When a link target does not exist, I get error messages like this:

testing-methodologies.qdoc:1: (qdoc) warning: Can't link to 'unit-test'

Here the line number of the error is actually the number of the line at which the documentation comment begins — if I insert an empty line at the beginning of the file, the error is reported as coming from line 2.

In this form, the error messages are not very helpful for .qdoc files that consist of a single big documentation comment.