__cplusplus undefined on Symbian

[bender86]

Hi.
I'm facing some odd problem with my application. I tried this main.cpp

#if ! defined __cplusplus
# error "Not C++!"
#endif
 
#include <iostream>
 
int main()
{
    std::cout << "Hello" << std::endl;
    return 0;
}

#if ! defined __cplusplus
# error "Not C++!"
#endif

#include <iostream>

int main()
{
    std::cout << "Hello" << std::endl;
    return 0;
}

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Then I open the Qt for Symbian prompt, run qmake and run make release-gcce. Then compilation stops due to "Not C++!" error message.

I use some libraries which have such checks, I found a workaround by adding DEFINES *= __cplusplus in the project file, then everything compiles correctly (so the C++ compiler is actually used, not the C one). Obviously I'm not quite satisfied with this, that macro should be defined automatically by the compiler.

Any idea what I'm doing wrong?

[SixDegrees]

I'm not used to the construct '#if ! defined __cplusplus'; I usually see this written as '#ifndef ...' or '#if !defined' (without the space), with the first being by far the most common. Try these and see if they work; if so, your preprocessor isn't quite up to snuff.

[bender86]

In the libraries it is actually written as "#ifndef ...", I also just tried it in my minimal example and still no changes. Also, after having defined the value manually it is recognised even with that syntax.

[SixDegrees]

Then it appears your compiler isn't defining the symbol. The last thing to check would be what compiler your build system is invoking; it's vaguely possible that it is using the C compiler for some reason, although that seems unlikely. If it turns out to be using the C++ compiler, you should contact whoever provides that compiler and let them know about this.

[bender86]

I'd say it is the C++ compiler, since after defining manually __cplusplus (or removing the check) it compiles C++ code (classes, templates…). The compiler is the one installed with Qt for Symbian (or Symbian SDK, I don't remember who exactly installed it, I just followed the installation procedure for Qt for Symbian), and should be some version of GCC. I was hoping someone could try the code and see if this happens only to me.