chore: Try to turn on Werror in the CI (#1261)

.github/workflows/ci.yml

@@ -68,7 +68,12 @@ jobs:
         # Configure CMake in a 'build' subdirectory. `CMAKE_BUILD_TYPE` is only required if you are using a single-configuration generator such as make.
         # See https://cmake.org/cmake/help/latest/variable/CMAKE_BUILD_TYPE.html?highlight=cmake_build_type
         run: |
-          cmake -B ${{github.workspace}}/build -DCMAKE_BUILD_TYPE=${{matrix.build-type}} -GNinja -DCMAKE_CXX_COMPILER_LAUNCHER=ccache -L
+          cmake -B ${{github.workspace}}/build \
+            -DCMAKE_BUILD_TYPE=${{matrix.build-type}} \
+            -GNinja \
+            -DCMAKE_CXX_COMPILER_LAUNCHER=ccache \
+            -DCMAKE_CXX_FLAGS="-Werror" \
+            -L
           cd ${{github.workspace}}/build && pwd
           du -hcs _deps/
       - name: Build & Test

CMakeLists.txt

@@ -1,6 +1,8 @@
 cmake_minimum_required(VERSION 3.15 FATAL_ERROR)
 set(PROJECT_CONTACT romange@gmail.com)
 
+include(CheckCXXCompilerFlag)
+
 enable_testing()
 
 set(CMAKE_EXPORT_COMPILE_COMMANDS 1)
@@ -10,6 +12,12 @@ set_property(GLOBAL PROPERTY USE_FOLDERS ON)
 project(DRAGONFLY C CXX)
 set(CMAKE_CXX_STANDARD 17)
 
+# Disabled because it has false positives with ref-counted intrusive pointers.
+CHECK_CXX_COMPILER_FLAG("-Wuse-after-free" HAS_USE_AFTER_FREE_WARN)
+if (HAS_USE_AFTER_FREE_WARN)
+    set(CMAKE_CXX_FLAGS "-Wno-use-after-free ${CMAKE_CXX_FLAGS}")
+endif()
+
 # We must define all the required variables from the root cmakefile, otherwise
 # they just disappear.
 set(CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/helio/cmake" ${CMAKE_MODULE_PATH})