Mutable Member in ConstExpr object in C ++ 11

Question

In the C ++ 14 standard (ISO / IEC 14882: 2014) in the section of paragraph 2 of section 5.19 (primary focus) the word " non-mutable " was added :

The conditional expression e is an expression of the basic constant if the estimate e, following the rules of the abstract machine (1.9), does not evaluate one of the following expressions:

• [...]
• lvalue-to-rvalue conversion (4.1) if it does not apply to
  • [...]
  • unchangeable value glvalue, which relates to a nonvolatile object determined via constexpr, or relates to a sub-object is not a variable of the object or

Therefore this code is incorrect in C ++ 14:

class A {
    public:
        mutable int x;
};

int main(){

    constexpr A a = {1};
    constexpr int y = a.x;

    return 0;
}

However, is this correct in C ++ 11?

(CD3) 1405, :

. , - constexpr , , .

, , ++ 11. , Clang GCC -std = ++ 11, , . ++ 14, ++ 11.

- , ++ 11?

. (CD3) 1428.

Answer 1

++ 11, ++ 11. DR, , DRWP WP ++.

++ 11 DR.

, - DR 1579:

• gcc 6.1.0
• gcc 4.9.3

: ++ ++ 11 ++ 14