# Extra Clang Tools 21.1.8 documentation

## clang-tidy - modernize-use-equals-delete

# modernize-use-equals-delete

Identifies unimplemented private special member functions, and recommends using `= delete` for them. Additionally, it recommends relocating any deleted member function from the `private` to the `public` section.

Before the introduction of C++11, the primary method to effectively “erase” a particular function involved declaring it as `private` without providing a definition. This approach would result in either a compiler error (when attempting to call a private function) or a linker error (due to an undefined reference).

However, subsequent to the advent of C++11, a more conventional approach emerged for achieving this purpose. It involves flagging functions as `= delete` and keeping them in the `public` section of the class.

To prevent false positives, this check is only active within a translation unit where all other member functions have been implemented. The check will generate partial fixes by introducing `= delete`, but the user is responsible for manually relocating functions to the `public` section.

    // Example: bad
    class A {
     private:
      A(const A&);
      A& operator=(const A&);
    };

    // Example: good
    class A {
     public:
      A(const A&) = delete;
      A& operator=(const A&) = delete;
    };

IgnoreMacros

  If this option is set to true (default is true), the check will not warn about functions declared inside macros.