1 files changed, 7 insertions, 0 deletions
diff --git a/absl/types/optional.h b/absl/types/optional.h
index f1b41ace8195..e952a04aa90c 100644
--- a/absl/types/optional.h
+++ b/absl/types/optional.h
@@ -118,6 +118,13 @@ namespace absl {
 //      and `is_nothrow_swappable()` is the same as `std::is_trivial()`.
 //    * `make_optional()` cannot be declared `constexpr` due to the absence of
 //      guaranteed copy elision.
+//    * The move constructor's `noexcept` specification is stronger, i.e. if the
+//      default allocator is non-throwing (via setting
+//      `ABSL_ALLOCATOR_NOTHROW`), it evaluates to `noexcept(true)`, because
+//      we assume
+//       a) move constructors should only throw due to allocation failure and
+//       b) if T's move constructor allocates, it uses the same allocation
+//          function as the default allocator.
 template <typename T>
 class optional;