From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id 97AAE3858D1E; Wed, 20 Apr 2022 18:47:32 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 97AAE3858D1E From: "bekenn at gmail dot com" To: gcc-bugs@gcc.gnu.org Subject: [Bug c++/105321] New: "non-constant condition" issued for function containing a short-circuited unevaluated non-constant expression Date: Wed, 20 Apr 2022 18:47:32 +0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: new X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: c++ X-Bugzilla-Version: 11.2.1 X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: bekenn at gmail dot com X-Bugzilla-Status: UNCONFIRMED X-Bugzilla-Resolution: X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org X-Bugzilla-Target-Milestone: --- X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: bug_id short_desc product version bug_status bug_severity priority component assigned_to reporter target_milestone Message-ID: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-BeenThere: gcc-bugs@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-bugs mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 20 Apr 2022 18:47:32 -0000 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D105321 Bug ID: 105321 Summary: "non-constant condition" issued for function containing a short-circuited unevaluated non-constant expression Product: gcc Version: 11.2.1 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: bekenn at gmail dot com Target Milestone: --- bool handle_error(); constexpr int echo(int value, bool yes =3D true) noexcept { return (yes || handle_error()), value; } static_assert(echo(10) =3D=3D 10, ""); --- :8:24: error: non-constant condition for static assertion 8 | static_assert(echo(10) =3D=3D 10, ""); | ~~~~~~~~~^~~~~ :8:19: in 'constexpr' expansion of 'echo(10, 1)' :3:36: error: 'yes' is not a constant expression 3 | constexpr int echo(int value, bool yes =3D true) noexcept | ~~~~~^~~~~~~~~~ https://godbolt.org/z/vsd9xdW5c --- It appears that the || operator isn't short-circuiting correctly during constant evaluation. This seems to be very particular; if I replace `yes` = with a more complicated expression (such as `!no`), the problem disappears. This issue shows up in every version of GCC I've tried, including 11.2 and = the current "trunk" release on Compiler Explorer.=