Fix build with external graphviz

Added a minimal workflow to test against external graphviz. Workflow
is separate, the main one was getting too convoluted, as macOS doesn't
have graphviz for x86_64. Rather have a few lines of copy-paste over
a big workflow full of 'ifs'

Author: drdanz

.github/workflows/build-external-graphviz.yml

@@ -0,0 +1,90 @@
+# SPDX-FileCopyrightText: 2023 Klarälvdalens Datakonsult AB, a KDAB Group company <[email protected]>
+#
+# SPDX-License-Identifier: LGPL-2.1-only OR LicenseRef-KDAB-KDStateMachineEditor
+
+name: CI with external graphviz
+
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+    branches:
+      - master
+
+jobs:
+  build:
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        os:
+          - ubuntu-latest
+          - macos-latest
+        build_type:
+          - Debug
+        config:
+          - qt_version: 6.6.2
+            qt_modules: qtscxml
+
+    steps:
+      - name: Install Dependencies on Linux
+        if: ${{ runner.os == 'Linux' }}
+        run: |
+          sudo apt update -qq
+          sudo apt install -y doxygen libgraphviz-dev
+
+      - name: Install Dependencies on macOS
+        if: ${{ runner.os == 'macOS' }}
+        run: brew install bison graphviz
+
+      - name: Install Qt ${{ matrix.config.qt_version }} with options and default aqtversion
+        uses: jurplel/install-qt-action@v3
+        with:
+          aqtversion: null # use whatever the default is
+          modules: ${{ matrix.config.qt_modules }}
+          version: ${{ matrix.config.qt_version }}
+          cache: true
+
+      - name: Install ninja-build tool (must be after Qt due PATH changes)
+        uses: turtlesec-no/get-ninja@main
+
+      - name: Add Bison to PATH (must be after Qt due PATH changes)
+        if: ${{ runner.os == 'macOS' }}
+        run: echo "/opt/homebrew/opt/bison/bin" >> $GITHUB_PATH
+
+      - name: Checkout sources
+        uses: actions/checkout@v4
+        with:
+          submodules: recursive
+
+      - name: Configure project
+        run: >
+          cmake -S . -B ./build -G Ninja
+          --warn-uninitialized -Werror=dev
+          -DCMAKE_BUILD_TYPE=${{ matrix.build_type }}
+          -DCMAKE_OSX_ARCHITECTURES="arm64"
+          -DBUILD_QT6=ON
+          -DBUILD_TESTS=${{ matrix.build_type == 'Debug' }}
+          -DBUILD_EXAMPLES=ON
+          -DBUILD_DOCS=${{ matrix.build_type == 'Debug' && runner.os == 'Linux' }}
+          -DWITH_INTERNAL_GRAPHVIZ=OFF
+
+      - name: Build Project
+        run: cmake --build ./build
+
+      - name: Run tests on Linux (offscreen)
+        if: ${{ matrix.build_type == 'Debug' && runner.os == 'Linux' }}
+        run: ctest --test-dir ./build -C ${{ matrix.build_type }} --output-on-failure
+        env:
+          QT_QPA_PLATFORM: offscreen
+
+      - name: Run tests on macOS
+        if: ${{ matrix.build_type == 'Debug' && runner.os != 'Linux' }}
+        run: ctest --test-dir ./build -C ${{ matrix.build_type }} --output-on-failure
+
+      - name: Read tests log when it fails
+        uses: andstor/file-reader-action@v1
+        if: ${{ failure() && matrix.build_type == 'Debug' }}
+        with:
+          path: "./build/Testing/Temporary/LastTest.log"

src/core/CMakeLists.txt

@@ -89,6 +89,10 @@ if(BUILD_QT6)
     target_link_libraries(kdstatemachineeditor_core PRIVATE Qt6::StateMachine)
 endif()
 
+if(NOT WITH_INTERNAL_GRAPHVIZ)
+    target_include_directories(kdstatemachineeditor_core PRIVATE ${GRAPHVIZ_INCLUDE_DIR})
+endif()
+
 set_target_properties(
     kdstatemachineeditor_core
     PROPERTIES SOVERSION ${KDSME_SOVERSION}
@@ -110,12 +114,19 @@ endif()
 
 generate_export_header(kdstatemachineeditor_core EXPORT_FILE_NAME kdsme_core_export.h BASE_NAME KDSME_CORE)
 
-if(NOT GRAPHVIZ_PLUGIN_DOT_LAYOUT_LIBRARY)
-    set(GRAPHVIZ_PLUGIN_DOT_LAYOUT_LIBRARY gvplugin_dot_layout)
+if(WITH_INTERNAL_GRAPHVIZ)
+    set(GRAPHVIZ_GVC_LIBRARY gvc)
+    set(GRAPHVIZ_CGRAPH_LIBRARY cgraph)
+    if(NOT GRAPHVIZ_PLUGIN_DOT_LAYOUT_LIBRARY)
+        set(GRAPHVIZ_PLUGIN_DOT_LAYOUT_LIBRARY gvplugin_dot_layout)
+    endif()
 endif()
 
 if(GRAPHVIZ_FOUND)
-    target_link_libraries(kdstatemachineeditor_core PRIVATE cgraph gvc ${GRAPHVIZ_PLUGIN_DOT_LAYOUT_LIBRARY})
+    target_link_libraries(
+        kdstatemachineeditor_core PRIVATE ${GRAPHVIZ_CGRAPH_LIBRARY} ${GRAPHVIZ_GVC_LIBRARY}
+                                          ${GRAPHVIZ_PLUGIN_DOT_LAYOUT_LIBRARY}
+    )
 endif()
 
 set(build_iface_dirs