clang-tidy - bugprone-capturing-this-in-member-variable — Extra Clang Tools 21.1.8 documentation

# Extra Clang Tools 21.1.8 documentation

## clang-tidy - bugprone-capturing-this-in-member-variable

# bugprone-capturing-this-in-member-variable

Finds lambda captures that capture the `this` pointer and store it as class members without handle the copy and move constructors and the assignments.

Capture this in a lambda and store it as a class member is dangerous because the lambda can outlive the object it captures. Especially when the object is copied or moved, the captured `this` pointer will be implicitly propagated to the new object. Most of the time, people will believe that the captured `this` pointer points to the new object, which will lead to bugs.

    struct C {
      C() : Captured([this]() -> C const * { return this; }) {}
      std::function<C const *()> Captured;
    };

    void foo() {
      C v1{};
      C v2 = v1; // v2.Captured capture v1's 'this' pointer
      assert(v2.Captured() == v1.Captured()); // v2.Captured capture v1's 'this' pointer
      assert(v2.Captured() == &v2); // assertion failed.
    }

Possible fixes:

  - marking copy and move constructors and assignment operators deleted.

  - using class member method instead of class member variable with function object types.

  - passing `this` pointer as parameter

## Options

FunctionWrapperTypes

  A semicolon-separated list of names of types. Used to specify function wrapper that can hold lambda expressions. Default is ::std::function;::std::move_only_function;::boost::function.

BindFunctions

  A semicolon-separated list of fully qualified names of functions that can capture `this` pointer. Default is ::std::bind;::boost::bind;::std::bind_front;::std::bind_back; ::boost::compat::bind_front;::boost::compat::bind_back.