[{"id":33613,"web_url":"https://patchwork.libcamera.org/comment/33613/","msgid":"","date":"2025-03-17T18:33:58","subject":"Re: [PATCH v1] libcamera: base: span: Explicitly default copy\n\tassignment","submitter":{"id":143,"url":"https://patchwork.libcamera.org/api/people/143/","name":"Jacopo Mondi","email":"jacopo.mondi@ideasonboard.com"},"content":"Hi Barnabás\n\nOn Mon, Mar 10, 2025 at 06:03:56PM +0100, Barnabás Pőcze wrote:\n> The `dynamic_extent` specialization is currently not trivially copyable\n> unlike its standard counterpart, `std::span`. This is because the copy\n> assignment operator is user-defined. Explicitly default it just like\n> it is done in the main template definition.\n>\n> Signed-off-by: Barnabás Pőcze \n\nReviewed-by: Jacopo Mondi \n\nThanks\n j\n\n> ---\n> include/libcamera/base/span.h | 8 +-------\n> 1 file changed, 1 insertion(+), 7 deletions(-)\n>\n> diff --git a/include/libcamera/base/span.h b/include/libcamera/base/span.h\n> index 92cce4f05..806db106e 100644\n> --- a/include/libcamera/base/span.h\n> +++ b/include/libcamera/base/span.h\n> @@ -346,13 +346,7 @@ public:\n> \t}\n>\n> \tconstexpr Span(const Span &other) noexcept = default;\n> -\n> -\tconstexpr Span &operator=(const Span &other) noexcept\n> -\t{\n> -\t\tdata_ = other.data_;\n> -\t\tsize_ = other.size_;\n> -\t\treturn *this;\n> -\t}\n> +\tconstexpr Span &operator=(const Span &other) noexcept = default;\n>\n> \tconstexpr iterator begin() const { return data(); }\n> \tconstexpr const_iterator cbegin() const { return begin(); }\n> --\n> 2.48.1\n>","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 9E249C32FA\n\tfor ;\n\tMon, 17 Mar 2025 18:34:03 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 4AC4D6894C;\n\tMon, 17 Mar 2025 19:34:03 +0100 (CET)","from perceval.ideasonboard.com (perceval.ideasonboard.com\n\t[IPv6:2001:4b98:dc2:55:216:3eff:fef7:d647])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id 33FEF617F8\n\tfor ;\n\tMon, 17 Mar 2025 19:34:02 +0100 (CET)","from ideasonboard.com (93-61-96-190.ip145.fastwebnet.it\n\t[93.61.96.190])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id 9A9D1352;\n\tMon, 17 Mar 2025 19:32:20 +0100 (CET)"],"Authentication-Results":"lancelot.ideasonboard.com; dkim=pass (1024-bit key;\n\tunprotected) header.d=ideasonboard.com header.i=@ideasonboard.com\n\theader.b=\"tDYvPeId\"; dkim-atps=neutral","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1742236340;\n\tbh=BJY6XYEGUPI5KX6qGQV9uu/ypEQUoNWYdGeT+OVXLNY=;\n\th=Date:From:To:Cc:Subject:References:In-Reply-To:From;\n\tb=tDYvPeIdeBjyR4yWoFPytShqevLFrQS2lqayGFrXUeUkiVP9ieQpOy2DMuKcjWMwi\n\tE+Cq88pJDLCfsbKNDSkVlO/tK9LabFilDUjGFoe4fXdL8KLVbeS1+TKtvdEP8cZtGy\n\tUAqa4CqEgFVaHIKeXI43dU3sjALSZeW0rBRQC7Mg=","Date":"Mon, 17 Mar 2025 19:33:58 +0100","From":"Jacopo Mondi ","To":"=?utf-8?q?Barnab=C3=A1s_P=C5=91cze?= ","Cc":"libcamera-devel@lists.libcamera.org","Subject":"Re: [PATCH v1] libcamera: base: span: Explicitly default copy\n\tassignment","Message-ID":"","References":"<20250310170356.185368-1-barnabas.pocze@ideasonboard.com>","MIME-Version":"1.0","Content-Type":"text/plain; charset=utf-8","Content-Disposition":"inline","Content-Transfer-Encoding":"8bit","In-Reply-To":"<20250310170356.185368-1-barnabas.pocze@ideasonboard.com>","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","Errors-To":"libcamera-devel-bounces@lists.libcamera.org","Sender":"\"libcamera-devel\" "}},{"id":33623,"web_url":"https://patchwork.libcamera.org/comment/33623/","msgid":"<174224841744.110831.14357890026377994583@ping.linuxembedded.co.uk>","date":"2025-03-17T21:53:37","subject":"Re: [PATCH v1] libcamera: base: span: Explicitly default copy\n\tassignment","submitter":{"id":4,"url":"https://patchwork.libcamera.org/api/people/4/","name":"Kieran Bingham","email":"kieran.bingham@ideasonboard.com"},"content":"Quoting Barnabás Pőcze (2025-03-10 17:03:56)\n> The `dynamic_extent` specialization is currently not trivially copyable\n> unlike its standard counterpart, `std::span`. This is because the copy\n> assignment operator is user-defined. Explicitly default it just like\n> it is done in the main template definition.