Including subprojects .pri in another folder - c++

Question

I have qt project proj1 which depends on another (proj2).
Directory tree is like this:
common/
`--/pr1/
proj1.pri
main.cpp
`--/pr2/
proj2.pri
src1.cpp
src2.cpp
proj1 includes proj2:
include(../proj2.pri)
while in proj2.pri sources are listed as they are in current (pr2) dir:
SOURCES += src1.cpp \
src2.cpp
So when I try to build proj1 I'm getting such error:
make: *** No rule to make target `src1.cpp', needed by `src1.o'. Stop.
Is there any correct way to include subproject's sources (I need to do so for debugging) with help of pri-files ?

Answer 1

In proj1.pri, before including proj2.pri:
PROJECT_ONE_IS_DEFINED = 1
In proj2.pri:
isEmpty(PROJECT_ONE_IS_DEFINED){
DEPENDPATH += pr2
INCLUDEPATH += pr2
} !isEmpty(PROJECT_ONE_IS_DEFINED){
DEPENDPATH += ..\pr2
INCLUDEPATH += ..\pr2
}
This way project 2 will be included normally if used by itself, and will be included properly if used as part of project 1....
Or, you can simply add path to pr2 to DEPENDPATH in project1, as long as path to your cpp files is added to dependpath, make will work fine
EDIT:
The most efficient way that allows to include .pri file in many projects without worrying about specific path for each case is to add
DEPENDPATH += $$PWD
INCLUDEPATH += $$PWD
in the beginning of each .pri file.