From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from NAM11-CO1-obe.outbound.protection.outlook.com (mail-co1nam11on2055.outbound.protection.outlook.com [40.107.220.55]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3F7AD27466; Tue, 22 Apr 2025 14:09:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=40.107.220.55 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745330996; cv=fail; b=nKOWICS1mGNxoHzN6wgqbir1CcCSJAucWhomWPub7yt3V21OzqgYavVwqIUs9coBGCy/sKAKsbF8BXA7bJgleV9epixHpJwYS0vfPI4nKVQQGEQs+5dOhkLjdW/xnZqI4Wj6A5sQ+EfXIj3jhG0CJ2Zw43JlTokg2PBTL4SHV/Q= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745330996; c=relaxed/simple; bh=2mFqTJMq/g21ivmzZC+FS+Nr/Is4O0FCImY1pQs6R3k=; h=Content-Type:Date:Message-Id:Subject:From:To:References: In-Reply-To:MIME-Version; b=ktKOMwEHyf5ya5lKkOqVI6pe5YeKneIy60Pc2qd6mo5YOSX+hgAsl0zJFBALG5T2l236GnB/yx77V7HH9xnpdxf/uxRo25KW6MydsGgEAeYXCr2BoVusQPMSQfpC764dIdju+pP42N+XeWZs4ncmsSNTbbw7ByJnwxijzICfY/M= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=nvidia.com; spf=fail smtp.mailfrom=nvidia.com; dkim=pass (2048-bit key) header.d=Nvidia.com header.i=@Nvidia.com header.b=bIq2SvG7; arc=fail smtp.client-ip=40.107.220.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=nvidia.com Authentication-Results: smtp.subspace.kernel.org; spf=fail smtp.mailfrom=nvidia.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=Nvidia.com header.i=@Nvidia.com header.b="bIq2SvG7" ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=Yk70ebqJ6nUF81oeuyAmzkd8Wpwfwh0Pm0yYYrzPStNIRXdvsNxgcdwcqM42+Asj7TrLmpxNgXGGh9OLxNI9Wc7A8FouS4O7vxLXAyEqVSdZIKoe2V69a3K+8BWlEktJjq4iZYptkd7Moo3blMv57p6MJdjWkZdnOvGsPkuSUi4PhPQVFYHp6G4I3cTRUU2MEOz3RAXZeN1Tg2YsboPN7mOaICt37+gzd5ti4b7mtTU0CLi9yHu/VgB8UgMeEh7doHmKhNtibPzlT6gj0Fe3gZSm09f4EK8i3tST4+pl9sDgFwTytOICFvKdnf0dRK8gT9Rc9VeM+OiDgbvrK8udbA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector10001; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=j3BTzr7bkZfQiRiBAAdH58ZEXdNwvoKmZMgeaNovsNc=; b=K/vOneygaE/xZw7/IqJhYKOQdZL5jdmWm77/IBKtkeY1OJsmvoj8BzGGxSjsF8FhO4SIHelmzLQXA3IjJun4mQb4ZzTKncurjgl6dDMuXYbGuOyCf78IKmnrC1/TIkyfTnhOqjvFoO1oCwYM6pt9B41yAMcmuQkBkWg9H0Ynmh0UjxoMk4QInzojCCI+Xp+LjsujAl9c/LikksVpH6xxXWWeEQUz/ecu0iX1GuNY/LXZi0qHlKA0xAqo6jpayQ+WVgG0tjT2Yg+Uxab9lioe7tbd+M4u3la1OfNs7gFpComFnS5o2JOu0oA73lAwEkOK4Hay0LY2X5FeSpiuS0/QGg== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=nvidia.com; dmarc=pass action=none header.from=nvidia.com; dkim=pass header.d=nvidia.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=Nvidia.com; s=selector2; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=j3BTzr7bkZfQiRiBAAdH58ZEXdNwvoKmZMgeaNovsNc=; b=bIq2SvG7hGw47+fUcQUi784JzkXkrmOYCvrZ6Yz+R1QmqCiC3t4HRUPOFrIkXBr5ph5CQ5Y2Q2I+eymvxrYmXa7sVuW93rJ1xBSoRmho9kcsoqi+FnjALSHSh0y/+fHbtvJujNnCJOEUXezc8V3UG6MgYExElAwatQS2Jh4Xr83t//K1Yt91k5KIXXm2vKB4AbdzSpPZeY0YbvuFdslXEpiO7QXrW+oaIloCwoNCYqU9uRlkZBlTVp8g8qmG+S+32Ld8zBdu6Qf8DdhHdXnoMmzjOTzQVDtcKA6ppYrcDpea+ZBv388Z3jQbPy/6uYrjl9KUD24VqlHQldqs0ZQKkg== Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=nvidia.com; Received: from CH2PR12MB3990.namprd12.prod.outlook.com (2603:10b6:610:28::18) by PH0PR12MB8822.namprd12.prod.outlook.com (2603:10b6:510:28d::17) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.8655.35; Tue, 22 Apr 2025 14:09:50 +0000 Received: from CH2PR12MB3990.namprd12.prod.outlook.com ([fe80::6e37:569f:82ee:3f99]) by CH2PR12MB3990.namprd12.prod.outlook.com ([fe80::6e37:569f:82ee:3f99%4]) with mapi id 15.20.8655.033; Tue, 22 Apr 2025 14:09:50 +0000 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Tue, 22 Apr 2025 23:09:47 +0900 Message-Id: Subject: Re: [PATCH v6] rust: transmute: Add methods for FromBytes trait From: "Alexandre Courbot" To: "Christian S. Lima" , , , "Miguel Ojeda" , "Alex Gaynor" , "Boqun Feng" , "Gary Guo" , =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= , "Benno Lossin" , "Andreas Hindborg" , "Alice Ryhl" , "Trevor Gross" , "Danilo Krummrich" , <~lkcamp/patches@lists.sr.ht>, X-Mailer: aerc 0.20.1-0-g2ecb8770224a References: <20250330234039.29814-1-christiansantoslima21@gmail.com> In-Reply-To: <20250330234039.29814-1-christiansantoslima21@gmail.com> X-ClientProxiedBy: TYAPR04CA0002.apcprd04.prod.outlook.com (2603:1096:404:15::14) To CH2PR12MB3990.namprd12.prod.outlook.com (2603:10b6:610:28::18) Precedence: bulk X-Mailing-List: rust-for-linux@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CH2PR12MB3990:EE_|PH0PR12MB8822:EE_ X-MS-Office365-Filtering-Correlation-Id: b0fc8aea-0fef-4e8a-1cb4-08dd81a7586e X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|366016|10070799003|1800799024|376014|7416014|7053199007|921020; X-Microsoft-Antispam-Message-Info: =?utf-8?B?a1RZT25CWDNZT3I1aVUva0R1RDJmYnNtTzdRdmJ0bWZNOWZsblFNY01IOVdo?= =?utf-8?B?YmpRRHBNRno4dzdlTDE5WXpoU2NGeUJwNGwzTkZIbExIc0VaVmhOcnpnSEZ4?= =?utf-8?B?YWxuUzhwVC9aRE1UQzJEWUxUUVFlTE5rTjZROEoxNXlPb3gzTzZBVHlSUm9C?= =?utf-8?B?a3YvR3NCVmlLby9PU1NRM3dVblFYQk1HMXhLaTQ1amlVUzFKQWxUMVNBRVN1?= =?utf-8?B?MXZhQVE4U0kxOGg3SzZybDNxaVJzUTA0YmpxWXNwS1JZdkhlTmpPWG1EUnJh?= =?utf-8?B?Q00yb2x1UmZ5Q2dVTTlLYmM1cUVUUmhrdzJLbVhqZTVQOEZhWVNtUitXbWdP?= =?utf-8?B?Q0JKbHlvZ3F0ZXRHZkJlZjd0YVlHMk1BYmt1RFd1VDFVbXpFT3piMUJ0cHFO?= =?utf-8?B?T3hoZjg5MXRBd2wvQWZuT3dTRlUxcVZmVytFK2NxK1drUVhSYnRwUUFhZHg4?= =?utf-8?B?TFQwS0RXN0EwcG00Wm5jbWRUdCt2YldIVTg0UE1ya3IxZFVpQmV1c1kyak52?= =?utf-8?B?QkdoM2VxeThSUVU1bHpEVDBveDUzRWdWWE55QkRKOVhVS0NTcnZ0eVhoNHBq?= =?utf-8?B?V3BEK0xNMkY2THhINUwrMXdnbEN0MDhpNXUrN25OdmlPMDRxdnJRbUYvV3Jh?= =?utf-8?B?cGtmcjhTcWlKckVrRTFwbTR6S0hXN1djaHNVV1pTN21sTHFZSEVramcvbVcy?= =?utf-8?B?d2tNRHkzWG5KcDFJaExRTC82VGQ2KzVhNFN1dkNUNDlJVFg2VEw2WWhKN0xw?= =?utf-8?B?ODUvRFU0YkRwL0xXWkUrdlhqSGduV2RCaE1kb21GQm5LWUllVW90dU42clVp?= =?utf-8?B?U25DbXlqajh3ait5UUl6UkxGb2VZZmFNTTB6V1RnWWlDQnBuQ0xHVGhJcHZM?= =?utf-8?B?R0RMQlZGT0N2VXdqbkY2QXFBT1AwRjBDNitIZ0ErV1FOalJWaEZ4QjdTYlhv?= =?utf-8?B?OXU5MG82eFRjeUR3RE9kMjZXUFRXakp4SU5HRk5Cb1hUYVQrV0IxTVVISjNy?= =?utf-8?B?dktPb2xsTmVTUTJIZVVEQVFNYVFUdUoyQTU4RUc4WFZ4OFpYaDZXRDE2VUZP?= =?utf-8?B?b1RSTWRBUjRVL3A5QXVybXIyb1J1YU1iQldmZVp6MG1ZeXdDb01uRUY1bXly?= =?utf-8?B?VUtPYURyWHFJaksrN0h1d1Y4ZmVSV0U5SXJhdTcwQlR5dGJTaFYxRmdyakdY?= =?utf-8?B?TXEzTERIZFA0VnMvNm5TRVV2c3BnUDBRaGI3U0hXcVhmUVpIN3QvL3p5RjVl?= =?utf-8?B?aEpWZnE4VFk0REVCclc1YTBJa2hlVWdsRk0zbGRvMC9TRHZReXhLVm9kVWxO?= =?utf-8?B?UmFwb3JqZTN0czZQR0RZYzdRKzJnRlRjUDM4cmJhQVduamZRc09oOU9uRlZX?= =?utf-8?B?ZDFVdUZzeEgveFpGKzRCSWEwR2pVakV6aXVPaVdjWGdKRzFNMXFwcUl6UUpi?= =?utf-8?B?ZFhvN25MZWUrN0lpckNtbjU0eDdPdklzRGpZVlhFY1lpNHpOeUE5YXlZY2tO?= =?utf-8?B?K1NHMktjVVNlL1ZERlZhZGhtRSttUE5vaDZXekV3Q2MzamlYRldBMVdDQmZo?= =?utf-8?B?NDZMNHo1VjBnK0dFQ2lObFRTcTNHTEFGeklsYlgxR0p0WHhWNnpoODE0K2Nn?= =?utf-8?B?YmYwRXNQQzdMVXVFVEZJK2ZNRGhiNUVMd09tOTRmQ2FGV1BqUUd6Q1JrZzU0?= =?utf-8?B?blpPd1NtV3luYkMvc3hYMS9FQ1UvV2hVcUhSN1NiRDhJUXZvQW10VU56ZXRY?= =?utf-8?B?Wm1JcXN5bTVSamQvM1hROE9DREY3L2NQN0lxdTQ5NnZtdlBUOUd4VUdpU2ds?= =?utf-8?B?WkpORzhzWDY4T3lWSmkwQjR6V3RRcGNNVFdqT0dub1h1MWFJNEgvTXlIQXZW?= =?utf-8?B?bmJuNmtMY29hd2FWYnFNQmF3OVRHdHVtVW1NQmFkU2N5cGFtSFBQT1Y2MjBj?= =?utf-8?B?Q215aUdjdXA1RlpRSVRkN3FxUG9OY3ZmS01JN2l6eFZhRDRRMWF3dlAza05w?= =?utf-8?B?engrUFVPYWtnPT0=?= X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:CH2PR12MB3990.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(366016)(10070799003)(1800799024)(376014)(7416014)(7053199007)(921020);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?VDEvZFh5aWM5L0VxdFRHb3d5OHo4UzBXMnVqWkJFbWhoZjlOeGFQaHBFbVhD?= =?utf-8?B?MzMwUVRJWEMrVkVXTjR3YzZ4K2VaSzNyb0doYmxmWDVQTFplbXh4amhVUzRq?= =?utf-8?B?MnZ4ZnJWZW0vNUM0bmQzenZ5YzJmbDRwNFdrMmVrem9IWDdTYTBMbC82QjBW?= =?utf-8?B?WHh1T2haRTFtM0VPSDd4MHl4K1NrRFRvcUcvRS95UU40VUsvSVFRUW4vS3k2?= =?utf-8?B?N2czSnpLOGhzZForWDRQaVlxTkhKL0YyRTdvdUU4cnNWOGs2TFhrNmwwdU5j?= =?utf-8?B?SG5VejloUFhEYWF4VDFsejdjZDZUczVSVnlBVFlpd0NIZVlZNlRPQTJRVEZh?= =?utf-8?B?WnBpN0Y1MnE2VURtMjEwbFkzRlY3QkF1bnhVM2RKM3VUNDhwbHorRXNocHFa?= =?utf-8?B?enhxTWJvY3ZmRmJsOE1zbDVCeWxZQ2FyeU1Lbys4NUp6dm5ndVpGRFM0VG00?= =?utf-8?B?TmpYQ0xlMXlWeWlqWEVnSzIxTm5XdExSNzNYNHcyS1NqTm5XZGxyUllSNmU3?= =?utf-8?B?MHgwS0kyY215UCtFNXY0M1hiUkt0bHJyWUhIdTZyMjBzaFdLWTJRV3orY01U?= =?utf-8?B?ODA4S0hLMFB5RFpncEwxR3ArU05UZXpTWkszTU1lZFlGNUdOM29UcjFaV2dC?= =?utf-8?B?SG9IbG9GK21YSjZCanpuZGpuQURHdGc2ZUlsK0RzdUZGVk95ekpYaGl1Zlh4?= =?utf-8?B?dDlpUDFGaVI1SjlOaFpCZEVNN0FKeXRSYTR4U3ROYUd1Z2ExRkdKR25jc25h?= =?utf-8?B?aVdOQVVuWEpZTU9qWHZlUE5sVTUwZzVmOTVsNzJJWVdlVEI3RHFVSlJWdlVR?= =?utf-8?B?RUh6R0NLb2U3Qkp6aURtajhNdWppUk5GZ01QOU9sUUNNalJjcC80L1VyVmha?= =?utf-8?B?WHYvNkRpaklqWUV0TEN5T3M4ZFNpd01uMkZ4MHRHSEtwaGdsRWE1NXM1ekNl?= =?utf-8?B?cWNNK2tVQkE0N2xtK1VLNkJkSlhYVmk5QlJVcXYwbWpvaDBhTEJTTWVBTS9M?= =?utf-8?B?ZkZCeVhDdUIzellBUE1TVnlwTDRYQ3g5aUNac3A3K3kxakxvQURYWm9GRXRJ?= =?utf-8?B?Y0dld0pzai8reVkwZGFKVjVwbWtIQ2tzYjBYcUNjWkpQSFNlWTIyU1ZWWFJq?= =?utf-8?B?VHh5cWQ5ZkZOZitRczN6dzMvOWhTa0xST2FQY2o4Y2lPSkY4MGp0L1pMY09R?= =?utf-8?B?emVXMkFkKzltR0VXKytOdUhPOGlNMnVlaTUrSXFBaHpSN0xNSzFEVUltRWUv?= =?utf-8?B?ZGJyTWVOSlZaYUduNGF2L0RwNUZNcTBLMjM1NWtoTkFuTmN3QkhYRnl6Y2F6?= =?utf-8?B?c0lPc29wZXk0NW1QZmtvN0phY040bXB0aGtOb2xENWpHU045Ly9mZUF5VndS?= =?utf-8?B?MUo0dHNteVcxd0ZPeXFlV0tvMEtjbVdUbDhuUkRvZGUza3NxeFpBWFhLOWtr?= =?utf-8?B?MmxFejhxV083bUxQeDcweTJzZGdqazlEUFZyT2J4OEMrOGY1TTFPbU1aYmR3?= =?utf-8?B?R1NjY3ljK2ZMaVFMNm9FNGI5bituTFZMb2RiaEZZMzZkb0F4UWEyeVhNbVVD?= =?utf-8?B?Z0Z6UU5RM1VRRnQvWkFsWWU3emlJS1g1Qjkyb0JQb2g0YXFvSjNtVGJHZDRx?= =?utf-8?B?cTNuR2ZOSnF1K2V4WGZHNlJ4aGVYK25SeXVLWThmWU0zYnIvODlBK05iUDRi?