{"id":25634,"url":"https://patchwork.libcamera.org/api/1.1/patches/25634/?format=json","web_url":"https://patchwork.libcamera.org/patch/25634/","project":{"id":1,"url":"https://patchwork.libcamera.org/api/1.1/projects/1/?format=json","name":"libcamera","link_name":"libcamera","list_id":"libcamera_core","list_email":"libcamera-devel@lists.libcamera.org","web_url":"","scm_url":"","webscm_url":""},"msgid":"<20260106165754.1759831-5-barnabas.pocze@ideasonboard.com>","date":"2026-01-06T16:57:36","name":"[v4,04/22] libcamera: base: cxx20: Add `type_identity{,_t}`","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"613d7a641ba9b1de9f4d925e004dda4f7d560cee","submitter":{"id":216,"url":"https://patchwork.libcamera.org/api/1.1/people/216/?format=json","name":"Barnabás Pőcze","email":"barnabas.pocze@ideasonboard.com"},"delegate":null,"mbox":"https://patchwork.libcamera.org/patch/25634/mbox/","series":[{"id":5688,"url":"https://patchwork.libcamera.org/api/1.1/series/5688/?format=json","web_url":"https://patchwork.libcamera.org/project/libcamera/list/?series=5688","date":"2026-01-06T16:57:32","name":"libcamera: Add `MetadataList`","version":4,"mbox":"https://patchwork.libcamera.org/series/5688/mbox/"}],"comments":"https://patchwork.libcamera.org/api/patches/25634/comments/","check":"pending","checks":"https://patchwork.libcamera.org/api/patches/25634/checks/","tags":{},"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 E30B2BDCBF\n\tfor ;\n\tTue, 6 Jan 2026 16:58:11 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id CEB8661FC4;\n\tTue, 6 Jan 2026 17:58:03 +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 EBD8161FA0\n\tfor ;\n\tTue, 6 Jan 2026 17:57:58 +0100 (CET)","from pb-laptop.local (185.221.143.114.nat.pool.zt.hu\n\t[185.221.143.114])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id DAC6D1340;\n\tTue, 6 Jan 2026 17:57:37 +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=\"ABelmhwS\"; dkim-atps=neutral","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1767718658;\n\tbh=3Wv7dFN/RmtdtVgzwW1D/1+hp3VVAILss1MVsZ07raU=;\n\th=From:To:Cc:Subject:Date:In-Reply-To:References:From;\n\tb=ABelmhwSBjFGKJl8iPRMSxHhGMmdZGhAPEWM+cxY6fxIP3p65LiZ57a5IG5ar+dLH\n\tceZNM/yRyA2uhF75uRyttRs6LXXIYVFVdU5cqjgQBAdLOQqCrdm8qt7kuvKScjwrFd\n\tV/SdGkoCBE59pBZAtiE7yJA9YDDuSaWeiWlyLWYA=","From":"=?utf-8?q?Barnab=C3=A1s_P=C5=91cze?= ","To":"libcamera-devel@lists.libcamera.org","Cc":"Jacopo Mondi ,\n\tPaul Elder ,\n\tKieran Bingham ","Subject":"[PATCH v4 04/22] libcamera: base: cxx20: Add `type_identity{,_t}`","Date":"Tue, 6 Jan 2026 17:57:36 +0100","Message-ID":"<20260106165754.1759831-5-barnabas.pocze@ideasonboard.com>","X-Mailer":"git-send-email 2.52.0","In-Reply-To":"<20260106165754.1759831-1-barnabas.pocze@ideasonboard.com>","References":"<20260106165754.1759831-1-barnabas.pocze@ideasonboard.com>","MIME-Version":"1.0","Content-Type":"text/plain; charset=UTF-8","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\" "},"content":"`type_identity_t` can be used to force non-deduced contexts\nin templates, such as:\n\n void f(T x, type_identity_t y)\n\nwhen calling `f(1u, 2)`, without `type_identity_t`, the compiler\ncould not unambiguously deduce `T` (unsigned int vs int). However,\nwith `type_identity_t`, the type of the argument passed to `y`\nwill not be used to deduce `T`, only the argument passed to `x`.\n\nSee https://en.cppreference.com/w/cpp/types/type_identity\n\nSigned-off-by: Barnabás Pőcze \nReviewed-by: Jacopo Mondi \nReviewed-by: Paul Elder \nReviewed-by: Kieran Bingham \n---\n include/libcamera/base/internal/cxx20.h | 24 ++++++++++++++++++++++++\n 1 file changed, 24 insertions(+)","diff":"diff --git a/include/libcamera/base/internal/cxx20.h b/include/libcamera/base/internal/cxx20.h\nindex 70a43f83c..1f4caf56f 100644\n--- a/include/libcamera/base/internal/cxx20.h\n+++ b/include/libcamera/base/internal/cxx20.h\n@@ -15,4 +15,28 @@\n \n namespace libcamera::internal::cxx20 {\n \n+/**\n+ * \\internal\n+ * \\brief std::type_identity\n+ *\n+ * Implementation of std::type_identity for C++17.\n+ */\n+template struct type_identity {\n+\t/**\n+\t * \\internal\n+\t * \\brief std::type_identity::type\n+\t *\n+\t * Type alias matching the template parameter.\n+\t */\n+\tusing type = T;\n+};\n+\n+/**\n+ * \\internal\n+ * \\brief std::type_identity_t\n+ *\n+ * Implementation of std::type_identity_t for C++17.\n+ */\n+template using type_identity_t = typename type_identity::type;\n+\n } /* namespace libcamera::internal::cxx20 */\n","prefixes":["v4","04/22"]}