This is to flag a small backward compatibility issue with the super-useful -distinct- command by Nick Cox.

When doing

Code:
distinct varname
where varname has all missing values, the current version (1.4.1, created on 10 October 2020) of the distinct command displays

Code:
note: no distinct values satisfy specification
It produces no error, and does not define the scalars r(ndistinct) and r(N).

On the other hand, in a previous version of the command (1.2.1, from 1 March 2012), these were defined, and r(ndistinct) was simply set to zero.

This inconsistency broke my code recently. Fixing it was easy, but I wanted to flag the problem. My personal preference is for the old behaviour, but perhaps Nick had good reasons to change it?