public inbox for gcc-bugs@sourceware.org
help / color / mirror / Atom feed
* [Bug c++/107744] New: Error in constant evaluation of dynamic_cast
@ 2022-11-18  7:34 fchelnokov at gmail dot com
  2023-05-19  4:45 ` [Bug c++/107744] " pinskia at gcc dot gnu.org
  0 siblings, 1 reply; 2+ messages in thread
From: fchelnokov at gmail dot com @ 2022-11-18  7:34 UTC (permalink / raw)
  To: gcc-bugs

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107744

            Bug ID: 107744
           Summary: Error in constant evaluation of dynamic_cast
           Product: gcc
           Version: 12.2.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: fchelnokov at gmail dot com
  Target Milestone: ---

The following program

struct A {
    constexpr A();
    virtual void f() {}
    bool x;
};

struct B : A {};

constexpr A::A() { 
    x = dynamic_cast<B*>(this);
}
constexpr bool b = B{}.x;

is accepted by Clang and MSVC, but GCC prints vague error:

<source>:12:24:   in 'constexpr' expansion of 'B()'
<source>:7:8:   in 'constexpr' expansion of '((B*)this)->B::<anonymous>.A::A()'
<source>:12:24: error: '((&<anonymous>.B::<anonymous>) != 0)' is not a constant
expression
   12 | constexpr bool b = B{}.x;

Online demo: https://godbolt.org/z/1xdq68aaM

^ permalink raw reply	[flat|nested] 2+ messages in thread

* [Bug c++/107744] Error in constant evaluation of dynamic_cast
  2022-11-18  7:34 [Bug c++/107744] New: Error in constant evaluation of dynamic_cast fchelnokov at gmail dot com
@ 2023-05-19  4:45 ` pinskia at gcc dot gnu.org
  0 siblings, 0 replies; 2+ messages in thread
From: pinskia at gcc dot gnu.org @ 2023-05-19  4:45 UTC (permalink / raw)
  To: gcc-bugs

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107744

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2023-05-19
     Ever confirmed|0                           |1

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed.

^ permalink raw reply	[flat|nested] 2+ messages in thread

end of thread, other threads:[~2023-05-19  4:45 UTC | newest]

Thread overview: 2+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-11-18  7:34 [Bug c++/107744] New: Error in constant evaluation of dynamic_cast fchelnokov at gmail dot com
2023-05-19  4:45 ` [Bug c++/107744] " pinskia at gcc dot gnu.org

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).