MISRA.COPY.CSTR.TMPL

Class has a template constructor with a single generic parameter, but has no copy constructor defined.

MISRA-C++ Rule 14-5-2 (required): A copy constructor shall be declared when there is a template constructor with a single parameter that is a generic parameter.

Rationale

Contrary to possible developer expectations, a template constructor will not suppress the compiler generated copy constructor. This may lead to incorrect copy semantics for members requiring deep copies.

Example

class A
{
public:
   A ( );
   // A ( A const & rhs ); Example 1 - implicitly generated

   template <typename T>
   A ( T const & rhs )    // Example 2
   : i ( new int32_t )
   {
      *i = *rhs.i;
   }

private:
   int32_t * i;           // Member requires deep copy
};

void f ( A const & a1 )
{
   A a2 ( a1 );           // Non-compliant - Unexpectedly uses Example 1
}

The implicitly generated copy constructor, Example 1, will be used to construct 'a2' from 'a1'.

Therefore, a shallow copy on the pointer member 'i' will result in both 'a1.i' and 'a2.i' pointing to the same object. Was this the intent, or was it expected that a new object would be created and initialized?