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https://sourceware.org/git/binutils-gdb.git
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284a0e3cbf
Since we use obstacks with objects that are not default constructible, we sometimes need to manually call the constructor by hand using placement new: foo *f = obstack_alloc (obstack, sizeof (foo)); f = new (f) foo; It's possible to use allocate_on_obstack instead, but there are types that we sometimes want to allocate on an obstack, and sometimes on the regular heap. This patch introduces a utility to make this pattern simpler if allocate_on_obstack is not an option: foo *f = obstack_new<foo> (obstack); Right now there's only one usage (in tdesc_data_init). To help catch places where we would forget to call new when allocating such an object on an obstack, this patch also poisons some other methods of allocating an instance of a type on an obstack: - OBSTACK_ZALLOC/OBSTACK_CALLOC - XOBNEW/XOBNEW - GDBARCH_OBSTACK_ZALLOC/GDBARCH_OBSTACK_CALLOC Unfortunately, there's no way to catch wrong usages of obstack_alloc. By pulling on that string though, it tripped on allocating struct template_symbol using OBSTACK_ZALLOC. The criterion currently used to know whether it's safe to "malloc" an instance of a struct is whether it is a POD. Because it inherits from struct symbol, template_symbol is not a POD. This criterion is a bit too strict however, it should still safe to allocate memory for a template_symbol and memset it to 0. We didn't use is_trivially_constructible as the criterion in the first place only because it is not available in gcc < 5. So here I considered two alternatives: 1. Relax that criterion to use std::is_trivially_constructible and add a bit more glue code to make it work with gcc < 5 2. Continue pulling on the string and change how the symbol structures are allocated and initialized I managed to do both, but I decided to go with #1 to keep this patch simpler and more focused. When building with a compiler that does not have is_trivially_constructible, the check will just not be enforced. gdb/ChangeLog: * common/traits.h (HAVE_IS_TRIVIALLY_COPYABLE): Define if compiler supports std::is_trivially_constructible. * common/poison.h: Include obstack.h. (IsMallocable): Define to is_trivially_constructible if the compiler supports it, define to true_type otherwise. (xobnew): New. (XOBNEW): Redefine. (xobnewvec): New. (XOBNEWVEC): Redefine. * gdb_obstack.h (obstack_zalloc): New. (OBSTACK_ZALLOC): Redefine. (obstack_calloc): New. (OBSTACK_CALLOC): Redefine. (obstack_new): New. * gdbarch.sh: Include gdb_obstack in gdbarch.h. (gdbarch_obstack): New declaration in gdbarch.h, definition in gdbarch.c. (GDBARCH_OBSTACK_CALLOC, GDBARCH_OBSTACK_ZALLOC): Use obstack_calloc/obstack_zalloc. (gdbarch_obstack_zalloc): Remove. * target-descriptions.c (tdesc_data_init): Use obstack_new.
249 lines
6.0 KiB
C++
249 lines
6.0 KiB
C++
/* Poison symbols at compile time.
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Copyright (C) 2017-2018 Free Software Foundation, Inc.
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#ifndef COMMON_POISON_H
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#define COMMON_POISON_H
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#include "traits.h"
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#include "obstack.h"
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/* Poison memset of non-POD types. The idea is catching invalid
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initialization of non-POD structs that is easy to be introduced as
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side effect of refactoring. For example, say this:
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struct S { VEC(foo_s) *m_data; };
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is converted to this at some point:
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struct S {
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S() { m_data.reserve (10); }
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std::vector<foo> m_data;
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};
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and old code was initializing S objects like this:
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struct S s;
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memset (&s, 0, sizeof (S)); // whoops, now wipes vector.
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Declaring memset as deleted for non-POD types makes the memset above
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be a compile-time error. */
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/* Helper for SFINAE. True if "T *" is memsettable. I.e., if T is
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either void, or POD. */
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template<typename T>
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struct IsMemsettable
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: gdb::Or<std::is_void<T>,
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std::is_pod<T>>
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{};
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template <typename T,
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typename = gdb::Requires<gdb::Not<IsMemsettable<T>>>>
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void *memset (T *s, int c, size_t n) = delete;
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#if HAVE_IS_TRIVIALLY_COPYABLE
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/* Similarly, poison memcpy and memmove of non trivially-copyable
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types, which is undefined. */
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/* True if "T *" is relocatable. I.e., copyable with memcpy/memmove.
