[libc++][test] Do not assume array::iterator is a pointer (#100603)

In the tests I added for `ranges::find_last{_if{_not}}`, I accidentally
introduced an assumption that `same_as<array<T, 0>::iterator, T*>`; this
is a faulty assumption on MSVC-STL.

Fixes #100498.

Author: strega-nil

libcxx/test/std/algorithms/alg.nonmodifying/alg.find.last/ranges.find_last.pass.cpp

@@ -25,6 +25,7 @@
 #include <algorithm>
 #include <array>
 #include <cassert>
+#include <memory>
 #include <ranges>
 #include <vector>
 
@@ -61,7 +62,8 @@ template <class It, class Sent = It>
 constexpr void test_iterators() {
   using ValueT    = std::iter_value_t<It>;
   auto make_range = [](auto& a) {
-    return std::ranges::subrange(It(std::ranges::begin(a)), Sent(It(std::ranges::end(a))));
+    return std::ranges::subrange(
+        It(std::to_address(std::ranges::begin(a))), Sent(It(std::to_address(std::ranges::end(a)))));
   };
   { // simple test
     {
@@ -91,7 +93,7 @@ constexpr void test_iterators() {
       std::array<ValueT, 0> a = {};
 
       auto ret = std::ranges::find_last(make_range(a), 1).begin();
-      assert(ret == It(a.begin()));
+      assert(ret == It(a.data()));
     }
   }
 

libcxx/test/std/algorithms/alg.nonmodifying/alg.find.last/ranges.find_last_if.pass.cpp

@@ -92,14 +92,14 @@ constexpr void test_iterator_classes() {
     {
       std::array<int, 0> a = {};
 
-      auto ret = std::ranges::find_last_if(it(a.data()), sent(it(a.data())), [](auto&&) { return true; }).begin();
-      assert(ret == it(a.data()));
+      auto ret = std::ranges::find_last_if(it(a.begin()), sent(it(a.end())), [](auto&&) { return true; }).begin();
+      assert(ret == it(a.end()));
     }
     {
       std::array<int, 0> a = {};
 
       auto ret = std::ranges::find_last_if(make_range<it, sent>(a), [](auto&&) { return true; }).begin();
-      assert(ret == it(a.begin()));
+      assert(ret == it(a.end()));
     }
   }
 
@@ -183,8 +183,17 @@ struct NonConstComparable {
   friend constexpr bool operator==(NonConstComparable&, const NonConstComparable&) { return true; }
 };
 
+// TODO: this should really use `std::const_iterator`
 template <class T>
-using add_const_to_ptr_t = std::add_pointer_t<std::add_const_t<std::remove_pointer_t<T>>>;
+struct add_const_to_ptr {
+  using type = T;
+};
+template <class T>
+struct add_const_to_ptr<T*> {
+  using type = const T*;
+};
+template <class T>
+using add_const_to_ptr_t = typename add_const_to_ptr<T>::type;
 
 constexpr bool test() {
   test_iterator_classes<std::type_identity_t, std::type_identity_t>();

libcxx/test/std/algorithms/alg.nonmodifying/alg.find.last/ranges.find_last_if_not.pass.cpp

@@ -92,14 +92,14 @@ constexpr void test_iterator_classes() {
     {
       std::array<int, 0> a = {};
 
-      auto ret = std::ranges::find_last_if_not(it(a.data()), sent(it(a.data())), [](auto&&) { return false; }).begin();
-      assert(ret == it(a.data()));
+      auto ret = std::ranges::find_last_if_not(it(a.begin()), sent(it(a.end())), [](auto&&) { return false; }).begin();
+      assert(ret == it(a.end()));
     }
     {
       std::array<int, 0> a = {};
 
       auto ret = std::ranges::find_last_if_not(make_range<it, sent>(a), [](auto&&) { return false; }).begin();
-      assert(ret == it(a.begin()));
+      assert(ret == it(a.end()));
     }
   }
 
@@ -183,8 +183,17 @@ struct NonConstComparable {
   friend constexpr bool operator!=(NonConstComparable&, const NonConstComparable&) { return false; }
 };
 
