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([2a0a:ef40:627:1f01:31b4:1316:18dc:6259]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4801ea19f94sm45483255e9.3.2026.01.17.09.40.08 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 17 Jan 2026 09:40:08 -0800 (PST) Message-ID: <6ae80903-3cc5-4017-9eac-0b3100b93b04@gmail.com> Date: Sat, 17 Jan 2026 17:40:08 +0000 Precedence: bulk X-Mailing-List: git@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 01/10] ivec: introduce the C side of ivec To: Ezekiel Newren , phillip.wood@dunelm.org.uk Cc: Ezekiel Newren via GitGitGadget , git@vger.kernel.org, Jeff King , =?UTF-8?Q?Ren=C3=A9_Scharfe?= References: <0437b899-5a36-4499-a30a-c2a074a80f7e@gmail.com> Content-Language: en-US From: Phillip Wood In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 17/01/2026 16:14, Ezekiel Newren wrote: > > If the size of different kinds of pointers ever differed from the size > of void* then wouldn't that make all calls to malloc undefined? I believe there are (Havard architecture?) platforms where function pointers are a different width to data pointers, and that's why you cannot store a function pointer in void*. I agree it would be weird for char* to have a different width to int*, I suspect the restrictions on casting from one type to another are about alignment. > I > don't see this as a problem since I'm not casting between structs with > different members that are not pointers. But isn't that is still undefined behavior as far as the C standard is concerned? It might make sense for it to work, but common sense has little to do with undefined behavior. > I could use void* for > everything, but then we'd need an accessor like *(T*)ivec_at(&vec, i), > but this is much more painful and error prone than simply vec.ptr[i]. Yeah that's horrible Thanks Phillip