From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gproxy4-pub.mail.unifiedlayer.com (gproxy4-pub.mail.unifiedlayer.com [69.89.23.142]) by sourceware.org (Postfix) with ESMTPS id 288333858D32 for ; Sat, 11 Feb 2023 16:18:02 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 288333858D32 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=tromey.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=tromey.com Received: from cmgw10.mail.unifiedlayer.com (unknown [10.0.90.125]) by progateway6.mail.pro1.eigbox.com (Postfix) with ESMTP id 8D61C10049526 for ; Sat, 11 Feb 2023 16:18:01 +0000 (UTC) Received: from box5379.bluehost.com ([162.241.216.53]) by cmsmtp with ESMTP id QsZdpiX86KCpNQsZdpNiND; Sat, 11 Feb 2023 16:18:01 +0000 X-Authority-Reason: nr=8 X-Authority-Analysis: v=2.4 cv=W8X96Tak c=1 sm=1 tr=0 ts=63e7bfb9 a=ApxJNpeYhEAb1aAlGBBbmA==:117 a=ApxJNpeYhEAb1aAlGBBbmA==:17 a=dLZJa+xiwSxG16/P+YVxDGlgEgI=:19 a=m04uMKEZRckA:10:nop_rcvd_month_year a=Qbun_eYptAEA:10:endurance_base64_authed_username_1 a=mxrHjCFiMZPwhWSGRuEA:9 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=tromey.com; s=default; h=Content-Transfer-Encoding:MIME-Version:Message-Id:Date:Subject: Cc:To:From:Sender:Reply-To:Content-Type:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: In-Reply-To:References:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=zLCDbIQD80n/RwrYiMFMEnsjgasP09WthXBxHgJx4fI=; b=t0fU9Zs/mhGd8XQfV56J1jXFxO MXH2YDzLmSpHSobAJXSsnXHCJkIuxGscJ0aJoAqNhF4CekzxE5iVKx/VCAX6DAWICYlqd//l4ba1B m58+RH5PB8VmRm4LuDNINNUiE; Received: from 75-166-130-93.hlrn.qwest.net ([75.166.130.93]:52860 helo=localhost.localdomain) by box5379.bluehost.com with esmtpsa (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.95) (envelope-from ) id 1pQsZd-002t06-9J; Sat, 11 Feb 2023 09:18:01 -0700 From: Tom Tromey To: gdb-patches@sourceware.org Cc: Tom Tromey Subject: [PATCH] Only allow downcasts in checked_static_cast Date: Sat, 11 Feb 2023 09:17:51 -0700 Message-Id: <20230211161751.3813270-1-tom@tromey.com> X-Mailer: git-send-email 2.39.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - box5379.bluehost.com X-AntiAbuse: Original Domain - sourceware.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - tromey.com X-BWhitelist: no X-Source-IP: 75.166.130.93 X-Source-L: No X-Exim-ID: 1pQsZd-002t06-9J X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: 75-166-130-93.hlrn.qwest.net (localhost.localdomain) [75.166.130.93]:52860 X-Source-Auth: tom+tromey.com X-Email-Count: 3 X-Source-Cap: ZWx5bnJvYmk7ZWx5bnJvYmk7Ym94NTM3OS5ibHVlaG9zdC5jb20= X-Local-Domain: yes X-Spam-Status: No, score=-3027.4 required=5.0 tests=BAYES_00,DKIM_SIGNED,DKIM_VALID,GIT_PATCH_0,JMQ_SPF_NEUTRAL,RCVD_IN_DNSWL_NONE,RCVD_IN_MSPIKE_H2,SPF_HELO_NONE,SPF_PASS,TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: It didn't make sense to me that checked_static_cast allows upcasts, as it seems to me that it is better to simply not write an explicit upcast, but instead just allow the implicit derived-to-base conversion. This patch removes the downcast check from checked_static_cast. It also doesn't allow casts to the identical type, as this also did not seem necessary. Tested by rebuilding. --- gdbsupport/gdb-checked-static-cast.h | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/gdbsupport/gdb-checked-static-cast.h b/gdbsupport/gdb-checked-static-cast.h index bc75244bddd..ede0f6da1bc 100644 --- a/gdbsupport/gdb-checked-static-cast.h +++ b/gdbsupport/gdb-checked-static-cast.h @@ -30,7 +30,10 @@ namespace gdb work for polymorphic types. In non-developer (i.e. production) builds, the dynamic_cast is replaced - with a static_cast which is usually significantly faster. */ + with a static_cast which is usually significantly faster. + + This is intended only to be used for downcasts. For upcasts, you + can safely omit the cast. */ template T @@ -48,10 +51,10 @@ checked_static_cast (V *v) /* In developer mode this cast uses dynamic_cast to confirm at run-time that the cast from V* to T is valid. However, we can catch some mistakes at compile time, this assert prevents anything other than - downcasts, or casts to same type. */ + downcasts. */ static_assert (std::is_base_of::value - || std::is_base_of::value, - "types must be related"); + && !std::is_same::value, + "target type must be derived from actual type"); #ifdef DEVELOPMENT if (v == nullptr) -- 2.39.1