BUG: Compile Errors Result for Certain ATL Method Parameters

ID: Q196837

The information in this article applies to:

Microsoft Visual C++, 32-bit Editions, version 5.0

SYMPTOMS

Using the ATL Interface Wizard from Visual C++ 5.0 to add a method to an interface, you will get compilation errors C2061 if you specified any of the following for parameters in the dialog box:


   SAFEARRAY(type) pSA
   SAFEARRAY(type) *ppSA

CAUSE

This problem is caused by a limitation in the ATL COM Interface Wizard.

RESOLUTION

To cause the ATL code to compile, you must make modifications to the method that was added with the ATL COM Interface wizard in the .h and .cpp files.

The correct declarations and definitions that must be used for each of the known data types that cause the problems are shown below (assume that the interface is IATLObj and the ATL class that is implementing the interface is CATLObj):

For instance, the following are wizard-generated function prototypes in the .h file:


   STDMETHOD(Test)(SAFEARRAY(BSTR) *ppArrayBstr);
   STDMETHOD(Test2)(SAFEARRAY(BSTR) pArrayBstr);

The correct declarations for header file should be:


   STDMETHOD(Test)(SAFEARRAY **ppArrayBstr);
   STDMETHOD(Test2)(SAFEARRAY *pArrayBstr);

The correct definitions for source file should be:


   STDMETHODIMP CATLObj::Test(SAFEARRAY **ppArrayBstr)
   {
      return S_OK;
   }

   STDMETHODIMP CATLObj::Test2(SAFEARRAY *pArrayBstr)
   {
      return S_OK;
   }

You will notice that if you use the above method, the Class view information in the Tree view may look different for CATLObj. Test and Test2 will not be in the IATLObj interface section in Class view for CATLObj as they were before. They are now in the member function section. You can correct this behavior by not making the changes above; and instead, using a macro. To do this, make the following modifications to the header file before the class definition:


   #define SAFEARRAY(X) SAFEARRAY*

Class view will now properly display the new methods under the interface section instead of under the member function section.

STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article.

MORE INFORMATION

Steps to Reproduce Behavior

Create a new ATL/COM Application Wizard Project.

Insert a new ATL COM Object with the default settings.

Add a new method with the ATL COM Object Wizard by right-clicking the interface to add the method and selecting "Add Method."

Give the method a name.

Add one parameter with SAFEARRAY(BSTR)* as the type. For example:
```
      [out] SAFEARRAY(BSTR) *pArrayBSTR 
```

Build the project.

You will receive Compiler Error C2061 due to the incorrect syntax for the parameter in the header and source files.

Additional query words:

Keywords : kbwizard kbATL200bug kbAutomation kbCOMt kbVC500bug kbGrpMFCATL kbCollectionClass
Version : winnt:5.0
Platform : winnt
Issue type : kbbug