From 8ec3116162e030709c42420fc70e7423db9a06df Mon Sep 17 00:00:00 2001 From: Stephan Bergmann Date: Tue, 8 Oct 2019 14:55:25 +0200 Subject: Introduce o3tl::unsafe_downcast for known-good dynamic_cast downcasts (This helps rewrite code that silences Coverity unchecked dynamic_cast warnings, like 57b89ea1c2ff07b53c3cc002e5ec9e52abd0c1bd "coverity#704563 Unchecked dynamic cast", in a way that is cleaner and potentially executes faster.) Change-Id: I3319c0eeec2aa822f686feacd499a76c8c9b9499 Reviewed-on: https://gerrit.libreoffice.org/80458 Tested-by: Jenkins Reviewed-by: Stephan Bergmann --- include/o3tl/unsafe_downcast.hxx | 35 +++++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+) create mode 100644 include/o3tl/unsafe_downcast.hxx (limited to 'include/o3tl') diff --git a/include/o3tl/unsafe_downcast.hxx b/include/o3tl/unsafe_downcast.hxx new file mode 100644 index 000000000000..b49994eff135 --- /dev/null +++ b/include/o3tl/unsafe_downcast.hxx @@ -0,0 +1,35 @@ +/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4; fill-column: 100 -*- */ +/* + * This file is part of the LibreOffice project. + * + * This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. + */ + +#ifndef INCLUDED_O3TL_UNSAFE_DOWNCAST_HXX +#define INCLUDED_O3TL_UNSAFE_DOWNCAST_HXX + +#include +#include + +namespace o3tl +{ +// Do a downcast from polymorphic `BasePtr` to `DerivedPtr` when it is known that `p` is actually +// pointing to an object of derived type (or is a nullptr). This is potentially cheaper than +// dynamic_cast and helps to avoid Coverity warnings about unchecked dynamic_cast. +template +std::enable_if_t< + (std::is_pointer_v< + DerivedPtr> && std::is_pointer_v && std::is_base_of_v, std::remove_pointer_t>), + DerivedPtr> +unsafe_downcast(BasePtr p) +{ + assert(p == nullptr || dynamic_cast(p) != nullptr); + return static_cast(p); +} +} + +#endif + +/* vim:set shiftwidth=4 softtabstop=4 expandtab cinoptions=b1,g0,N-s cinkeys+=0=break: */ -- cgit