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I.e., T is either trivially copyable, or void. */
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template<typename T>
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struct IsRelocatable
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: gdb::Or<std::is_void<T>,
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std::is_trivially_copyable<T>>
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{};
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/* True if both source and destination are relocatable. */
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template <typename D, typename S>
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using BothAreRelocatable
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= gdb::And<IsRelocatable<D>, IsRelocatable<S>>;
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template <typename D, typename S,
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typename = gdb::Requires<gdb::Not<BothAreRelocatable<D, S>>>>
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void *memcpy (D *dest, const S *src, size_t n) = delete;
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template <typename D, typename S,
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typename = gdb::Requires<gdb::Not<BothAreRelocatable<D, S>>>>
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void *memmove (D *dest, const S *src, size_t n) = delete;
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#endif /* HAVE_IS_TRIVIALLY_COPYABLE */
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/* Poison XNEW and friends to catch usages of malloc-style allocations on
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objects that require new/delete. */
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template<typename T>
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#if HAVE_IS_TRIVIALLY_CONSTRUCTIBLE
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using IsMallocable = std::is_trivially_constructible<T>;
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#else
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using IsMallocable = std::true_type;
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#endif
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template<typename T>
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using IsFreeable = gdb::Or<std::is_trivially_destructible<T>, std::is_void<T>>;
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template <typename T, typename = gdb::Requires<gdb::Not<IsFreeable<T>>>>
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void free (T *ptr) = delete;
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template<typename T>
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static T *
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xnew ()
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{
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static_assert (IsMallocable<T>::value, "Trying to use XNEW with a non-POD \
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data type. Use operator new instead.");
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return XNEW (T);
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}
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#undef XNEW
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#define XNEW(T) xnew<T>()
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template<typename T>
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static T *
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xcnew ()
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{
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static_assert (IsMallocable<T>::value, "Trying to use XCNEW with a non-POD \
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data type. Use operator new instead.");
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return XCNEW (T);
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}
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#undef XCNEW
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#define XCNEW(T) xcnew<T>()
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template<typename T>
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static void
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xdelete (T *p)
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{
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static_assert (IsFreeable<T>::value, "Trying to use XDELETE with a non-POD \
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data type. Use operator delete instead.");
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XDELETE (p);
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}
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#undef XDELETE
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#define XDELETE(P) xdelete (P)
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template<typename T>
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static T *
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xnewvec (size_t n)
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{
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static_assert (IsMallocable<T>::value, "Trying to use XNEWVEC with a \
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non-POD data type. Use operator new[] (or std::vector) instead.");
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return XNEWVEC (T, n);
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}
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#undef XNEWVEC
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#define XNEWVEC(T, N) xnewvec<T> (N)
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template<typename T>
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static T *
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xcnewvec (size_t n)
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{
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static_assert (IsMallocable<T>::value, "Trying to use XCNEWVEC with a \
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non-POD data type. Use operator new[] (or std::vector) instead.");
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return XCNEWVEC (T, n);
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}
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#undef XCNEWVEC
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#define XCNEWVEC(T, N) xcnewvec<T> (N)
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template<typename T>
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static T *
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xresizevec (T *p, size_t n)
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{
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static_assert (IsMallocable<T>::value, "Trying to use XRESIZEVEC with a \
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non-POD data type.");
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return XRESIZEVEC (T, p, n);
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}
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#undef XRESIZEVEC
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#define XRESIZEVEC(T, P, N) xresizevec<T> (P, N)
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template<typename T>
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static void
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xdeletevec (T *p)
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{
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static_assert (IsFreeable<T>::value, "Trying to use XDELETEVEC with a \
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non-POD data type. Use operator delete[] (or std::vector) instead.");
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XDELETEVEC (p);
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}
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#undef XDELETEVEC
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#define XDELETEVEC(P) xdeletevec (P)
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template<typename T>
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static T *
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xnewvar (size_t s)
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{
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static_assert (IsMallocable<T>::value, "Trying to use XNEWVAR with a \
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non-POD data type.");
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return XNEWVAR (T, s);;
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}
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#undef XNEWVAR
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#define XNEWVAR(T, S) xnewvar<T> (S)
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template<typename T>
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static T *
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xcnewvar (size_t s)
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{
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static_assert (IsMallocable<T>::value, "Trying to use XCNEWVAR with a \
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non-POD data type.");
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return XCNEWVAR (T, s);
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}
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#undef XCNEWVAR
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#define XCNEWVAR(T, S) xcnewvar<T> (S)
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template<typename T>
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static T *
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xresizevar (T *p, size_t s)
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{
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static_assert (IsMallocable<T>::value, "Trying to use XRESIZEVAR with a \
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non-POD data type.");
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return XRESIZEVAR (T, p, s);
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}
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#undef XRESIZEVAR
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#define XRESIZEVAR(T, P, S) xresizevar<T> (P, S)
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template<typename T>
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static T *
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xobnew (obstack *ob)
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{
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static_assert (IsMallocable<T>::value, "Trying to use XOBNEW with a \
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non-POD data type.");
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return XOBNEW (ob, T);
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}
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#undef XOBNEW
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#define XOBNEW(O, T) xobnew<T> (O)
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template<typename T>
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static T *
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xobnewvec (obstack *ob, size_t n)
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{
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static_assert (IsMallocable<T>::value, "Trying to use XOBNEWVEC with a \
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non-POD data type.");
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return XOBNEWVEC (ob, T, n);
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}
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#undef XOBNEWVEC
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#define XOBNEWVEC(O, T, N) xobnewvec<T> (O, N)
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#endif /* COMMON_POISON_H */
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