Exception when using CMAKE_CXX_VISIBILITY_PRESET=hidden #1919
Description
When using the option CMAKE_CXX_VISIBILITY_PRESET=hidden, an exception can be thrown when using metadata in an application. It seems that classes created in the application can have different type information than the classes in OTIO, causing an exception when serializing the OTIO file:
libc++abi: terminating due to uncaught exception of type std::bad_any_cast: bad any cast
This only seems to happen with some compilers (clang), and when OTIO is linked as a shared library.
Example:
#include <opentimelineio/marker.h>
#include <opentimelineio/timeline.h>
int main(int argc, char** argv)
{
OTIO_NS::SerializableObject::Retainer<OTIO_NS::Timeline> timeline(new OTIO_NS::Timeline);
OTIO_NS::SerializableObject::Retainer<OTIO_NS::Track> track(new OTIO_NS::Track);
timeline->tracks()->append_child(track);
OTIO_NS::SerializableObject::Retainer<OTIO_NS::Marker> marker(new OTIO_NS::Marker);
//
// This AnyDictionary will have different type information than OTIO.
//
OTIO_NS::AnyDictionary md;
md["type"] = static_cast<int64_t>(23);
marker->metadata()["kdenlive"] = md;
track->markers().push_back(marker);
//
// std::bad_any_cast will be thrown when serializing the file with -DCMAKE_CXX_VISIBILITY_PRESET=hidden
//
if (!timeline->to_json_file("test.otio"))
{
return 1;
}
return 0;
}
Example CMake file:
cmake_minimum_required(VERSION 3.3)
project(test)
set(CMAKE_CXX_STANDARD 17)
find_package(OpenTimelineIO REQUIRED)
set(CMAKE_CXX_VISIBILITY_PRESET hidden)
add_executable(test test.cpp)
target_link_libraries(test OTIO::opentimelineio)
Adding __attribute__((__visibility__("default"))) to the AnyDictionary class seems to fix the example.
Related:
https://developers.redhat.com/articles/2021/10/27/compiler-option-hidden-visibility-and-weak-symbol-walk-bar#the_llvm_package_build
https://cmake.org/cmake/help/latest/module/GenerateExportHeader.html
Thanks to @jlskuz for troubleshooting the issue.