--- /dev/null
+/* See port_def.inc. This should #undef all macros #defined there. */
+
+#undef UPB_SIZE
+#undef UPB_FIELD_AT
+#undef UPB_READ_ONEOF
+#undef UPB_WRITE_ONEOF
+#undef UPB_INLINE
+#undef UPB_FORCEINLINE
+#undef UPB_NOINLINE
+#undef UPB_NORETURN
+#undef UPB_MAX
+#undef UPB_MIN
+#undef UPB_UNUSED
+#undef UPB_ASSERT
+#undef UPB_ASSERT_DEBUGVAR
+#undef UPB_UNREACHABLE
+#undef UPB_INFINITY
+#undef UPB_MSVC_VSNPRINTF
+#undef _upb_snprintf
+#undef _upb_vsnprintf
+#undef _upb_va_copy