[{"id":36789,"web_url":"https://patchwork.libcamera.org/comment/36789/","msgid":"<176303540741.567526.12694728534244247378@ping.linuxembedded.co.uk>","date":"2025-11-13T12:03:27","subject":"Re: [RFC PATCH v1 1/1] treewide: Update to the C++20 standard","submitter":{"id":4,"url":"https://patchwork.libcamera.org/api/people/4/","name":"Kieran Bingham","email":"kieran.bingham@ideasonboard.com"},"content":"Hi Naush,\n\nQuoting Naushir Patuck (2025-11-13 11:05:31)\n> Switch to using the C++20 standard when compiling libcamera. This causes\n> a build error due to the deprecation of the following specialisation [1]\n> \n> std::shared_ptr atomic_load(const std::shared_ptr* p)\n> \n> ../src/libcamera/base/log.cpp: In member function 'void libcamera::Logger::write(const libcamera::LogMessage&)':\n> ../src/libcamera/base/log.cpp:468:61: error: 'std::shared_ptr<_Tp> std::atomic_load(const shared_ptr<_Tp>*) [with _Tp = libcamera::LogOutput]' is deprecated: use 'std::atomic>' instead [-Werror=deprecated-declarations]\n> 468 | std::shared_ptr output = std::atomic_load(&output_);\n> | ~~~~~~~~~~~~~~~~^~~~~~~~~~\n> \n> This error is fixed by switching to the std::atomic>\n> specialisation instead. Unfortunately, this is not backward compatible\n> with C++17, so the fix must be included in this commit.\n\nThank you for this,\n\nI think I'm in favour of updating here when we can.\n\nWe'll have to do a bit of a check to see if this impacts any projects\nusing libcamera but I think it's workable.\n\nFirst part though will be CI:\n\n https://gitlab.freedesktop.org/camera/libcamera/-/pipelines/1546400\n\nQuite a few breakages to tackle and that may be the hard part.\n\nWith a large matrix of compilers and differing support that might be the\ntricky part. We'll have to identify if this will restict us to any\nspecific compiler version minimum.\n\n--\nKieran\n\n\n> \n> [1]: https://en.cppreference.com/w/cpp/memory/shared_ptr/atomic.html\n> Signed-off-by: Naushir Patuck \n> ---\n> meson.build | 2 +-\n> src/libcamera/base/log.cpp | 6 +++---\n> 2 files changed, 4 insertions(+), 4 deletions(-)\n> \n> diff --git a/meson.build b/meson.build\n> index fd508fd7f6b5..74153e1e6ce9 100644\n> --- a/meson.build\n> +++ b/meson.build\n> @@ -6,7 +6,7 @@ project('libcamera', 'c', 'cpp',\n> default_options : [\n> 'werror=true',\n> 'warning_level=2',\n> - 'cpp_std=c++17',\n> + 'cpp_std=c++20',\n> ],\n> license : 'LGPL 2.1+')\n> \n> diff --git a/src/libcamera/base/log.cpp b/src/libcamera/base/log.cpp\n> index 81b550e21402..e65d83739315 100644\n> --- a/src/libcamera/base/log.cpp\n> +++ b/src/libcamera/base/log.cpp\n> @@ -325,7 +325,7 @@ private:\n> std::vector> categories_ LIBCAMERA_TSA_GUARDED_BY(mutex_);\n> std::list> levels_;\n> \n> - std::shared_ptr output_;\n> + std::atomic> output_;\n> };\n> \n> bool Logger::destroyed_ = false;\n> @@ -465,7 +465,7 @@ Logger *Logger::instance()\n> */\n> void Logger::write(const LogMessage &msg)\n> {\n> - std::shared_ptr output = std::atomic_load(&output_);\n> + std::shared_ptr output = output_.load();\n> if (!output)\n> return;\n> \n> @@ -477,7 +477,7 @@ void Logger::write(const LogMessage &msg)\n> */\n> void Logger::backtrace()\n> {\n> - std::shared_ptr output = std::atomic_load(&output_);\n> + std::shared_ptr output = output_.load();\n> if (!output)\n> return;\n> \n> -- \n> 2.51.0\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 49764C3263\n\tfor ;\n\tThu, 13 Nov 2025 12:03:33 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 74517609D8;\n\tThu, 13 Nov 2025 13:03:32 +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 0C8B160805\n\tfor ;\n\tThu, 13 Nov 2025 13:03:31 +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 9E85F446;\n\tThu, 13 Nov 2025 13:01:30 +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=\"cbLujg9c\"; dkim-atps=neutral","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1763035290;\n\tbh=izK8NWYr8zcoRkmyZI4al75lRUsaoRdFbVVgu4LoRe4=;\n\th=In-Reply-To:References:Subject:From:Cc:To:Date:From;\n\tb=cbLujg9cn5ZD0kmweBL65CQmINognNdZyj/d6JxThEn8mz2P5Kr3+9IsVxQisXxqg\n\t1KUnGC8sd9wbwDrYqOkPuHKl7ctF72yiFrc/f/vguc0ERUizG5VjcO60+G73jP52dX\n\tU1LDj7WDW5B0UDFLF8XNDREgLvRLIqXKPg9kKqlg=","Content-Type":"text/plain; charset=\"utf-8\"","MIME-Version":"1.0","Content-Transfer-Encoding":"quoted-printable","In-Reply-To":"<20251113110958.1117065-2-naush@raspberrypi.com>","References":"<20251113110958.1117065-1-naush@raspberrypi.com>\n\t<20251113110958.1117065-2-naush@raspberrypi.com>","Subject":"Re: [RFC PATCH v1 1/1] treewide: Update to the C++20 standard","From":"Kieran Bingham ","Cc":"Naushir Patuck ","To":"Naushir Patuck ,\n\tlibcamera-devel@lists.libcamera.org","Date":"Thu, 13 Nov 2025 12:03:27 +0000","Message-ID":"<176303540741.567526.12694728534244247378@ping.linuxembedded.co.uk>","User-Agent":"alot/0.9.1","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":36790,"web_url":"https://patchwork.libcamera.org/comment/36790/","msgid":"","date":"2025-11-13T12:24:18","subject":"Re: [RFC PATCH v1 1/1] treewide: Update to the C++20 standard","submitter":{"id":216,"url":"https://patchwork.libcamera.org/api/people/216/","name":"Barnabás Pőcze","email":"barnabas.pocze@ideasonboard.com"},"content":"2025. 11. 13. 13:03 keltezéssel, Kieran Bingham írta:\n> Hi Naush,\n> \n> Quoting Naushir Patuck (2025-11-13 11:05:31)\n>> Switch to using the C++20 standard when compiling libcamera. This causes\n>> a build error due to the deprecation of the following specialisation [1]\n>>\n>> std::shared_ptr atomic_load(const std::shared_ptr* p)\n>>\n>> ../src/libcamera/base/log.cpp: In member function 'void libcamera::Logger::write(const libcamera::LogMessage&)':\n>> ../src/libcamera/base/log.cpp:468:61: error: 'std::shared_ptr<_Tp> std::atomic_load(const shared_ptr<_Tp>*) [with _Tp = libcamera::LogOutput]' is deprecated: use 'std::atomic>' instead [-Werror=deprecated-declarations]\n>> 468 | std::shared_ptr output = std::atomic_load(&output_);\n>> | ~~~~~~~~~~~~~~~~^~~~~~~~~~\n>>\n>> This error is fixed by switching to the std::atomic>\n>> specialisation instead. Unfortunately, this is not backward compatible\n>> with C++17, so the fix must be included in this commit.\n> \n> Thank you for this,\n> \n> I think I'm in favour of updating here when we can.\n> \n> We'll have to do a bit of a check to see if this impacts any projects\n> using libcamera but I think it's workable.\n> \n> First part though will be CI:\n> \n> https://gitlab.freedesktop.org/camera/libcamera/-/pipelines/1546400\n> \n> Quite a few breakages to tackle and that may be the hard part.