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IDebugHostType2::IsTypedef method (dbgmodel.h)

  • Article

The IsTypedef method is the only method capable of seeing whether a type is a typedef. The GetTypeKind method will behave as if called on the underlying type.

Syntax

HRESULT IsTypedef(
  bool *isTypedef
);

Parameters

isTypedef

Will return true if the type symbol is a typedef and false if it is not.

Return value

This method returns HRESULT.

Remarks

Sample Code

ComPtr<IDebugHostType> spType; /* get a type for a typedef (only FindTypeByName 
                                  since the compiler usually only emits base types 
                                  in the symbols for data) */

ComPtr<IDebugHostType2> spType2;
if (SUCCEEDED(spType.As(&spType2)))
{
    bool isTypeDef;
    if (SUCCEEDED(spType2->IsTypedef(&isTypeDef)))
    {
        // isTypeDef indicates whether the type is a typedef.
    }
}

Any type which is a typedef will behave as if the type is the final type underlying the typedef. This means that methods such as GetTypeKind will not indicate that the type is a typedef. Likewise, GetBaseType will not return the type the definition refers to. They will instead indicate behave as if they were called on the final definition underlying the typedef. As an example:

typedef MYSTRUCT *PMYSTRUCT;
typedef PMYSTRUCT PTRMYSTRUCT;

An IDebugHostType for 'either PMYSTRUCT or PTRMYSTRUCT will report the following information:

  • The GetTypeKind method will return TypePointer. The final underlying type MYSTRUCT * is indeed a pointer.

  • The 'GetBaseType method will return a type for MYSTRUCT. The underlying type of MYSTRUCT * is MYSTRUCT.

The only difference here is how the typedef specific methods on IDebugHostType2 behave. Those methods are:

STDMETHOD(IsTypedef)(_Out_ bool* isTypedef) PURE;

STDMETHOD(GetTypedefBaseType)(_Out_ IDebugHostType2** baseType) PURE;

STDMETHOD(GetTypedefFinalBaseType)(_Out_ IDebugHostType2** finalBaseType) PURE;

In this example:

  • The IsTypedef method will return true for both PMYSTRUCT and PTRMYSTRUCT
  • The GetTypedefBaseType method will return MYSTRUCT * for PMYSTRUCT and PMYSTRUCT for PTRMYSTRUCT
  • The GetTypedefFinalBaseType method will return MYSTRUCT * for both types

Requirements

Requirement Value
Header dbgmodel.h

See also

IDebugHostType2 interface