From df15fbc4520402a00b053bd02c782b77a5b72f61 Mon Sep 17 00:00:00 2001
From: Gael Guennebaud <g.gael@free.fr>
Date: Thu, 28 Jan 2016 13:16:30 +0100
Subject: [PATCH] bug #1158: PartialReduxExpr is a vector expression, and it
 thus must expose the LinearAccessBit flag

---
 Eigen/src/Core/CoreEvaluators.h | 2 +-
 test/vectorwiseop.cpp           | 3 +++
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/Eigen/src/Core/CoreEvaluators.h b/Eigen/src/Core/CoreEvaluators.h
index 8bd73b814..7776948d1 100644
--- a/Eigen/src/Core/CoreEvaluators.h
+++ b/Eigen/src/Core/CoreEvaluators.h
@@ -994,7 +994,7 @@ struct evaluator<PartialReduxExpr<ArgType, MemberOp, Direction> >
     CoeffReadCost = TraversalSize==Dynamic ? HugeCost
                   : TraversalSize * evaluator<ArgType>::CoeffReadCost + int(CostOpType::value),
     
-    Flags = (traits<XprType>::Flags&RowMajorBit) | (evaluator<ArgType>::Flags&(HereditaryBits&(~RowMajorBit))),
+    Flags = (traits<XprType>::Flags&RowMajorBit) | (evaluator<ArgType>::Flags&(HereditaryBits&(~RowMajorBit))) | LinearAccessBit,
     
     Alignment = 0 // FIXME this will need to be improved once PartialReduxExpr is vectorized
   };
diff --git a/test/vectorwiseop.cpp b/test/vectorwiseop.cpp
index 87476f95b..3cc198772 100644
--- a/test/vectorwiseop.cpp
+++ b/test/vectorwiseop.cpp
@@ -210,6 +210,9 @@ template<typename MatrixType> void vectorwiseop_matrix(const MatrixType& m)
   VERIFY_IS_APPROX(m1.cwiseAbs().colwise().maxCoeff(), m1.colwise().template lpNorm<Infinity>());
   VERIFY_IS_APPROX(m1.cwiseAbs().rowwise().maxCoeff(), m1.rowwise().template lpNorm<Infinity>());
 
+  // regression for bug 1158
+  VERIFY_IS_APPROX(m1.cwiseAbs().colwise().sum().x(), m1.col(0).cwiseAbs().sum());
+
   // test normalized
   m2 = m1.colwise().normalized();
   VERIFY_IS_APPROX(m2.col(c), m1.col(c).normalized());