# Extra Clang Tools 19.1.7 documentation

## clang-tidy - bugprone-return-const-ref-from-parameter

# bugprone-return-const-ref-from-parameter

Detects return statements that return a constant reference parameter as constant reference. This may cause use-after-free errors if the caller uses xvalues as arguments.

In C++, constant reference parameters can accept xvalues which will be destructed after the call. When the function returns such a parameter also as constant reference, then the returned reference can be used after the object it refers to has been destroyed.

## Example

    struct S {
      int v;
      S(int);
      ~S();
    };

    const S &fn(const S &a) {
      return a;
    }

    const S& s = fn(S{1});
    s.v; // use after free