From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id AD2E9C10F27 for ; Tue, 10 Mar 2020 18:26:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5063B208C3 for ; Tue, 10 Mar 2020 18:26:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=pobox.com header.i=@pobox.com header.b="WFz20hgI" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727123AbgCJS0Z (ORCPT ); Tue, 10 Mar 2020 14:26:25 -0400 Received: from pb-smtp2.pobox.com ([64.147.108.71]:50557 "EHLO pb-smtp2.pobox.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726426AbgCJS0Z (ORCPT ); Tue, 10 Mar 2020 14:26:25 -0400 Received: from pb-smtp2.pobox.com (unknown [127.0.0.1]) by pb-smtp2.pobox.com (Postfix) with ESMTP id 1DDAC5AE30; Tue, 10 Mar 2020 14:26:23 -0400 (EDT) (envelope-from junio@pobox.com) DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=pobox.com; h=from:to:cc :subject:references:date:in-reply-to:message-id:mime-version :content-type; s=sasl; bh=+vJ/Sy/4/y+Bs0GPQNlfvZWeFNA=; b=WFz20h gIjlffmtS0Knp6FbnTVVsXePXg183SyDEDZGKVMiXHJTguldfzLaPi6A5gFXNdnC t1VT4r6LpJcTdRaPV5dvVMc0VtoQIFddJRYQ2QM+OEy3vMXIRi++mileCwJ7vH7s OYRn+XdxmnAb9znCpeBJTBONLiJVclrsORwns= DomainKey-Signature: a=rsa-sha1; c=nofws; d=pobox.com; h=from:to:cc :subject:references:date:in-reply-to:message-id:mime-version :content-type; q=dns; s=sasl; b=aHIPrecOeyPhKP/2bKIGXpAkIy/QPT8z puPXy8qzAdjAmgAo9DeUfpHBWQXIuCwDDUXTMaOGlwn87LqsGkz90rCYMxvicsXz QXZqa8V28BqtVsLTdfy3tgEw4Zfw7lRrdtEIT6IVPZJ2c/DXTC4zCaOMEzmTyeVL c8njclqvzCs= Received: from pb-smtp2.nyi.icgroup.com (unknown [127.0.0.1]) by pb-smtp2.pobox.com (Postfix) with ESMTP id 149EF5AE2F; Tue, 10 Mar 2020 14:26:23 -0400 (EDT) (envelope-from junio@pobox.com) Received: from pobox.com (unknown [34.74.119.39]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by pb-smtp2.pobox.com (Postfix) with ESMTPSA id 8FEB35AE2E; Tue, 10 Mar 2020 14:26:22 -0400 (EDT) (envelope-from junio@pobox.com) From: Junio C Hamano To: Jeff King Cc: SZEDER =?utf-8?Q?G=C3=A1bor?= , git@vger.kernel.org Subject: Re: [PATCH] commit-slab: clarify slabname##_peek()'s return value References: <20200310153049.3482-1-szeder.dev@gmail.com> <20200310175446.GB549010@coredump.intra.peff.net> Date: Tue, 10 Mar 2020 11:26:21 -0700 In-Reply-To: (Junio C. Hamano's message of "Tue, 10 Mar 2020 11:19:33 -0700") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Pobox-Relay-ID: A4E69DF4-62FC-11EA-B8C9-D1361DBA3BAF-77302942!pb-smtp2.pobox.com Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Junio C Hamano writes: > Jeff King writes: > >> But that would get a bit awkward, because peek() returns a pointer, not >> a value (as it should, because the type we're storing may be a compound >> type, which we generally avoid passing or returning by value). So we'd >> actually need to return a pointer to a zero-initialized dummy value. Not >> impossible, but getting a bit odd. > > Do we have a guarantee that callers of the peek only look at, never > touch, the location? As long as we make it return a "const *", it > might be OK, but a quick look at commit-slab.h tells me that we do > not say "const". Ah, should have read the other message ;-)