\n\nI have been compiling libcamera as C++20 forever. Apart from the above\nchange, one needs to:\n\n (1) disable -Wvolatile because of g_once_init() in glib\n (2) disable -Wredundant-move in gcc 12 as well\n\n---\n\nAs far as I remember `std::atomic>` is not supported\nin some versions, so I ended up using\n\n #pragma GCC diagnostic ignored \"-Wdeprecated-declarations\"\n\n---\n\nAlso, libpisp did not compile without warnings in C++20 the last time I checked.\n\n---\n\nThere is also this peculiar issue: https://gitlab.freedesktop.org/camera/libcamera/-/issues/267\n\n---\n\nC++20 also triggers this error: https://gitlab.freedesktop.org/camera/libcamera/-/jobs/87812672#L364\n\n/usr/include/c++/12/bits/char_traits.h:431:56: error: ‘void* __builtin_memcpy(void*, const void*, long unsigned int)’ accessing 9223372036854775810 or more bytes at offsets [2, 9223372036854775807] and 1 may overlap up to 9223372036854775813 bytes at offset -3 [-Werror=restrict]\n 431 | return static_cast(__builtin_memcpy(__s1, __s2, __n));\n\n\nAfter some time I have given up on trying to fix this.\n\n---\n\nActually, to address (1), it should be sufficient to use `std::call_once()`, e.g.\n\ndiff --git a/src/gstreamer/gstlibcameraallocator.cpp b/src/gstreamer/gstlibcameraallocator.cpp\nindex d4492d994b..3de6fc42a7 100644\n--- a/src/gstreamer/gstlibcameraallocator.cpp\n+++ b/src/gstreamer/gstlibcameraallocator.cpp\n@@ -8,6 +8,7 @@\n \n #include \"gstlibcameraallocator.h\"\n \n+#include \n #include \n \n #include \n@@ -77,11 +78,11 @@ FrameWrap::~FrameWrap()\n GQuark FrameWrap::getQuark()\n {\n static gsize frame_quark = 0;\n+ static std::once_flag frame_quark_once;\n \n- if (g_once_init_enter(&frame_quark)) {\n- GQuark quark = g_quark_from_string(\"GstLibcameraFrameWrap\");\n- g_once_init_leave(&frame_quark, quark);\n- }\n+ std::call_once(frame_quark_once, [&] {\n+ frame_quark = g_quark_from_string(\"GstLibcameraFrameWrap\");\n+ });\n \n return frame_quark;\n }\n\n\nRegards,\nBarnabás Pőcze\n\n> \n> With a large matrix of compilers and differing support that might be the\n> tricky part. We'll have to identify if this will restict us to any\n> specific compiler version minimum.\n> \n> --\n> Kieran\n> \n> \n>>\n>> [1]: https://en.cppreference.com/w/cpp/memory/shared_ptr/atomic.html\n>> Signed-off-by: Naushir Patuck \n>> ---\n>> meson.build | 2 +-\n>> src/libcamera/base/log.cpp | 6 +++---\n>> 2 files changed, 4 insertions(+), 4 deletions(-)\n>>\n>> diff --git a/meson.build b/meson.build\n>> index fd508fd7f6b5..74153e1e6ce9 100644\n>> --- a/meson.build\n>> +++ b/meson.build\n>> @@ -6,7 +6,7 @@ project('libcamera', 'c', 'cpp',\n>> default_options : [\n>> 'werror=true',\n>> 'warning_level=2',\n>> - 'cpp_std=c++17',\n>> + 'cpp_std=c++20',\n>> ],\n>> license : 'LGPL 2.1+')\n>> \n>> diff --git a/src/libcamera/base/log.cpp b/src/libcamera/base/log.cpp\n>> index 81b550e21402..e65d83739315 100644\n>> --- a/src/libcamera/base/log.cpp\n>> +++ b/src/libcamera/base/log.cpp\n>> @@ -325,7 +325,7 @@ private:\n>> std::vector> categories_ LIBCAMERA_TSA_GUARDED_BY(mutex_);\n>> std::list> levels_;\n>> \n>> - std::shared_ptr output_;\n>> + std::atomic> output_;\n>> };\n>> \n>> bool Logger::destroyed_ = false;\n>> @@ -465,7 +465,7 @@ Logger *Logger::instance()\n>> */\n>> void Logger::write(const LogMessage &msg)\n>> {\n>> - std::shared_ptr output = std::atomic_load(&output_);\n>> + std::shared_ptr output = output_.load();\n>> if (!output)\n>> return;\n>> \n>> @@ -477,7 +477,7 @@ void Logger::write(const LogMessage &msg)\n>> */\n>> void Logger::backtrace()\n>> {\n>> - std::shared_ptr output = std::atomic_load(&output_);\n>> + std::shared_ptr output = output_.load();\n>> if (!output)\n>> return;\n>> \n>> -- \n>> 2.51.0\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 AF296C3241\n\tfor ;\n\tThu, 13 Nov 2025 12:24:24 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 8937D60A80;\n\tThu, 13 Nov 2025 13:24:23 +0100 (CET)","from perceval.ideasonboard.com (perceval.ideasonboard.com\n\t[213.167.242.64])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id 34EED60805\n\tfor ;\n\tThu, 13 Nov 2025 13:24:22 +0100 (CET)","from [192.168.33.32] (185.221.140.239.nat.pool.zt.hu\n\t[185.221.140.239])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id CDB125B2;\n\tThu, 13 Nov 2025 13:22:21 +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=\"bNmL3VWg\"; dkim-atps=neutral","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1763036542;\n\tbh=OrouLtPCYE6SviGfa+GYcvHlp5uI/JPA4TqinhbVy3o=;\n\th=Date:Subject:To:References:From:In-Reply-To:From;\n\tb=bNmL3VWgDSYEV3bZyJso4G+IYMKN0kcOkMAquDCtAVwiwhDZbkfQ1FrEzW11ednZp\n\taZgmn+GAxGGkwDg0LfBNB6t09wp2x9oi3NSFlfnszvUO3p5v4c1P7Ytu3uG/voxiMn\n\tBtLQbmVjMoLSUZ5L3aV1MTdNU2zmerJZ+78ieGeQ=","Message-ID":"","Date":"Thu, 13 Nov 2025 13:24:18 +0100","MIME-Version":"1.0","User-Agent":"Mozilla Thunderbird","Subject":"Re: [RFC PATCH v1 1/1] treewide: Update to the C++20 standard","To":"Kieran Bingham ,\n\tNaushir Patuck ,\n\tlibcamera-devel@lists.libcamera.org","References":"<20251113110958.1117065-1-naush@raspberrypi.com>\n\t<20251113110958.1117065-2-naush@raspberrypi.com>\n\t<176303540741.567526.12694728534244247378@ping.linuxembedded.co.uk>","From":"=?utf-8?q?Barnab=C3=A1s_P=C5=91cze?= ","Content-Language":"en-US, hu-HU","In-Reply-To":"<176303540741.567526.12694728534244247378@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\" "}},{"id":36792,"web_url":"https://patchwork.libcamera.org/comment/36792/","msgid":"<20251113124940.GB30434@pendragon.ideasonboard.com>","date":"2025-11-13T12:49:40","subject":"Re: [RFC PATCH v1 1/1] treewide: Update to the C++20 standard","submitter":{"id":2,"url":"https://patchwork.libcamera.org/api/people/2/","name":"Laurent Pinchart","email":"laurent.pinchart@ideasonboard.com"},"content":"On Thu, Nov 13, 2025 at 01:24:18PM +0100, Barnabás Pőcze wrote:\n> 2025. 11. 13. 13:03 keltezéssel, Kieran Bingham írta:\n> > Quoting Naushir Patuck (2025-11-13 11:05:31)\n> >> Switch to using the C++20 standard when compiling libcamera. This causes\n> >> a build error due to the deprecation of the following specialisation [1]\n> >>\n> >> std::shared_ptr atomic_load(const std::shared_ptr* p)\n> >>\n> >> ../src/libcamera/base/log.cpp: In member function 'void libcamera::Logger::write(const libcamera::LogMessage&)':\n> >> ../src/libcamera/base/log.cpp:468:61: error: 'std::shared_ptr<_Tp> std::atomic_load(const shared_ptr<_Tp>*) [with _Tp = libcamera::LogOutput]' is deprecated: use 'std::atomic>' instead [-Werror=deprecated-declarations]\n> >> 468 | std::shared_ptr output = std::atomic_load(&output_);\n> >> | ~~~~~~~~~~~~~~~~^~~~~~~~~~\n> >>\n> >> This error is fixed by switching to the std::atomic>\n> >> specialisation instead. Unfortunately, this is not backward compatible\n> >> with C++17, so the fix must be included in this commit.\n> > \n> > Thank you for this,\n> > \n> > I think I'm in favour of updating here when we can.