From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id 0CC463858C20; Wed, 16 Feb 2022 17:42:19 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 0CC463858C20 From: "cvs-commit at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: =?UTF-8?B?W0J1ZyBjKysvMTA0NTA3XSBbMTAvMTEvMTIgUmVncmVzc2lvbl0g?= =?UTF-8?B?aW50ZXJuYWwgY29tcGlsZXIgZXJyb3I6IHVuZXhwZWN0ZWQgZXhwcmVzc2lv?= =?UTF-8?B?biDigJgoaW50KShfX3JldCnigJkgb2Yga2luZCBjYXN0X2V4cHI=?= Date: Wed, 16 Feb 2022 17:42:19 +0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: c++ X-Bugzilla-Version: 11.2.0 X-Bugzilla-Keywords: ice-on-valid-code X-Bugzilla-Severity: normal X-Bugzilla-Who: cvs-commit at gcc dot gnu.org X-Bugzilla-Status: ASSIGNED X-Bugzilla-Resolution: X-Bugzilla-Priority: P2 X-Bugzilla-Assigned-To: ppalka at gcc dot gnu.org X-Bugzilla-Target-Milestone: 10.4 X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: Message-ID: In-Reply-To: References: 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, 16 Feb 2022 17:42:20 -0000 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D104507 --- Comment #7 from CVS Commits --- The master branch has been updated by Patrick Palka : https://gcc.gnu.org/g:c19f317a78c0e4c1b51d0e5a8e4c0a3b985b7a8e commit r12-7264-gc19f317a78c0e4c1b51d0e5a8e4c0a3b985b7a8e Author: Patrick Palka Date: Wed Feb 16 12:41:35 2022 -0500 c++: treat NON_DEPENDENT_EXPR as not potentially constant [PR104507] Here we're crashing from potential_constant_expression because it tries to perform trial evaluation of the first operand '(bool)__r' of the conjunction (which is overall wrapped in a NON_DEPENDENT_EXPR), but cxx_eval_constant_expression ICEs on unsupported trees (of which CAST_E= XPR is one). The sequence of events is: 1. build_non_dependent_expr for the array subscript yields NON_DEPENDENT_EXPR<<<(bool)__r && __s>>> ? 1 : 2 2. cp_build_array_ref calls fold_non_dependent_expr on this subscript (after this point, processing_template_decl is cleared) 3. during which, the COND_EXPR case of tsubst_copy_and_build calls fold_non_dependent_expr on the first operand 4. during which, we crash from p_c_e_1 because it attempts trial evaluation of the CAST_EXPR '(bool)__r'. Note that even if this crash didn't happen, fold_non_dependent_expr from cp_build_array_ref would still ultimately be one big no-op here since neither constexpr evaluation nor tsubst handle NON_DEPENDENT_EXPR. In light of this and of the observation that we should never see NON_DEPENDENT_EXPR in a context where a constant expression is needed (it's used primarily in the build_x_* family of functions), it seems futile for p_c_e_1 to ever return true for NON_DEPENDENT_EXPR. And the otherwise inconsistent handling of NON_DEPENDENT_EXPR between p_c_e_1, cxx_evaluate_constexpr_expression and tsubst apparently leads to weird bugs such as this one. PR c++/104507 gcc/cp/ChangeLog: * constexpr.cc (potential_constant_expression_1) : Return false instead of recursing. Assert tf_error isn't set. gcc/testsuite/ChangeLog: * g++.dg/template/non-dependent21.C: New test.=