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From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/114580] New: Bogus warning on if constexpr
Date: Thu, 04 Apr 2024 10:02:04 +0000	[thread overview]
Message-ID: <bug-114580-4@http.gcc.gnu.org/bugzilla/> (raw)

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114580

            Bug ID: 114580
           Summary: Bogus warning on if constexpr
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jakub at gcc dot gnu.org
  Target Milestone: ---

#include <type_traits>

template <typename T>
void foo ()
{
  if constexpr ((T) std::is_constant_evaluated ())
    ;
}

void
bar ()
{
  foo <bool> ();
}

emits bogus warning with -std=c++17 -Wall.
Once it (incorrectly) warns about
warning: ‘std::is_constant_evaluated’ always evaluates to false in a
non-‘constexpr’ function [-Wtautological-compare]
and once it correctly warns about
warning: ‘std::is_constant_evaluated’ always evaluates to true in ‘if
constexpr’ [-Wtautological-compare]
on the same line.  In reality, std::is_constant_evaluated () here always
evaluates to true, never to false.

             reply	other threads:[~2024-04-04 10:02 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-04-04 10:02 jakub at gcc dot gnu.org [this message]
2024-04-04 10:31 ` [Bug c++/114580] " jakub at gcc dot gnu.org
2024-04-09  7:32 ` cvs-commit at gcc dot gnu.org
2024-04-09  7:39 ` jakub at gcc dot gnu.org
2024-04-21  4:09 ` cvs-commit at gcc dot gnu.org
2024-04-23  6:45 ` jakub at gcc dot gnu.org

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