\n> > \n> > We'll have to do a bit of a check to see if this impacts any projects\n> > using libcamera but I think it's workable.\n> > \n> > First part though will be CI:\n> > \n> > https://gitlab.freedesktop.org/camera/libcamera/-/pipelines/1546400\n> > \n> > Quite a few breakages to tackle and that may be the hard part.\n> \n> I have been compiling libcamera as C++20 forever. Apart from the above\n> change, one needs to:\n> \n> (1) disable -Wvolatile because of g_once_init() in glib\n> (2) disable -Wredundant-move in gcc 12 as well\n> \n> ---\n> \n> As far as I remember `std::atomic>` is not supported\n> in some versions, so I ended up using\n> \n> #pragma GCC diagnostic ignored \"-Wdeprecated-declarations\"\n> \n> ---\n> \n> Also, libpisp did not compile without warnings in C++20 the last time I checked.\n> \n> ---\n> \n> There is also this peculiar issue: https://gitlab.freedesktop.org/camera/libcamera/-/issues/267\n> \n> ---\n> \n> C++20 also triggers this error: https://gitlab.freedesktop.org/camera/libcamera/-/jobs/87812672#L364\n> \n> /usr/include/c++/12/bits/char_traits.h:431:56: error: ‘void* __builtin_memcpy(void*, const void*, long unsigned int)’ accessing 9223372036854775810 or more bytes at offsets [2, 9223372036854775807] and 1 may overlap up to 9223372036854775813 bytes at offset -3 [-Werror=restrict]\n> 431 | return static_cast(__builtin_memcpy(__s1, __s2, __n));\n> \n> \n> After some time I have given up on trying to fix this.\n> \n> ---\n> \n> Actually, to address (1), it should be sufficient to use `std::call_once()`, e.g.\n> \n> diff --git a/src/gstreamer/gstlibcameraallocator.cpp b/src/gstreamer/gstlibcameraallocator.cpp\n> index d4492d994b..3de6fc42a7 100644\n> --- a/src/gstreamer/gstlibcameraallocator.cpp\n> +++ b/src/gstreamer/gstlibcameraallocator.cpp\n> @@ -8,6 +8,7 @@\n> \n> #include \"gstlibcameraallocator.h\"\n> \n> +#include \n> #include \n> \n> #include \n> @@ -77,11 +78,11 @@ FrameWrap::~FrameWrap()\n> GQuark FrameWrap::getQuark()\n> {\n> static gsize frame_quark = 0;\n> + static std::once_flag frame_quark_once;\n> \n> - if (g_once_init_enter(&frame_quark)) {\n> - GQuark quark = g_quark_from_string(\"GstLibcameraFrameWrap\");\n> - g_once_init_leave(&frame_quark, quark);\n> - }\n> + std::call_once(frame_quark_once, [&] {\n> + frame_quark = g_quark_from_string(\"GstLibcameraFrameWrap\");\n> + });\n> \n> return frame_quark;\n> }\n\nHow about\n\nGQuark FrameWrap::getQuark()\n{\n\tstatic gsize frame_quark = g_quark_from_string(\"GstLibcameraFrameWrap\");\n\treturn frame_quark;\n}\n\nAccording to\nhttps://en.cppreference.com/w/cpp/language/storage_duration.html#Static_block_variables,\n\n If multiple threads attempt to initialize the same static local\n variable concurrently, the initialization occurs exactly once (similar\n behavior can be obtained for arbitrary functions with std::call_once).\n\n> > With a large matrix of compilers and differing support that might be the\n> > tricky part. We'll have to identify if this will restict us to any\n> > specific compiler version minimum.\n> > \n> >> [1]: https://en.cppreference.com/w/cpp/memory/shared_ptr/atomic.html\n> >> Signed-off-by: Naushir Patuck \n> >> ---\n> >> meson.build | 2 +-\n> >> src/libcamera/base/log.cpp | 6 +++---\n> >> 2 files changed, 4 insertions(+), 4 deletions(-)\n> >>\n> >> diff --git a/meson.build b/meson.build\n> >> index fd508fd7f6b5..74153e1e6ce9 100644\n> >> --- a/meson.build\n> >> +++ b/meson.build\n> >> @@ -6,7 +6,7 @@ project('libcamera', 'c', 'cpp',\n> >> default_options : [\n> >> 'werror=true',\n> >> 'warning_level=2',\n> >> - 'cpp_std=c++17',\n> >> + 'cpp_std=c++20',\n> >> ],\n> >> license : 'LGPL 2.1+')\n> >> \n> >> diff --git a/src/libcamera/base/log.cpp b/src/libcamera/base/log.cpp\n> >> index 81b550e21402..e65d83739315 100644\n> >> --- a/src/libcamera/base/log.cpp\n> >> +++ b/src/libcamera/base/log.cpp\n> >> @@ -325,7 +325,7 @@ private:\n> >> std::vector> categories_ LIBCAMERA_TSA_GUARDED_BY(mutex_);\n> >> std::list> levels_;\n> >> \n> >> - std::shared_ptr output_;\n> >> + std::atomic> output_;\n> >> };\n> >> \n> >> bool Logger::destroyed_ = false;\n> >> @@ -465,7 +465,7 @@ Logger *Logger::instance()\n> >> */\n> >> void Logger::write(const LogMessage &msg)\n> >> {\n> >> - std::shared_ptr output = std::atomic_load(&output_);\n> >> + std::shared_ptr output = output_.load();\n> >> if (!output)\n> >> return;\n> >> \n> >> @@ -477,7 +477,7 @@ void Logger::write(const LogMessage &msg)\n> >> */\n> >> void Logger::backtrace()\n> >> {\n> >> - std::shared_ptr output = std::atomic_load(&output_);\n> >> + std::shared_ptr output = output_.load();\n> >> if (!output)\n> >> return;\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 3E677C3263\n\tfor ;\n\tThu, 13 Nov 2025 12:49:55 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 5FFAF609D8;\n\tThu, 13 Nov 2025 13:49:54 +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 DB33060805\n\tfor ;\n\tThu, 13 Nov 2025 13:49:52 +0100 (CET)","from pendragon.ideasonboard.com (unknown [213.216.211.176])\n\tby perceval.ideasonboard.com (Postfix) with UTF8SMTPSA id 84DE15B2;\n\tThu, 13 Nov 2025 13:47:52 +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=\"Z2G5WcW6\"; dkim-atps=neutral","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1763038072;\n\tbh=mNFlFxwUW87C8S5N9nHT/WyHSlHS54V9L2HFZPi4UJM=;\n\th=Date:From:To:Cc:Subject:References:In-Reply-To:From;\n\tb=Z2G5WcW6krrKIQdFJGdN8FzzavGyfdv0Z16hzjKYKMHjiOjJoA4qViSs5en0IRwca\n\tnNAURmKPK/SRXEoo7+2AcClxFgVOhMKlYdaVUhkstSnagLwTwIFVCLrDgqh5QQNlQy\n\tOSMZO8i99dygTgqcRSuXjQ/Tw3+d7i1GwVpoLkKY=","Date":"Thu, 13 Nov 2025 14:49:40 +0200","From":"Laurent Pinchart ","To":"=?utf-8?q?Barnab=C3=A1s_P=C5=91cze?= ","Cc":"Kieran Bingham ,\n\tNaushir Patuck ,\n\tlibcamera-devel@lists.libcamera.org","Subject":"Re: [RFC PATCH v1 1/1] treewide: Update to the C++20 standard","Message-ID":"<20251113124940.GB30434@pendragon.ideasonboard.com>","References":"<20251113110958.1117065-1-naush@raspberrypi.com>\n\t<20251113110958.1117065-2-naush@raspberrypi.com>\n\t<176303540741.567526.12694728534244247378@ping.linuxembedded.co.uk>\n\t","MIME-Version":"1.0","Content-Type":"text/plain; charset=utf-8","Content-Disposition":"inline","Content-Transfer-Encoding":"8bit","In-Reply-To":"","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":36793,"web_url":"https://patchwork.libcamera.org/comment/36793/","msgid":"<00cbe340-364d-4d85-a4c4-d1a0fa1175cc@ideasonboard.com>","date":"2025-11-13T12:54:54","subject":"Re: [RFC PATCH v1 1/1] treewide: Update to the C++20 standard","submitter":{"id":216,"url":"https://patchwork.libcamera.org/api/people/216/","name":"Barnabás Pőcze","email":"barnabas.pocze@ideasonboard.com"},"content":"2025. 11. 13. 13:49 keltezéssel, Laurent Pinchart írta:\n> On Thu, Nov 13, 2025 at 01:24:18PM +0100, Barnabás Pőcze wrote:\n>> 2025. 11. 13. 