bug#24532: GNU wc --lines doesn't report last line when that doesn't end on a new-line.

[Paul Eggert]

Carlo Wood wrote:
> You can argue that this is a feature, but I consider it a bug for all
> practical purposes.

POSIX requires that wc -l must just count newlines, so it is indeed a feature.

If wc -l also counted incomplete lines at the end of a file, this would result 
in counterintuitive behavior of a different sort. For example:

cat a b >c
wc -l a
wc -l b
wc -l c

Currently the first two numbers must sum to the third, but that would not be 
true under the change you're proposing.

Incomplete lines must cause a problem of some sort, and I'm afraid that the 
longstanding tradition is to cause the problem you ran into.