moc file not found

rpieket

Using Qt Creator 12.0.1, plodding along just fine until all of a sudden, moc files are no longer getting created. This was working before, but now I get an error saying that the moc file cannot be found. How do I get this working again? I have reduced my code to the following. Why is this not compiling?

#include <QCoreApplication>
#include <QTest>

class TestQString: public QObject
{
    Q_OBJECT
private slots:
    void toUpper()
    {
        QString str = "Hello";
        QVERIFY(str.toUpper() == "HELLO");
    }
};

QTEST_MAIN(TestQString)
#include "testqstring.moc"

Christian Ehrlicher

Please show your CMakeLists.txt

rpieket

@Christian-Ehrlicher Thanks. I don't see that file. I'm using qmake. There is a generated makefile that is too large to attach.

jsulm

@rpieket said in moc file not found:

I'm using qmake

Then you can show the pro file

rpieket

@jsulm Here is the pro file:

QT = core testlib

CONFIG += c++17 cmdline

# You can make your code fail to compile if it uses deprecated APIs.
# In order to do so, uncomment the following line.
#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0

SOURCES += \
    tests.cpp

# Default rules for deployment.
qnx: target.path = /tmp/$${TARGET}/bin
else: unix:!android: target.path = /opt/$${TARGET}/bin
!isEmpty(target.path): INSTALLS += target

Christian Ehrlicher

Why do you include testqstring.moc when your source file is tests.cpp?

ChrisW67

@Christian-Ehrlicher Beat me to it.

The qmake "magic" that generates a Makefile rule for moc when it sees this style of include requires that it matches on the base name of the source file concerned.

rpieket

The mismatch is due to my attempt to simplify before posting. This is my actual main file, named tests.cpp. And yes, both TestOneToOne and TestOneToMany have the Q_OBJECT macro.

#include <QCoreApplication>
#include <QTest>

#include "TestOneToOne.h"
#include "TestOneToMany.h"

int main(int argc, char *argv[])
{
    int status = 0;
    status |= QTest::qExec(new TestOneToOne, argc, argv);
    status |= QTest::qExec(new TestOneToMany, argc, argv);

    return status;
}

#include "TestOneToOne.moc"
#include "TestOneToMany.moc"

Christian Ehrlicher

There is no need for foo.moc files when it's in a header. Then qmake/cmake automatically creates and adds moc_foo.cpp files.

rpieket

@Christian-Ehrlicher Without the moc files, I get:

ld: Undefined symbols:
  vtable for TestOneToOne, referenced from:
      _main in tests.o
  vtable for TestOneToMany, referenced from:
      _main in tests.o

With the moc files, it was working until this afternoon. Somehow I broke something, but I don't know what.

Christian Ehrlicher

Please show a minmal, compileable example and move code into source files and not in headers. qmake will not generate a moc_foo.cpp when there is no corresponding source file.

ChrisW67

The headers need to be listed in the PRO file:

HEADERS += TestOneToOne.h TestOneToMany.h

and qmake re-run. The magic moc includes are not required.

Edit: Maybe @Christian-Ehrlicher has a point: a one-to-one header-source relationship.

Christian Ehrlicher

@ChrisW67 said in moc file not found:

Edit: Maybe @Christian-Ehrlicher has a point: a one-to-one header-source relationship

I'm not completely sure since I don't use qmake since 15 years or so but how else should qmake know that it has to moc those files.

SGaist

Hi,

You can see in this thread a way to put together multiple tests.

That said, it will break the output. You should really keep the one class per test file.

@Christian-Ehrlicher the moc file include is standard when you define classes in the implementation file. It has some other benefits.

This blog article gives a pretty good summary about them.

rpieket

Minimal code. First main.cpp

#include <QCoreApplication>
#include <QTest>
QTEST_MAIN(TestQString)

And qteststring.h:

#pragma once
#include <QObject>
class TestQString: public QObject
{
    Q_OBJECT
private slots:
    void toUpper();
};

And qteststring.cpp:

#include <QTest>
#include "testqstring.h"
void TestQString::toUpper()
{
    QString str = "Hello";
    QCOMPARE(str.toUpper(), QString("HELLO"));
}
#include "testqstring.moc"

Finally the auto-generated .pro file:

QT = core

CONFIG += c++17 cmdline

# You can make your code fail to compile if it uses deprecated APIs.
# In order to do so, uncomment the following line.
#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0

SOURCES += \
        main.cpp \
        testqstring.cpp

# Default rules for deployment.
qnx: target.path = /tmp/$${TARGET}/bin
else: unix:!android: target.path = /opt/$${TARGET}/bin
!isEmpty(target.path): INSTALLS += target

HEADERS += \
    testqstring.h

Resulting output:

make: *** No rule to make target `testqstring.moc', needed by `testqstring.o'.  Stop.
make: *** Waiting for unfinished jobs....
../Test_with_qmake/main.cpp:2:10: fatal error: 'QTest' file not found
#include <QTest>
         ^~~~~~~
1 error generated.
make: *** [main.o] Error 1
14:28:39: The process "/usr/bin/make" exited with code 2.
Error while building/deploying project Test_with_qmake (kit: Qt 6.6.1 for macOS)
When executing step "Make"

BTW I have never seen a moc_*.cpp, only a *.moc, and then only until yesterday afternoon, when it stopped working altogether.
Should I be using cmake? I have no preference. I'm using qmake only because it was the default.

Christian Ehrlicher

@rpieket said in moc file not found:

#include <QTest>

Then you should also add the correct qmake command as written in the documentation.

ChrisW67

@rpieket
The file names in the PRO file do not match those in your post.

Simple fix so that qmake now finds files.

A Qt test is just another Qt program, following all the same rules. It is just that the Test Lib writes main() for you to allow it to provide a lot of plumbing for you behind the scenes.
If you have the test class declaration in a separate header, as in this case, then that header should be listed in the PRO file HEADERS variable and not in the source file as an #include "blah.moc".

No longer get: make: *** No rule to make target `testqstring.moc', needed by `testqstring.o'. Stop

The QT variable in the PRO file needs QT += testlib so that the test Lib elements are included at compile and link time.
Rerun qmake after changing the PRO file

No longer get: ./Test_with_qmake/main.cpp:2:10: fatal error: 'QTest' file not found

Remaining problems are to do with the construction of the sources and not qmake.
main.cpp needs to #include "qteststring.h" so that the QTEST_MAIN macro expansion, which references TestString, knows what the class looks like.

Test compiles