mirror of
https://sourceware.org/git/binutils-gdb.git
synced 2024-12-21 04:42:53 +08:00
11da1b13b3
This commit was inspired by these mailing list posts: https://sourceware.org/pipermail/gdb-patches/2022-June/190323.html https://sourceware.org/pipermail/gdb-patches/2022-April/188098.html The idea is to add a new function gdb::checked_static_cast, which can, in some cases, be used as a drop-in replacement for static_cast. And so, if I previously wrote this: BaseClass *base = get_base_class_pointer (); DerivedClass *derived = static_cast<DerivedClass *> (base); I can now write: BaseClass *base = get_base_class_pointer (); DerivedClass *derived = gdb::checked_static_cast<DerivedClass *> (base); The requirement is that BaseClass and DerivedClass must be polymorphic. The benefit of making this change is that, when GDB is built in developer mode, a run-time check will be made to ensure that `base` really is of type DerivedClass before the cast is performed. If `base` is not of type DerivedClass then GDB will assert. In a non-developer build gdb::checked_static_cast is equivalent to a static_cast, and there should be no performance difference. This commit adds the support function, but does not make use of this function, a use will be added in the next commit. Co-Authored-By: Pedro Alves <pedro@palves.net> Co-Authored-By: Tom Tromey <tom@tromey.com>
69 lines
2.3 KiB
C++
69 lines
2.3 KiB
C++
/* Copyright (C) 2022 Free Software Foundation, Inc.
|
|
|
|
This file is part of GDB.
|
|
|
|
This program is free software; you can redistribute it and/or modify
|
|
it under the terms of the GNU General Public License as published by
|
|
the Free Software Foundation; either version 3 of the License, or
|
|
(at your option) any later version.
|
|
|
|
This program is distributed in the hope that it will be useful,
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
GNU General Public License for more details.
|
|
|
|
You should have received a copy of the GNU General Public License
|
|
along with this program. If not, see <http://www.gnu.org/licenses/>. */
|
|
|
|
#ifndef COMMON_GDB_CHECKED_DYNAMIC_CAST_H
|
|
#define COMMON_GDB_CHECKED_DYNAMIC_CAST_H
|
|
|
|
#include "gdbsupport/traits.h"
|
|
|
|
namespace gdb
|
|
{
|
|
|
|
/* This function can be used in place of static_cast when casting between
|
|
pointers of polymorphic types. The benefit of using this call is that,
|
|
when compiling in developer mode, dynamic_cast will be used to validate
|
|
the cast. This use of dynamic_cast is why this function will only
|
|
work for polymorphic types.
|
|
|
|
In non-developer (i.e. production) builds, the dynamic_cast is replaced
|
|
with a static_cast which is usually significantly faster. */
|
|
|
|
template<typename T, typename V>
|
|
T
|
|
checked_static_cast (V *v)
|
|
{
|
|
/* We only support casting to pointer types. */
|
|
static_assert (std::is_pointer<T>::value, "target must be a pointer type");
|
|
|
|
/* Check for polymorphic types explicitly in case we're in release mode. */
|
|
static_assert (std::is_polymorphic<V>::value, "types must be polymorphic");
|
|
|
|
/* Figure out the type that T points to. */
|
|
using T_no_P = typename std::remove_pointer<T>::type;
|
|
|
|
/* In developer mode this cast uses dynamic_cast to confirm at run-time
|
|
that the cast from V* to T is valid. However, we can catch some
|
|
mistakes at compile time, this assert prevents anything other than
|
|
downcasts, or casts to same type. */
|
|
static_assert (std::is_base_of<V, T_no_P>::value
|
|
|| std::is_base_of<T_no_P, V>::value,
|
|
"types must be related");
|
|
|
|
#ifdef DEVELOPMENT
|
|
T result = dynamic_cast<T> (v);
|
|
gdb_assert (result != nullptr);
|
|
#else
|
|
T result = static_cast<T> (v);
|
|
#endif
|
|
|
|
return result;
|
|
}
|
|
|
|
}
|
|
|
|
#endif /* COMMON_GDB_CHECKED_DYNAMIC_CAST_H */
|