fix test

Author: changkhothuychung

libcxx/test/std/ranges/range.adaptors/range.concat/constraints.pass.cpp

@@ -35,6 +35,8 @@ struct InputRange {
   int* end_;
 };
 
+template <typename... Ts>
+concept ConcatViewConstraintsPass = requires(Ts&&... a) { std::views::concat(a...); };
 
 int main(int, char**) {
 
@@ -59,5 +61,28 @@ int main(int, char**) {
     static_assert(WellFormedView<std::vector<int>>);
   }
 
+  {
+    // LWG 4082
+    std::vector<int> v{1, 2, 3};
+    auto r = std::views::counted(std::back_inserter(v), 3);
+    //auto c = std::views::concat(r);
+    static_assert(!ConcatViewConstraintsPass<decltype(r)>);
+  }
+
+  {
+    // input is a view and has 0 size
+    static_assert(!ConcatViewConstraintsPass<>);
+  }
+
+  {
+    // input is a view and has at least an element
+    static_assert(ConcatViewConstraintsPass<std::vector<int>>);
+  }
+
+  {
+    // inputs are non-concatable
+    static_assert(!ConcatViewConstraintsPass<std::vector<int>, std::vector<std::string>>);
+  }
+
   return 0;
 }

libcxx/test/std/ranges/range.adaptors/range.concat/ctor.verify.cpp

@@ -66,12 +66,12 @@ constexpr void test() {
     decltype(auto) it2 = view.begin() + 3;
 
     assert(it1 != it2);
-    assert(*it1 = 0);
-    assert(*it1 = 4);
+    assert(*it1 == 0);
+    assert(*it2 == 4);
     it1++;
     it2++;
-    assert(*it1 = 1);
-    assert(*it1 = 5);
+    assert(*it1 == 1);
+    assert(*it2 == 5);
   }
 
   {

libcxx/test/std/ranges/range.adaptors/range.concat/iterator/compare.pass.cpp

@@ -13,6 +13,7 @@
 #include <array>
 #include <cassert>
 #include <ranges>
+#include <vector>
 
 #include "test_iterators.h"
 #include "../types.h"
@@ -50,29 +51,6 @@ constexpr void test() {
     assert(*it1 == *it2);
   }
 
-  {
-    // test with more than one view of different types
-    using View           = minimal_view<Iter, Sent>;
-    using ConcatView     = std::ranges::concat_view<View>;
-    using ConcatIterator = std::ranges::iterator_t<ConcatView>;
-
-    auto make_concat_view = [](auto begin, auto end) {
-      View view{Iter(begin), Sent(Iter(end))};
-      return ConcatView(std::move(view));
-    };
-
-    std::array<int, 3> array1{0, 1, 2};
-    std::array<int, 3> array2{3, 4, 5};
-    ConcatView view = make_concat_view(array1.data(), array1.data() + array1.size());
-    std::ranges::concat_view cv(view, std::views::all(array2));
-    decltype(auto) it1 = cv.begin();
-    decltype(auto) it2 = cv.begin() + 3;
-
-    ASSERT_SAME_TYPE(int&, decltype(*it1));
-    assert(*it1 == 0);
-    assert(*it2 == 3);
-  }
-
   {
     // constness
     constexpr static std::array<int, 3> array1{0, 1, 2};
@@ -94,6 +72,23 @@ constexpr bool tests() {
   test<contiguous_iterator<int*>>();
   test<int*>();
 
+  {
+    // test with more than one view of different types
+    std::vector<int> array1{0, 1, 2};
+    std::array<int, 3> array2{3, 4, 5};
+    std::ranges::concat_view cv(std::views::all(array1), std::views::all(array2));
+    decltype(auto) it1 = cv.begin();
+    decltype(auto) it2 = cv.begin();
+
+    ASSERT_SAME_TYPE(int&, decltype(*it1));
+    it2++;
+    assert(*it1 == 0);
+    assert(*it2 == 1);
+    it2++;
+    it2++;
+    assert(*it2 == 3);
+  }
+
   return true;
 }
 

libcxx/test/std/ranges/range.adaptors/range.concat/iterator/deref.pass.cpp

@@ -111,7 +111,7 @@ constexpr bool test() {
 
   {
     //two ranges with different size type
-    std::ranges::concat_view v(UnsignedSizeView(), IntSizeView());
+    std::ranges::concat_view v(UnsignedSizeView{}, IntSizeView{});
     assert(v.size() == 18);
     // common type between size_t and int should be size_t
     ASSERT_SAME_TYPE(decltype(v.size()), unsigned int);