= =?utf-8?B?Nkw0c2MvckM3SXUzU3lweWxqa3I2Tkc3cWl1WmFNNlNhSTYyaTRLMUJLL253?= =?utf-8?B?ZUZMM1FYMHErSk96NGdla2k4bHBIN1VCS05vSWt5blBQcG9yaFFXWERmRFNC?= =?utf-8?B?cElnUnQrWWwyRWQxak1aaUdQczFORU10eEcyN1M5d2l2d3pWcjZiV2E4OWNS?= =?utf-8?B?ODNVWi9ZckRLOGFveHI2cG9Xam5WZGNFSGhuVEdEemhvLzBCMDBCYXd1N2Iw?= =?utf-8?B?ZFdUczJTVDR3TE0vU2FjNkJJNHJ4UHB3ejVFTWZOZzd0eldubU5EU3hnRU9I?= =?utf-8?B?eG1PbERpUnVIK2lnVnRXOGxBTUN1bGN6L2RLOGhYL2RvRDdWejMrTG13ejBJ?= =?utf-8?B?K05RcThTaUdDTDg5cTZXb25CNk42cFZXVXpIMVM3b3lUdkVjeHhveTU1eGdN?= =?utf-8?B?TUpLMkpBeUc1Y081MTBtRG5ibGZhUnpKcUxYOU80SXc2bnNMM09LRTJaZEZ6?= =?utf-8?Q?xMgkcB9fPTmgxLhR5HGRZDxNUL8spHLyl60rWhnkOzQh?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: b0fc8aea-0fef-4e8a-1cb4-08dd81a7586e X-MS-Exchange-CrossTenant-AuthSource: CH2PR12MB3990.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 22 Apr 2025 14:09:50.1070 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: HFREV/5HgUwgVH1RjJFau9Vd3UVXJGrwMwwbd5kRO8lgshw66Ewb7rfY0IQYbVG2iNVOijmfVlf4HJxpGApXcw== X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH0PR12MB8822 On Mon Mar 31, 2025 at 8:40 AM JST, Christian S. Lima wrote: > Methods receive a slice and perform size check to add a valid way to make > conversion safe. An Option is used, in error case just return `None`. > > The conversion between slices `[T]` is separated from others, because I > couldn't implement it in the same way as the other conversions. > > Link: https://github.com/Rust-for-Linux/linux/issues/1119 > Signed-off-by: Christian S. Lima > --- > Changes in v2: > - Rollback the implementation for the macro in the repository and impleme= nt > methods in trait > - Link to v2: https://lore.kernel.org/rust-for-linux/20241012193657.290cc= 79c@eugeo/T/#t > > Changes in v3: > - Fix grammar errors > - Remove repeated tests > - Fix alignment errors > - Fix tests not building > - Link to v3: https://lore.kernel.org/rust-for-linux/20241109055442.85190= -1-christiansantoslima21@gmail.com/ > > Changes in v4: > - Removed core::simd::ToBytes > - Changed trait and methods to safe Add > - Result<&Self, Error> in order to make safe methods > - Link to v4: https://lore.kernel.org/rust-for-linux/20250314034910.13446= 3-1-christiansantoslima21@gmail.com/ > > Changes in v5: > - Changed from Result to Option > - Removed commentaries > - Returned trait impl to unsafe > - Link to v5: https://lore.kernel.org/rust-for-linux/20250320014041.10147= 0-1-christiansantoslima21@gmail.com/ > > Changes in v6: > - Add endianess check to doc test and use match to check > success case > - Reformulated safety comments > --- > rust/kernel/transmute.rs | 89 +++++++++++++++++++++++++++++++++++++--- > 1 file changed, 83 insertions(+), 6 deletions(-) > > diff --git a/rust/kernel/transmute.rs b/rust/kernel/transmute.rs > index 1c7d43771a37..16dfa5c7d467 100644 > --- a/rust/kernel/transmute.rs > +++ b/rust/kernel/transmute.rs > @@ -9,29 +9,106 @@ > /// > /// It's okay for the type to have padding, as initializing those bytes = has no effect. > /// > +/// # Example > +/// ``` > +/// let foo =3D &[1, 2, 3, 4]; > +/// > +/// let result =3D u32::from_bytes(foo); > +/// > +/// #[cfg(target_endian =3D "little")] > +/// match result { > +/// Some(x) =3D> assert_eq!(*x, 0x4030201), > +/// None =3D> unreachable!() > +/// } > +/// > +/// #[cfg(target_endian =3D "big")] > +/// match result { > +/// Some(x) =3D> assert_eq!(*x, 0x1020304), > +/// None =3D> unreachable!() > +/// } > +/// ``` > +/// > /// # Safety > /// > /// All bit-patterns must be valid for this type. This type must not hav= e interior mutability. > -pub unsafe trait FromBytes {} > +pub unsafe trait FromBytes { > + /// Converts a slice of bytes to a reference to `Self` when possible= . > + fn from_bytes(bytes: &[u8]) -> Option<&Self>; > + > + /// Converts a mutable slice of bytes to a reference to `Self` when = possible. > + fn from_bytes_mut(bytes: &mut [u8]) -> Option<&mut Self> > + where > + Self: AsBytes; > +} > =20 > macro_rules! impl_frombytes { > ($($({$($generics:tt)*})? $t:ty, )*) =3D> { > // SAFETY: Safety comments written in the macro invocation. > - $(unsafe impl$($($generics)*)? FromBytes for $t {})* > + $(unsafe impl$($($generics)*)? FromBytes for $t { > + fn from_bytes(bytes: &[u8]) -> Option<&$t> { > + if bytes.len() =3D=3D core::mem::size_of::<$t>() { > + let slice_ptr =3D bytes.as_ptr().cast::<$t>(); > + unsafe { Some(&*slice_ptr) } > + } else { > + None > + } > + } This is probably a naive question, but is there a reason why this cannot be the default implementation of `from_bytes`? IIUC other implementors would have to come with their own implementation, which adds an extra burden.