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Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.9.1 Subject: Re: Local type inference with auto is in C2X Content-Language: en-GB To: Michael Matz , Florian Weimer Cc: gcc@gcc.gnu.org References: <87zgd8fhn4.fsf@oldenburg.str.redhat.com> From: David Brown In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-ClientProxiedBy: SV0P279CA0065.NORP279.PROD.OUTLOOK.COM (2603:10a6:f10:14::16) To SV0P279MB0233.NORP279.PROD.OUTLOOK.COM (2603:10a6:f10:b::13) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: SV0P279MB0233:EE_|SV0P279MB0009:EE_ X-MS-Office365-Filtering-Correlation-Id: 8dc4eb49-5f03-4c3d-ea52-08dabe6f279e X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:SV0P279MB0233.NORP279.PROD.OUTLOOK.COM;PTR:;CAT:NONE;SFS:(13230022)(4636009)(366004)(376002)(346002)(39840400004)(136003)(396003)(451199015)(66476007)(4326008)(6486002)(66556008)(478600001)(66946007)(186003)(8676002)(5660300002)(41300700001)(316002)(2616005)(38100700002)(2906002)(110136005)(36756003)(83380400001)(31686004)(53546011)(6506007)(8936002)(86362001)(26005)(31696002)(6512007)(45980500001)(43740500002);DIR:OUT;SFP:1101; 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GCC 14 might want to switch >> to C23/C24 mode by default, activating auto support, if the standard >> comes out in 2023 (which apparently is the plan). >> >> Then we would go from >> warning to changed semantics in a single release. >> >> Comments? > > I would argue that changing the default C mode to c23 in the year that > comes out (or even a year later) is too aggressive and early. Existing > sources are often compiled with defaults, and hence would change > semantics, which seems unattractive. New code can instead easily use > -std=c23 for a time. > > E.g. c99/gnu99 (a largish deviation from gnu90) was never default and > gnu11 was made default only in 2014. > That's true - and the software world still has not recovered from the endless mass of drivel that gcc (and other compilers) accepted in lieu of decent C as a result of not changing to C99 as the standard. Good C programmers put the standards flag explicitly in their makefile (or other build system). Bad ones use whatever the compiler gives them by default and believe "the compiler accepted it, it must be good code". My vote would be to make "-std=c17 -Wall -Wextra -Wpedantic -Werror -O2" the default flags. Force those who don't really know what they are doing, to learn - it's not /that/ hard, and the effort pays off quickly. (Or they can give up and move to Python.) Those who understand how to use their tools can happily change the standards and warnings to suit their needs. And the person who first decided "implicit declaration of function" should merely be a /warning/ should be sentenced to 10 years Cobol programming. It's probably a good thing that it is not I who decides the default flags for gcc !