QtRO return values from .rep SLOT not marshalled for some types

In Qt Remote Objects, some types are not marshalled correctly when used as return values from a SLOT, even though those types are correctly marshalled when used as parameters.

Specifically, my problem is with standard C++ integral types (int32_t, size_t, etc) but I suspect the issue is larger.

Minimal example:

In .rep

class Foo {

    SLOT(uint32_t foo(uint32_t value))

}

Source implementation

uint32_t FooImpl::foo(uint32_t value) {

    qDebug() << value; // OK, prints 44

    return 42;

}

Replica usage

auto reply = replica->foo(44);

reply.waitForFinished();

qDebug() << reply.returnValue(); // NOT OK: prints 0, should be 42

After examination, the QVariant in QRemoteObjectPendingCall is invalid.

If I change the .rep to read:

    SLOT(unsigned int foo(uint32_t value))

and without changing anything else (which compiles fine because unsigned int and uint32_t are the same on my platform), the return value is now correctly marshalled.