From 14a5f135a32eed85033a5061d96e2d45e23d50aa Mon Sep 17 00:00:00 2001
From: Gael Guennebaud <g.gael@free.fr>
Date: Fri, 6 Mar 2015 17:51:31 +0100
Subject: [PATCH] bug #969: workaround abiguous calls to Ref using enable_if.

---
 Eigen/src/Core/Ref.h | 16 +++++++++++-----
 test/ref.cpp         | 24 ++++++++++++++++++++++++
 2 files changed, 35 insertions(+), 5 deletions(-)

diff --git a/Eigen/src/Core/Ref.h b/Eigen/src/Core/Ref.h
index 0cb117949..ea5a2bd5c 100644
--- a/Eigen/src/Core/Ref.h
+++ b/Eigen/src/Core/Ref.h
@@ -105,7 +105,8 @@ struct traits<Ref<_PlainObjectType, _Options, _StrideType> >
       OuterStrideMatch = Derived::IsVectorAtCompileTime
                       || int(StrideType::OuterStrideAtCompileTime)==int(Dynamic) || int(StrideType::OuterStrideAtCompileTime)==int(Derived::OuterStrideAtCompileTime),
       AlignmentMatch = (_Options!=Aligned) || ((PlainObjectType::Flags&AlignedBit)==0) || ((traits<Derived>::Flags&AlignedBit)==AlignedBit),
-      MatchAtCompileTime = HasDirectAccess && StorageOrderMatch && InnerStrideMatch && OuterStrideMatch && AlignmentMatch
+      ScalarTypeMatch = internal::is_same<typename PlainObjectType::Scalar, typename Derived::Scalar>::value,
+      MatchAtCompileTime = HasDirectAccess && StorageOrderMatch && InnerStrideMatch && OuterStrideMatch && AlignmentMatch && ScalarTypeMatch
     };
     typedef typename internal::conditional<MatchAtCompileTime,internal::true_type,internal::false_type>::type type;
   };
@@ -184,9 +185,11 @@ protected:
 template<typename PlainObjectType, int Options, typename StrideType> class Ref
   : public RefBase<Ref<PlainObjectType, Options, StrideType> >
 {
+  private:
     typedef internal::traits<Ref> Traits;
     template<typename Derived>
-    EIGEN_DEVICE_FUNC inline Ref(const PlainObjectBase<Derived>& expr);
+    EIGEN_DEVICE_FUNC inline Ref(const PlainObjectBase<Derived>& expr,
+                                 typename internal::enable_if<bool(Traits::template match<Derived>::MatchAtCompileTime),Derived>::type* = 0);
   public:
 
     typedef RefBase<Ref> Base;
@@ -195,13 +198,15 @@ template<typename PlainObjectType, int Options, typename StrideType> class Ref
 
     #ifndef EIGEN_PARSED_BY_DOXYGEN
     template<typename Derived>
-    EIGEN_DEVICE_FUNC inline Ref(PlainObjectBase<Derived>& expr)
+    EIGEN_DEVICE_FUNC inline Ref(PlainObjectBase<Derived>& expr,
+                                 typename internal::enable_if<bool(Traits::template match<Derived>::MatchAtCompileTime),Derived>::type* = 0)
     {
       EIGEN_STATIC_ASSERT(bool(Traits::template match<Derived>::MatchAtCompileTime), STORAGE_LAYOUT_DOES_NOT_MATCH);
       Base::construct(expr.derived());
     }
     template<typename Derived>
-    EIGEN_DEVICE_FUNC inline Ref(const DenseBase<Derived>& expr)
+    EIGEN_DEVICE_FUNC inline Ref(const DenseBase<Derived>& expr,
+                                 typename internal::enable_if<bool(Traits::template match<Derived>::MatchAtCompileTime),Derived>::type* = 0)
     #else
     template<typename Derived>
     inline Ref(DenseBase<Derived>& expr)
@@ -228,7 +233,8 @@ template<typename TPlainObjectType, int Options, typename StrideType> class Ref<
     EIGEN_DENSE_PUBLIC_INTERFACE(Ref)
 
     template<typename Derived>
-    EIGEN_DEVICE_FUNC inline Ref(const DenseBase<Derived>& expr)
+    EIGEN_DEVICE_FUNC inline Ref(const DenseBase<Derived>& expr,
+                                 typename internal::enable_if<bool(Traits::template match<Derived>::ScalarTypeMatch),Derived>::type* = 0)
     {
 //      std::cout << match_helper<Derived>::HasDirectAccess << "," << match_helper<Derived>::OuterStrideMatch << "," << match_helper<Derived>::InnerStrideMatch << "\n";
 //      std::cout << int(StrideType::OuterStrideAtCompileTime) << " - " << int(Derived::OuterStrideAtCompileTime) << "\n";
diff --git a/test/ref.cpp b/test/ref.cpp
index b9470213c..fbe2c450f 100644
--- a/test/ref.cpp
+++ b/test/ref.cpp
@@ -228,6 +228,28 @@ void call_ref()
   VERIFY_EVALUATION_COUNT( call_ref_7(c,c), 0);
 }
 
+typedef Matrix<double,Dynamic,Dynamic,RowMajor> RowMatrixXd;
+int test_ref_overload_fun1(Ref<MatrixXd> )       { return 1; }
+int test_ref_overload_fun1(Ref<RowMatrixXd> )    { return 2; }
+int test_ref_overload_fun1(Ref<MatrixXf> )       { return 3; }
+
+int test_ref_overload_fun2(Ref<const MatrixXd> ) { return 4; }
+int test_ref_overload_fun2(Ref<const MatrixXf> ) { return 5; }
+
+// See also bug 969
+void test_ref_overloads()
+{
+  MatrixXd Ad, Bd;
+  RowMatrixXd rAd, rBd;
+  VERIFY( test_ref_overload_fun1(Ad)==1 );
+  VERIFY( test_ref_overload_fun1(rAd)==2 );
+  
+  MatrixXf Af, Bf;
+  VERIFY( test_ref_overload_fun2(Ad)==4 );
+  VERIFY( test_ref_overload_fun2(Ad+Bd)==4 );
+  VERIFY( test_ref_overload_fun2(Af+Bf)==5 );
+}
+
 void test_ref()
 {
   for(int i = 0; i < g_repeat; i++) {
@@ -248,4 +270,6 @@ void test_ref()
     CALL_SUBTEST_5( ref_matrix(MatrixXi(internal::random<int>(1,10),internal::random<int>(1,10))) );
     CALL_SUBTEST_6( call_ref() );
   }
+  
+  CALL_SUBTEST_7( test_ref_overloads() );
 }