[libc++][test] Test flat_meow with proper underlying iterators (#131290)

Flat container adaptors require the iterators of underlying containers
to be random access, and it is required that random access container
iterators must support three-way comparison ([container.reqmts]/39 - /41).

As a result, we should at least avoid testing "containers" with random
access but not three-way comparable iterators for flat container
adaptors.

This patch adds a new class template `three_way_random_access_iterator`
to `test_iterators.h` and fixes some usages of `MinSequenceContainer`
with the new iterators.

Author: frederick-vs-ja

libcxx/test/std/containers/container.adaptors/flat.map/flat.map.iterators/iterator_comparison.pass.cpp

@@ -28,7 +28,6 @@ void test() {
   using Key   = typename KeyContainer::value_type;
   using Value = typename ValueContainer::value_type;
   using M     = std::flat_map<Key, Value, std::less<Key>, KeyContainer, ValueContainer>;
-  using KI    = typename KeyContainer::iterator;
   using I     = M::iterator;
   using CI    = M::const_iterator;
   using RI    = M::reverse_iterator;
@@ -115,34 +114,32 @@ void test() {
   assert(cri2 >= cri2);
   assert(!(cri1 >= cri2));
 
-  if constexpr (std::three_way_comparable<KI>) {
-    static_assert(std::three_way_comparable<I>); // ...of course the wrapped iterators still support <=>.
-    static_assert(std::three_way_comparable<CI>);
-    static_assert(std::three_way_comparable<RI>);
-    static_assert(std::three_way_comparable<CRI>);
-    static_assert(std::same_as<decltype(I() <=> I()), std::strong_ordering>);
-    static_assert(std::same_as<decltype(I() <=> CI()), std::strong_ordering>);
-    static_assert(std::same_as<decltype(CI() <=> CI()), std::strong_ordering>);
-    static_assert(std::same_as<decltype(RI() <=> RI()), std::strong_ordering>);
-    static_assert(std::same_as<decltype(RI() <=> CRI()), std::strong_ordering>);
-    static_assert(std::same_as<decltype(CRI() <=> CRI()), std::strong_ordering>);
-
-    assert(i1 <=> i1 == std::strong_ordering::equivalent);
-    assert(i1 <=> i2 == std::strong_ordering::less);
-    assert(i2 <=> i1 == std::strong_ordering::greater);
-
-    assert(ci1 <=> ci1 == std::strong_ordering::equivalent);
-    assert(ci1 <=> ci2 == std::strong_ordering::less);
-    assert(ci2 <=> ci1 == std::strong_ordering::greater);
-
-    assert(ri1 <=> ri1 == std::strong_ordering::equivalent);
-    assert(ri1 <=> ri2 == std::strong_ordering::less);
-    assert(ri2 <=> ri1 == std::strong_ordering::greater);
-
-    assert(cri1 <=> cri1 == std::strong_ordering::equivalent);
-    assert(cri1 <=> cri2 == std::strong_ordering::less);
-    assert(cri2 <=> cri1 == std::strong_ordering::greater);
-  }
+  static_assert(std::three_way_comparable<I>); // ...of course the wrapped iterators still support <=>.
+  static_assert(std::three_way_comparable<CI>);
+  static_assert(std::three_way_comparable<RI>);
+  static_assert(std::three_way_comparable<CRI>);
+  static_assert(std::same_as<decltype(I() <=> I()), std::strong_ordering>);
+  static_assert(std::same_as<decltype(I() <=> CI()), std::strong_ordering>);
+  static_assert(std::same_as<decltype(CI() <=> CI()), std::strong_ordering>);
+  static_assert(std::same_as<decltype(RI() <=> RI()), std::strong_ordering>);
+  static_assert(std::same_as<decltype(RI() <=> CRI()), std::strong_ordering>);
+  static_assert(std::same_as<decltype(CRI() <=> CRI()), std::strong_ordering>);
+
+  assert(i1 <=> i1 == std::strong_ordering::equivalent);
+  assert(i1 <=> i2 == std::strong_ordering::less);
+  assert(i2 <=> i1 == std::strong_ordering::greater);
+
+  assert(ci1 <=> ci1 == std::strong_ordering::equivalent);
+  assert(ci1 <=> ci2 == std::strong_ordering::less);
+  assert(ci2 <=> ci1 == std::strong_ordering::greater);
+
+  assert(ri1 <=> ri1 == std::strong_ordering::equivalent);
+  assert(ri1 <=> ri2 == std::strong_ordering::less);
+  assert(ri2 <=> ri1 == std::strong_ordering::greater);
+
+  assert(cri1 <=> cri1 == std::strong_ordering::equivalent);
+  assert(cri1 <=> cri2 == std::strong_ordering::less);
+  assert(cri2 <=> cri1 == std::strong_ordering::greater);
 }
 
 int main(int, char**) {

libcxx/test/std/containers/container.adaptors/flat.multimap/flat.multimap.iterators/iterator_comparison.pass.cpp

