QMake 'subdirs' template - executing a target? - c++

Question

I am putting together a build system for my Qt app using a qmake .pro file that uses the 'subdirs' template. This works fine, and allows me to specify the order that each target is built, so dependencies work nicely. However, I have now added a tool to the project that generates a version number (containing the build date, SVN revision, etc,) that is used by the main app - I can build this version tool first but when it is built I want to execute it before any more targets are built (it generates a header file containing the version number that the main app includes.)
For example, my simple qmake file looks like something this:
TEMPLATE = subdirs
CONFIG += ordered
SUBDIRS = version \
lib \
tests \
mainapp
When 'version' is built I want to execute it (passing some arguments on the command-line) before 'lib' is built.
Does anyone know if this is possible? I see that qmake has a 'system' command that can execute apps, but I don't know how I could leverage this.
A related question concerns my unit tests. These live in the 'test' project and use the QTest framework. I want to execute the tests exe before building 'mainapp' and if the tests fail (i.e. the tests exe doesn't return zero) I want to quit the build process.
I realise that qmake is designed to generate makefiles, so I may be wishing for a little too much here but if anyone can give me some pointers it would be very welcome.

Answer 1

I currently use qmake to exec my unit tests automatically for two years - and it works fine.
Have a look here - I made a mini-howto for that:
Qt: Automated Unit Tests with QMAKE
Abridged summary:
Structure
/myproject/
myproject.h
myproject.cpp
main.cpp
myproject.pro
/myproject/tests/
MyUnitTest.h
MyUnitTest.cpp
main.cpp
tests.pro
Using QMake to automatically run unit tests on build
The QMake target QMAKE_POST_LINK will run a user defined command after linking.
tests.pri (common file)
TEMPLATE = app
DEPENDPATH += . ../
INCLUDEPATH += . ../
DESTDIR = ./
CONFIG += qtestlib
unix:QMAKE_POST_LINK=./$$TARGET
win32:QMAKE_POST_LINK=$${TARGET}.exe
tests.pro (project-specific file)
TARGET = MyUnitTest
HEADERS += MyUnitTest.h
SOURCES += MyUnitTest.cpp main.cpp
include(tests.pri)
Running multiple unit tests in a single main()
main.cpp
#include "MyUnitTest1.h"
#include "MyUnitTest2.h"
int main(int argc, char** argv) {
QApplication app(argc, argv);
int retval(0);
retval +=QTest::qExec(&MyTest1(), argc, argv);
retval +=QTest::qExec(&MyTest2(), argc, argv);
return (retval ? 1 : 0);
}
This runs your tests on each build and aborts if an error is found.
Note
If you get linker errors such as "LNK2005: xxx already defined...", add a new .cpp file for each test class header and move some test method implementations.
You can use exactly that mechanism to exec your versioning tool after compile/building - so your questions should be solved :-)
If you have any further questions don't hesitate to ask me.
PS: Here you can find more (undocumented) tricks around QMake: Undocumented QMake

Answer 2

I posted a message on the Qt Interest mailing list about a 'pre build' step and it can be done using a combination of PRE_TARGETDEPS and QMAKE_EXTRA_TARGETS. Here is the response:
You can specify custom build steps,
eg. this would call makemyversion.sh
to create myversion.cpp every time
before it builds something:
versiontarget.target = myversion.cpp
versiontarget.commands = ./makemyversion.sh
versiontarget.depends = FORCE
PRE_TARGETDEPS += myversion.cpp
QMAKE_EXTRA_TARGETS += versiontarget
I am now using something similar to this to generate my app's version number each time it is built.

Answer 3

I've tried to do a lot of stuff with qmake as a build system over the years. Eventually I just resorted to having a pre-qmake step. Ie. a configure script.
You can build your version tool in there and then execute it before calling qmake to generate the Makefiles.
I found the easiest way to get data into the pro files, if you need that too, is to generate a .pro.inc file and include it from your main pro.

Answer 4

As 3DH mentioned, you want a QMAKE_POST_LINK option specified in your .pro files that contain something you want executed. So for your example, I would do something like this with the version.pro file:
TEMPLATE = app
TARGET = version
HEADERS = version.h
SOURCES = version.cpp
QMAKE_POST_LINK=./version
Something similar should work with your test directory.