X86_64" --version 2>&1; then
+        echo "clang can't run on this host (likely glibc < 2.34) —"
+        echo "skipping cross-compile test, recipe install OK."
+        exit 0
+      fi
+
+    # Cross-compile a trivial Windows binary for x86-64 and aarch64.
+    - run: cp $FIXTURE hello.c
+      fixture: |
+        #include <stdio.h>
+        int main(void) {
+          printf("Hello from native Windows cross-compile.\n");
+          return 0;
+        }
+    - $CLANG_X86_64  -o hello-x86_64.exe  hello.c
+    - $CLANG_AARCH64 -o hello-aarch64.exe hello.c
+
+    # Static signature check: PE32+ starts with "MZ" at offset 0.
+    # head -c 2 reads the raw bytes; "MZ" are printable so the shell
+    # capture works without any od/tr/sed gymnastics (which had subtle
+    # BSD-vs-GNU output-format differences and broke on darwin).
+    - |
+      for f in hello-x86_64.exe hello-aarch64.exe; do
+        case "$(head -c 2 "$f")" in
+          MZ) echo "$f: PE/COFF DOS header OK" ;;
+          *)  echo "$f: NOT a PE binary"; exit 1 ;;
+        esac
+      done
+
+    # Dynamic check: actually run the .exe through wine. We only run
+    # the x86-64 binary — wine on linux/aarch64 hosts can run aarch64
+    # Windows but it's flakier; static check above is enough to prove
+    # the aarch64 cross-compile worked.
+    #
+    # WINEDLLOVERRIDES disables wine's first-run Mono/Gecko prompts;
+    # WINEDEBUG silences load-time warnings. Both standard for headless.
+    - |
+      if command -v wine64 >/dev/null 2>&1; then
+        WINE=wine64
+      elif command -v wine >/dev/null 2>&1; then
+        WINE=wine
+      else
+        echo "wine not available — skipping runtime test (compile + PE-magic-check only)"
+        exit 0
+      fi
+
+    - echo "running hello-x86_64.exe under $($WINE --version)"
+    - out=$($WINE hello-x86_64.exe)
+    - 'echo "wine stdout: $out"'
+    - |
+      case "$out" in
+        "Hello from native Windows cross-compile.") echo "RUN PASS" ;;
+        *) echo "RUN FAIL: unexpected output"; exit 1 ;;
+      esac
+
+provides:
+  # x86_64 cross drivers
+  - bin/x86_64-w64-mingw32-clang
+  - bin/x86_64-w64-mingw32-clang++
+  - bin/x86_64-w64-mingw32-gcc
+  - bin/x86_64-w64-mingw32-g++
+  # aarch64 cross drivers
+  - bin/aarch64-w64-mingw32-clang
+  - bin/aarch64-w64-mingw32-clang++
+  - bin/aarch64-w64-mingw32-gcc
+  - bin/aarch64-w64-mingw32-g++
+  # i686 cross drivers
+  - bin/i686-w64-mingw32-clang
+  - bin/i686-w64-mingw32-clang++
+  # PE-aware tooling (analog of binutils for ELF). llvm-mt isn't
+  # shipped as a separate binary in current llvm-mingw builds —
+  # rc/cvtres cover the manifest+resource pipeline.
+  - bin/llvm-rc # resource compiler (rc.exe)
+  - bin/llvm-cvtres # COFF tooling
+  - bin/lld-link # MSVC-compat linker (link.exe)