\n> \n> Signed-off-by: Barnabás Pőcze \n> ---\n> include/libcamera/base/span.h | 8 +-------\n> 1 file changed, 1 insertion(+), 7 deletions(-)\n> \n> diff --git a/include/libcamera/base/span.h b/include/libcamera/base/span.h\n> index 92cce4f05..806db106e 100644\n> --- a/include/libcamera/base/span.h\n> +++ b/include/libcamera/base/span.h\n> @@ -346,13 +346,7 @@ public:\n> }\n> \n> constexpr Span(const Span &other) noexcept = default;\n> -\n> - constexpr Span &operator=(const Span &other) noexcept\n> - {\n> - data_ = other.data_;\n> - size_ = other.size_;\n> - return *this;\n> - }\n> + constexpr Span &operator=(const Span &other) noexcept = default;\n\nThis sounds sane, as the default copy should do identically as above I\nthink.\n\nBut wasn't there some rule of 5+-2 that says you're supposed to define\nall if you define one ?\n\nIs there any ABI breakage in this patch ? Or will it compile to\nsomething directly compatible ?\n\nFor the change itself:\n\nReviewed-by: Kieran Bingham \n\nBut if it's an ABI change I'd like to batch up all the ABI changes\ntogether.\n\n--\nKieran\n\n\n> \n> constexpr iterator begin() const { return data(); }\n> constexpr const_iterator cbegin() const { return begin(); }\n> -- \n> 2.48.1\n>","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 8197DC32FA\n\tfor ;\n\tMon, 17 Mar 2025 21:53:42 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id D1F0268947;\n\tMon, 17 Mar 2025 22:53:41 +0100 (CET)","from perceval.ideasonboard.com (perceval.ideasonboard.com\n\t[213.167.242.64])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id 2E67168826\n\tfor ;\n\tMon, 17 Mar 2025 22:53:40 +0100 (CET)","from pendragon.ideasonboard.com\n\t(cpc89244-aztw30-2-0-cust6594.18-1.cable.virginm.net [86.31.185.195])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id 4A0B7352;\n\tMon, 17 Mar 2025 22:51:58 +0100 (CET)"],"Authentication-Results":"lancelot.ideasonboard.com; dkim=pass (1024-bit key;\n\tunprotected) header.d=ideasonboard.com header.i=@ideasonboard.com\n\theader.b=\"Pr4ikjlo\"; dkim-atps=neutral","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1742248318;\n\tbh=5mYYswUMcpDG7ZYQmPx4bFmC6BVYZxbBuKdpn3QeoA4=;\n\th=In-Reply-To:References:Subject:From:To:Date:From;\n\tb=Pr4ikjloAQaCs0n10Sje9tnYEfYeuBU4K+0yUASAXA1G83Yhh+f4sXGJT1ut8EjXS\n\tytoAiVvzDH0bHQK74EC8ROoikh22nn7b3qJ4j6c2sI5IbzpuMBAsQOaAOOdvVln8mF\n\t1UJFtDvIU7eb5JyFYr5UeYpw8Vkcdr3VlHYDXVgM=","Content-Type":"text/plain; charset=\"utf-8\"","MIME-Version":"1.0","Content-Transfer-Encoding":"quoted-printable","In-Reply-To":"<20250310170356.185368-1-barnabas.pocze@ideasonboard.com>","References":"<20250310170356.185368-1-barnabas.pocze@ideasonboard.com>","Subject":"Re: [PATCH v1] libcamera: base: span: Explicitly default copy\n\tassignment","From":"Kieran Bingham ","To":"=?utf-8?q?Barnab=C3=A1s_P=C5=91cze?= ,\n\tlibcamera-devel@lists.libcamera.org","Date":"Mon, 17 Mar 2025 21:53:37 +0000","Message-ID":"<174224841744.110831.14357890026377994583@ping.linuxembedded.co.uk>","User-Agent":"alot/0.10","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","Errors-To":"libcamera-devel-bounces@lists.libcamera.org","Sender":"\"libcamera-devel\" "}},{"id":33656,"web_url":"https://patchwork.libcamera.org/comment/33656/","msgid":"","date":"2025-03-19T16:45:04","subject":"Re: [PATCH v1] libcamera: base: span: Explicitly default copy\n\tassignment","submitter":{"id":216,"url":"https://patchwork.libcamera.org/api/people/216/","name":"Barnabás Pőcze","email":"barnabas.pocze@ideasonboard.com"},"content":"Hi\n\n\n2025. 03. 17. 