13:03 keltezéssel, Kieran Bingham írta:\n>>> Quoting Naushir Patuck (2025-11-13 11:05:31)\n>>>> Switch to using the C++20 standard when compiling libcamera. This causes\n>>>> a build error due to the deprecation of the following specialisation [1]\n>>>>\n>>>> std::shared_ptr atomic_load(const std::shared_ptr* p)\n>>>>\n>>>> ../src/libcamera/base/log.cpp: In member function 'void libcamera::Logger::write(const libcamera::LogMessage&)':\n>>>> ../src/libcamera/base/log.cpp:468:61: error: 'std::shared_ptr<_Tp> std::atomic_load(const shared_ptr<_Tp>*) [with _Tp = libcamera::LogOutput]' is deprecated: use 'std::atomic>' instead [-Werror=deprecated-declarations]\n>>>> 468 | std::shared_ptr output = std::atomic_load(&output_);\n>>>> | ~~~~~~~~~~~~~~~~^~~~~~~~~~\n>>>>\n>>>> This error is fixed by switching to the std::atomic>\n>>>> specialisation instead. Unfortunately, this is not backward compatible\n>>>> with C++17, so the fix must be included in this commit.\n>>>\n>>> Thank you for this,\n>>>\n>>> I think I'm in favour of updating here when we can.\n>>>\n>>> We'll have to do a bit of a check to see if this impacts any projects\n>>> using libcamera but I think it's workable.\n>>>\n>>> First part though will be CI:\n>>>\n>>> https://gitlab.freedesktop.org/camera/libcamera/-/pipelines/1546400\n>>>\n>>> Quite a few breakages to tackle and that may be the hard part.\n>>\n>> I have been compiling libcamera as C++20 forever. Apart from the above\n>> change, one needs to:\n>>\n>> (1) disable -Wvolatile because of g_once_init() in glib\n>> (2) disable -Wredundant-move in gcc 12 as well\n>>\n>> ---\n>>\n>> As far as I remember `std::atomic>` is not supported\n>> in some versions, so I ended up using\n>>\n>> #pragma GCC diagnostic ignored \"-Wdeprecated-declarations\"\n>>\n>> ---\n>>\n>> Also, libpisp did not compile without warnings in C++20 the last time I checked.\n>>\n>> ---\n>>\n>> There is also this peculiar issue: https://gitlab.freedesktop.org/camera/libcamera/-/issues/267\n>>\n>> ---\n>>\n>> C++20 also triggers this error: https://gitlab.freedesktop.org/camera/libcamera/-/jobs/87812672#L364\n>>\n>> /usr/include/c++/12/bits/char_traits.h:431:56: error: ‘void* __builtin_memcpy(void*, const void*, long unsigned int)’ accessing 9223372036854775810 or more bytes at offsets [2, 9223372036854775807] and 1 may overlap up to 9223372036854775813 bytes at offset -3 [-Werror=restrict]\n>> 431 | return static_cast(__builtin_memcpy(__s1, __s2, __n));\n>>\n>>\n>> After some time I have given up on trying to fix this.\n>>\n>> ---\n>>\n>> Actually, to address (1), it should be sufficient to use `std::call_once()`, e.g.\n>>\n>> diff --git a/src/gstreamer/gstlibcameraallocator.cpp b/src/gstreamer/gstlibcameraallocator.cpp\n>> index d4492d994b..3de6fc42a7 100644\n>> --- a/src/gstreamer/gstlibcameraallocator.cpp\n>> +++ b/src/gstreamer/gstlibcameraallocator.cpp\n>> @@ -8,6 +8,7 @@\n>> \n>> #include \"gstlibcameraallocator.h\"\n>> \n>> +#include \n>> #include \n>> \n>> #include \n>> @@ -77,11 +78,11 @@ FrameWrap::~FrameWrap()\n>> GQuark FrameWrap::getQuark()\n>> {\n>> static gsize frame_quark = 0;\n>> + static std::once_flag frame_quark_once;\n>> \n>> - if (g_once_init_enter(&frame_quark)) {\n>> - GQuark quark = g_quark_from_string(\"GstLibcameraFrameWrap\");\n>> - g_once_init_leave(&frame_quark, quark);\n>> - }\n>> + std::call_once(frame_quark_once, [&] {\n>> + frame_quark = g_quark_from_string(\"GstLibcameraFrameWrap\");\n>> + });\n>> \n>> return frame_quark;\n>> }\n> \n> How about\n> \n> GQuark FrameWrap::getQuark()\n> {\n> \tstatic gsize frame_quark = g_quark_from_string(\"GstLibcameraFrameWrap\");\n> \treturn frame_quark;\n> }\n\nAhh, yes, that should work, and is much better.\n\n\n> \n> According to\n> https://en.cppreference.com/w/cpp/language/storage_duration.html#Static_block_variables,\n> \n> If multiple threads attempt to initialize the same static local\n> variable concurrently, the initialization occurs exactly once (similar\n> behavior can be obtained for arbitrary functions with std::call_once).\n> \n>>> With a large matrix of compilers and differing support that might be the\n>>> tricky part. We'll have to identify if this will restict us to any\n>>> specific compiler version minimum.\n>>>\n>>>> [1]: https://en.cppreference.com/w/cpp/memory/shared_ptr/atomic.html\n>>>> Signed-off-by: Naushir Patuck \n>>>> ---\n>>>> meson.build | 2 +-\n>>>> src/libcamera/base/log.cpp | 6 +++---\n>>>> 2 files changed, 4 insertions(+), 4 deletions(-)\n>>>>\n>>>> diff --git a/meson.build b/meson.build\n>>>> index fd508fd7f6b5..74153e1e6ce9 100644\n>>>> --- a/meson.build\n>>>> +++ b/meson.build\n>>>> @@ -6,7 +6,7 @@ project('libcamera', 'c', 'cpp',\n>>>> default_options : [\n>>>> 'werror=true',\n>>>> 'warning_level=2',\n>>>> - 'cpp_std=c++17',\n>>>> + 'cpp_std=c++20',\n>>>> ],\n>>>> license : 'LGPL 2.1+')\n>>>> \n>>>> diff --git a/src/libcamera/base/log.cpp b/src/libcamera/base/log.cpp\n>>>> index 81b550e21402..e65d83739315 100644\n>>>> --- a/src/libcamera/base/log.cpp\n>>>> +++ b/src/libcamera/base/log.cpp\n>>>> @@ -325,7 +325,7 @@ private:\n>>>> std::vector> categories_ LIBCAMERA_TSA_GUARDED_BY(mutex_);\n>>>> std::list> levels_;\n>>>> \n>>>> - std::shared_ptr output_;\n>>>> + std::atomic> output_;\n>>>> };\n>>>> \n>>>> bool Logger::destroyed_ = false;\n>>>> @@ -465,7 +465,7 @@ Logger *Logger::instance()\n>>>> */\n>>>> void Logger::write(const LogMessage &msg)\n>>>> {\n>>>> - std::shared_ptr output = std::atomic_load(&output_);\n>>>> + std::shared_ptr output = output_.load();\n>>>> if (!output)\n>>>> return;\n>>>> \n>>>> @@ -477,7 +477,7 @@ void Logger::write(const LogMessage &msg)\n>>>> */\n>>>> void Logger::backtrace()\n>>>> {\n>>>> - std::shared_ptr output = std::atomic_load(&output_);\n>>>> + std::shared_ptr output = output_.load();\n>>>> if (!output)\n>>>> return;\n>>>> \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 2782FC3241\n\tfor ;\n\tThu, 13 Nov 2025 12:55:00 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 67E11609D8;\n\tThu, 13 Nov 2025 13:54:59 +0100 (CET)","from perceval.ideasonboard.com (perceval.ideasonboard.com\n\t[213.167.242.64])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id 8F9CD60805\n\tfor ;\n\tThu, 13 Nov 2025 13:54:57 +0100 (CET)","from [192.168.33.32] (185.221.140.239.nat.pool.zt.hu\n\t[185.221.140.239])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id 2BD705B2;\n\tThu, 13 Nov 2025 13:52:57 +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=\"WISpoTaO\"; dkim-atps=neutral","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1763038377;\n\tbh=WyufiuDEH5nYxTMFEuWVXGNp4/lk7QviPHis2JQVRsE=;\n\th=Date:Subject:To:Cc:References:From:In-Reply-To:From;\n\tb=WISpoTaOdsJq9QHVK3vv07jbnhyZ6Gf+q2KaLdzP4hOiLkzfDoJlDAkrmfhQdl6el\n\thYdgJKrK0+AHrhSMDqPYavrpF7D5BaeGfxAJVINwWiT7xxaBQ/mEVm4/+IqAn30cgR\n\t/66dMqBy1A8x/2LiCjDKBgbpxLbA+sgPCtB46JX8=","Message-ID":"<00cbe340-364d-4d85-a4c4-d1a0fa1175cc@ideasonboard.com>","Date":"Thu, 13 Nov 2025 13:54:54 +0100","MIME-Version":"1.0","User-Agent":"Mozilla Thunderbird","Subject":"Re: [RFC PATCH v1 1/1] treewide: Update to the C++20 standard","To":"Laurent Pinchart ","Cc":"Kieran Bingham ,\n\tNaushir Patuck ,\n\tlibcamera-devel@lists.libcamera.org","References":"<20251113110958.1117065-1-naush@raspberrypi.com>\n\t<20251113110958.1117065-2-naush@raspberrypi.com>\n\t<176303540741.567526.12694728534244247378@ping.linuxembedded.co.uk>\n\t\n\t<20251113124940.GB30434@pendragon.ideasonboard.com>","From":"=?utf-8?q?Barnab=C3=A1s_P=C5=91cze?