# Enable -Wdelete-non-virtual-dtor if available.
add_flag_if_supported("-Wdelete-non-virtual-dtor" DELETE_NON_VIRTUAL_DTOR_FLAG)
- # Enable -Wsuggest-override if available.
- add_flag_if_supported("-Wsuggest-override" SUGGEST_OVERRIDE_FLAG)
+ # Enable -Wsuggest-override if it's available, and only if it doesn't
+ # suggest adding 'override' to functions that are already marked 'final'
+ # (which means it is disabled for GCC < 9.2).
+ check_cxx_compiler_flag("-Wsuggest-override" CXX_SUPPORTS_SUGGEST_OVERRIDE_FLAG)
+ if (CXX_SUPPORTS_SUGGEST_OVERRIDE_FLAG)
+ set(OLD_CMAKE_REQUIRED_FLAGS ${CMAKE_REQUIRED_FLAGS})
+ set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -Werror=suggest-override")
+ CHECK_CXX_SOURCE_COMPILES("class base {public: virtual void anchor();};
+ class derived : base {public: void anchor() final;};
+ int main() { return 0; }"
+ CXX_WSUGGEST_OVERRIDE_ALLOWS_ONLY_FINAL)
+ set(CMAKE_REQUIRED_FLAGS ${OLD_CMAKE_REQUIRED_FLAGS})
+ append_if(CXX_WSUGGEST_OVERRIDE_ALLOWS_ONLY_FINAL "-Wsuggest-override" CMAKE_CXX_FLAGS)
+ endif()
# Check if -Wcomment is OK with an // comment ending with '\' if the next
# line is also a // comment.