fix the flags and matrix options, to always have the right RowMajor bit in the vector case

1 files changed, 4 insertions, 2 deletions

diff --git a/Eigen/src/Core/ProductBase.h b/Eigen/src/Core/ProductBase.h
index 789aecfb6..be32189e1 100644
--- a/Eigen/src/Core/ProductBase.h
+++ b/Eigen/src/Core/ProductBase.h
@@ -42,8 +42,10 @@ struct ei_traits<ProductBase<Derived,_Lhs,_Rhs> > //: ei_traits<typename ei_clea
     ColsAtCompileTime = ei_traits<Rhs>::ColsAtCompileTime,
     MaxRowsAtCompileTime = ei_traits<Lhs>::MaxRowsAtCompileTime,
     MaxColsAtCompileTime = ei_traits<Rhs>::MaxColsAtCompileTime,
-    Flags = EvalBeforeNestingBit | EvalBeforeAssigningBit | NestByRefBit, // Note that EvalBeforeNestingBit and NestByRefBit
-                                                                          // are not used in practice because ei_nested is overloaded for products
+    Flags = (RowsAtCompileTime==1 ? RowMajorBit : 0)
+          | EvalBeforeNestingBit | EvalBeforeAssigningBit | NestByRefBit,
+                  // Note that EvalBeforeNestingBit and NestByRefBit
+                  // are not used in practice because ei_nested is overloaded for products
     CoeffReadCost = 0 // FIXME why is it needed ?
   };
 };