From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 21346 invoked by alias); 21 Jun 2018 18:22:38 -0000 Mailing-List: contact gcc-patches-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-patches-owner@gcc.gnu.org Received: (qmail 19666 invoked by uid 89); 21 Jun 2018 18:22:35 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-11.8 required=5.0 tests=AWL,BAYES_00,GIT_PATCH_2,GIT_PATCH_3,KAM_LAZY_DOMAIN_SECURITY,SPF_HELO_PASS autolearn=ham version=3.3.2 spammy=rendering, 5858 X-HELO: mx1.redhat.com Received: from mx3-rdu2.redhat.com (HELO mx1.redhat.com) (66.187.233.73) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Thu, 21 Jun 2018 18:22:34 +0000 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id B3614F68AE for ; Thu, 21 Jun 2018 18:22:32 +0000 (UTC) Received: from redhat.com (dhcp-17-187.bos.redhat.com [10.18.17.187]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 936432156880; Thu, 21 Jun 2018 18:22:32 +0000 (UTC) Date: Thu, 21 Jun 2018 18:22:00 -0000 From: Marek Polacek To: GCC Patches , Jason Merrill Subject: C++ PATCH for c++/86184, rejects-valid with ?: and omitted operand Message-ID: <20180621182231.GP15879@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.10.0 (2018-05-17) X-SW-Source: 2018-06/txt/msg01345.txt.bz2 The following testcase is rejected because, for this line: bool b = X() ?: false; arg2 is missing and arg1 is a TARGET_EXPR. A TARGET_EXPR is a class prvalue so we wrap it in a SAVE_EXPR. Later when building 'this' we call build_this (SAVE_EXPR >) which triggers lvalue_error: 5856 cp_lvalue_kind kind = lvalue_kind (arg); 5857 if (kind == clk_none) 5858 { 5859 if (complain & tf_error) 5860 lvalue_error (input_location, lv_addressof); because all SAVE_EXPRs are non-lvalue. Since a) cp_build_addr_expr_1 can process xvalues and class prvalues, b) TARGET_EXPRs are only evaluated once (gimplify_target_expr), I thought we could do the following. The testcase ensures that with the omitted operand we only construct X once. Bootstrapped/regtested on x86_64-linux, ok for trunk? 2018-06-21 Marek Polacek PR c++/86184 * call.c (build_conditional_expr_1): Don't wrap TARGET_EXPRs in a SAVE_EXPR. * g++.dg/ext/cond3.C: New test. --- gcc/cp/call.c +++ gcc/cp/call.c @@ -4806,6 +4806,10 @@ build_conditional_expr_1 (location_t loc, tree arg1, tree arg2, tree arg3, /* Make sure that lvalues remain lvalues. See g++.oliva/ext1.C. */ if (lvalue_p (arg1)) arg2 = arg1 = cp_stabilize_reference (arg1); + else if (TREE_CODE (arg1) == TARGET_EXPR) + /* TARGET_EXPRs are only expanded once, don't wrap it in a SAVE_EXPR, + rendering it clk_none of clk_class. */ + arg2 = arg1; else arg2 = arg1 = cp_save_expr (arg1); } --- gcc/testsuite/g++.dg/ext/cond3.C +++ gcc/testsuite/g++.dg/ext/cond3.C @@ -0,0 +1,20 @@ +// PR c++/86184 +// { dg-do run } +// { dg-options "" } + +int j; +struct X { + X() { j++; } + operator bool() { return true; } +}; + +/* Only create X once. */ +bool b = X() ?: false; +bool b2 = X() ? X() : false; + +int +main () +{ + if (j != 3) + __builtin_abort (); +}