From 46a2487c73a349064b7a0e2f9992ee23b8a28b5c Mon Sep 17 00:00:00 2001
From: Kim Laine <kim.laine@microsoft.com>
Date: Sat, 30 May 2020 22:30:22 -0700
Subject: [PATCH] Fixed bug in IterTuple value_type

---
 native/src/seal/evaluator.cpp   |  8 +++----
 native/src/seal/util/iterator.h | 37 ++++++++++++++++++---------------
 2 files changed, 24 insertions(+), 21 deletions(-)

diff --git a/native/src/seal/evaluator.cpp b/native/src/seal/evaluator.cpp
index 60bfba71a..fec767d3a 100644
--- a/native/src/seal/evaluator.cpp
+++ b/native/src/seal/evaluator.cpp
@@ -323,14 +323,14 @@ namespace seal
 
         // This lambda function takes as input an IterTuple with three components:
         //
-        // 1. ConstRNSIter to read an input polynomial from
+        // 1. (Const)RNSIter to read an input polynomial from
         // 2. RNSIter for the output in base q
         // 3. RNSIter for the output in base Bsk
         //
         // It performs steps (1)-(3) of the BEHZ multiplication (see above) on the given input polynomial (given as an
         // RNSIter or ConstRNSIter) and writes the results in base q and base Bsk to the given output
         // iterators.
-        auto behz_extend_base_convert_to_ntt = [&](IterTuple<ConstRNSIter, RNSIter, RNSIter> I) {
+        auto behz_extend_base_convert_to_ntt = [&](auto I) {
             // Make copy of input polynomial (in base q) and convert to NTT form
             // Lazy reduction
             set_poly(get<0>(I), coeff_count, base_q_size, get<1>(I));
@@ -607,13 +607,13 @@ namespace seal
 
         // This lambda function takes as input an IterTuple with three components:
         //
-        // 1. ConstRNSIter to read an input polynomial from
+        // 1. (Const)RNSIter to read an input polynomial from
         // 2. RNSIter for the output in base q
         // 3. RNSIter for the output in base Bsk
         //
         // It performs steps (1)-(3) of the BEHZ multiplication on the given input polynomial (given as an RNSIter
         // or ConstRNSIter) and writes the results in base q and base Bsk to the given output iterators.
-        auto behz_extend_base_convert_to_ntt = [&](IterTuple<ConstRNSIter, RNSIter, RNSIter> I) {
+        auto behz_extend_base_convert_to_ntt = [&](auto I) {
             // Make copy of input polynomial (in base q) and convert to NTT form
             // Lazy reduction
             set_poly(get<0>(I), coeff_count, base_q_size, get<1>(I));
diff --git a/native/src/seal/util/iterator.h b/native/src/seal/util/iterator.h
index 285a1d91d..9b6f2b1c6 100644
--- a/native/src/seal/util/iterator.h
+++ b/native/src/seal/util/iterator.h
@@ -1573,6 +1573,24 @@ namespace seal
             }
         };
 
+        namespace iterator_internal
+        {
+            template <typename... SEALIters>
+            struct extend_iter_tuple;
+
+            template <typename SEALIter, typename... Rest>
+            struct extend_iter_tuple<SEALIter, IterTuple<Rest...>>
+            {
+                using type = IterTuple<SEALIter, Rest...>;
+            };
+
+            template <typename SEALIter1, typename SEALIter2>
+            struct extend_iter_tuple<SEALIter1, SEALIter2>
+            {
+                using type = IterTuple<SEALIter1, SEALIter2>;
+            };
+        }
+
         template <typename SEALIter, typename... Rest>
         class IterTuple<SEALIter, Rest...> : public SEALIterBase
         {
@@ -1584,9 +1602,9 @@ namespace seal
             using self_type = IterTuple<SEALIter, Rest...>;
 
             // Standard iterator typedefs
-            using value_type = IterTuple<
+            using value_type = typename iterator_internal::extend_iter_tuple<
                 typename std::iterator_traits<SEALIter>::value_type,
-                typename std::iterator_traits<IterTuple<Rest>>::value_type...>;
+                typename std::iterator_traits<IterTuple<Rest...>>::value_type>::type;
             using pointer = void;
             using reference = const value_type &;
             using iterator_category = std::random_access_iterator_tag;
@@ -1970,21 +1988,6 @@ namespace seal
                 return iterator_internal::GetHelperStruct<N>::apply(it);
             }
 
-            template <typename... SEALIters>
-            struct extend_iter_tuple;
-
-            template <typename SEALIter, typename... Rest>
-            struct extend_iter_tuple<SEALIter, IterTuple<Rest...>>
-            {
-                using type = IterTuple<SEALIter, Rest...>;
-            };
-
-            template <typename SEALIter1, typename SEALIter2>
-            struct extend_iter_tuple<SEALIter1, SEALIter2>
-            {
-                using type = IterTuple<SEALIter1, SEALIter2>;
-            };
-
             template <typename T, typename... Rest>
             struct iter_type<
                 std::void_t<