diff --git a/libc/src/__support/CPP/array.h b/libc/src/__support/CPP/array.h
--- a/libc/src/__support/CPP/array.h
+++ b/libc/src/__support/CPP/array.h
@@ -43,6 +43,9 @@
   constexpr const_iterator begin() const { return Data; }
 
   constexpr iterator end() { return Data + N; }
+
+  // TODO: Marking this constexpr causes a variety of test/build failures. Look
+  // into that and fix.
   const_iterator end() const { return Data + N; }
 };