= ","Content-Language":"en-US, hu-HU","In-Reply-To":"<20251113124940.GB30434@pendragon.ideasonboard.com>","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\" "}},{"id":36796,"web_url":"https://patchwork.libcamera.org/comment/36796/","msgid":"","date":"2025-11-13T13:40:10","subject":"Re: [RFC PATCH v1 1/1] treewide: Update to the C++20 standard","submitter":{"id":34,"url":"https://patchwork.libcamera.org/api/people/34/","name":"Naushir Patuck","email":"naush@raspberrypi.com"},"content":"Hi all,\n\nI should have mentioned that I was expecting many more compile errors\nto crop up with the CI compiler matrix :) I'll attempt at bashing\nthrough them to see what's involved with making this change. But good\nto see there's an appetite to get C++20 support merged!\n\nRegards,\nNaush\n\n\n\nOn Thu, 13 Nov 2025 at 12:54, Barnabás Pőcze\n wrote:\n>\n> 2025. 11. 13. 13:49 keltezéssel, Laurent Pinchart írta:\n> > On Thu, Nov 13, 2025 at 01:24:18PM +0100, Barnabás Pőcze wrote:\n> >> 2025. 11. 13. 13:03 keltezéssel, Kieran Bingham írta:\n> >>> Quoting Naushir Patuck (2025-11-13 11:05:31)\n> >>>> Switch to using the C++20 standard when compiling libcamera. This causes\n> >>>> a build error due to the deprecation of the following specialisation [1]\n> >>>>\n> >>>> std::shared_ptr atomic_load(const std::shared_ptr* p)\n> >>>>\n> >>>> ../src/libcamera/base/log.cpp: In member function 'void libcamera::Logger::write(const libcamera::LogMessage&)':\n> >>>> ../src/libcamera/base/log.cpp:468:61: error: 'std::shared_ptr<_Tp> std::atomic_load(const shared_ptr<_Tp>*) [with _Tp = libcamera::LogOutput]' is deprecated: use 'std::atomic>' instead [-Werror=deprecated-declarations]\n> >>>> 468 | std::shared_ptr output = std::atomic_load(&output_);\n> >>>> | ~~~~~~~~~~~~~~~~^~~~~~~~~~\n> >>>>\n> >>>> This error is fixed by switching to the std::atomic>\n> >>>> specialisation instead. Unfortunately, this is not backward compatible\n> >>>> with C++17, so the fix must be included in this commit.\n> >>>\n> >>> Thank you for this,\n> >>>\n> >>> I think I'm in favour of updating here when we can.\n> >>>\n> >>> We'll have to do a bit of a check to see if this impacts any projects\n> >>> using libcamera but I think it's workable.\n> >>>\n> >>> First part though will be CI:\n> >>>\n> >>> https://gitlab.freedesktop.org/camera/libcamera/-/pipelines/1546400\n> >>>\n> >>> Quite a few breakages to tackle and that may be the hard part.\n> >>\n> >> I have been compiling libcamera as C++20 forever. Apart from the above\n> >> change, one needs to:\n> >>\n> >> (1) disable -Wvolatile because of g_once_init() in glib\n> >> (2) disable -Wredundant-move in gcc 12 as well\n> >>\n> >> ---\n> >>\n> >> As far as I remember `std::atomic>` is not supported\n> >> in some versions, so I ended up using\n> >>\n> >> #pragma GCC diagnostic ignored \"-Wdeprecated-declarations\"\n> >>\n> >> ---\n> >>\n> >> Also, libpisp did not compile without warnings in C++20 the last time I checked.\n> >>\n> >> ---\n> >>\n> >> There is also this peculiar issue: https://gitlab.freedesktop.org/camera/libcamera/-/issues/267\n> >>\n> >> ---\n> >>\n> >> C++20 also triggers this error: https://gitlab.freedesktop.org/camera/libcamera/-/jobs/87812672#L364\n> >>\n> >> /usr/include/c++/12/bits/char_traits.h:431:56: error: ‘void* __builtin_memcpy(void*, const void*, long unsigned int)’ accessing 9223372036854775810 or more bytes at offsets [2, 9223372036854775807] and 1 may overlap up to 9223372036854775813 bytes at offset -3 [-Werror=restrict]\n> >> 431 | return static_cast(__builtin_memcpy(__s1, __s2, __n));\n> >>\n> >>\n> >> After some time I have given up on trying to fix this.\n> >>\n> >> ---\n> >>\n> >> Actually, to address (1), it should be sufficient to use `std::call_once()`, e.g.\n> >>\n> >> diff --git a/src/gstreamer/gstlibcameraallocator.cpp b/src/gstreamer/gstlibcameraallocator.cpp\n> >> index d4492d994b..3de6fc42a7 100644\n> >> --- a/src/gstreamer/gstlibcameraallocator.cpp\n> >> +++ b/src/gstreamer/gstlibcameraallocator.cpp\n> >> @@ -8,6 +8,7 @@\n> >>\n> >> #include \"gstlibcameraallocator.h\"\n> >>\n> >> +#include \n> >> #include \n> >>\n> >> #include \n> >> @@ -77,11 +78,11 @@ FrameWrap::~FrameWrap()\n> >> GQuark FrameWrap::getQuark()\n> >> {\n> >> static gsize frame_quark = 0;\n> >> + static std::once_flag frame_quark_once;\n> >>\n> >> - if (g_once_init_enter(&frame_quark)) {\n> >> - GQuark quark = g_quark_from_string(\"GstLibcameraFrameWrap\");\n> >> - g_once_init_leave(&frame_quark, quark);\n> >> - }\n> >> + std::call_once(frame_quark_once, [&] {\n> >> + frame_quark = g_quark_from_string(\"GstLibcameraFrameWrap\");\n> >> + });\n> >>\n> >> return frame_quark;\n> >> }\n> >\n> > How about\n> >\n> > GQuark FrameWrap::getQuark()\n> > {\n> > static gsize frame_quark = g_quark_from_string(\"GstLibcameraFrameWrap\");\n> > return frame_quark;\n> > }\n>\n> Ahh, yes, that should work, and is much better.\n>\n>\n> >\n> > According to\n> > https://en.cppreference.com/w/cpp/language/storage_duration.html#Static_block_variables,\n> >\n> > If multiple threads attempt to initialize the same static local\n> > variable concurrently, the initialization occurs exactly once (similar\n> > behavior can be obtained for arbitrary functions with std::call_once).\n> >\n> >>> With a large matrix of compilers and differing support that might be the\n> >>> tricky part. We'll have to identify if this will restict us to any\n> >>> specific compiler version minimum.