Cleanup [[no_unique_address]] tests

Related comments:
* #65536 (comment)
* #65536 (comment)
* #65536 (comment)

Author: JMazurkiewicz

libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.iterator/no_unique_address.compile.pass.cpp

@@ -22,31 +22,36 @@ struct IntRange : std::ranges::view_base {
   int* end();
 };
 
-class InputIter {
+class Iter {
 public:
   using value_type      = IntRange;
   using difference_type = ptrdiff_t;
 
-  InputIter& operator++();
+  Iter& operator++();
   void operator++(int);
   value_type& operator*() const;
-  bool operator==(const InputIter&) const;
+  bool operator==(std::default_sentinel_t) const;
 
 private:
   int* ptr_;
 };
 
-static_assert(std::input_iterator<InputIter>);
-static_assert(!std::forward_iterator<InputIter>);
+static_assert(std::input_iterator<Iter>);
+static_assert(!std::forward_iterator<Iter>);
 
-struct InputView : std::ranges::view_base {
-  InputIter begin();
-  InputIter end();
+struct View : std::ranges::view_base {
+  Iter begin();
+  std::default_sentinel_t end();
 };
 
-static_assert(std::ranges::input_range<InputView>);
-static_assert(!std::ranges::forward_range<InputView>);
+static_assert(std::ranges::input_range<View>);
+static_assert(!std::ranges::forward_range<View>);
 
-static_assert(alignof(void*) == alignof(std::variant<int*, int*>)); // alignof(__parent_) == alignof(__inner_it_)
-static_assert(sizeof(std::ranges::iterator_t<std::ranges::join_with_view<InputView, IntRange>>) ==
+using JWV = std::ranges::join_with_view<View, IntRange>;
+
+// Expected JWV::iterator layout:
+// _Parent* __parent_;                           // offset: 0
+// [[no_unique_address]] __empty __outer_it;     //         0
+// variant<_PatternIter, _InnerIter> __pattern_; //         8
+static_assert(sizeof(std::ranges::iterator_t<JWV>) ==
               sizeof(void*) + sizeof(std::variant<int*, int*>)); // sizeof(__parent_) + sizeof(__inner_it_)

libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.view/no_unique_address.compile.pass.cpp

@@ -33,8 +33,15 @@ struct Pattern : std::ranges::view_base {
 template <class View>
 struct Test {
   [[no_unique_address]] View view;
-  char c;
+  unsigned char pad;
 };
 
-static_assert(sizeof(Test<std::ranges::join_with_view<ForwardView, Pattern>>) ==
-              sizeof(std::ranges::join_with_view<ForwardView, Pattern>));
+using JWV = std::ranges::join_with_view<ForwardView, Pattern>;
+
+// Expected JWV layout:
+// [[no_unique_address]] _View __base_             // offset: 0
+// [[no_unique_address]] __empty_cache __outer_it; //         0
+// [[no_unique_address]] __empty_cache __inner_;   //         1
+// [[no_unique_address]] _Patter __pattern_        //         0
+static_assert(sizeof(JWV) == 2);
+static_assert(sizeof(Test<JWV>) == 2);