CI(macos): build source deps from source with caching

Add a CI step to build GTSAM 4.2.1, libnabo 1.1.2 and libpointmatcher
1.4.4 from source (not available/usable from Homebrew), with patches
under .github/patches fixing Eigen 5 / Boost compatibility.

Installs are staged via DESTDIR into an actions/cache directory and
copied into /usr/local. The cache key includes the pinned versions, the
patch hashes, and the linked Homebrew (eigen/boost/yaml-cpp) + Xcode
toolchain versions, so the deps rebuild only when something relevant
changes. Also add yaml-cpp brew dep and drop the unused extra_deps
matrix field.

Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>

.github/workflows/cmake-macos.yml

@@ -26,19 +26,15 @@ jobs:
         include:
         - build_name: macos-sequoia-intel
           os: macos-15-intel
-          extra_deps: ""
           extra_cmake_def: '-DBUILD_AS_BUNDLE=ON'
         - build_name: macos-sequoia-apple-silicon
           os: macos-15
-          extra_deps: ""
           extra_cmake_def: '-DBUILD_AS_BUNDLE=ON'
         - build_name: macos-tahoe-intel
           os: macos-26-intel
-          extra_deps: ""
           extra_cmake_def: '-DBUILD_AS_BUNDLE=ON'
         - build_name: macos-tahoe-apple-silicon
           os: macos-26
-          extra_deps: ""
           extra_cmake_def: '-DBUILD_AS_BUNDLE=ON'
 
     steps:
@@ -47,7 +43,88 @@ jobs:
     - name: Install Brew Dependencies
       run: |
         # Update brew and install from Brewfile if present, or specific packages
-        brew install pcl opencv octomap g2o pdal
+        brew install pcl opencv octomap g2o pdal yaml-cpp
+
+    - name: Resolve dependency versions
+      id: depver
+      # The source dependencies link against these Homebrew libraries and are
+      # compiled with Xcode's toolchain, so both are folded into the source-deps
+      # cache key: a Homebrew bump (e.g. a new Eigen) or an Xcode update
+      # invalidates the cache and forces a rebuild.
+      run: |
+        BREW=$(brew list --versions eigen boost yaml-cpp | sort)
+        XCODE=$(xcodebuild -version 2>/dev/null || clang --version | head -1)
+        HASH=$(printf '%s\n%s\n' "$BREW" "$XCODE" | shasum | cut -d' ' -f1)
+        echo "hash=$HASH" >> "$GITHUB_OUTPUT"
+
+    - name: Cache Source Dependencies
+      id: cache-src-deps
+      uses: actions/cache@v4
+      with:
+        # Staged install tree (DESTDIR) of the source-built dependencies.
+        path: ${{ runner.temp }}/deps-stage
+        # Rebuild when the OS image, pinned versions, patches, the linked
+        # Homebrew library versions or the Xcode toolchain change.
+        key: src-deps-${{ matrix.os }}-gtsam4.2.1-libnabo1.1.2-lpm1.4.4-deps${{ steps.depver.outputs.hash }}-${{ hashFiles('.github/patches/*.patch') }}
+
+    - name: Build Source Dependencies
+      # Dependencies not available (or not in a usable version) from Homebrew are
+      # built from source and staged into the cached directory via DESTDIR.
+      # Patches under .github/patches fix compatibility with the current Homebrew
+      # Eigen/Boost versions. Skipped entirely on a cache hit.
+      if: steps.cache-src-deps.outputs.cache-hit != 'true'
+      run: |
+        set -e
+        NPROC=$(sysctl -n hw.logicalcpu)
+        PATCHES="${{ github.workspace }}/.github/patches"
+        SRC="${{ runner.temp }}/src-deps"
+        STAGE="${{ runner.temp }}/deps-stage"
+        mkdir -p "$SRC" "$STAGE"
+
+        # --- GTSAM 4.2.1 ---
+        git clone --depth 1 --branch 4.2.1 https://github.com/borglab/gtsam.git "$SRC/gtsam"
+        cd "$SRC/gtsam"
+        git apply "$PATCHES/gtsam-4.2.1-eigen5.patch"
+        cmake -B build \
+          -DCMAKE_BUILD_TYPE=${{ env.BUILD_TYPE }} \
+          -DGTSAM_BUILD_WITH_MARCH_NATIVE=OFF \
+          -DGTSAM_WITH_TBB=OFF \
+          -DGTSAM_BUILD_EXAMPLES_ALWAYS=OFF \
+          -DGTSAM_BUILD_TESTS=OFF \
+          -DGTSAM_BUILD_UNSTABLE=OFF \
+          -DGTSAM_USE_SYSTEM_EIGEN=ON \
+          -DCMAKE_POLICY_VERSION_MINIMUM=3.5
+        cmake --build build -j$NPROC
+        DESTDIR="$STAGE" cmake --install build
+
+        # --- libnabo 1.1.2 (required by libpointmatcher) ---
+        git clone --depth 1 --branch 1.1.2 https://github.com/ethz-asl/libnabo.git "$SRC/libnabo"
+        cd "$SRC/libnabo"
+        git apply "$PATCHES/libnabo-1.1.2.patch"
+        cmake -B build -DCMAKE_BUILD_TYPE=${{ env.BUILD_TYPE }}
+        cmake --build build -j$NPROC
+        DESTDIR="$STAGE" cmake --install build
+
+        # --- libpointmatcher 1.4.4 (finds libnabo from the staged prefix) ---
+        git clone --depth 1 --branch 1.4.4 https://github.com/ethz-asl/libpointmatcher.git "$SRC/libpointmatcher"
+        cd "$SRC/libpointmatcher"
+        git apply "$PATCHES/libpointmatcher-1.4.4-boost.patch"
+        cmake -B build -DCMAKE_BUILD_TYPE=${{ env.BUILD_TYPE }} -DCMAKE_PREFIX_PATH="$STAGE/usr/local"
+        cmake --build build -j$NPROC
+        DESTDIR="$STAGE" cmake --install build
+
+    - name: Install Source Dependencies
+      # Copy the (possibly cached) staged install tree into /usr/local so
+      # rtabmap's find_package() and the bundle fixup (which search /usr/local)
+      # pick the dependencies up. Runs on both cache hit and miss.
+      run: |
+        set -e
+        STAGE="${{ runner.temp }}/deps-stage"
+        if [ ! -d "$STAGE/usr/local" ]; then
+          echo "No staged dependencies found at $STAGE/usr/local" >&2
+          exit 1
+        fi
+        sudo cp -a "$STAGE/usr/local/." /usr/local/
 
     - name: Configure CMake
       run: |