From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id 6CE093858400; Fri, 3 Dec 2021 19:00:37 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 6CE093858400 From: "cvs-commit at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug c++/103403] [11/12 Regression] auto return type with a trailing return type of decl(auto) uses rvalue reference type instead of reference type Date: Fri, 03 Dec 2021 19:00:37 +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: rejects-valid, wrong-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: 11.3 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: Fri, 03 Dec 2021 19:00:37 -0000 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D103403 --- Comment #5 from CVS Commits --- The trunk branch has been updated by Marek Polacek : https://gcc.gnu.org/g:abd7712f91c99690f8b0046ea168b2782afbac69 commit r12-5778-gabd7712f91c99690f8b0046ea168b2782afbac69 Author: Marek Polacek Date: Tue Nov 30 21:07:25 2021 -0500 c++: Fix for decltype(auto) and parenthesized expr [PR103403] In r11-4758, I tried to fix this problem: int &&i =3D 0; decltype(auto) j =3D i; // should behave like int &&j =3D i; error wherein do_auto_deduction was getting confused with a REFERENCE_REF_P and it didn't realize its operand was a name, not an expression, and deduced the wrong type. Unfortunately that fix broke this: int&& r =3D 1; decltype(auto) rr =3D (r); where 'rr' should be 'int &' since '(r)' is an expression, not a name. = But because I stripped the INDIRECT_REF with the r11-4758 change, we deduced 'rr's type as if decltype had gotten a name, resulting in 'int &&'. I suspect I thought that the REF_PARENTHESIZED_P check when setting 'bool id' in do_auto_deduction would handle the (r) case, but that's not the case; while the documentation for REF_PARENTHESIZED_P specifically = says it can be set in INDIRECT_REF, we don't actually do so. This patch sets REF_PARENTHESIZED_P even on REFERENCE_REF_P, so that do_auto_deduction can use it. It also removes code in maybe_undo_parenthesized_ref that I think is dead -- and we don't hit it while running dg.exp. To adduce more data, it also looks dead here: https://splichal.eu/lcov/gcc/cp/semantics.c.gcov.html (It's dead since r9-1417.) Also add a fixed test for c++/81176. PR c++/103403 gcc/cp/ChangeLog: * cp-gimplify.c (cp_fold): Don't recurse if maybe_undo_parenthesized_ref doesn't change its argument. * pt.c (do_auto_deduction): Don't strip REFERENCE_REF_P trees if they are REF_PARENTHESIZED_P. Use stripped_init when checking for id-expression. * semantics.c (force_paren_expr): Set REF_PARENTHESIZED_P on REFERENCE_REF_P trees too. (maybe_undo_parenthesized_ref): Remove dead code. gcc/testsuite/ChangeLog: * g++.dg/cpp1y/decltype-auto2.C: New test. * g++.dg/cpp1y/decltype-auto3.C: New test. * g++.dg/cpp1y/decltype-auto4.C: New test. * g++.dg/cpp1z/decomp-decltype1.C: New test.=