[eigen] a problem with RowsAtCompileTime in SparseVector

[Daniel Lowengrub <lowdanie@xxxxxxxxx>]

Hi,
I noticed that the following code complies but crashes with an assert:
Vector10d d = Vector10d::Random(); //Vector10d is the obvious typedef
sd = d.sparseView();

The assert is:
Assertion `( ((ei_traits<Derived>::SupportedAccessPatterns&OuterRandomAccessPattern)==OuterRandomAccessPattern)
|| (!((Flags & RowMajorBit) != (OtherDerived::Flags & RowMajorBit))))
&& "the transpose operation is supposed to be handled in
SparseMatrix::operator="' failed.

On the other hand, this code is fine:
VectorXd d = Vector10d::Random();
sd = d.sparseView();

I think that the problem is that in the SparseVector assignment
operator, the RowsAtCompileTime is checked:
inline SparseVector& operator=(const SparseMatrixBase<OtherDerived>& other)
    {
      if (int(RowsAtCompileTime)!=int(OtherDerived::RowsAtCompileTime))
        return Base::operator=(other.transpose());
....
    }
And then since d.sparseView() takes the same RowsAtCompileTime as d
(which is 10 in the first case but -1 in the second) but sd has -1
RowsAtCompileTime, d.sparseView() is transposed in the first case
which leads to the assertation.


Should SparseView explicitly set RowsAtCompileTime to -1 (Dynamic)?
Or should the assignment operator call the resize method like in the
SparseMatrix class?

Daniel