\n> >>>\n> >>>> [1]: https://en.cppreference.com/w/cpp/memory/shared_ptr/atomic.html\n> >>>> Signed-off-by: Naushir Patuck \n> >>>> ---\n> >>>> meson.build | 2 +-\n> >>>> src/libcamera/base/log.cpp | 6 +++---\n> >>>> 2 files changed, 4 insertions(+), 4 deletions(-)\n> >>>>\n> >>>> diff --git a/meson.build b/meson.build\n> >>>> index fd508fd7f6b5..74153e1e6ce9 100644\n> >>>> --- a/meson.build\n> >>>> +++ b/meson.build\n> >>>> @@ -6,7 +6,7 @@ project('libcamera', 'c', 'cpp',\n> >>>> default_options : [\n> >>>> 'werror=true',\n> >>>> 'warning_level=2',\n> >>>> - 'cpp_std=c++17',\n> >>>> + 'cpp_std=c++20',\n> >>>> ],\n> >>>> license : 'LGPL 2.1+')\n> >>>>\n> >>>> diff --git a/src/libcamera/base/log.cpp b/src/libcamera/base/log.cpp\n> >>>> index 81b550e21402..e65d83739315 100644\n> >>>> --- a/src/libcamera/base/log.cpp\n> >>>> +++ b/src/libcamera/base/log.cpp\n> >>>> @@ -325,7 +325,7 @@ private:\n> >>>> std::vector> categories_ LIBCAMERA_TSA_GUARDED_BY(mutex_);\n> >>>> std::list> levels_;\n> >>>>\n> >>>> - std::shared_ptr output_;\n> >>>> + std::atomic> output_;\n> >>>> };\n> >>>>\n> >>>> bool Logger::destroyed_ = false;\n> >>>> @@ -465,7 +465,7 @@ Logger *Logger::instance()\n> >>>> */\n> >>>> void Logger::write(const LogMessage &msg)\n> >>>> {\n> >>>> - std::shared_ptr output = std::atomic_load(&output_);\n> >>>> + std::shared_ptr output = output_.load();\n> >>>> if (!output)\n> >>>> return;\n> >>>>\n> >>>> @@ -477,7 +477,7 @@ void Logger::write(const LogMessage &msg)\n> >>>> */\n> >>>> void Logger::backtrace()\n> >>>> {\n> >>>> - std::shared_ptr output = std::atomic_load(&output_);\n> >>>> + std::shared_ptr output = output_.load();\n> >>>> if (!output)\n> >>>> return;\n> >>>>\n> >\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 74358C3263\n\tfor ;\n\tThu, 13 Nov 2025 13:40:49 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 1B12160A80;\n\tThu, 13 Nov 2025 14:40:49 +0100 (CET)","from mail-vk1-xa2d.google.com (mail-vk1-xa2d.google.com\n\t[IPv6:2607:f8b0:4864:20::a2d])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id 1FDEF60805\n\tfor ;\n\tThu, 13 Nov 2025 14:40:47 +0100 (CET)","by mail-vk1-xa2d.google.com with SMTP id\n\t71dfb90a1353d-557412a9de0so26969e0c.2\n\tfor ;\n\tThu, 13 Nov 2025 05:40:47 -0800 (PST)"],"Authentication-Results":"lancelot.ideasonboard.com; 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charset=\"UTF-8\"","Content-Transfer-Encoding":"quoted-printable","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":36797,"web_url":"https://patchwork.libcamera.org/comment/36797/","msgid":"<57a97964-27fc-43af-bb41-71ae556daa65@ideasonboard.com>","date":"2025-11-13T13:41:52","subject":"Re: [RFC PATCH v1 1/1] treewide: Update to the C++20 standard","submitter":{"id":216,"url":"https://patchwork.libcamera.org/api/people/216/","name":"Barnabás Pőcze","email":"barnabas.pocze@ideasonboard.com"},"content":"2025. 11. 13. 13:54 keltezéssel, Barnabás Pőcze írta:\n> 2025. 11. 13. 13:49 keltezéssel, Laurent Pinchart írta:\n>> On Thu, Nov 13, 2025 at 01:24:18PM +0100, Barnabás Pőcze wrote:\n>>> 2025. 11. 13. 13:03 keltezéssel, Kieran Bingham írta:\n>>>> Quoting Naushir Patuck (2025-11-13 11:05:31)\n>>>>> Switch to using the C++20 standard when compiling libcamera. This causes\n>>>>> a build error due to the deprecation of the following specialisation [1]\n>>>>>\n>>>>> std::shared_ptr atomic_load(const std::shared_ptr* p)\n>>>>>\n>>>>> ../src/libcamera/base/log.cpp: In member function 'void libcamera::Logger::write(const libcamera::LogMessage&)':\n>>>>> ../src/libcamera/base/log.cpp:468:61: error: 'std::shared_ptr<_Tp> std::atomic_load(const shared_ptr<_Tp>*) [with _Tp = libcamera::LogOutput]' is deprecated: use 'std::atomic>' instead [-Werror=deprecated-declarations]\n>>>>>     468 |         std::shared_ptr output = std::atomic_load(&output_);\n>>>>>         |                                             ~~~~~~~~~~~~~~~~^~~~~~~~~~\n>>>>>\n>>>>> This error is fixed by switching to the std::atomic>\n>>>>> specialisation instead. Unfortunately, this is not backward compatible\n>>>>> with C++17, so the fix must be included in this commit.\n>>>>\n>>>> Thank you for this,\n>>>>\n>>>> I think I'm in favour of updating here when we can.\n>>>>\n>>>> We'll have to do a bit of a check to see if this impacts any projects\n>>>> using libcamera but I think it's workable.\n>>>>\n>>>> First part though will be CI:\n>>>>\n>>>>    https://gitlab.freedesktop.org/camera/libcamera/-/pipelines/1546400\n>>>>\n>>>> Quite a few breakages to tackle and that may be the hard part.\n>>>\n>>> I have been compiling libcamera as C++20 forever. Apart from the above\n>>> change, one needs to:\n>>>\n>>>    (1) disable -Wvolatile because of g_once_init() in glib\n>>>    (2) disable -Wredundant-move in gcc 12 as well\n>>>\n>>> ---\n>>>\n>>> As far as I remember `std::atomic>` is not supported\n>>> in some versions, so I ended up using\n>>>\n>>>     #pragma GCC diagnostic ignored \"-Wdeprecated-declarations\"\n>>>\n>>> ---\n>>>\n>>> Also, libpisp did not compile without warnings in C++20 the last time I checked.\n>>>\n>>> ---\n>>>\n>>> There is also this peculiar issue: https://gitlab.freedesktop.org/camera/libcamera/-/issues/267\n>>>\n>>> ---\n>>>\n>>> C++20 also triggers this error: https://gitlab.freedesktop.org/camera/libcamera/-/jobs/87812672#L364\n>>>\n>>> /usr/include/c++/12/bits/char_traits.h:431:56: error: ‘void* __builtin_memcpy(void*, const void*, long unsigned int)’ accessing 9223372036854775810 or more bytes at offsets [2, 9223372036854775807] and 1 may overlap up to 9223372036854775813 bytes at offset -3 [-Werror=restrict]\n>>>     431 |         return static_cast(__builtin_memcpy(__s1, __s2, __n));\n>>>\n>>>\n>>> After some time I have given up on trying to fix this.\n>>>\n>>> ---\n>>>\n>>> Actually, to address (1), it should be sufficient to use `std::call_once()`, e.g.\n>>>\n>>> diff --git a/src/gstreamer/gstlibcameraallocator.cpp b/src/gstreamer/gstlibcameraallocator.cpp\n>>> index d4492d994b..3de6fc42a7 100644\n>>> --- a/src/gstreamer/gstlibcameraallocator.cpp\n>>> +++ b/src/gstreamer/gstlibcameraallocator.cpp\n>>> @@ -8,6 +8,7 @@\n>>>    #include \"gstlibcameraallocator.h\"\n>>> +#include \n>>>    #include \n>>>    #include \n>>> @@ -77,11 +78,11 @@ FrameWrap::~FrameWrap()\n>>>    GQuark FrameWrap::getQuark()\n>>>    {\n>>>           static gsize frame_quark = 0;\n>>> +       static std::once_flag frame_quark_once;\n>>> -       if (g_once_init_enter(&frame_quark)) {\n>>> -               GQuark quark = g_quark_from_string(\"GstLibcameraFrameWrap\");\n>>> -               g_once_init_leave(&frame_quark, quark);\n>>> -       }\n>>> +       std::call_once(frame_quark_once, [&] {\n>>> +               frame_quark = g_quark_from_string(\"GstLibcameraFrameWrap\");\n>>> +       });\n>>>           return frame_quark;\n>>>    }\n>>\n>> How about\n>>\n>> GQuark FrameWrap::getQuark()\n>> {\n>>     static gsize frame_quark = g_quark_from_string(\"GstLibcameraFrameWrap\");\n>>     return frame_quark;\n>> }\n> \n> Ahh, yes, that should work, and is much better.\n\nUnfortunately I misremembered and this is not enough. `-Wno-volatile` is needed\nbecause `G_DEFINE_TYPE_*()` macros contain `g_once_init()`.\n\nRegardless, it might still be worth it to simplify the code.\n\n> \n> \n>>\n>> According to\n>> https://en.cppreference.com/w/cpp/language/storage_duration.html#Static_block_variables,\n>>\n>>    If multiple threads attempt to initialize the same static local\n>>    variable concurrently, the initialization occurs exactly once (similar\n>>    behavior can be obtained for arbitrary functions with std::call_once).\n>>\n>>>> With a large matrix of compilers and differing support that might be the\n>>>> tricky part. We'll have to identify if this will restict us to any\n>>>> specific compiler version minimum.\n>>>>\n>>>>> [1]: https://en.cppreference.com/w/cpp/memory/shared_ptr/atomic.html\n>>>>> Signed-off-by: Naushir Patuck \n>>>>> ---\n>>>>>    meson.build                | 2 +-\n>>>>>    src/libcamera/base/log.cpp | 6 +++---\n>>>>>    2 files changed, 4 insertions(+), 4 deletions(-)\n>>>>>\n>>>>> diff --git a/meson.build b/meson.build\n>>>>> index fd508fd7f6b5..74153e1e6ce9 100644\n>>>>> --- a/meson.build\n>>>>> +++ b/meson.build\n>>>>> @@ -6,7 +6,7 @@ project('libcamera', 'c', 'cpp',\n>>>>>        default_options : [\n>>>>>            'werror=true',\n>>>>>            'warning_level=2',\n>>>>> -        'cpp_std=c++17',\n>>>>> +        'cpp_std=c++20',\n>>>>>        ],\n>>>>>        license : 'LGPL 2.1+')\n>>>>> diff --git a/src/libcamera/base/log.cpp b/src/libcamera/base/log.cpp\n>>>>> index 81b550e21402..e65d83739315 100644\n>>>>> --- a/src/libcamera/base/log.cpp\n>>>>> +++ b/src/libcamera/base/log.cpp\n>>>>> @@ -325,7 +325,7 @@ private:\n>>>>>           std::vector> categories_ LIBCAMERA_TSA_GUARDED_BY(mutex_);\n>>>>>           std::list> levels_;\n>>>>> -       std::shared_ptr output_;\n>>>>> +       std::atomic> output_;\n>>>>>    };\n>>>>>    bool Logger::destroyed_ = false;\n>>>>> @@ -465,7 +465,7 @@ Logger *Logger::instance()\n>>>>>     */\n>>>>>    void Logger::write(const LogMessage &msg)\n>>>>>    {\n>>>>> -       std::shared_ptr output = std::atomic_load(&output_);\n>>>>> +       std::shared_ptr output = output_.load();\n>>>>>           if (!output)\n>>>>>                   return;\n>>>>> @@ -477,7 +477,7 @@ void Logger::write(const LogMessage &msg)\n>>>>>     */\n>>>>>    void Logger::backtrace()\n>>>>>    {\n>>>>> -       std::shared_ptr output = std::atomic_load(&output_);\n>>>>> +       std::shared_ptr output = output_.load();\n>>>>>           if (!output)\n>>>>>                   return;\n>>\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 A13D3C3263\n\tfor ;\n\tThu, 13 Nov 2025 13:41:58 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 5393860A80;\n\tThu, 13 Nov 2025 14:41:58 +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 E70CA60805\n\tfor ;\n\tThu, 13 Nov 2025 14:41:56 +0100 (CET)","from [192.168.33.32] (185.221.140.239.nat.pool.zt.hu\n\t[185.221.140.239])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id 7EABF446;\n\tThu, 13 Nov 2025 14:39:56 +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=\"HeDawKyi\"; dkim-atps=neutral","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1763041196;\n\tbh=GBsQe2culJ5wqbxYFDeFB5+kzxbZOkNrA7jmeDl6A2w=;\n\th=Date:Subject:From:To:Cc:References:In-Reply-To:From;\n\tb=HeDawKyiHBH5yD5N0CeEB+Y8APPTlOQKXBzbuaahulQe9MDj/Gm1vcBUIclTRH/Zp\n\tvUyuaqh+VRznfWjK0ZUfWU7c7Nn4CQEodXGNEqRCB0alfBD19xAZnXg/AL2XPLdEwu\n\tGyrW3Ylon5GOpV85nL6002X51/rfjMsHUTk6xqPA=","Message-ID":"<57a97964-27fc-43af-bb41-71ae556daa65@ideasonboard.com>","Date":"Thu, 13 Nov 2025 14:41:52 +0100","MIME-Version":"1.0","User-Agent":"Mozilla Thunderbird","Subject":"Re: [RFC PATCH v1 1/1] treewide: Update to the C++20 standard","From":"=?utf-8?q?Barnab=C3=A1s_P=C5=91cze?= ","To":"Laurent Pinchart ","Cc":"Kieran Bingham ,\n\tNaushir Patuck ,\n\tlibcamera-devel@lists.libcamera.org","References":"<20251113110958.1117065-1-naush@raspberrypi.com>\n\t<20251113110958.1117065-2-naush@raspberrypi.com>\n\t<176303540741.567526.12694728534244247378@ping.linuxembedded.co.uk>\n\t\n\t<20251113124940.GB30434@pendragon.ideasonboard.com>\n\t<00cbe340-364d-4d85-a4c4-d1a0fa1175cc@ideasonboard.com>","Content-Language":"en-US, hu-HU","In-Reply-To":"<00cbe340-364d-4d85-a4c4-d1a0fa1175cc@ideasonboard.com>","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\" "}},{"id":36807,"web_url":"https://patchwork.libcamera.org/comment/36807/","msgid":"<20251113153241.GG30434@pendragon.ideasonboard.com>","date":"2025-11-13T15:32:41","subject":"Re: [RFC PATCH v1 1/1] treewide: Update to the C++20 standard","submitter":{"id":2,"url":"https://patchwork.libcamera.org/api/people/2/","name":"Laurent Pinchart","email":"laurent.pinchart@ideasonboard.com"},"content":"On Thu, Nov 13, 2025 at 02:41:52PM +0100, Barnabás Pőcze wrote:\n> 2025. 11. 13. 13:54 keltezéssel, Barnabás Pőcze írta:\n> > 2025. 11. 13. 13:49 keltezéssel, Laurent Pinchart írta:\n> >> On Thu, Nov 13, 2025 at 01:24:18PM +0100, Barnabás Pőcze wrote:\n> >>> 2025. 11. 13. 13:03 keltezéssel, Kieran Bingham írta:\n> >>>> Quoting Naushir Patuck (2025-11-13 11:05:31)\n> >>>>> Switch to using the C++20 standard when compiling libcamera. This causes\n> >>>>> a build error due to the deprecation of the following specialisation [1]\n> >>>>>\n> >>>>> std::shared_ptr atomic_load(const std::shared_ptr* p)\n> >>>>>\n> >>>>> ../src/libcamera/base/log.cpp: In member function 'void libcamera::Logger::write(const libcamera::LogMessage&)':\n> >>>>> ../src/libcamera/base/log.cpp:468:61: error: 'std::shared_ptr<_Tp> std::atomic_load(const shared_ptr<_Tp>*) [with _Tp = libcamera::LogOutput]' is deprecated: use 'std::atomic>' instead [-Werror=deprecated-declarations]\n> >>>>>     468 |         std::shared_ptr output = std::atomic_load(&output_);\n> >>>>>         |                                             ~~~~~~~~~~~~~~~~^~~~~~~~~~\n> >>>>>\n> >>>>> This error is fixed by switching to the std::atomic>\n> >>>>> specialisation instead. Unfortunately, this is not backward compatible\n> >>>>> with C++17, so the fix must be included in this commit.\n> >>>>\n> >>>> Thank you for this,\n> >>>>\n> >>>> I think I'm in favour of updating here when we can.\n> >>>>\n> >>>> We'll have to do a bit of a check to see if this impacts any projects\n> >>>> using libcamera but I think it's workable.\n> >>>>\n> >>>> First part though will be CI:\n> >>>>\n> >>>>    https://gitlab.freedesktop.org/camera/libcamera/-/pipelines/1546400\n> >>>>\n> >>>> Quite a few breakages to tackle and that may be the hard part.\n> >>>\n> >>> I have been compiling libcamera as C++20 forever. Apart from the above\n> >>> change, one needs to:\n> >>>\n> >>>    (1) disable -Wvolatile because of g_once_init() in glib\n> >>>    (2) disable -Wredundant-move in gcc 12 as well\n> >>>\n> >>> ---\n> >>>\n> >>> As far as I remember `std::atomic>` is not supported\n> >>> in some versions, so I ended up using\n> >>>\n> >>>     #pragma GCC diagnostic ignored \"-Wdeprecated-declarations\"\n> >>>\n> >>> ---\n> >>>\n> >>> Also, libpisp did not compile without warnings in C++20 the last time I checked.