+// TODO: this should really use `std::const_iterator`
 template <class T>
-using add_const_to_ptr_t = std::add_pointer_t<std::add_const_t<std::remove_pointer_t<T>>>;
+struct add_const_to_ptr {
+  using type = T;
+};
+template <class T>
+struct add_const_to_ptr<T*> {
+  using type = const T*;
+};
+template <class T>
+using add_const_to_ptr_t = typename add_const_to_ptr<T>::type;
 
 constexpr bool test() {
   test_iterator_classes<std::type_identity_t, std::type_identity_t>();

libcxx/test/support/test_iterators.h

@@ -339,62 +339,92 @@ cpp20_random_access_iterator(It) -> cpp20_random_access_iterator<It>;
 
 static_assert(std::random_access_iterator<cpp20_random_access_iterator<int*>>);
 
-template <class It>
-class contiguous_iterator
-{
-    static_assert(std::is_pointer_v<It>, "Things probably break in this case");
+template <std::contiguous_iterator It>
+class contiguous_iterator {
+  It it_;
 
-    It it_;
+  template <std::contiguous_iterator U>
+  friend class contiguous_iterator;
 
-    template <class U> friend class contiguous_iterator;
 public:
-    typedef          std::contiguous_iterator_tag              iterator_category;
-    typedef typename std::iterator_traits<It>::value_type      value_type;
-    typedef typename std::iterator_traits<It>::difference_type difference_type;
-    typedef It                                                 pointer;
-    typedef typename std::iterator_traits<It>::reference       reference;
-    typedef typename std::remove_pointer<It>::type             element_type;
+  using iterator_category = std::contiguous_iterator_tag;
+  using value_type        = typename std::iterator_traits<It>::value_type;
+  using difference_type   = typename std::iterator_traits<It>::difference_type;
+  using pointer           = typename std::iterator_traits<It>::pointer;
+  using reference         = typename std::iterator_traits<It>::reference;
+  using element_type      = value_type;
 
-    TEST_CONSTEXPR_CXX14 It base() const {return it_;}
+  constexpr It base() const { return it_; }
 
-    TEST_CONSTEXPR_CXX14 contiguous_iterator() : it_() {}
-    TEST_CONSTEXPR_CXX14 explicit contiguous_iterator(It it) : it_(it) {}
+  constexpr contiguous_iterator() : it_() {}
+  constexpr explicit contiguous_iterator(It it) : it_(it) {}
 
-    template <class U>
-    TEST_CONSTEXPR_CXX14 contiguous_iterator(const contiguous_iterator<U>& u) : it_(u.it_) {}
+  template <class U>
+  constexpr contiguous_iterator(const contiguous_iterator<U>& u) : it_(u.it_) {}
 
-    template <class U, class = typename std::enable_if<std::is_default_constructible<U>::value>::type>
-    constexpr contiguous_iterator(contiguous_iterator<U>&& u) : it_(u.it_) { u.it_ = U(); }
+  template <class U, class = typename std::enable_if<std::is_default_constructible<U>::value>::type>
+  constexpr contiguous_iterator(contiguous_iterator<U>&& u) : it_(u.it_) {
+    u.it_ = U();
+  }
 
