Build with the official Swift Android SDK 6.3.2 in Docker

.github/docker/Dockerfile

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+# Build image for cross-compiling the package with the official
+# Swift SDK for Android.
+FROM swift:6.3.2-noble
+
+ARG SWIFT_SDK_URL=https://download.swift.org/swift-6.3.2-release/android-sdk/swift-6.3.2-RELEASE/swift-6.3.2-RELEASE_android.artifactbundle.tar.gz
+ARG SWIFT_SDK_CHECKSUM=939e933549d12d28f2e0bf71019d734d309859e9773c572657ce565a81f85d68
+ARG ANDROID_NDK_VERSION=r27d
+
+ENV ANDROID_NDK_HOME=/usr/local/lib/android/sdk/ndk/${ANDROID_NDK_VERSION}
+
+RUN apt-get update \
+    && apt-get install -y --no-install-recommends ca-certificates curl unzip \
+    && rm -rf /var/lib/apt/lists/*
+
+# the Swift SDK links against the NDK sysroot, which it does not bundle
+RUN mkdir -p "$(dirname "$ANDROID_NDK_HOME")" \
+    && curl -fsSL -o /tmp/ndk.zip \
+        "https://dl.google.com/android/repository/android-ndk-${ANDROID_NDK_VERSION}-linux.zip" \
+    && unzip -q /tmp/ndk.zip -d /tmp \
+    && mv "/tmp/android-ndk-${ANDROID_NDK_VERSION}" "$ANDROID_NDK_HOME" \
+    && rm /tmp/ndk.zip
+
+RUN swift sdk install "$SWIFT_SDK_URL" --checksum "$SWIFT_SDK_CHECKSUM" \
+    && swift sdk list
+
+# the bundle ships a script that links the NDK sysroot, the clang resource
+# directory and swiftrt.o into place, using ANDROID_NDK_HOME
+RUN BUNDLE=$(dirname "$(find / -path '*swift-sdks*' -name 'swift-sdk.json' | head -1)") \
+    && "$BUNDLE/scripts/setup-android-sdk.sh" \
+    && test -f "$BUNDLE/ndk-sysroot/usr/include/jni.h"
+
+WORKDIR /package

.github/workflows/docker.yml

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+name: Docker
+
+on:
+  push:
+    branches: [master]
+  workflow_dispatch:
+  pull_request:
+
+jobs:
+  android:
+    name: Android (Swift SDK ${{ matrix.swift }} / API ${{ matrix.android-api }} / ${{ matrix.arch }})
+    runs-on: ubuntu-24.04
+    timeout-minutes: 90
+    strategy:
+      fail-fast: false
+      matrix:
+        swift: ['6.3.2']
+        android-api: ['28', '29', '31', '33']
+        arch: ['aarch64', 'armv7', 'x86_64']
+    steps:
+      - uses: actions/checkout@v6
+
+      - name: "Build Docker image"
+        run: |
+          docker build \
+            --tag swift-android-sdk:${{ matrix.swift }} \
+            --file .github/docker/Dockerfile \
+            .github/docker
+
+      - name: "Build Swift Package for Android (${{ matrix.arch }})"
+        run: |
+          case "${{ matrix.arch }}" in
+            aarch64) TRIPLE="aarch64-unknown-linux-android${{ matrix.android-api }}" ;;
+            armv7)   TRIPLE="armv7-unknown-linux-android${{ matrix.android-api }}" ;;
+            x86_64)  TRIPLE="x86_64-unknown-linux-android${{ matrix.android-api }}" ;;
+          esac
+          docker run --rm \
+            --volume "$PWD:/package" \
+            --env ANDROID_SDK_VERSION=${{ matrix.android-api }} \
+            --env TRIPLE="$TRIPLE" \
+            swift-android-sdk:${{ matrix.swift }} \
+            bash -c '
+              set -eu
+              # the prebuilt swift-syntax bundle omits SwiftIfConfig, which swift-java needs
+              swift build --swift-sdk "$TRIPLE" --disable-experimental-prebuilts
+            '