From 7a39439904751f0269a4fe39805785a5353238b5 Mon Sep 17 00:00:00 2001
From: Benoit Steiner <benoit.steiner.goog@gmail.com>
Date: Fri, 17 Jul 2015 16:46:30 -0700
Subject: [PATCH] Rewrote Eigen::dimensions_match to prevent a static assertion
 when the rank of the tensors is different.

---
 .../Eigen/CXX11/src/Tensor/TensorDimensions.h   | 17 ++++++++++-------
 unsupported/test/cxx11_tensor_dimension.cpp     |  4 ++++
 2 files changed, 14 insertions(+), 7 deletions(-)

diff --git a/unsupported/Eigen/CXX11/src/Tensor/TensorDimensions.h b/unsupported/Eigen/CXX11/src/Tensor/TensorDimensions.h
index 7a1d40d7d..2b5de4f55 100644
--- a/unsupported/Eigen/CXX11/src/Tensor/TensorDimensions.h
+++ b/unsupported/Eigen/CXX11/src/Tensor/TensorDimensions.h
@@ -401,15 +401,21 @@ template <std::size_t n, std::size_t V1, std::size_t V2, std::size_t V3, std::si
 #endif
 
 
-template <typename Dims1, typename Dims2, size_t n>
+template <typename Dims1, typename Dims2, size_t n, size_t m>
 struct sizes_match_up_to_dim {
+  static inline bool run(Dims1& dims1, Dims2& dims2) {
+    return false;
+  }
+};
+template <typename Dims1, typename Dims2, size_t n>
+struct sizes_match_up_to_dim<Dims1, Dims2, n, n> {
   static inline bool run(Dims1& dims1, Dims2& dims2) {
     return (array_get<n>(dims1) == array_get<n>(dims2)) &
-        sizes_match_up_to_dim<Dims1, Dims2, n-1>::run(dims1, dims2);
+        sizes_match_up_to_dim<Dims1, Dims2, n-1, n-1>::run(dims1, dims2);
   }
 };
 template <typename Dims1, typename Dims2>
-struct sizes_match_up_to_dim<Dims1, Dims2, 0> {
+struct sizes_match_up_to_dim<Dims1, Dims2, 0, 0> {
   static inline bool run(Dims1& dims1, Dims2& dims2) {
     return (array_get<0>(dims1) == array_get<0>(dims2));
   }
@@ -420,10 +426,7 @@ struct sizes_match_up_to_dim<Dims1, Dims2, 0> {
 
 template <typename Dims1, typename Dims2>
 bool dimensions_match(Dims1& dims1, Dims2& dims2) {
-  if (static_cast<size_t>(internal::array_size<Dims1>::value) != static_cast<size_t>(internal::array_size<Dims2>::value)) {
-    return false;
-  }
-  return internal::sizes_match_up_to_dim<Dims1, Dims2, internal::array_size<Dims1>::value-1>::run(dims1, dims2);
+  return internal::sizes_match_up_to_dim<Dims1, Dims2, internal::array_size<Dims1>::value-1, internal::array_size<Dims2>::value-1>::run(dims1, dims2);
 }
 
 } // end namespace Eigen
diff --git a/unsupported/test/cxx11_tensor_dimension.cpp b/unsupported/test/cxx11_tensor_dimension.cpp
index 247d312ae..22c58450c 100644
--- a/unsupported/test/cxx11_tensor_dimension.cpp
+++ b/unsupported/test/cxx11_tensor_dimension.cpp
@@ -43,6 +43,10 @@ static void test_match()
   Eigen::DSizes<int, 3> dyn(2,3,7);
   Eigen::Sizes<2,3,7> stat;
   VERIFY_IS_EQUAL(Eigen::dimensions_match(dyn, stat), true);
+
+  Eigen::DSizes<int, 3> dyn1(2,3,7);
+  Eigen::DSizes<int, 2> dyn2(2,3);
+  VERIFY_IS_EQUAL(Eigen::dimensions_match(dyn, stat), false);
 }