From patchwork Mon Jun 19 22:12:29 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alex Yursha X-Patchwork-Id: 777998 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from sourceware.org (server1.sourceware.org [209.132.180.131]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 3ws4wR3GVJz9s0g for ; Tue, 20 Jun 2017 08:12:39 +1000 (AEST) Authentication-Results: ozlabs.org; dkim=pass (1024-bit key; secure) header.d=sourceware.org header.i=@sourceware.org header.b="rcXpL3Cu"; dkim-atps=neutral DomainKey-Signature: a=rsa-sha1; c=nofws; d=sourceware.org; h=list-id :list-unsubscribe:list-subscribe:list-archive:list-post :list-help:sender:mime-version:from:date:message-id:subject:to :content-type; q=dns; s=default; b=u8uHcd931/P3u8iHSdkarcO5KcCLw /1zaGaWZ+C2nEzRLnBz2YN90mdNAMEQkcJ7w0kC8fj1lRx4/iLFvgP+QIojB0NT3 h8oz6PzciPSXwDYCxTZ0AtPnZiZNPGMe+9lN7nm2/yoRTn/jk+AuPyT3vP/00vTt aoKBVYDypI00GY= DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=sourceware.org; h=list-id :list-unsubscribe:list-subscribe:list-archive:list-post :list-help:sender:mime-version:from:date:message-id:subject:to :content-type; s=default; bh=ifl8yOFvq8YT10nuTa+BtlZqwOU=; b=rcX pL3CuKhpx/72gl8Hre1gCZx3HjdGDYSKB674Q5gQKzOqJwjhaR15zt/2N74RDjuL mLsRrelZLJ7aJWo5Y9WCge2b9+65vaYHtXqfl0ALJ9GNt2FwUHP7W1UgA81cd3Q8 mI9Gda444gmnD4c2OHoKF1JF5113afWKeCsjwgH8= Received: (qmail 119954 invoked by alias); 19 Jun 2017 22:12:29 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Delivered-To: mailing list libc-alpha@sourceware.org Received: (qmail 119941 invoked by uid 89); 19 Jun 2017 22:12:28 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-16.4 required=5.0 tests=AWL, BAYES_00, FREEMAIL_FROM, GIT_PATCH_1, GIT_PATCH_2, GIT_PATCH_3, RCVD_IN_DNSWL_NONE, SPF_PASS autolearn=ham version=3.3.2 spammy= X-HELO: mail-qt0-f171.google.com X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:from:date:message-id:subject:to; bh=VUpEMtLQu9DYewU8xE/T56+2bkc6sCWVDVQCT6AmMnI=; b=sr3uY8okVNrw9tJkdI9J5LDCXU6/77UKtSiu5NpPqew45nx6JHfAsg9Zl0qONSLHpL XbMvh6pN1KYqcCaW2GnyAcXDO8/E5YXM87d34ozyJl64I0nc6hms9/bFlhesMToo2dg7 V22RXwrA0ajGxFjExS2u4FkAU5G2QDkxD4jvMhllK5Z+Ypn+R9ClfWZfSIkrINGYcw8W e3EwvkRUx7zG/JSD6HU45TX+CbAkN/k8epWjG48il81zMrpPiQPE2pu4tgBkCCYYHIcD bsj4ztZPLVEY1Gg+LrPxtHiRPMQYtP3G1cW0f/2qjoXGCxTqP0e4FjJMztvAboyCDWD3 7XYQ== X-Gm-Message-State: AKS2vOyKA0lAzq7zX9VJTjCvVJh9rvTLG8eDWaE4NDXYfWX6CGEfnwNE 3GCADT+BEUaMhZ+gMFndwMyOLjRPiyXMVjQ= X-Received: by 10.237.47.39 with SMTP id l36mr31720077qtd.44.1497910350266; Mon, 19 Jun 2017 15:12:30 -0700 (PDT) MIME-Version: 1.0 From: Alex Yursha Date: Mon, 19 Jun 2017 15:12:29 -0700 Message-ID: Subject: features.h - confusing branch logic in preprocessor directives To: libc-alpha@sourceware.org Hi all, There seem to be some tech debt in `features.h` on glibc master branch when falling back to _DEFAULT_SOURCE. See the patch below: 1. Comment redundantly mentions _GNU_SOURCE but it is not tested anywhere. 2. Testing for _DEFAULT_SOURCE and redefining it if its already defined makes no sense. index 972cbd2..aa1bad8 100644 --- include/features.h +++ include/features.h @@ -209,13 +209,11 @@ # define _ATFILE_SOURCE 1 #endif -/* If nothing (other than _GNU_SOURCE and _DEFAULT_SOURCE) is defined, - define _DEFAULT_SOURCE. */ -#if (defined _DEFAULT_SOURCE \ - || (!defined __STRICT_ANSI__ \ +/* If nothing is defined, define _DEFAULT_SOURCE. */ +#if (!defined __STRICT_ANSI__ \ && !defined _ISOC99_SOURCE \ && !defined _POSIX_SOURCE && !defined _POSIX_C_SOURCE \ - && !defined _XOPEN_SOURCE)) + && !defined _XOPEN_SOURCE) # undef _DEFAULT_SOURCE # define _DEFAULT_SOURCE 1 #endif