qRegisterMetaType of custom C-style struct for usae with QSignalSpy in QTest

[Vasiliy]

Hi,
1. I have C headers for driver, which contains a lot of structures. I use the structures as signals' arguments. Here is example of a such a like structure (most simple one just for example)

typedef struct
{
	uint16_t Capabilities;
} PingSrspFormat_t;

2. I've made simplest QTest, and in 'testCase1()' try to get signals from my DUT object this way:

	// 1. Register custom C-Style struct type
qRegisterMetaType<PingSrspFormat_t>("PingSrspFormat_t"); 
	// 2. Connect signal of my DUT object (znpHost) already instantiated above
QSignalSpy spy(znpHost,SIGNAL(pfnSysPingSrsp(const PingSrspFormat_t&)));
	// 3. just in case clear spy list
spy.clear();
	// 4. issue method of my DUT object to get signal from it
znpHost->sysPing(); 
	// 5. wait for a while..
spy.wait(500);
	// 6. get the signal argument
PingSrspFormat_t result = qvariant_cast<PingSrspFormat_t>(spy.at(0).at(0));
	// 7. check the argument
QVERIFY(result.Capabilities == 0x0000); 

3. due compilation get an error:

/home/dev/Qt/5.5/gcc_64/include/QtCore/qglobal.h:703: error: invalid application of 'sizeof' to incomplete type 'QStaticAssertFailure<false>'
     enum {Q_STATIC_ASSERT_PRIVATE_JOIN(q_static_assert_result, __COUNTER__) = sizeof(QStaticAssertFailure<!!(Condition)>)}
                                                                                     ^

Any suggestions how to fix the compilation error are very welcome

Thanks

[kshegunov]

@Vasiliy
Hello,
Do you have Q_DECLARE_METATYPE(PingSrspFormat_t) at the appropriate place?

Kind regards.

[Vasiliy]

Hi!

• Well, should i put the macros in C headers?
• Am I correct if say that for signal/slot usage of qRegisterMetaType is enough?

Thanks for reply

[kshegunov]

@Vasiliy
Hello,
Usually you put the macro after the declarations, however I believe the moc will be forgiving enough if you put it into your own header (not to modify the externals). Something like this in mycwrapheader.h:

#include <somecheader.h>

Q_DECALARE_METATYPE(PingSrspFormat_t)
// ... more code

Am I correct if say that for signal/slot usage of qRegisterMetaType is enough?

Whether or not this is true is besides the point, because you're making a qvariant_cast and for that you'd need the Q_DECLARE_METATYPE macro. Additionally, you need to register the type with the runtime (through qRegisterMetaType) only if you're using queued connections (usually when multithreading is involved).

Kind regards.

[Vasiliy]

@kshegunov wow!
Seems you are right I've just put the macros at hte top of my Unity test *.cpp right after all #includes and the compilation passed!
Thanks a lot for the advice!

[kshegunov]

@Vasiliy
No problem, however you should really put that macro in a header .h, not in your source file .cpp. :)

[Vasiliy]

@kshegunov yes, you are correct, but for fast issue fix it was ok to put it in *.cpp :) now I can gloss the code with calm after your great advice!
Thanks!