From d58678069c6c90ac6fe6bdeac5e95fd9ea1a2235 Mon Sep 17 00:00:00 2001
From: Christoph Hertzberg <chtz@informatik.uni-bremen.de>
Date: Fri, 9 Apr 2021 17:03:28 +0000
Subject: Make iterators default constructible and assignable, by making...

---
 test/stl_iterators.cpp | 30 +++++++++++++++++++++++++++++-
 1 file changed, 29 insertions(+), 1 deletion(-)

(limited to 'test')

diff --git a/test/stl_iterators.cpp b/test/stl_iterators.cpp
index 997f8016c..72bbf8250 100644
--- a/test/stl_iterators.cpp
+++ b/test/stl_iterators.cpp
@@ -7,9 +7,9 @@
 // Public License v. 2.0. If a copy of the MPL was not distributed
 // with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
+#include "main.h"
 #include <iterator>
 #include <numeric>
-#include "main.h"
 
 template< class Iterator >
 std::reverse_iterator<Iterator>
@@ -47,6 +47,18 @@ bool is_pointer_based_stl_iterator(const internal::pointer_based_stl_iterator<Xp
 template<typename XprType>
 bool is_generic_randaccess_stl_iterator(const internal::generic_randaccess_stl_iterator<XprType> &) { return true; }
 
+template<typename Iter>
+bool is_default_constructible_and_assignable(const Iter& it)
+{
+#if EIGEN_HAS_CXX11
+  VERIFY(std::is_default_constructible<Iter>::value);
+  VERIFY(std::is_nothrow_default_constructible<Iter>::value);
+#endif
+  Iter it2;
+  it2 = it;
+  return (it==it2);
+}
+
 template<typename Xpr>
 void check_begin_end_for_loop(Xpr xpr)
 {
@@ -124,6 +136,22 @@ void test_stl_iterators(int rows=Rows, int cols=Cols)
   
   Index i, j;
 
+  // Verify that iterators are default constructible (See bug #1900)
+  {
+    VERIFY( is_default_constructible_and_assignable(v.begin()));
+    VERIFY( is_default_constructible_and_assignable(v.end()));
+    VERIFY( is_default_constructible_and_assignable(cv.begin()));
+    VERIFY( is_default_constructible_and_assignable(cv.end()));
+
+    VERIFY( is_default_constructible_and_assignable(A.row(0).begin()));
+    VERIFY( is_default_constructible_and_assignable(A.row(0).end()));
+    VERIFY( is_default_constructible_and_assignable(cA.row(0).begin()));
+    VERIFY( is_default_constructible_and_assignable(cA.row(0).end()));
+
+    VERIFY( is_default_constructible_and_assignable(B.row(0).begin()));
+    VERIFY( is_default_constructible_and_assignable(B.row(0).end()));
+  }
+
   // Check we got a fast pointer-based iterator when expected
   {
     VERIFY( is_pointer_based_stl_iterator(v.begin()) );
-- 
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