@@ -28,7 +28,6 @@ void test() {
   using Key   = typename KeyContainer::value_type;
   using Value = typename ValueContainer::value_type;
   using M     = std::flat_multimap<Key, Value, std::less<Key>, KeyContainer, ValueContainer>;
-  using KI    = typename KeyContainer::iterator;
   using I     = M::iterator;
   using CI    = M::const_iterator;
   using RI    = M::reverse_iterator;
@@ -115,34 +114,32 @@ void test() {
   assert(cri2 >= cri2);
   assert(!(cri1 >= cri2));
 
-  if constexpr (std::three_way_comparable<KI>) {
-    static_assert(std::three_way_comparable<I>); // ...of course the wrapped iterators still support <=>.
-    static_assert(std::three_way_comparable<CI>);
-    static_assert(std::three_way_comparable<RI>);
-    static_assert(std::three_way_comparable<CRI>);
-    static_assert(std::same_as<decltype(I() <=> I()), std::strong_ordering>);
-    static_assert(std::same_as<decltype(I() <=> CI()), std::strong_ordering>);
-    static_assert(std::same_as<decltype(CI() <=> CI()), std::strong_ordering>);
-    static_assert(std::same_as<decltype(RI() <=> RI()), std::strong_ordering>);
-    static_assert(std::same_as<decltype(RI() <=> CRI()), std::strong_ordering>);
-    static_assert(std::same_as<decltype(CRI() <=> CRI()), std::strong_ordering>);
-
-    assert(i1 <=> i1 == std::strong_ordering::equivalent);
-    assert(i1 <=> i2 == std::strong_ordering::less);
-    assert(i2 <=> i1 == std::strong_ordering::greater);
-
-    assert(ci1 <=> ci1 == std::strong_ordering::equivalent);
-    assert(ci1 <=> ci2 == std::strong_ordering::less);
-    assert(ci2 <=> ci1 == std::strong_ordering::greater);
-
-    assert(ri1 <=> ri1 == std::strong_ordering::equivalent);
-    assert(ri1 <=> ri2 == std::strong_ordering::less);
-    assert(ri2 <=> ri1 == std::strong_ordering::greater);
-
-    assert(cri1 <=> cri1 == std::strong_ordering::equivalent);
-    assert(cri1 <=> cri2 == std::strong_ordering::less);
-    assert(cri2 <=> cri1 == std::strong_ordering::greater);
-  }
+  static_assert(std::three_way_comparable<I>); // ...of course the wrapped iterators still support <=>.
+  static_assert(std::three_way_comparable<CI>);
+  static_assert(std::three_way_comparable<RI>);
+  static_assert(std::three_way_comparable<CRI>);
+  static_assert(std::same_as<decltype(I() <=> I()), std::strong_ordering>);
+  static_assert(std::same_as<decltype(I() <=> CI()), std::strong_ordering>);
+  static_assert(std::same_as<decltype(CI() <=> CI()), std::strong_ordering>);
+  static_assert(std::same_as<decltype(RI() <=> RI()), std::strong_ordering>);
+  static_assert(std::same_as<decltype(RI() <=> CRI()), std::strong_ordering>);
+  static_assert(std::same_as<decltype(CRI() <=> CRI()), std::strong_ordering>);
+
+  assert(i1 <=> i1 == std::strong_ordering::equivalent);
+  assert(i1 <=> i2 == std::strong_ordering::less);
+  assert(i2 <=> i1 == std::strong_ordering::greater);
+
+  assert(ci1 <=> ci1 == std::strong_ordering::equivalent);
+  assert(ci1 <=> ci2 == std::strong_ordering::less);
+  assert(ci2 <=> ci1 == std::strong_ordering::greater);
+
+  assert(ri1 <=> ri1 == std::strong_ordering::equivalent);
+  assert(ri1 <=> ri2 == std::strong_ordering::less);
+  assert(ri2 <=> ri1 == std::strong_ordering::greater);
+
+  assert(cri1 <=> cri1 == std::strong_ordering::equivalent);
+  assert(cri1 <=> cri2 == std::strong_ordering::less);
+  assert(cri2 <=> cri1 == std::strong_ordering::greater);
 }
 
 int main(int, char**) {

libcxx/test/std/containers/container.adaptors/flat.multiset/flat.multiset.iterators/iterator_comparison.pass.cpp

