yaml-cpp

This means the installed libyaml-cpp.a was built without position-independent code, but your project is linking it into a shared library. Rebuild and reinstall yaml-cpp with PIC enabled:

git clone https://github.com/jbeder/yaml-cpp.git
cd yaml-cpp
mkdir -p build && cd build
cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_POSITION_INDEPENDENT_CODE=ON ..
cmake --build .
sudo make install

Alternatively, pass the flags directly:

env CFLAGS="-fPIC" CXXFLAGS="-fPIC" cmake -DCMAKE_BUILD_TYPE=Release ..
make
sudo make install

Another workaround is to build yaml-cpp as a shared library instead:

cmake -DCMAKE_BUILD_TYPE=Release -DBUILD_SHARED_LIBS=ON ..
make
sudo make install

Use a clean build directory or delete CMakeCache.txt first so the new compiler flags are applied.

Upgrade yaml-cpp to a release containing the fix for issue #1248, or apply the linked PR. The undefined behavior comes from &m_data[0] being evaluated when the internal std::vector is empty. Replace it with std::vector::data(), which is valid for an empty vector:

char* data() { return m_data.data(); }
const char* data() const { return m_data.data(); }

As a temporary local workaround, you can also guard the old code:

return m_data.empty() ? nullptr : &m_data[0];

Rebuild yaml-cpp and your project after the change.

Build yaml-cpp as a static library with the shared MSVC runtime disabled:

cmake -S . -B build -DYAML_BUILD_SHARED_LIBS=OFF -DYAML_MSVC_SHARED_RT=OFF
cmake --build build --config Release

For Debug builds, use --config Debug; CMake will then select /MTd.

In older yaml-cpp versions where YAML_MSVC_SHARED_RT defaults to ON, set it explicitly to OFF. Alternatively, in each generated Visual Studio project, set Project Properties → C/C++ → Code Generation → Runtime Library to Multi-Threaded (/MT) for Release or Multi-Threaded Debug (/MTd) for Debug.

When consuming the static library, define YAML_CPP_STATIC_DEFINE for your target:

target_compile_definitions(myapp PRIVATE YAML_CPP_STATIC_DEFINE)
target_link_libraries(myapp PRIVATE yaml-cpp)

Or add YAML_CPP_STATIC_DEFINE to your Visual Studio project's preprocessor definitions. Ensure yaml-cpp and your MFC application use the same runtime library setting to avoid linker conflicts.

Upgrade to a yaml-cpp version containing the fix for issue #408. YAML::Load and YAML::LoadAll now reject streams that are already in a failed state and propagate stream failures encountered during parsing, while empty or EOF-only streams still produce a null node or no documents. On older versions, enable stream exceptions before parsing:

stream.exceptions(std::ios::failbit | std::ios::badbit);
try {
    YAML::Node node = YAML::Load(stream);
} catch (const std::ios::failure& e) {
    // Handle failed or unreadable input stream.
}

If the stream may already be failed, also check it first:

if (!stream) {
    throw std::runtime_error("input stream is already in a failed state");
}

The static pkg-config metadata must define YAML_CPP_STATIC_DEFINE so yaml-cpp headers use static symbol declarations. Upgrade to a yaml-cpp release containing the fix, or manually add this line to the installed yaml-cpp.pc file:

Cflags.private: -DYAML_CPP_STATIC_DEFINE

Then use pkg-config with --static, for example:

pkg-config --static --cflags yaml-cpp
pkg-config --static --libs yaml-cpp

As an immediate workaround, compile your project with -DYAML_CPP_STATIC_DEFINE. The define should only be used for static builds; shared-build pkg-config output must not include it.