From 7dc0c4e8f6fdb0110fdcbb536a6146abc31dd39f Mon Sep 17 00:00:00 2001
From: Gael Guennebaud <g.gael@free.fr>
Date: Wed, 18 Nov 2015 23:27:18 +0100
Subject: [PATCH] make Visitor honors nesting requirements (fix
 prod.maxCoeff(i) and similar)

---
 Eigen/src/Core/Visitor.h | 7 +++++--
 test/visitor.cpp         | 5 +++++
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/Eigen/src/Core/Visitor.h b/Eigen/src/Core/Visitor.h
index 64867b7a2..dd94eb8f0 100644
--- a/Eigen/src/Core/Visitor.h
+++ b/Eigen/src/Core/Visitor.h
@@ -76,14 +76,17 @@ template<typename Derived>
 template<typename Visitor>
 void DenseBase<Derived>::visit(Visitor& visitor) const
 {
+  typedef typename internal::remove_all<typename Derived::Nested>::type ThisNested;
+  typename Derived::Nested thisNested(derived());
+
   enum { unroll = SizeAtCompileTime != Dynamic
                    && CoeffReadCost != Dynamic
                    && (SizeAtCompileTime == 1 || internal::functor_traits<Visitor>::Cost != Dynamic)
                    && SizeAtCompileTime * CoeffReadCost + (SizeAtCompileTime-1) * internal::functor_traits<Visitor>::Cost
                       <= EIGEN_UNROLLING_LIMIT };
-  return internal::visitor_impl<Visitor, Derived,
+  return internal::visitor_impl<Visitor, ThisNested,
       unroll ? int(SizeAtCompileTime) : Dynamic
-    >::run(derived(), visitor);
+    >::run(thisNested, visitor);
 }
 
 namespace internal {
diff --git a/test/visitor.cpp b/test/visitor.cpp
index 39a5d6b5f..844170ec6 100644
--- a/test/visitor.cpp
+++ b/test/visitor.cpp
@@ -55,6 +55,11 @@ template<typename MatrixType> void matrixVisitor(const MatrixType& p)
   VERIFY_IS_APPROX(maxc, eigen_maxc);
   VERIFY_IS_APPROX(minc, m.minCoeff());
   VERIFY_IS_APPROX(maxc, m.maxCoeff());
+
+  eigen_maxc = (m.adjoint()*m).maxCoeff(&eigen_maxrow,&eigen_maxcol);
+  eigen_maxc = (m.adjoint()*m).eval().maxCoeff(&maxrow,&maxcol);
+  VERIFY(maxrow == eigen_maxrow);
+  VERIFY(maxcol == eigen_maxcol);
 }
 
 template<typename VectorType> void vectorVisitor(const VectorType& w)