cpp_feature.h breaks external code
slavanap opened this issue · comments
Precisely, this definition breaks this code on a compiler without __cpp_sized_deallocation being supported.
Which C++ 14 toolchain does not implement sized deallocation?
Specifically, clang that comes with Infer static analyzer does not export this operator, does not have aforementioned define although it supports 20 standard.
That header was mainly for historical toolchains where feature detection macros were poorly implemented. I'm minded to have it disable itself entirely if a toolchain is new enough. This is why I was asking what toolchain you are using.
I'm currently thinking if:
__cplusplusis C++ 23 or later_MSC_VERis 1920 or later__GNUC__is 12 or later__clang_major__is 17 or later
... we'll have that header self disable entirely as a first step. This work for you?
Which C++ 14 toolchain does not implement sized deallocation?
Clang required an explicit opt in for sized deallocations up until clang 19: llvm/llvm-project@130e93c
Here's STL file where these methods are defined.
As you may see, they are defined only if the aforementioned define is specified. If the definition does not present by any reason, then the methods are inaccessible. When cpp_feature.h is included after <new> is included, then the code is broken.
Furthermore, there's a compiler option -fno-sized-deallocation available that may break code in a similar way.
root@6db8013c22ac:/# cat /usr/lib/gcc/x86_64-linux-gnu/11/../../../../include/c++/11/new
// The -*- C++ -*- dynamic memory management header.
// Copyright (C) 1994-2021 Free Software Foundation, Inc.
// This file is part of GCC.
//
// GCC 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, or (at your option)
// any later version.
//
// GCC 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.
//
// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.
// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
// <http://www.gnu.org/licenses/>.
/** @file new
* This is a Standard C++ Library header.
*
* The header @c new defines several functions to manage dynamic memory and
* handling memory allocation errors; see
* https://gcc.gnu.org/onlinedocs/libstdc++/manual/dynamic_memory.html
* for more.
*/
#ifndef _NEW
#define _NEW
#pragma GCC system_header
#include <bits/c++config.h>
#include <bits/exception.h>
#pragma GCC visibility push(default)
extern "C++" {
namespace std
{
/**
* @brief Exception possibly thrown by @c new.
* @ingroup exceptions
*
* @c bad_alloc (or classes derived from it) is used to report allocation
* errors from the throwing forms of @c new. */
class bad_alloc : public exception
{
public:
bad_alloc() throw() { }
#if __cplusplus >= 201103L
bad_alloc(const bad_alloc&) = default;
bad_alloc& operator=(const bad_alloc&) = default;
#endif
// This declaration is not useless:
// http://gcc.gnu.org/onlinedocs/gcc-3.0.2/gcc_6.html#SEC118
virtual ~bad_alloc() throw();
// See comment in eh_exception.cc.
virtual const char* what() const throw();
};
#if __cplusplus >= 201103L
class bad_array_new_length : public bad_alloc
{
public:
bad_array_new_length() throw() { }
// This declaration is not useless:
// http://gcc.gnu.org/onlinedocs/gcc-3.0.2/gcc_6.html#SEC118
virtual ~bad_array_new_length() throw();
// See comment in eh_exception.cc.
virtual const char* what() const throw();
};
#endif
#if __cpp_aligned_new
enum class align_val_t: size_t {};
#endif
struct nothrow_t
{
#if __cplusplus >= 201103L
explicit nothrow_t() = default;
#endif
};
extern const nothrow_t nothrow;
/** If you write your own error handler to be called by @c new, it must
* be of this type. */
typedef void (*new_handler)();
/// Takes a replacement handler as the argument, returns the
/// previous handler.
new_handler set_new_handler(new_handler) throw();
#if __cplusplus >= 201103L
/// Return the current new handler.
new_handler get_new_handler() noexcept;
#endif
} // namespace std
//@{
/** These are replaceable signatures:
* - normal single new and delete (no arguments, throw @c bad_alloc on error)
* - normal array new and delete (same)
* - @c nothrow single new and delete (take a @c nothrow argument, return
* @c NULL on error)
* - @c nothrow array new and delete (same)
*
* Placement new and delete signatures (take a memory address argument,
* does nothing) may not be replaced by a user's program.
