From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id 171ED3858C51; Tue, 29 Mar 2022 01:44:19 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 171ED3858C51 From: "cvs-commit at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug c++/101371] [9/10/11 Regression] constexpr expansions trigger internal Compiler Error Date: Tue, 29 Mar 2022 01:44:19 +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: 10.3.1 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: mpolacek at gcc dot gnu.org X-Bugzilla-Target-Milestone: 9.5 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: Tue, 29 Mar 2022 01:44:19 -0000 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D101371 --- Comment #8 from CVS Commits --- The releases/gcc-11 branch has been updated by Marek Polacek : https://gcc.gnu.org/g:da47a84e277c7fbeebbf9c1e7dc1e8ba3277fe53 commit r11-9710-gda47a84e277c7fbeebbf9c1e7dc1e8ba3277fe53 Author: Marek Polacek Date: Tue Jul 13 17:16:54 2021 -0400 c++: constexpr array reference and value-initialization [PR101371] This PR gave me a hard time: I saw multiple issues starting with different revisions. But ultimately the root cause seems to be the following, and the attached patch fixes all issues I've found here. In cxx_eval_array_reference we create a new constexpr context for the CP_AGGREGATE_TYPE_P case, but we also have to create it for the non-aggregate case. In this test, we are evaluating ((B *)this)->a =3D rhs->a which means that we set ctx.object to ((B *)this)->a. Then we proceed to evaluate the initializer, rhs->a. For *rhs, we eval rhs, a PARM_DEC= L, for which we have (const B &) &c.arr[0] in the hash table. Then cxx_fold_indirect_ref gives us c.arr[0]. c is evaluated to {.arr=3D{}}= so c.arr is {}. Now we want c.arr[0], so we end up in cxx_eval_array_reference and since we're initializing from {}, we call build_value_init which gives us an AGGR_INIT_EXPR that calls 'constexpr B::B()'. Then we evaluate this AGGR_INIT_EXPR and since its first argument is dummy, we take ctx.object instead. But that is the wrong object, we're not initializing ((B *)this)->a here. And so we wound up with an initializer for A, and then crash in cxx_eval_component_reference: gcc_assert (DECL_CONTEXT (part) =3D=3D TYPE_MAIN_VARIANT (TREE_TYPE (whole))); where DECL_CONTEXT (part) is B (as it should be) but the type of whole was A. So create a new object, if there already was one, and the element type is not a scalar. PR c++/101371 gcc/cp/ChangeLog: * constexpr.c (cxx_eval_array_reference): Create a new .object and .ctor for the non-aggregate non-scalar case too when value-initializing. gcc/testsuite/ChangeLog: * g++.dg/cpp1y/constexpr-101371-2.C: New test. * g++.dg/cpp1y/constexpr-101371.C: New test. (cherry picked from commit a42f8120442cf3ba25d621bed857b5be19019d0c)=