From 20991c3203818e685dbfd89e20408e5f1b254346 Mon Sep 17 00:00:00 2001
From: Gael Guennebaud <g.gael@free.fr>
Date: Fri, 13 Jul 2018 17:47:28 +0200
Subject: bug #1571: fix is_convertible<from,to> with "from" a reference.

---
 Eigen/src/Core/util/Meta.h |  2 +-
 test/meta.cpp              | 10 +++++++++-
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/Eigen/src/Core/util/Meta.h b/Eigen/src/Core/util/Meta.h
index 748f24b1e..658cfa9eb 100755
--- a/Eigen/src/Core/util/Meta.h
+++ b/Eigen/src/Core/util/Meta.h
@@ -161,7 +161,7 @@ private:
   static no  test(any_conversion, ...);
 
 public:
-  static From* ms_from;
+  static typename internal::remove_reference<From>::type* ms_from;
 #ifdef __INTEL_COMPILER
   #pragma warning push
   #pragma warning ( disable : 2259 )
diff --git a/test/meta.cpp b/test/meta.cpp
index 4904f3ba4..34c5520a6 100644
--- a/test/meta.cpp
+++ b/test/meta.cpp
@@ -80,7 +80,15 @@ void test_meta()
   STATIC_CHECK(( internal::is_convertible<double,std::complex<double> >::value ));
   STATIC_CHECK((!internal::is_convertible<std::complex<double>,double>::value ));
   STATIC_CHECK(( internal::is_convertible<Array33f,Matrix3f>::value ));
-//   VERIFY((!internal::is_convertible<Matrix3f,Matrix3d>::value )); //does not work because the conversion is prevented by a static assertion
+  STATIC_CHECK(( internal::is_convertible<Matrix3f&,Matrix3f>::value ));
+  STATIC_CHECK(( internal::is_convertible<Matrix3f&,Matrix3f&>::value ));
+  STATIC_CHECK(( internal::is_convertible<Matrix3f&,const Matrix3f&>::value ));
+  STATIC_CHECK(( internal::is_convertible<const Matrix3f&,Matrix3f>::value ));
+  STATIC_CHECK(( internal::is_convertible<const Matrix3f&,const Matrix3f&>::value ));
+  STATIC_CHECK((!internal::is_convertible<const Matrix3f&,Matrix3f&>::value ));
+  STATIC_CHECK((!internal::is_convertible<const Matrix3f,Matrix3f&>::value ));
+  STATIC_CHECK(( internal::is_convertible<Matrix3f,Matrix3f&>::value )); // std::is_convertible returns false here though Matrix3f from; Matrix3f& to = from; is valid.
+  //STATIC_CHECK((!internal::is_convertible<Matrix3f,Matrix3d>::value )); //does not work because the conversion is prevented by a static assertion
   STATIC_CHECK((!internal::is_convertible<Array33f,int>::value ));
   STATIC_CHECK((!internal::is_convertible<MatrixXf,float>::value ));
   {
-- 
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