Fix the BinaryPredicate form of std::is_permutation to not rely on operator==

According to [1], forms 2 and 4 of std::is_permutation should use the passed in
binary predicate to compare elements. operator== should only be used for forms
1 and 3 which do not take a binary predicate.

This CL fixes forms 2 and 4 which relied on operator== for some comparisons.

[1] http://en.cppreference.com/w/cpp/algorithm/is_permutation

Patch by Thomas Anderson!

Differential Revision: https://reviews.llvm.org/D42518

llvm-svn: 323563

1 files changed, 24 insertions, 0 deletions

diff --git a/libcxx/test/std/algorithms/alg.nonmodifying/alg.is_permutation/is_permutation_pred.pass.cpp b/libcxx/test/std/algorithms/alg.nonmodifying/alg.is_permutation/is_permutation_pred.pass.cpp
index 6c40ce368db..12bd938d296 100644
--- a/libcxx/test/std/algorithms/alg.nonmodifying/alg.is_permutation/is_permutation_pred.pass.cpp
+++ b/libcxx/test/std/algorithms/alg.nonmodifying/alg.is_permutation/is_permutation_pred.pass.cpp
@@ -738,6 +738,30 @@ int main()
                                    std::equal_to<const int>()) == false);
 #endif
     }
+    {
+      struct S {
+          S(int i) : i_(i) {}
+          bool operator==(const S& other) = delete;
+          int i_;
+      };
+      struct eq {
+          bool operator()(const S& a, const S&b) { return a.i_ == b.i_; }
+      };
+      const S a[] = {S(0), S(1)};
+      const S b[] = {S(1), S(0)};
+      const unsigned sa = sizeof(a)/sizeof(a[0]);
+      assert(std::is_permutation(forward_iterator<const S*>(a),
+                                 forward_iterator<const S*>(a + sa),
+                                 forward_iterator<const S*>(b),
+                                 eq()));
+#if TEST_STD_VER >= 14
+      assert(std::is_permutation(forward_iterator<const S*>(a),
+                                 forward_iterator<const S*>(a + sa),
+                                 forward_iterator<const S*>(b),
+                                 forward_iterator<const S*>(b + sa),
+                                 eq()));
+#endif
+    }
 
 #if TEST_STD_VER > 17
     static_assert(test_constexpr());