Created attachment 851 [details]
2x2 test case
The SparseQR_QProduct object calculates incorrect results in the non-transpose case for complex scalars. Test case attached.
Similar to the dense case, the problem is a missing conjugate operator (PR to follow).
This obviously can't work, since for SparseQRMatrixQReturnType the result of adjoint() is the same as transpose().
For future reference: The related dense case was Bug 1493.
PR 386 (https://bitbucket.org/eigen/eigen/pull-requests/386/bugfix-sparseq-complex/diff) is a simple fix for this problem.
Fixed in 3.3 and default: