{"id":9674,"url":"https://patchwork.libcamera.org/api/1.1/patches/9674/?format=json","web_url":"https://patchwork.libcamera.org/patch/9674/","project":{"id":1,"url":"https://patchwork.libcamera.org/api/1.1/projects/1/?format=json","name":"libcamera","link_name":"libcamera","list_id":"libcamera_core","list_email":"libcamera-devel@lists.libcamera.org","web_url":"","scm_url":"","webscm_url":""},"msgid":"<20200920173447.10064-1-laurent.pinchart@ideasonboard.com>","date":"2020-09-20T17:34:47","name":"[libcamera-devel] Documentation: Adjust guidelines regarding math.h header","commit_ref":null,"pull_url":null,"state":"accepted","archived":false,"hash":"8d210554c592478c25fb55f6c34f4a2d83eb02b4","submitter":{"id":2,"url":"https://patchwork.libcamera.org/api/1.1/people/2/?format=json","name":"Laurent Pinchart","email":"laurent.pinchart@ideasonboard.com"},"delegate":null,"mbox":"https://patchwork.libcamera.org/patch/9674/mbox/","series":[{"id":1300,"url":"https://patchwork.libcamera.org/api/1.1/series/1300/?format=json","web_url":"https://patchwork.libcamera.org/project/libcamera/list/?series=1300","date":"2020-09-20T17:34:47","name":"[libcamera-devel] Documentation: Adjust guidelines regarding math.h header","version":1,"mbox":"https://patchwork.libcamera.org/series/1300/mbox/"}],"comments":"https://patchwork.libcamera.org/api/patches/9674/comments/","check":"pending","checks":"https://patchwork.libcamera.org/api/patches/9674/checks/","tags":{},"headers":{"Return-Path":"","X-Original-To":"parsemail@patchwork.libcamera.org","Delivered-To":"parsemail@patchwork.libcamera.org","Received":["from lancelot.ideasonboard.com (lancelot.ideasonboard.com\n\t[92.243.16.209])\n\tby patchwork.libcamera.org (Postfix) with ESMTPS id 141B5C3B5B\n\tfor ;\n\tSun, 20 Sep 2020 17:35:26 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 986F662FBF;\n\tSun, 20 Sep 2020 19:35:25 +0200 (CEST)","from perceval.ideasonboard.com (perceval.ideasonboard.com\n\t[213.167.242.64])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id 5DAE962E65\n\tfor ;\n\tSun, 20 Sep 2020 19:35:23 +0200 (CEST)","from pendragon.lan (62-78-145-57.bb.dnainternet.fi [62.78.145.57])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id D0EAC2D7;\n\tSun, 20 Sep 2020 19:35:22 +0200 (CEST)"],"Authentication-Results":"lancelot.ideasonboard.com;\n\tdkim=fail reason=\"signature verification failed\" (1024-bit key;\n\tunprotected) header.d=ideasonboard.com header.i=@ideasonboard.com\n\theader.b=\"rGqYO5q1\"; dkim-atps=neutral","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1600623323;\n\tbh=mGWKYAUOUhb9R5hPBlWA+kxWJrhVepOAcGRrhACVHMc=;\n\th=From:To:Cc:Subject:Date:From;\n\tb=rGqYO5q1zCIIlvugTqmwbIJB/dZAJYIf+KOM5ZZFc4Fdv0AcnUladMA2yfO7FNKBR\n\t+Iw5hcX8YpL+FvUeQIccuBAGw7hW7+0Yc58/OEjAQc8BeFxwT1uYRRejtMqg6CjyBh\n\tmG6zqv3EJFmKe1uoclAQtcF0E+NqVcHXSPf1SrOw=","From":"Laurent Pinchart ","To":"libcamera-devel@lists.libcamera.org","Date":"Sun, 20 Sep 2020 20:34:47 +0300","Message-Id":"<20200920173447.10064-1-laurent.pinchart@ideasonboard.com>","X-Mailer":"git-send-email 2.27.0","MIME-Version":"1.0","Subject":"[libcamera-devel] [PATCH] Documentation: Adjust guidelines\n\tregarding math.h header","X-BeenThere":"libcamera-devel@lists.libcamera.org","X-Mailman-Version":"2.1.29","Precedence":"list","List-Id":"","List-Unsubscribe":",\n\t","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n\t","Content-Type":"text/plain; charset=\"us-ascii\"","Content-Transfer-Encoding":"7bit","Errors-To":"libcamera-devel-bounces@lists.libcamera.org","Sender":"\"libcamera-devel\" "},"content":"While libcamera prefers usage of the C standard library headers (xxx.h)\nover the C++ version (cxxx), we make an exception for cmath as the\noverloaded versions of the math functions are convenient. Document this,\nand adjust checkstyle.py accordingly.\n\nSigned-off-by: Laurent Pinchart \n---\n Documentation/coding-style.rst | 14 +++++++++++---\n utils/checkstyle.py | 6 +++---\n 2 files changed, 14 insertions(+), 6 deletions(-)\n\nJacopo, this originates from a discussion in the review of \"[PATCH]\nlibcamera: ipu3: Fix compilation issues with gcc5\". I haven't assigned\nthe authorship to you as you didn't provide a formal patch with an SoB\nline. Please let me know if I should (and give me your SoB in that\ncase). Otherwise, a review is always appreciated :-)","diff":"diff --git a/Documentation/coding-style.rst b/Documentation/coding-style.rst\nindex 7c56a1b70014..d467a5a1b1ad 100644\n--- a/Documentation/coding-style.rst\n+++ b/Documentation/coding-style.rst\n@@ -195,9 +195,17 @@ them, defines C compatibility headers. The former have a name of the form\n while the later are named . The C++ headers declare names in the\n std namespace, and may declare the same names in the global namespace. The C\n compatibility headers declare names in the global namespace, and may declare\n-the same names in the std namespace. Usage of the C compatibility headers is\n-strongly preferred. Code shall not rely on the optional declaration of names in\n-the global or std namespace.\n+the same names in the std namespace. Code shall not rely on the optional\n+declaration of names in the global or std namespace.\n+\n+Usage of the C compatibility headers is preferred, except for the math.h header.\n+Where math.h defines separate functions for different argument types (e.g.\n+abs(int), labs(long int), fabs(double) and fabsf(float)) and requires the\n+developer to pick the right function, cmath defines overloaded functions\n+(std::abs(int), std::abs(long int), std::abs(double) and std::abs(float) and let\n+the compiler select the right function. This avoids potential errors such as\n+calling abs(int) with a float argument, performing an unwanted implicit integer\n+conversion. For this reason, cmath is preferred over math.h.\n \n \n Documentation\ndiff --git a/utils/checkstyle.py b/utils/checkstyle.py\nindex b594a19aed5b..d5dc26c0f666 100755\n--- a/utils/checkstyle.py\n+++ b/utils/checkstyle.py\n@@ -244,9 +244,9 @@ class IncludeChecker(StyleChecker):\n patterns = ('*.cpp', '*.h')\n \n headers = ('assert', 'ctype', 'errno', 'fenv', 'float', 'inttypes',\n- 'limits', 'locale', 'math', 'setjmp', 'signal', 'stdarg',\n- 'stddef', 'stdint', 'stdio', 'stdlib', 'string', 'time', 'uchar',\n- 'wchar', 'wctype')\n+ 'limits', 'locale', 'setjmp', 'signal', 'stdarg', 'stddef',\n+ 'stdint', 'stdio', 'stdlib', 'string', 'time', 'uchar', 'wchar',\n+ 'wctype')\n include_regex = re.compile('^#include ')\n \n def __init__(self, content):\n","prefixes":["libcamera-devel"]}