\n> >>>\n> >>> ---\n> >>>\n> >>> There is also this peculiar issue: https://gitlab.freedesktop.org/camera/libcamera/-/issues/267\n> >>>\n> >>> ---\n> >>>\n> >>> C++20 also triggers this error: https://gitlab.freedesktop.org/camera/libcamera/-/jobs/87812672#L364\n> >>>\n> >>> /usr/include/c++/12/bits/char_traits.h:431:56: error: ‘void* __builtin_memcpy(void*, const void*, long unsigned int)’ accessing 9223372036854775810 or more bytes at offsets [2, 9223372036854775807] and 1 may overlap up to 9223372036854775813 bytes at offset -3 [-Werror=restrict]\n> >>>     431 |         return static_cast(__builtin_memcpy(__s1, __s2, __n));\n> >>>\n> >>>\n> >>> After some time I have given up on trying to fix this.\n> >>>\n> >>> ---\n> >>>\n> >>> Actually, to address (1), it should be sufficient to use `std::call_once()`, e.g.\n> >>>\n> >>> diff --git a/src/gstreamer/gstlibcameraallocator.cpp b/src/gstreamer/gstlibcameraallocator.cpp\n> >>> index d4492d994b..3de6fc42a7 100644\n> >>> --- a/src/gstreamer/gstlibcameraallocator.cpp\n> >>> +++ b/src/gstreamer/gstlibcameraallocator.cpp\n> >>> @@ -8,6 +8,7 @@\n> >>>    #include \"gstlibcameraallocator.h\"\n> >>> +#include \n> >>>    #include \n> >>>    #include \n> >>> @@ -77,11 +78,11 @@ FrameWrap::~FrameWrap()\n> >>>    GQuark FrameWrap::getQuark()\n> >>>    {\n> >>>           static gsize frame_quark = 0;\n> >>> +       static std::once_flag frame_quark_once;\n> >>> -       if (g_once_init_enter(&frame_quark)) {\n> >>> -               GQuark quark = g_quark_from_string(\"GstLibcameraFrameWrap\");\n> >>> -               g_once_init_leave(&frame_quark, quark);\n> >>> -       }\n> >>> +       std::call_once(frame_quark_once, [&] {\n> >>> +               frame_quark = g_quark_from_string(\"GstLibcameraFrameWrap\");\n> >>> +       });\n> >>>           return frame_quark;\n> >>>    }\n> >>\n> >> How about\n> >>\n> >> GQuark FrameWrap::getQuark()\n> >> {\n> >>     static gsize frame_quark = g_quark_from_string(\"GstLibcameraFrameWrap\");\n> >>     return frame_quark;\n> >> }\n> > \n> > Ahh, yes, that should work, and is much better.\n> \n> Unfortunately I misremembered and this is not enough. `-Wno-volatile` is needed\n> because `G_DEFINE_TYPE_*()` macros contain `g_once_init()`.\n\nPlease make this conditional to the glib version.\n\n> Regardless, it might still be worth it to simplify the code.\n> \n> >> According to\n> >> https://en.cppreference.com/w/cpp/language/storage_duration.html#Static_block_variables,\n> >>\n> >>    If multiple threads attempt to initialize the same static local\n> >>    variable concurrently, the initialization occurs exactly once (similar\n> >>    behavior can be obtained for arbitrary functions with std::call_once).\n> >>\n> >>>> With a large matrix of compilers and differing support that might be the\n> >>>> tricky part. We'll have to identify if this will restict us to any\n> >>>> specific compiler version minimum.\n> >>>>\n> >>>>> [1]: https://en.cppreference.com/w/cpp/memory/shared_ptr/atomic.html\n> >>>>> Signed-off-by: Naushir Patuck \n> >>>>> ---\n> >>>>>    meson.build                | 2 +-\n> >>>>>    src/libcamera/base/log.cpp | 6 +++---\n> >>>>>    2 files changed, 4 insertions(+), 4 deletions(-)\n> >>>>>\n> >>>>> diff --git a/meson.build b/meson.build\n> >>>>> index fd508fd7f6b5..74153e1e6ce9 100644\n> >>>>> --- a/meson.build\n> >>>>> +++ b/meson.build\n> >>>>> @@ -6,7 +6,7 @@ project('libcamera', 'c', 'cpp',\n> >>>>>        default_options : [\n> >>>>>            'werror=true',\n> >>>>>            'warning_level=2',\n> >>>>> -        'cpp_std=c++17',\n> >>>>> +        'cpp_std=c++20',\n> >>>>>        ],\n> >>>>>        license : 'LGPL 2.1+')\n> >>>>> diff --git a/src/libcamera/base/log.cpp b/src/libcamera/base/log.cpp\n> >>>>> index 81b550e21402..e65d83739315 100644\n> >>>>> --- a/src/libcamera/base/log.cpp\n> >>>>> +++ b/src/libcamera/base/log.cpp\n> >>>>> @@ -325,7 +325,7 @@ private:\n> >>>>>           std::vector> categories_ LIBCAMERA_TSA_GUARDED_BY(mutex_);\n> >>>>>           std::list> levels_;\n> >>>>> -       std::shared_ptr output_;\n> >>>>> +       std::atomic> output_;\n> >>>>>    };\n> >>>>>    bool Logger::destroyed_ = false;\n> >>>>> @@ -465,7 +465,7 @@ Logger *Logger::instance()\n> >>>>>     */\n> >>>>>    void Logger::write(const LogMessage &msg)\n> >>>>>    {\n> >>>>> -       std::shared_ptr output = std::atomic_load(&output_);\n> >>>>> +       std::shared_ptr output = output_.load();\n> >>>>>           if (!output)\n> >>>>>                   return;\n> >>>>> @@ -477,7 +477,7 @@ void Logger::write(const LogMessage &msg)\n> >>>>>     */\n> >>>>>    void Logger::backtrace()\n> >>>>>    {\n> >>>>> -       std::shared_ptr output = std::atomic_load(&output_);\n> >>>>> +       std::shared_ptr output = output_.load();\n> >>>>>           if (!output)\n> >>>>>                   return;","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 00B01C3241\n\tfor ;\n\tThu, 13 Nov 2025 15:32:56 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 4B80A609D8;\n\tThu, 13 Nov 2025 16:32:56 +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 EEF0760805\n\tfor ;\n\tThu, 13 Nov 2025 16:32:53 +0100 (CET)","from pendragon.ideasonboard.com (unknown [213.216.211.176])\n\tby perceval.ideasonboard.com (Postfix) with UTF8SMTPSA id 645815B2;\n\tThu, 13 Nov 2025 16:30:53 +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=\"GD6glYGS\"; dkim-atps=neutral","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1763047853;\n\tbh=bxSCVMpr3IgXhOQ1GhrxnlSh7rRlInP/2KsDRfFHMLI=;\n\th=Date:From:To:Cc:Subject:References:In-Reply-To:From;\n\tb=GD6glYGS/PDRK7yR2Pnr/wqtfrQU6r3JhsrAmr5T/U+AXLeTaGhaxKBwIaLIJcInK\n\to9qqf4hemYXPf0uFwtwMn+5KUMLsITe3gnZieymalPqWcfUMrlROwrSI5rV+9nxMEn\n\tX0th4WYdCJUVPvy1VDnaBD4Mg/o1kp6Xsa0RL7C4=","Date":"Thu, 13 Nov 2025 17:32:41 +0200","From":"Laurent Pinchart ","To":"=?utf-8?q?Barnab=C3=A1s_P=C5=91cze?= ","Cc":"Kieran Bingham ,\n\tNaushir Patuck ,\n\tlibcamera-devel@lists.libcamera.org","Subject":"Re: [RFC PATCH v1 1/1] treewide: Update to the C++20 standard","Message-ID":"<20251113153241.GG30434@pendragon.ideasonboard.com>","References":"<20251113110958.1117065-1-naush@raspberrypi.com>\n\t<20251113110958.1117065-2-naush@raspberrypi.com>\n\t<176303540741.567526.12694728534244247378@ping.linuxembedded.co.uk>\n\t\n\t<20251113124940.GB30434@pendragon.ideasonboard.com>\n\t<00cbe340-364d-4d85-a4c4-d1a0fa1175cc@ideasonboard.com>\n\t<57a97964-27fc-43af-bb41-71ae556daa65@ideasonboard.com>","MIME-Version":"1.0","Content-Type":"text/plain; charset=utf-8","Content-Disposition":"inline","Content-Transfer-Encoding":"8bit","In-Reply-To":"<57a97964-27fc-43af-bb41-71ae556daa65@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\" "}}]