Eigen looks for __EXCEPTIONS to determine if exceptions are enabled. On macOS
matrix is compiled with -ObjC++, which sets __EXCEPTIONS, causing the build to
fail. The right solution is likely to change Eigen to look for a different
define, or perhaps an override to ignore __EXCEPTIONS.


diff --git a/third_party/mediapipe/src/mediapipe/framework/formats/matrix.h b/third_party/mediapipe/src/mediapipe/framework/formats/matrix.h
index 13a6576157186..0eed6fed87841 100644
--- a/third_party/mediapipe/src/mediapipe/framework/formats/matrix.h
+++ b/third_party/mediapipe/src/mediapipe/framework/formats/matrix.h
@@ -21,6 +21,15 @@
 #ifndef MEDIAPIPE_FRAMEWORK_FORMATS_MATRIX_H_
 #define MEDIAPIPE_FRAMEWORK_FORMATS_MATRIX_H_
 
+// TODO: Eigen looks for __EXCEPTIONS to determine if exceptions are enabled.
+// This file may be compiled with -ObjC++ on macOS, which sets __EXCEPTIONS,
+// causing the build to fail. The right solution is likely to change Eigen
+// to look for a different define, or perhaps an override to ignore
+// __EXCEPTIONS.
+#if defined(__EXCEPTIONS)
+#undef __EXCEPTIONS
+#endif
+
 #include <string>
 
 #include "Eigen/Core"