Qt Creator doesn't parse cpp files referenced through DEPENDPATH

After opening my project, Qt Creator quick search widget does not contain functions defined in most of my cpp files.
The files themselves are there.

I've tested with some modifications of project files and now try to explain the problem.
In .pro file I have

BASE_DIR = ..

In included .pri file I have

DEPENDPATH = $$BASE_DIR/src

In included .in file I have

SOURCES += somefile.cpp

And in this situation symbols from somefile.cpp does not appear in quick search widget. If I change the line in .in file to the following, everything works OK

SOURCES += $$BASE_DIR/src/somefile.cpp

This is broken in commit 3aab8beaf4c585e66179f14fac2f63b51f034520.

The qmake documentation about DEPENDPATH is not clear, so I've also tried adding to VPATH in the same way as DEPENDPATH, but that doesn't help.
Also can be a related issue
https://bugreports.qt-project.org/browse/QTBUG-11912