Does the Compiler-Generated Copy Constructor Guarantee Deep Copying in Nested Classes?

Impact of Compiler-Generated Copy Constructors on Classes Containing External Objects

In C , a default copy constructor is automatically provided by the compiler if not explicitly defined by the user. Understanding its behavior is crucial, especially when a class contains other objects without their own declared copy constructors.

Consider the following class hierarchy:

Default Copy Constructor Behavior

When creating an instance of Foo using a copy constructor:

The following behavior will occur:

• The default copy constructor for Foo: Foo::Foo(Foo const&) will be invoked.
• This constructor will call the default copy constructor for Bar: Bar::Bar(Bar const&) to copy the bar member.
• Subsequently, the Bar copy constructor will call the default copy constructor for Baz: Baz::Baz(Baz const&) to copy the baz member.

Note: The compiler-generated copy constructors perform a shallow copy, copying the pointers of the members, which is equivalent to a bitwise copy.

Implications

This behavior ensures that a deep copy of all nested objects is performed, as long as each member has its own valid copy constructor. This helps prevent dangling pointers or object ownership issues.

However, it's important to note that if any of the nested objects do not have a defined copy constructor or have issues in their own copy constructor implementation, the compiler-generated copy constructor may fail to perform the deep copy correctly, leading to potential data integrity issues.

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