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{ "id": 25634, "url": "https://patchwork.libcamera.org/api/patches/25634/?format=api", "web_url": "https://patchwork.libcamera.org/patch/25634/", "project": { "id": 1, "url": "https://patchwork.libcamera.org/api/projects/1/?format=api", "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/people/216/?format=api", "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/series/5688/?format=api", "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": "<libcamera-devel-bounces@lists.libcamera.org>", "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 <parsemail@patchwork.libcamera.org>;\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 <libcamera-devel@lists.libcamera.org>;\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?= <barnabas.pocze@ideasonboard.com>", "To": "libcamera-devel@lists.libcamera.org", "Cc": "Jacopo Mondi <jacopo.mondi@ideasonboard.com>,\n\tPaul Elder <paul.elder@ideasonboard.com>,\n\tKieran Bingham <kieran.bingham@ideasonboard.com>", "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": "<libcamera-devel.lists.libcamera.org>", "List-Unsubscribe": "<https://lists.libcamera.org/options/libcamera-devel>,\n\t<mailto:libcamera-devel-request@lists.libcamera.org?subject=unsubscribe>", "List-Archive": "<https://lists.libcamera.org/pipermail/libcamera-devel/>", "List-Post": "<mailto:libcamera-devel@lists.libcamera.org>", "List-Help": "<mailto:libcamera-devel-request@lists.libcamera.org?subject=help>", "List-Subscribe": "<https://lists.libcamera.org/listinfo/libcamera-devel>,\n\t<mailto:libcamera-devel-request@lists.libcamera.org?subject=subscribe>", "Errors-To": "libcamera-devel-bounces@lists.libcamera.org", "Sender": "\"libcamera-devel\" <libcamera-devel-bounces@lists.libcamera.org>" }, "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<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 <barnabas.pocze@ideasonboard.com>\nReviewed-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>\nReviewed-by: Paul Elder <paul.elder@ideasonboard.com>\nReviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>\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<typename T> struct type_identity {\n+\t/**\n+\t * \\internal\n+\t * \\brief std::type_identity<T>::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<typename T> using type_identity_t = typename type_identity<T>::type;\n+\n } /* namespace libcamera::internal::cxx20 */\n", "prefixes": [ "v4", "04/22" ] }