CMS - C++ Analyzer FAQ

C++ Analyzer FAQ

Q: Are there any limitations with virtual functions?

  • A: Yes, there are limitations with virtual functions. The limitation that we have is that we are not always able to know which function is called. The following example will provide a clearer understanding of what happens:

    class CMother {
    public:
    virtual void TheFunction() { MessageBox( NULL, “CMother..”, “CMother..”, MB_OK); }
    };

    class CDaugther : public CMother {
    public:
    void TheFunction() { MessageBox( NULL, “CDaugther..”, “CDaugther..”, MB_OK); }
    };

    void CTestDlg::OnOK()
    {
    CDaugther cDaugther;
    CMother * pcMother=&cDaugther;
    pcMother->TheFunction();
    }

    When you run this program, “CDaugther::TheFunction” is called, but in the analysis will return “CMother::TheFunction”.

Q: Are there known issues with regard to “typedef struct {…} b;” code?

  • A: When an unnamed struct is  typedef’ed with an alias, access to the typedef is resolved directly to the underlying struct, and no typedef object is created.

    For example:

    typedef struct foo {
       int bar;
    } foo;

    void someFunc ()
    {
       foo aFoo;
       aFoo.bar = 256;
    }

    Only two objects are created: “struct foo” and “someFunc”, the link from “someFunc” goes directly to “struct foo”. No “typedef foo” object is created:

Q: Are there issues with regard to the internal preprocessor?

  • A: The internal preprocessor is currently not aware of macros that may be predefined by various compilers, with exception of the standard predefined macros such as  __FILE__, __LINE__, __cplusplus, __DATE__, __TIME__, __STDC__ etc.

    As a result, when analyzing an application that has been developed using Microsoft Visual C++, it is strongly recommended that you select the appropriate version in the IDE used to create this application option  create your own Environment Profile.

Q: Are there differences between the C++ preprocessor and the C preprocessor?

  • A: The C++ preprocessor functions in the same way as the C preprocessor and thus leverages C specific features, with the following slight differences:
    • The _._cplusplus macro is defined as 199711L in C++ mode - The implementation defined _._STDC_._ macro is defined also in C++ mode and its value is set to 0
  • A: Variadic macros (macros of form #define X(param,param2, …) ) are supported in C and in C++ mode.
  • A: Empty macro arguments (calling MAC(x,y,z) by the means of MAX(1, ,3) ) are supported in both C and C++ modes.

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