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This version of the code has the advantage that it is exception-safe: if the call of new throws an exception, the original Thingy (and the Widget that it contains) remains unchanged.

Compliant Solution 3

Alternatively, a resource managing smart pointer (or other resource managing container) may be used to hold the external resource:

class Thingy {
    public:
        ...
        // compiler-generated copy assignment now correct
    private:
        std::tr1::shared_ptr<Widget> w;
};

This version of the code is also exception-safe, because the implementation of shared_ptr is exception-safe.

Risk Assessment

Allowing a copy assignment operator to corrupt an object could lead to undefined behavior.

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