Add tests to cover odd sizes

Author: winner245

libcxx/include/__bit_reference

@@ -870,8 +870,6 @@ private:
   template <class _Dp, bool _IC>
   _LIBCPP_CONSTEXPR_SINCE_CXX20 friend __bit_iterator<_Dp, false> __copy_backward_unaligned(
       __bit_iterator<_Dp, _IC> __first, __bit_iterator<_Dp, _IC> __last, __bit_iterator<_Dp, false> __result);
-  // Note: dependent nested name specifier __copy_backward_impl<_AlgPolicy>::operator() for friend declaration
-  // is not supported in clang. Thus, we use a friend declaration for the entire class.
   template <class _AlgPolicy>
   friend struct __copy_backward_impl;
   template <class _Cl, class _Cr>

libcxx/test/std/algorithms/alg.modifying.operations/alg.copy/copy_backward.pass.cpp

@@ -115,9 +115,11 @@ TEST_CONSTEXPR_CXX20 bool test() {
 
   { // Test vector<bool>::iterator optimization
     assert(test_vector_bool(8));
-    assert(test_vector_bool(16));
+    assert(test_vector_bool(19));
     assert(test_vector_bool(32));
+    assert(test_vector_bool(49));
     assert(test_vector_bool(64));
+    assert(test_vector_bool(199));
     assert(test_vector_bool(256));
   }
 

libcxx/test/std/algorithms/alg.modifying.operations/alg.copy/ranges.copy_backward.pass.cpp

@@ -348,9 +348,11 @@ constexpr bool test() {
 #if TEST_STD_VER >= 23
   { // Test vector<bool>::iterator optimization
     assert(test_vector_bool(8));
-    assert(test_vector_bool(16));
+    assert(test_vector_bool(19));
     assert(test_vector_bool(32));
+    assert(test_vector_bool(49));
     assert(test_vector_bool(64));
+    assert(test_vector_bool(199));
     assert(test_vector_bool(256));
   }
 #endif