[Bug c++/99495] New: constexpr virtual destructor is used before its definition

[Bug c++/99495] New: constexpr virtual destructor is used before its definition

[oleksandr.koval.dev at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99495

            Bug ID: 99495
           Summary: constexpr virtual destructor is used before its
                    definition
           Product: gcc
           Version: 11.0
               URL: https://godbolt.org/z/GGY6aa
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: oleksandr.koval.dev at gmail dot com
  Target Milestone: ---

I found this while playing with constexpr virtual functions. This code gives
"error: 'virtual constexpr Derived2::~Derived2()' used before its definition".
Error always refers to the last variable, e.g. if we swap d1 and d2
declarations, it will complain about d1. If x is decalred without constexpr it
works fine.

struct Base{
    constexpr virtual ~Base() = default;
    virtual int Get() const = 0;    // non-constexpr
};

struct Derived1 : Base{
    constexpr int Get() const override {
        return 1;
    }
};

struct Derived2 : Base{
    constexpr int Get() const override {
        return 2;
    }
};

constexpr auto GetSum(){
    const Derived1 d1;
    const Derived2 d2;
    const Base* pb1 = &d1;
    const Base* pb2 = &d2;

    return pb1->Get() + pb2->Get();
}

constexpr         // error
int x = GetSum();   // OK if not in constexpr context

[Bug c++/99495] constexpr virtual destructor is used before its definition

[pdimov at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99495

Peter Dimov <pdimov at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |pdimov at gmail dot com

--- Comment #1 from Peter Dimov <pdimov at gmail dot com> ---
Simplified:

```
struct Base
{
    constexpr virtual ~Base() = default;
};

constexpr Base b;
```

https://godbolt.org/z/qGn1nx9ET

[Bug c++/99495] constexpr virtual destructor is used before its definition

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99495

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|---                         |DUPLICATE

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Dup of bug 93413.

*** This bug has been marked as a duplicate of bug 93413 ***