CWG3192 [class.local] An enum nested in local class should be allowed to be defined out-of-line

[localspook]

Full name of submitter: Victor Chernyakin

Issue Description

[class.local]/3 says:

A class nested within a local class is a local class. A member of a local class X shall be declared only in the definition of X or, if the member is a nested class, in the nearest enclosing block scope of X.

Under this wording, defining a struct out-of-line is allowed, but defining an enum is not:

void f() {
  struct X {
    struct S;
    enum E : int;
  };
  struct X::S {}; // okay
  enum X::E : int {}; // ill-formed
}

However, all major implementations accept this code, and there seems to be no reason that it should be disallowed.

Proposed resolution

A class nested within a local class is a local class. A member of a local class X shall be declared only in the definition of X or, if the member is an enumeration or a nested class, in the nearest enclosing block scope of X.

[jensmaurer]

CWG3192

[safocl]

Isn't this a discussion for the EWG?

[localspook]

Is it? I was under the impression that these kinds of small issues go directly to CWG, only bigger proposals (such as papers) need to go through the whole pipeline involving EWG.

[jensmaurer]

One could argue that "nested class" in the status quo text ought to be read as "nested type", and it's an issue-level consistency fix. I'll make sure this gets a trip through EWG (of some sort), depending on the CWG reaction.