From 6719e56b5bfe9ae4badc9a6e894c5824f663d62e Mon Sep 17 00:00:00 2001
From: Gael Guennebaud <g.gael@free.fr>
Date: Sun, 11 Aug 2013 17:52:43 +0200
Subject: [PATCH] Ref<> objects must be nested by reference because they
 potentially store a temporary object

---
 Eigen/src/Core/Ref.h                                | 5 +++--
 test/ref.cpp                                        | 4 ++--
 unsupported/Eigen/src/AutoDiff/AutoDiffScalar.h     | 2 +-
 unsupported/Eigen/src/MatrixFunctions/MatrixPower.h | 2 +-
 4 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/Eigen/src/Core/Ref.h b/Eigen/src/Core/Ref.h
index aba795bdb..00d9e6d2b 100644
--- a/Eigen/src/Core/Ref.h
+++ b/Eigen/src/Core/Ref.h
@@ -94,7 +94,8 @@ struct traits<Ref<_PlainObjectType, _Options, _StrideType> >
   typedef _PlainObjectType PlainObjectType;
   typedef _StrideType StrideType;
   enum {
-    Options = _Options
+    Options = _Options,
+    Flags = traits<Map<_PlainObjectType, _Options, _StrideType> >::Flags | NestByRefBit
   };
 
   template<typename Derived> struct match {
@@ -111,7 +112,7 @@ struct traits<Ref<_PlainObjectType, _Options, _StrideType> >
     };
     typedef typename internal::conditional<MatchAtCompileTime,internal::true_type,internal::false_type>::type type;
   };
-
+  
 };
 
 template<typename Derived>
diff --git a/test/ref.cpp b/test/ref.cpp
index 65b4f5a3e..f639d900b 100644
--- a/test/ref.cpp
+++ b/test/ref.cpp
@@ -14,9 +14,9 @@
 
 static int nb_temporaries;
 
-inline void on_temporary_creation(int size) {
+inline void on_temporary_creation(int) {
   // here's a great place to set a breakpoint when debugging failures in this test!
-  if(size!=0) nb_temporaries++;
+  nb_temporaries++;
 }
   
 
diff --git a/unsupported/Eigen/src/AutoDiff/AutoDiffScalar.h b/unsupported/Eigen/src/AutoDiff/AutoDiffScalar.h
index 8d42e69b9..763ed414a 100644
--- a/unsupported/Eigen/src/AutoDiff/AutoDiffScalar.h
+++ b/unsupported/Eigen/src/AutoDiff/AutoDiffScalar.h
@@ -604,7 +604,7 @@ atan2(const AutoDiffScalar<DerTypeA>& a, const AutoDiffScalar<DerTypeB>& b)
   Scalar tmp4 = tmp3/(tmp2+tmp3);
   
   if (tmp4!=0)
-    ret.derivatives() = (a.derivatives() * b.value() - a.value() * b.derivatives()) * (tmp2+tmp3);
+    ret.derivatives() = (a.value() * b.derivatives() - a.derivatives() * b.value()) * (tmp2+tmp3);
 
   return ret;
 }
diff --git a/unsupported/Eigen/src/MatrixFunctions/MatrixPower.h b/unsupported/Eigen/src/MatrixFunctions/MatrixPower.h
index ee665c18e..b91d8632a 100644
--- a/unsupported/Eigen/src/MatrixFunctions/MatrixPower.h
+++ b/unsupported/Eigen/src/MatrixFunctions/MatrixPower.h
@@ -299,7 +299,7 @@ MatrixPowerAtomic<MatrixType>::computeSuperDiag(const ComplexScalar& curr, const
   ComplexScalar logCurr = log(curr);
   ComplexScalar logPrev = log(prev);
   int unwindingNumber = ceil((numext::imag(logCurr - logPrev) - M_PI) / (2*M_PI));
-  ComplexScalar w = numext::atanh2(curr - prev, curr + prev) + ComplexScalar(0, M_PI*unwindingNumber);
+  ComplexScalar w = numext::atanh2(curr - prev, curr + prev) + ComplexScalar(RealScalar(0), RealScalar(M_PI*unwindingNumber));
   return RealScalar(2) * exp(RealScalar(0.5) * p * (logCurr + logPrev)) * sinh(p * w) / (curr - prev);
 }