[Bug c++/118661] [12/13/14/15 regression] Reading volatile qualified std::nullptr_t should be valid in a constant expression

[mpolacek at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118661

Marek Polacek <mpolacek at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P2
           Keywords|needs-bisection             |
                 CC|                            |mpolacek at gcc dot gnu.org

--- Comment #4 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #3)
> Confirmed. Note I think there is 2 different changes which caused this.
> 
> That is a change in 8 caused use to reject:
> ```
> typedef decltype(nullptr) tt;
> constexpr volatile tt n{};
> constexpr tt m=n;
> ```

Since my r9-4793:

commit 3c393a2c012f7f5f1c3df7d6d7b17a9cf992af17
Author: Marek Polacek <pola...@redhat.com>
Date:   Tue Dec 11 18:53:03 2018 +0000

    PR c++/86608 - reading constexpr volatile variable.


> But it was not until GCC 9 we (correctly) rejected:
> ```
> constexpr volatile int n1{};
> constexpr short m1=n1;
> ```

Same change.