bug #696: enable zero-sized block at compile-time by relaxing the respective assertion

2 files changed, 20 insertions, 2 deletions

diff --git a/Eigen/src/Core/Block.h b/Eigen/src/Core/Block.h
index cee5591f2..cf962aed1 100644
--- a/Eigen/src/Core/Block.h
+++ b/Eigen/src/Core/Block.h
@@ -129,8 +129,8 @@ template<typename XprType, int BlockRows, int BlockCols, bool InnerPanel> class
       : Impl(xpr, startRow, startCol)
     {
       EIGEN_STATIC_ASSERT(RowsAtCompileTime!=Dynamic && ColsAtCompileTime!=Dynamic,THIS_METHOD_IS_ONLY_FOR_FIXED_SIZE)
-      eigen_assert(startRow >= 0 && BlockRows >= 1 && startRow + BlockRows <= xpr.rows()
-             && startCol >= 0 && BlockCols >= 1 && startCol + BlockCols <= xpr.cols());
+      eigen_assert(startRow >= 0 && BlockRows >= 0 && startRow + BlockRows <= xpr.rows()
+             && startCol >= 0 && BlockCols >= 0 && startCol + BlockCols <= xpr.cols());
     }
 
     /** Dynamic-size constructor
diff --git a/test/zerosized.cpp b/test/zerosized.cpp
index da7dd0481..85c553453 100644
--- a/test/zerosized.cpp
+++ b/test/zerosized.cpp
@@ -25,6 +25,7 @@ template<typename MatrixType> void zeroReduction(const MatrixType& m) {
 template<typename MatrixType> void zeroSizedMatrix()
 {
   MatrixType t1;
+  typedef typename MatrixType::Scalar Scalar;
 
   if (MatrixType::SizeAtCompileTime == Dynamic || MatrixType::SizeAtCompileTime == 0)
   {
@@ -45,6 +46,23 @@ template<typename MatrixType> void zeroSizedMatrix()
       VERIFY(t1==t2);
     }
   }
+
+  if(MatrixType::MaxColsAtCompileTime!=0 && MatrixType::MaxRowsAtCompileTime!=0)
+  {
+    Index rows = MatrixType::RowsAtCompileTime==Dynamic ? internal::random<Index>(1,10) : MatrixType::RowsAtCompileTime;
+    Index cols = MatrixType::ColsAtCompileTime==Dynamic ? internal::random<Index>(1,10) : MatrixType::ColsAtCompileTime;
+    MatrixType m(rows,cols);
+    zeroReduction(m.template block<0,MatrixType::ColsAtCompileTime>(0,0,0,cols));
+    zeroReduction(m.template block<MatrixType::RowsAtCompileTime,0>(0,0,rows,0));
+    zeroReduction(m.template block<0,1>(0,0));
+    zeroReduction(m.template block<1,0>(0,0));
+    Matrix<Scalar,Dynamic,Dynamic> prod = m.template block<MatrixType::RowsAtCompileTime,0>(0,0,rows,0) * m.template block<0,MatrixType::ColsAtCompileTime>(0,0,0,cols);
+    VERIFY(prod.rows()==rows && prod.cols()==cols);
+    VERIFY(prod.isZero());
+    prod = m.template block<1,0>(0,0) * m.template block<0,1>(0,0);
+    VERIFY(prod.size()==1);
+    VERIFY(prod.isZero());
+  }
 }
 
 template<typename VectorType> void zeroSizedVector()