ci: add cross-platform build matrix workflow

Author: sw1sh

.github/workflows/ci.yml

@@ -0,0 +1,92 @@
+name: CI
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+  workflow_dispatch:
+
+jobs:
+  build:
+    name: Build (matrix)
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - os: ubuntu-latest
+            target: x86_64-unknown-linux-gnu
+          - os: ubuntu-latest
+            target: aarch64-unknown-linux-gnu
+          - os: macos-latest
+            target: aarch64-apple-darwin
+          - os: macos-13  # Intel mac
+            target: x86_64-apple-darwin
+          - os: windows-latest
+            target: x86_64-pc-windows-msvc
+    steps:
+      - uses: actions/checkout@v4
+      - name: Install Rust toolchain
+        uses: dtolnay/rust-toolchain@stable
+        with:
+          targets: ${{ matrix.target }}
+      - name: Cache cargo
+        uses: actions/cache@v4
+        with:
+          path: |
+            ~/.cargo/registry
+            ~/.cargo/git
+            target
+          key: ${{ runner.os }}-${{ matrix.target }}-cargo-${{ hashFiles('**/Cargo.lock') }}
+      - name: Install cross deps (Linux aarch64)
+        if: matrix.target == 'aarch64-unknown-linux-gnu'
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y gcc-aarch64-linux-gnu
+          mkdir -p .cargo
+          echo '[target.aarch64-unknown-linux-gnu]\nlinker = "aarch64-linux-gnu-gcc"' >> .cargo/config.toml
+      - name: Build
+        run: cargo build --release --target ${{ matrix.target }}
+      - name: Upload artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: cotengra-${{ matrix.target }}
+          path: target/${{ matrix.target }}/release/*cotengra*.*
+
+  universal-macos:
+    name: Create universal macOS dylib
+    needs: build
+    runs-on: macos-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Download macOS artifacts
+        uses: actions/download-artifact@v4
+        with:
+          path: artifacts
+      - name: Create universal binary
+        run: |
+          mkdir -p dist
+          LIPO_INPUTS="$(find artifacts -name 'libcotengra.dylib' -maxdepth 4)"
+          echo "Inputs: $LIPO_INPUTS"
+          lipo -create $LIPO_INPUTS -output dist/libcotengra_universal.dylib
+      - name: Upload universal binary
+        uses: actions/upload-artifact@v4
+        with:
+          name: cotengra-macos-universal
+          path: dist/libcotengra_universal.dylib
+
+  publish:
+    name: Publish (manual)
+    if: github.event_name == 'workflow_dispatch'
+    needs: [build]
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Download artifacts
+        uses: actions/download-artifact@v4
+        with:
+          path: dist
+      - name: List artifacts
+        run: ls -R dist
+