*/
_GLIBCXX_NODISCARD void* operator new(std::size_t) _GLIBCXX_THROW (std::bad_alloc)
__attribute__((__externally_visible__));
_GLIBCXX_NODISCARD void* operator new[](std::size_t) _GLIBCXX_THROW (std::bad_alloc)
__attribute__((__externally_visible__));
void operator delete(void*) _GLIBCXX_USE_NOEXCEPT
__attribute__((__externally_visible__));
void operator delete[](void*) _GLIBCXX_USE_NOEXCEPT
__attribute__((__externally_visible__));
#if __cpp_sized_deallocation
void operator delete(void*, std::size_t) _GLIBCXX_USE_NOEXCEPT
__attribute__((__externally_visible__));
void operator delete[](void*, std::size_t) _GLIBCXX_USE_NOEXCEPT
__attribute__((__externally_visible__));
#endif
_GLIBCXX_NODISCARD void* operator new(std::size_t, const std::nothrow_t&) _GLIBCXX_USE_NOEXCEPT
__attribute__((__externally_visible__, __alloc_size__ (1), __malloc__));
_GLIBCXX_NODISCARD void* operator new[](std::size_t, const std::nothrow_t&) _GLIBCXX_USE_NOEXCEPT
__attribute__((__externally_visible__, __alloc_size__ (1), __malloc__));
void operator delete(void*, const std::nothrow_t&) _GLIBCXX_USE_NOEXCEPT
__attribute__((__externally_visible__));
void operator delete[](void*, const std::nothrow_t&) _GLIBCXX_USE_NOEXCEPT
__attribute__((__externally_visible__));
#if __cpp_aligned_new
_GLIBCXX_NODISCARD void* operator new(std::size_t, std::align_val_t)
__attribute__((__externally_visible__, __alloc_size__ (1), __malloc__));
_GLIBCXX_NODISCARD void* operator new(std::size_t, std::align_val_t, const std::nothrow_t&)
_GLIBCXX_USE_NOEXCEPT __attribute__((__externally_visible__, __alloc_size__ (1), __malloc__));
void operator delete(void*, std::align_val_t)
_GLIBCXX_USE_NOEXCEPT __attribute__((__externally_visible__));
void operator delete(void*, std::align_val_t, const std::nothrow_t&)
_GLIBCXX_USE_NOEXCEPT __attribute__((__externally_visible__));
_GLIBCXX_NODISCARD void* operator new[](std::size_t, std::align_val_t)
__attribute__((__externally_visible__, __alloc_size__ (1), __malloc__));
_GLIBCXX_NODISCARD void* operator new[](std::size_t, std::align_val_t, const std::nothrow_t&)
_GLIBCXX_USE_NOEXCEPT __attribute__((__externally_visible__, __alloc_size__ (1), __malloc__));
void operator delete[](void*, std::align_val_t)
_GLIBCXX_USE_NOEXCEPT __attribute__((__externally_visible__));
void operator delete[](void*, std::align_val_t, const std::nothrow_t&)
_GLIBCXX_USE_NOEXCEPT __attribute__((__externally_visible__));
#if __cpp_sized_deallocation
void operator delete(void*, std::size_t, std::align_val_t)
_GLIBCXX_USE_NOEXCEPT __attribute__((__externally_visible__));
void operator delete[](void*, std::size_t, std::align_val_t)
_GLIBCXX_USE_NOEXCEPT __attribute__((__externally_visible__));
#endif // __cpp_sized_deallocation
#endif // __cpp_aligned_new
// Default placement versions of operator new.
_GLIBCXX_NODISCARD inline void* operator new(std::size_t, void* __p) _GLIBCXX_USE_NOEXCEPT
{ return __p; }
_GLIBCXX_NODISCARD inline void* operator new[](std::size_t, void* __p) _GLIBCXX_USE_NOEXCEPT
{ return __p; }
// Default placement versions of operator delete.
inline void operator delete (void*, void*) _GLIBCXX_USE_NOEXCEPT { }
inline void operator delete[](void*, void*) _GLIBCXX_USE_NOEXCEPT { }
//@}
} // extern "C++"
#if __cplusplus >= 201703L
#ifdef _GLIBCXX_HAVE_BUILTIN_LAUNDER
namespace std
{
#define __cpp_lib_launder 201606
/// Pointer optimization barrier [ptr.launder]
template<typename _Tp>
[[nodiscard]] constexpr _Tp*
launder(_Tp* __p) noexcept
{ return __builtin_launder(__p); }
// The program is ill-formed if T is a function type or
// (possibly cv-qualified) void.
template<typename _Ret, typename... _Args _GLIBCXX_NOEXCEPT_PARM>
void launder(_Ret (*)(_Args...) _GLIBCXX_NOEXCEPT_QUAL) = delete;
template<typename _Ret, typename... _Args _GLIBCXX_NOEXCEPT_PARM>
void launder(_Ret (*)(_Args......) _GLIBCXX_NOEXCEPT_QUAL) = delete;
void launder(void*) = delete;
void launder(const void*) = delete;
void launder(volatile void*) = delete;
void launder(const volatile void*) = delete;
}
#endif // _GLIBCXX_HAVE_BUILTIN_LAUNDER
#endif // C++17
#if __cplusplus > 201703L
namespace std
{
/// Tag type used to declare a class-specific operator delete that can
/// invoke the destructor before deallocating the memory.
struct destroying_delete_t
{
explicit destroying_delete_t() = default;
};
/// Tag variable of type destroying_delete_t.
inline constexpr destroying_delete_t destroying_delete{};
}
// Only define the feature test macro if the compiler supports the feature:
#if __cpp_impl_destroying_delete
# define __cpp_lib_destroying_delete 201806L
#endif
#endif // C++20
#pragma GCC visibility pop
#endif
Here’s an example of similar case being solved in
android-ndk-r26d/toolchains/llvm/prebuilt/linux-x86_64/sysroot/usr/include/c++/v1/new
#if !defined(__cpp_sized_deallocation) || __cpp_sized_deallocation < 201309L
#define _LIBCPP_HAS_NO_LANGUAGE_SIZED_DEALLOCATION
#endif
See what you make of that fix.
@ned14, thank you for the fix! I can't reproduce the issue with the updated file.