Fix a comment, forgot a noexcept test

Author: smallp-o-p

libcxx/test/std/utilities/optional/optional.iterator/begin.pass.cpp

@@ -28,7 +28,7 @@ constexpr bool test() {
     assert(noexcept(nonconst_opt.begin()));
   }
 
-  { // Dereferencing an iterator at the beggining as indexing the 0th element, and that those iterators are the same value returned by calling begin() again.
+  { // Dereferencing an iterator at the beginning == indexing the 0th element, and that calling begin() again return the same iterator.
     auto iter1 = opt.begin();
     auto iter2 = nonconst_opt.begin();
     assert(*iter1 == iter1[0]);

libcxx/test/std/utilities/optional/optional.iterator/end.pass.cpp

@@ -23,6 +23,11 @@ constexpr bool test() {
   std::optional<T> unengaged{std::nullopt};
   constexpr std::optional<T> unengaged2{std::nullopt};
 
+  { // end() is marked noexcept
+    assert(noexcept(opt.end()));
+    assert(noexcept(nonconst_opt.end()));
+  }
+
   { // end() == begin() and end() == end() if the optional is unengaged
     auto it  = unengaged.end();
     auto it2 = unengaged2.end();