@@ -27,7 +27,6 @@ template <class KeyContainer>
 void test_one() {
   using Key = typename KeyContainer::value_type;
   using M   = std::flat_multiset<Key, std::less<Key>, KeyContainer>;
-  using KI  = typename KeyContainer::iterator;
   using I   = M::iterator;
   using CI  = M::const_iterator;
   using RI  = M::reverse_iterator;
@@ -114,34 +113,32 @@ void test_one() {
   assert(cri2 >= cri2);
   assert(!(cri1 >= cri2));
 
-  if constexpr (std::three_way_comparable<KI>) {
-    static_assert(std::three_way_comparable<I>); // ...of course the wrapped iterators still support <=>.
-    static_assert(std::three_way_comparable<CI>);
-    static_assert(std::three_way_comparable<RI>);
-    static_assert(std::three_way_comparable<CRI>);
-    static_assert(std::same_as<decltype(I() <=> I()), std::strong_ordering>);
-    static_assert(std::same_as<decltype(I() <=> CI()), std::strong_ordering>);
-    static_assert(std::same_as<decltype(CI() <=> CI()), std::strong_ordering>);
-    static_assert(std::same_as<decltype(RI() <=> RI()), std::strong_ordering>);
-    static_assert(std::same_as<decltype(RI() <=> CRI()), std::strong_ordering>);
-    static_assert(std::same_as<decltype(CRI() <=> CRI()), std::strong_ordering>);
-
-    assert(i1 <=> i1 == std::strong_ordering::equivalent);
-    assert(i1 <=> i2 == std::strong_ordering::less);
-    assert(i2 <=> i1 == std::strong_ordering::greater);
-
-    assert(ci1 <=> ci1 == std::strong_ordering::equivalent);
-    assert(ci1 <=> ci2 == std::strong_ordering::less);
-    assert(ci2 <=> ci1 == std::strong_ordering::greater);
-
-    assert(ri1 <=> ri1 == std::strong_ordering::equivalent);
-    assert(ri1 <=> ri2 == std::strong_ordering::less);
-    assert(ri2 <=> ri1 == std::strong_ordering::greater);
-
-    assert(cri1 <=> cri1 == std::strong_ordering::equivalent);
-    assert(cri1 <=> cri2 == std::strong_ordering::less);
-    assert(cri2 <=> cri1 == std::strong_ordering::greater);
-  }
+  static_assert(std::three_way_comparable<I>); // ...of course the wrapped iterators still support <=>.
+  static_assert(std::three_way_comparable<CI>);
+  static_assert(std::three_way_comparable<RI>);
+  static_assert(std::three_way_comparable<CRI>);
+  static_assert(std::same_as<decltype(I() <=> I()), std::strong_ordering>);
+  static_assert(std::same_as<decltype(I() <=> CI()), std::strong_ordering>);
+  static_assert(std::same_as<decltype(CI() <=> CI()), std::strong_ordering>);
+  static_assert(std::same_as<decltype(RI() <=> RI()), std::strong_ordering>);
+  static_assert(std::same_as<decltype(RI() <=> CRI()), std::strong_ordering>);
+  static_assert(std::same_as<decltype(CRI() <=> CRI()), std::strong_ordering>);
+
+  assert(i1 <=> i1 == std::strong_ordering::equivalent);
+  assert(i1 <=> i2 == std::strong_ordering::less);
+  assert(i2 <=> i1 == std::strong_ordering::greater);
+
+  assert(ci1 <=> ci1 == std::strong_ordering::equivalent);
+  assert(ci1 <=> ci2 == std::strong_ordering::less);
+  assert(ci2 <=> ci1 == std::strong_ordering::greater);
+
+  assert(ri1 <=> ri1 == std::strong_ordering::equivalent);
+  assert(ri1 <=> ri2 == std::strong_ordering::less);
+  assert(ri2 <=> ri1 == std::strong_ordering::greater);
+
+  assert(cri1 <=> cri1 == std::strong_ordering::equivalent);
+  assert(cri1 <=> cri2 == std::strong_ordering::less);
+  assert(cri2 <=> cri1 == std::strong_ordering::greater);
 }
 
 void test() {

libcxx/test/std/containers/container.adaptors/flat.set/flat.set.iterators/iterator_comparison.pass.cpp

