Rationale (November, 2018):

See also issue 2362, which asks for the ability to use __func__ in a constexpr function. These two goals are incompatible, so EWG input is requested.

EWG 2022-11-11

Paper requested. This is tracked in github issue cplusplus/papers#1375.

Notes from the May, 2015 meeting:

CWG agreed with the suggested direction.

Two questions have arisen regarding the treatment of the type of the __func__ built-in variable. First, some implementations accept

  void f() {
    typedef decltype(__func__) T;
    T x = __func__;
  }

even though T is specified to be an array type.

In a related question, it was noted that __func__ is implicitly required to be unique in each function, and that not only the value but the type of __func__ are implementation-defined; e.g., in something like

  inline auto f() { return &__func__; }

the function type is implementation-specific. These concerns could be addressed by making the value a prvalue of type const char* instead of an array lvalue.