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charset=UTF-8 Date: Fri, 05 Jun 2026 08:44:47 +0900 Message-Id: Subject: Re: [PATCH v2 3/6] rust: ptr: add panicking index projection variant From: "Alexandre Courbot" To: "Gary Guo" Cc: "Miguel Ojeda" , "Boqun Feng" , =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= , "Benno Lossin" , "Andreas Hindborg" , "Alice Ryhl" , "Trevor Gross" , "Danilo Krummrich" , "Abdiel Janulgue" , "Daniel Almeida" , "Robin Murphy" , "David Airlie" , "Simona Vetter" , , , , , References: <20260602-projection-syntax-rework-v2-0-6989470f5440@garyguo.net> <20260602-projection-syntax-rework-v2-3-6989470f5440@garyguo.net> In-Reply-To: <20260602-projection-syntax-rework-v2-3-6989470f5440@garyguo.net> X-ClientProxiedBy: TY4P301CA0034.JPNP301.PROD.OUTLOOK.COM (2603:1096:405:2be::11) To CH2PR12MB3990.namprd12.prod.outlook.com (2603:10b6:610:28::18) Precedence: bulk X-Mailing-List: driver-core@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: MN2PR12MB3997:EE_|SJ1PR12MB6099:EE_ X-MS-Office365-Filtering-Correlation-Id: 246bead2-380d-4082-c838-08dec293450c X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|7416014|376014|10070799003|366016|11063799006|18002099003|22082099003|6133799003|4143699003|56012099006; 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This is also > compiler-version-dependent, so using build indexing here can be > problematic. On the other hand, it is also not ideal to use the fallible > variant, as it adds an error handling path that is never hit. > > Add a new panicking index projection for this scenario. Like all panickin= g > operations, this should be used carefully only in cases where the user > knows the index is going to be in bounds, and panicking would indicate > something is catastrophically wrong. > > To signify this, require users to explicitly denote the type of index bei= ng > used. The existing two types of index projections also gain the keyworded > version, which will be the recommended way going forward. > > The keyworded syntax also paves the way of perhaps adding more flavors in > the future, e.g. `unsafe` index projection. However, unless the code is > extremely performance sensitive and bounds checking cannot be tolerated, > the panicking variant is safer and should be preferred, so it will be lef= t > to the future when demand arises. > > Signed-off-by: Gary Guo Thanks for splitting the renaming part out! Reviewed-by: Alexandre Courbot