-    TEST_CONSTEXPR reference operator*() const {return *it_;}
-    TEST_CONSTEXPR pointer operator->() const {return it_;}
-    TEST_CONSTEXPR reference operator[](difference_type n) const {return it_[n];}
-
-    TEST_CONSTEXPR_CXX14 contiguous_iterator& operator++() {++it_; return *this;}
-    TEST_CONSTEXPR_CXX14 contiguous_iterator& operator--() {--it_; return *this;}
-    TEST_CONSTEXPR_CXX14 contiguous_iterator operator++(int) {return contiguous_iterator(it_++);}
-    TEST_CONSTEXPR_CXX14 contiguous_iterator operator--(int) {return contiguous_iterator(it_--);}
-
-    TEST_CONSTEXPR_CXX14 contiguous_iterator& operator+=(difference_type n) {it_ += n; return *this;}
-    TEST_CONSTEXPR_CXX14 contiguous_iterator& operator-=(difference_type n) {it_ -= n; return *this;}
-    friend TEST_CONSTEXPR_CXX14 contiguous_iterator operator+(contiguous_iterator x, difference_type n) {x += n; return x;}
-    friend TEST_CONSTEXPR_CXX14 contiguous_iterator operator+(difference_type n, contiguous_iterator x) {x += n; return x;}
-    friend TEST_CONSTEXPR_CXX14 contiguous_iterator operator-(contiguous_iterator x, difference_type n) {x -= n; return x;}
-    friend TEST_CONSTEXPR difference_type operator-(contiguous_iterator x, contiguous_iterator y) {return x.it_ - y.it_;}
-
-    friend TEST_CONSTEXPR bool operator==(const contiguous_iterator& x, const contiguous_iterator& y) {return x.it_ == y.it_;}
-    friend TEST_CONSTEXPR bool operator!=(const contiguous_iterator& x, const contiguous_iterator& y) {return x.it_ != y.it_;}
-    friend TEST_CONSTEXPR bool operator< (const contiguous_iterator& x, const contiguous_iterator& y) {return x.it_ <  y.it_;}
-    friend TEST_CONSTEXPR bool operator<=(const contiguous_iterator& x, const contiguous_iterator& y) {return x.it_ <= y.it_;}
-    friend TEST_CONSTEXPR bool operator> (const contiguous_iterator& x, const contiguous_iterator& y) {return x.it_ >  y.it_;}
-    friend TEST_CONSTEXPR bool operator>=(const contiguous_iterator& x, const contiguous_iterator& y) {return x.it_ >= y.it_;}
+  constexpr reference operator*() const { return *it_; }
+  constexpr pointer operator->() const { return it_; }
+  constexpr reference operator[](difference_type n) const { return it_[n]; }
+
+  constexpr contiguous_iterator& operator++() {
+    ++it_;
+    return *this;
+  }
+  constexpr contiguous_iterator& operator--() {
+    --it_;
+    return *this;
+  }
+  constexpr contiguous_iterator operator++(int) { return contiguous_iterator(it_++); }
+  constexpr contiguous_iterator operator--(int) { return contiguous_iterator(it_--); }
+
+  constexpr contiguous_iterator& operator+=(difference_type n) {
+    it_ += n;
+    return *this;
+  }
+  constexpr contiguous_iterator& operator-=(difference_type n) {
+    it_ -= n;
+    return *this;
+  }
+  friend constexpr contiguous_iterator operator+(contiguous_iterator x, difference_type n) {
+    x += n;
+    return x;
+  }
+  friend constexpr contiguous_iterator operator+(difference_type n, contiguous_iterator x) {
+    x += n;
+    return x;
+  }
+  friend constexpr contiguous_iterator operator-(contiguous_iterator x, difference_type n) {
+    x -= n;
+    return x;
+  }
+  friend constexpr difference_type operator-(contiguous_iterator x, contiguous_iterator y) { return x.it_ - y.it_; }
+
+  friend constexpr bool operator==(const contiguous_iterator& x, const contiguous_iterator& y) {
+    return x.it_ == y.it_;
+  }
+  friend constexpr bool operator!=(const contiguous_iterator& x, const contiguous_iterator& y) {
+    return x.it_ != y.it_;
+  }
+  friend constexpr bool operator<(const contiguous_iterator& x, const contiguous_iterator& y) { return x.it_ < y.it_; }
+  friend constexpr bool operator<=(const contiguous_iterator& x, const contiguous_iterator& y) {
+    return x.it_ <= y.it_;
+  }
+  friend constexpr bool operator>(const contiguous_iterator& x, const contiguous_iterator& y) { return x.it_ > y.it_; }
+  friend constexpr bool operator>=(const contiguous_iterator& x, const contiguous_iterator& y) {
+    return x.it_ >= y.it_;
+  }
 
     // Note no operator<=>, use three_way_contiguous_iterator for testing operator<=>
 
-    friend TEST_CONSTEXPR It base(const contiguous_iterator& i) { return i.it_; }
+  friend constexpr It base(const contiguous_iterator& i) { return i.it_; }
 
-    template <class T>
-    void operator,(T const &) = delete;
+  template <class T>
+  void operator,(T const&) = delete;
 };
 template <class It>
 contiguous_iterator(It) -> contiguous_iterator<It>;