Constness in block expressions changed behavior

Submitted by Simon Praetorius

Assigned to Nobody

Link to original bugzilla bug (#1410)
Version: 3.3 (current stable)

Description

When converting a matrix into an array and extracting a block-view afterwards, the behavior is changed due to const-properties from 3.2.x to 3.3.x:

Example:

using Matrix = Eigen::Matrix<double, Eigen::Dynamic, Eigen::Dynamic>;  
Matrix const m(10,10);  
auto a = m.array();  
auto r = a.row(1); // error: invalid conversion from `const double*` to `double*`  

The code works find in 3.2.x but not in 3.3.x. If I change auto a = ... to auto const a = ... all is fine in 3.3.

I have not found a note in the changelogs or this bug-tracker that addresses this issue, but maybe I just missed it.

What is the correct behavior? The old one, or the new one, i.e. should it be auto const a = ...?