[PR] fmayer - add description comment

Author: cjappl

compiler-rt/lib/rtsan/rtsan_interceptors_posix.cpp

@@ -464,6 +464,10 @@ INTERCEPTOR(void *, valloc, SIZE_T size) {
 }
 
 #if SANITIZER_INTERCEPT_ALIGNED_ALLOC
+
+// In some cases, when targeting older Darwin versions, this warning may pop up.
+// We know that aligned_alloc will never be called on older systems because the
+// client OSX won't provide it, so we can ignore guarding the call.
 #pragma clang diagnostic push
 #pragma clang diagnostic ignored "-Wunguarded-availability-new"
 INTERCEPTOR(void *, aligned_alloc, SIZE_T alignment, SIZE_T size) {