22:53 keltezéssel, Kieran Bingham írta:\n> Quoting Barnabás Pőcze (2025-03-10 17:03:56)\n>> The `dynamic_extent` specialization is currently not trivially copyable\n>> unlike its standard counterpart, `std::span`. This is because the copy\n>> assignment operator is user-defined. Explicitly default it just like\n>> it is done in the main template definition.\n>>\n>> Signed-off-by: Barnabás Pőcze \n>> ---\n>> include/libcamera/base/span.h | 8 +-------\n>> 1 file changed, 1 insertion(+), 7 deletions(-)\n>>\n>> diff --git a/include/libcamera/base/span.h b/include/libcamera/base/span.h\n>> index 92cce4f05..806db106e 100644\n>> --- a/include/libcamera/base/span.h\n>> +++ b/include/libcamera/base/span.h\n>> @@ -346,13 +346,7 @@ public:\n>> }\n>> \n>> constexpr Span(const Span &other) noexcept = default;\n>> -\n>> - constexpr Span &operator=(const Span &other) noexcept\n>> - {\n>> - data_ = other.data_;\n>> - size_ = other.size_;\n>> - return *this;\n>> - }\n>> + constexpr Span &operator=(const Span &other) noexcept = default;\n> \n> This sounds sane, as the default copy should do identically as above I\n> think.\n> \n> But wasn't there some rule of 5+-2 that says you're supposed to define\n> all if you define one ?\n\nRule of 0/3/5: https://en.cppreference.com/w/cpp/language/rule_of_three\n\nI think another option would be removing all special member functions and letting\nthe compiler implicitly define them (rule of 0). I guess I went with this change\nbecause it was the simplest/shortest considering the current code.\n\n\n> \n> Is there any ABI breakage in this patch ? Or will it compile to\n> something directly compatible ?\n\nI'm pretty sure even if it is theoretically an ABI break, it will\nnot be one in practice.\n\n\nRegards,\nBarnabás Pőcze\n\n> \n> For the change itself:\n> \n> Reviewed-by: Kieran Bingham \n> \n> But if it's an ABI change I'd like to batch up all the ABI changes\n> together.\n> \n> --\n> Kieran\n> \n> \n>> \n>> constexpr iterator begin() const { return data(); }\n>> constexpr const_iterator cbegin() const { return begin(); }\n>> -- \n>> 2.48.1\n>>","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 22162C32FE\n\tfor ;\n\tWed, 19 Mar 2025 16:45:30 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 0D9AC68951;\n\tWed, 19 Mar 2025 17:45:29 +0100 (CET)","from perceval.ideasonboard.com (perceval.ideasonboard.com\n\t[IPv6:2001:4b98:dc2:55:216:3eff:fef7:d647])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id 54AD9687FA\n\tfor ;\n\tWed, 19 Mar 2025 17:45:28 +0100 (CET)","from [192.168.33.18] (185.221.143.221.nat.pool.zt.hu\n\t[185.221.143.221])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id B6ADE55A;\n\tWed, 19 Mar 2025 17:43:30 +0100 (CET)"],"Authentication-Results":"lancelot.ideasonboard.com; dkim=pass (1024-bit key;\n\tunprotected) header.d=ideasonboard.com header.i=@ideasonboard.com\n\theader.b=\"lF2dz1jv\"; dkim-atps=neutral","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1742402625;\n\tbh=/izDz66OEDVXPfWyTd3bjhwOQsohPU4f+BizIXmCy2A=;\n\th=Date:Subject:To:References:From:In-Reply-To:From;\n\tb=lF2dz1jvHA/k5Uwnu5pd2kqt8Y6wZhgygkW1czbrhOnPPhEE/5qsj5oCdmql3Kya1\n\t9IltLeyF8xrynMEsgjSktMUEdzuPV2309CzYKdewefMxyuKpWkmxkFuBaXvGP09g52\n\to2lWgf0JiT3I1OI3UOIedoXS1IyQMuTQ6Seh2zQ4=","Message-ID":"","Date":"Wed, 19 Mar 2025 17:45:04 +0100","MIME-Version":"1.0","User-Agent":"Mozilla Thunderbird","Subject":"Re: [PATCH v1] libcamera: base: span: Explicitly default copy\n\tassignment","To":"Kieran Bingham ,\n\tlibcamera-devel@lists.libcamera.org","References":"<20250310170356.185368-1-barnabas.pocze@ideasonboard.com>\n\t<174224841744.110831.14357890026377994583@ping.linuxembedded.co.uk>","From":"=?utf-8?q?Barnab=C3=A1s_P=C5=91cze?= ","Content-Language":"en-US, hu-HU","In-Reply-To":"<174224841744.110831.14357890026377994583@ping.linuxembedded.co.uk>","Content-Type":"text/plain; charset=UTF-8; format=flowed","Content-Transfer-Encoding":"8bit","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","Errors-To":"libcamera-devel-bounces@lists.libcamera.org","Sender":"\"libcamera-devel\" "}}]