Incorrect output for RowMajor

[alecjacobson]

Here's a small example:

#include <Eigen/Core>

int main()
{
  Eigen::Matrix<double, 3, 4> A;
  A << 1, 2, 3, 4,
      5, 6, 7, 8,
      9, 10, 11, 12;
    Eigen::Matrix<double, 3, 4, Eigen::RowMajor> B;
  B << 1, 2, 3, 4,
      5, 6, 7, 8,
      9, 10, 11, 12;
  assert(false);
}

and then if you print B in the debugger:

Assertion failed: (false), function main, file test.cpp, line 13.
Process 75559 stopped
* thread #1, queue = 'com.apple.main-thread', stop reason = hit program assert
    frame #4: 0x0000000100002908 a.out`main at test.cpp:13:1
   10  	B << 1, 2, 3, 4,
   11  	    5, 6, 7, 8,
   12  	    9, 10, 11, 12;
-> 13  	assert(false);
   14  	}
Target 0: (a.out) stopped.
Process 75559 launched: '/Users/alecjacobson/a.out' (arm64)
(lldb) p B
(Eigen::Matrix<double, 3, 4, 1, 3, 4>) $0 = rows: 3, cols: 4
[  1  4  7 10;
   2  5  8 11;
   3  6  9 12;
 ]

(PR coming forthwith)