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Compiler Warning (level 2) C4150

deletion of pointer to incomplete type 'type'; no destructor called

The delete operator is called to delete a type that was declared but not defined. The compiler can't find the destructor to call because the definition isn't in the same translation unit as the delete.

Example

The following sample generates C4150 by declaring but not defining class IncClass:

// compile with: /W2
class IncClass;

void NoDestruct( IncClass* pIncClass )
{
   delete pIncClass; // C4150
}

To fix the issue, put the definition of IncClass in the same file as the delete. If the class is declared in a header file, it can be added to the file using #include. If the class isn't declared in a header file, the NoDestruct function definition may need to be moved into the same file as the IncClass definition.

// compile with: /W2
#include "IncClass.h"

void NoDestruct( IncClass* pIncClass )
{
   delete pIncClass;
}

C4150 will be emitted when the class is defined after the destructor call in the same file. In the following example IncClass is declared before being used, but defined after the delete:

// C4150.cpp
// compile with: /W2
class IncClass;

void NoDestruct( IncClass* pIncClass )
{
   delete pIncClass; // C4150
}

class IncClass
{
public:
    IncClass() = default;
    ~IncClass() = default;
};

In this scenario, the use of delete needs to be after the class definition.

// C4150.cpp
// compile with: /W2
class  IncClass;

void NoDestruct( IncClass* pIncClass );

class IncClass
{
public:
    IncClass() = default;
    ~IncClass() = default;
};

void NoDestruct( IncClass* pIncClass )
{
   delete pIncClass;
}

See also