[STABLE ABI] Verify that torchaudio is torch ABI stable.

CMakeLists.txt

@@ -152,6 +152,9 @@ else()
 endif()
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${warning_flags} ${TORCH_CXX_FLAGS}")
 
+# Ensure that torchaudio is torch ABI stable.
+set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -DTORCH_TARGET_VERSION=0x020a000000000000")
+
 find_program(CCACHE_PROGRAM ccache)
 if(CCACHE_PROGRAM)
   message(STATUS "Found ccache")

src/libtorchaudio/cuctc/src/python_binding.cpp

@@ -23,12 +23,25 @@
 // OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// It is safe to temporarily disable TORCH_TARGET_VERSION for pybind11
+// as it is a header-only library.
+#ifdef TORCH_TARGET_VERSION
+#define SAVE_TORCH_TARGET_VERSION TORCH_TARGET_VERSION
+#undef TORCH_TARGET_VERSION
+#endif
 #include <pybind11/pybind11.h>
 #include <pybind11/stl.h>
+#ifdef SAVE_TORCH_TARGET_VERSION
+#define TORCH_TARGET_VERSION SAVE_TORCH_TARGET_VERSION
+#undef SAVE_TORCH_TARGET_VERSION
+#endif
+
 #include <tuple>
 #include <utility>
 #include <vector>
 #include "include/ctc_prefix_decoder.h"
+
 namespace py = pybind11;
 
 std::tuple<size_t, std::vector<std::vector<std::pair<float, std::vector<int>>>>>

src/libtorchaudio/pybind/pybind.cpp

@@ -1,6 +1,17 @@
 #include <libtorchaudio/utils.h>
+
+// It is safe to temporarily disable TORCH_TARGET_VERSION for pybind11
+// as it is a header-only library.
+#ifdef TORCH_TARGET_VERSION
+#define SAVE_TORCH_TARGET_VERSION TORCH_TARGET_VERSION
+#undef TORCH_TARGET_VERSION
+#endif
 #include <pybind11/pybind11.h>
 #include <pybind11/stl.h>
+#ifdef SAVE_TORCH_TARGET_VERSION
+#define TORCH_TARGET_VERSION SAVE_TORCH_TARGET_VERSION
+#undef SAVE_TORCH_TARGET_VERSION
+#endif
 
 namespace torchaudio {
 namespace {