cppcoreguidelines-special-member-functions requires default destructors when move and copy are deleted

[fekir]

Consider following class

    class c
    {
    public:
      int a;
      int b;

      c( int a1, int b1 )
          : a{ a1 }
          , b{ b1 }
      {
      }
      c( const c& ) = delete;
      c& operator=( const c& ) = delete;
      c( c&& ) = delete;
      c& operator=( c&& ) = delete;
};

clang-tidy, with cppcoreguidelines-special-member-functions claims that one should also define the destructor

warning: class 'c' defines a copy constructor and a copy assignment operator but does not define a destructor [cppcoreguidelines-special-member-functions]

I think it might be beneficial to avoid defining ~c() = default.
Contrary to move and copy operations, destruction is a little bit different.
I am currently not able to think about one use-case where adding a defaulted destructor helps to clarify what this class does.

Would it be possible to not to warn for non-user-defined destructors when copy and move operators are deleted?

[llvmbot]

@llvm/issue-subscribers-clang-tidy

Author: Federico Kircheis (fekir)

Consider following class

    class c
    {
    public:
      int a;
      int b;

      c( int a1, int b1 )
          : a{ a1 }
          , b{ b1 }
      {
      }
      c( const c& ) = delete;
      c& operator=( const c& ) = delete;
      c( c&& ) = delete;
      c& operator=( c&& ) = delete;
};

clang-tidy, with cppcoreguidelines-special-member-functions claims that one should also define the destructor

> warning: class 'c' defines a copy constructor and a copy assignment operator but does not define a destructor [cppcoreguidelines-special-member-functions]

I think it might be beneficial to avoid defining ~c() = default.
Contrary to move and copy operations, destruction is a little bit different.
I am currently not able to think about one use-case where adding a defaulted destructor helps to clarify what this class does.

Would it be possible to not to warn for non-user-defined destructors when copy and move operators are deleted?

[PiotrZSL]

Check is correct, because there is an user provided constructor.
What could be done, check could be extended with option AllowMissingTrivialDestructor.

[fekir]

But it does not make much sense for deleted constructors, does it?

[PiotrZSL]

Depend, but for me does not make sense. Probably some option like AllowExplictlyDeletedCopyOrMove need to be added.

[fekir]

Considering

class c {
  public:
    std::unique_ptr<int> a

    c() { /* init a */ }
    c( const c& ) = delete;
    c& operator=( const c& ) = delete;
    c( c&& ) = delete;
    c& operator=( c&& ) = delete;
};

maybe a better name would be AllowMissingDestructorIfAssignmentIsDeleted