@@ -27,7 +27,6 @@ template <class KeyContainer>
 void test_one() {
   using Key = typename KeyContainer::value_type;
   using M   = std::flat_set<Key, std::less<Key>, KeyContainer>;
-  using KI  = typename KeyContainer::iterator;
   using I   = M::iterator;
   using CI  = M::const_iterator;
   using RI  = M::reverse_iterator;
@@ -114,34 +113,32 @@ void test_one() {
   assert(cri2 >= cri2);
   assert(!(cri1 >= cri2));
 
-  if constexpr (std::three_way_comparable<KI>) {
-    static_assert(std::three_way_comparable<I>); // ...of course the wrapped iterators still support <=>.
-    static_assert(std::three_way_comparable<CI>);
-    static_assert(std::three_way_comparable<RI>);
-    static_assert(std::three_way_comparable<CRI>);
-    static_assert(std::same_as<decltype(I() <=> I()), std::strong_ordering>);
-    static_assert(std::same_as<decltype(I() <=> CI()), std::strong_ordering>);
-    static_assert(std::same_as<decltype(CI() <=> CI()), std::strong_ordering>);
-    static_assert(std::same_as<decltype(RI() <=> RI()), std::strong_ordering>);
-    static_assert(std::same_as<decltype(RI() <=> CRI()), std::strong_ordering>);
-    static_assert(std::same_as<decltype(CRI() <=> CRI()), std::strong_ordering>);
-
-    assert(i1 <=> i1 == std::strong_ordering::equivalent);
-    assert(i1 <=> i2 == std::strong_ordering::less);
-    assert(i2 <=> i1 == std::strong_ordering::greater);
-
-    assert(ci1 <=> ci1 == std::strong_ordering::equivalent);
-    assert(ci1 <=> ci2 == std::strong_ordering::less);
-    assert(ci2 <=> ci1 == std::strong_ordering::greater);
-
-    assert(ri1 <=> ri1 == std::strong_ordering::equivalent);
-    assert(ri1 <=> ri2 == std::strong_ordering::less);
-    assert(ri2 <=> ri1 == std::strong_ordering::greater);
-
-    assert(cri1 <=> cri1 == std::strong_ordering::equivalent);
-    assert(cri1 <=> cri2 == std::strong_ordering::less);
-    assert(cri2 <=> cri1 == std::strong_ordering::greater);
-  }
+  static_assert(std::three_way_comparable<I>); // ...of course the wrapped iterators still support <=>.
+  static_assert(std::three_way_comparable<CI>);
+  static_assert(std::three_way_comparable<RI>);
+  static_assert(std::three_way_comparable<CRI>);
+  static_assert(std::same_as<decltype(I() <=> I()), std::strong_ordering>);
+  static_assert(std::same_as<decltype(I() <=> CI()), std::strong_ordering>);
+  static_assert(std::same_as<decltype(CI() <=> CI()), std::strong_ordering>);
+  static_assert(std::same_as<decltype(RI() <=> RI()), std::strong_ordering>);
+  static_assert(std::same_as<decltype(RI() <=> CRI()), std::strong_ordering>);
+  static_assert(std::same_as<decltype(CRI() <=> CRI()), std::strong_ordering>);
+
+  assert(i1 <=> i1 == std::strong_ordering::equivalent);
+  assert(i1 <=> i2 == std::strong_ordering::less);
+  assert(i2 <=> i1 == std::strong_ordering::greater);
+
+  assert(ci1 <=> ci1 == std::strong_ordering::equivalent);
+  assert(ci1 <=> ci2 == std::strong_ordering::less);
+  assert(ci2 <=> ci1 == std::strong_ordering::greater);
+
+  assert(ri1 <=> ri1 == std::strong_ordering::equivalent);
+  assert(ri1 <=> ri2 == std::strong_ordering::less);
+  assert(ri2 <=> ri1 == std::strong_ordering::greater);
+
+  assert(cri1 <=> cri1 == std::strong_ordering::equivalent);
+  assert(cri1 <=> cri2 == std::strong_ordering::less);
+  assert(cri2 <=> cri1 == std::strong_ordering::greater);
 }
 
 void test() {

libcxx/test/support/MinSequenceContainer.h

@@ -14,7 +14,9 @@
 
 #include "test_iterators.h"
 
-template <class T, class Iterator = random_access_iterator<T*>, class ConstIterator = random_access_iterator<const T*>>
+template <class T,
+          class Iterator      = three_way_random_access_iterator<T*>,
+          class ConstIterator = three_way_random_access_iterator<const T*>>
 struct MinSequenceContainer {
   using value_type      = T;
   using difference_type = int;