gcc/libstdc++-v3/include/debug/formatter.h
Jonathan Wakely c2fb0a1a2e libstdc++: Make self-move well-defined for containers [PR 85828]
The C++ LWG recently confirmed that self-move assignment should not have
undefined behaviour for standard containers (see the proposed resolution
of LWG 2839). The result should be a valid but unspecified value, just
like other times when a container is moved from.

Our std::list, std::__cxx11::basic_string and unordered containers all
have bugs which result in undefined behaviour.

For std::list the problem is that we clear the previous contents using
_M_clear() instead of clear(). This means the _M_next, _M_prev and
_M_size members are not zeroed, and so after we "update" them (with
their existing values), we are left with dangling pointers and a
non-zero size, but no elements.

For the unordered containers the problem is similar. _Hashtable first
deallocates the existing contents, then takes ownership of the pointers
from the RHS object (which has just had its contents deallocated so the
pointers are dangling).

For std::basic_string it's a little more subtle. When the string is
local (i.e. fits in the SSO buffer) we use char_traits::copy to copy the
contents from this->data() to __rhs.data(). When &__rhs == this that
copy violates the precondition that the ranges don't overlap. We only
need to check for self-move for this case where it's local, because the
only other case that can be true for self-move is that it's non-local
but the allocators compare equal. In that case the data pointer is
neither deallocated nor leaked, so the result is well-defined.

This patch also makes a small optimization for std::deque move
assignment, to use the efficient move when is_always_equal is false, but
the allocators compare equal at runtime.

Finally, we need to remove all the Debug Mode checks which abort the
program when a self-move is detected, because it's not undefined to do
that.

Before PR 85828 can be closed we should also look into fixing
std::shuffle so it doesn't do any redundant self-swaps.

libstdc++-v3/ChangeLog:

	PR libstdc++/85828
	* include/bits/basic_string.h (operator=(basic_string&&)): Check
	for self-move before copying with char_traits::copy.
	* include/bits/hashtable.h (operator=(_Hashtable&&)): Check for
	self-move.
	* include/bits/stl_deque.h (_M_move_assign1(deque&&, false_type)):
	Check for equal allocators.
	* include/bits/stl_list.h (_M_move_assign(list&&, true_type)):
	Call clear() instead of _M_clear().
	* include/debug/formatter.h (__msg_self_move_assign): Change
	comment.
	* include/debug/macros.h (__glibcxx_check_self_move_assign):
	(_GLIBCXX_DEBUG_VERIFY): Remove.
	* include/debug/safe_container.h (operator=(_Safe_container&&)):
	Remove assertion check for safe move and make it well-defined.
	* include/debug/safe_iterator.h (operator=(_Safe_iterator&&)):
	Remove assertion check for self-move.
	* include/debug/safe_local_iterator.h
	(operator=(_Safe_local_iterator&&)): Likewise.
	* testsuite/21_strings/basic_string/cons/char/self_move.cc: New test.
	* testsuite/23_containers/deque/cons/self_move.cc: New test.
	* testsuite/23_containers/forward_list/cons/self_move.cc: New test.
	* testsuite/23_containers/list/cons/self_move.cc: New test.
	* testsuite/23_containers/set/cons/self_move.cc: New test.
	* testsuite/23_containers/unordered_set/cons/self_move.cc: New test.
	* testsuite/23_containers/vector/cons/self_move.cc: New test.
2020-08-12 20:36:00 +01:00

594 lines
17 KiB
C++

// Debug-mode error formatting implementation -*- C++ -*-
// Copyright (C) 2003-2020 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library. This library 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.
// This library 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 debug/formatter.h
* This file is a GNU debug extension to the Standard C++ Library.
*/
#ifndef _GLIBCXX_DEBUG_FORMATTER_H
#define _GLIBCXX_DEBUG_FORMATTER_H 1
#include <bits/c++config.h>
#if __cpp_rtti
# include <typeinfo>
# define _GLIBCXX_TYPEID(_Type) &typeid(_Type)
#else
namespace std
{
class type_info;
}
# define _GLIBCXX_TYPEID(_Type) 0
#endif
#if __cplusplus >= 201103L
namespace __gnu_cxx
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _Iterator, typename _Container>
class __normal_iterator;
_GLIBCXX_END_NAMESPACE_VERSION
}
namespace std
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _Iterator>
class reverse_iterator;
template<typename _Iterator>
class move_iterator;
_GLIBCXX_END_NAMESPACE_VERSION
}
#endif
namespace __gnu_debug
{
using std::type_info;
template<typename _Iterator>
bool __check_singular(const _Iterator&);
class _Safe_sequence_base;
template<typename _Iterator, typename _Sequence, typename _Category>
class _Safe_iterator;
template<typename _Iterator, typename _Sequence>
class _Safe_local_iterator;
template<typename _Sequence>
class _Safe_sequence;
enum _Debug_msg_id
{
// General checks
__msg_valid_range,
__msg_insert_singular,
__msg_insert_different,
__msg_erase_bad,
__msg_erase_different,
__msg_subscript_oob,
__msg_empty,
__msg_unpartitioned,
__msg_unpartitioned_pred,
__msg_unsorted,
__msg_unsorted_pred,
__msg_not_heap,
__msg_not_heap_pred,
// std::bitset checks
__msg_bad_bitset_write,
__msg_bad_bitset_read,
__msg_bad_bitset_flip,
// std::list checks
__msg_self_splice,
__msg_splice_alloc,
__msg_splice_bad,
__msg_splice_other,
__msg_splice_overlap,
// iterator checks
__msg_init_singular,
__msg_init_copy_singular,
__msg_init_const_singular,
__msg_copy_singular,
__msg_bad_deref,
__msg_bad_inc,
__msg_bad_dec,
__msg_iter_subscript_oob,
__msg_advance_oob,
__msg_retreat_oob,
__msg_iter_compare_bad,
__msg_compare_different,
__msg_iter_order_bad,
__msg_order_different,
__msg_distance_bad,
__msg_distance_different,
// istream_iterator
__msg_deref_istream,
__msg_inc_istream,
// ostream_iterator
__msg_output_ostream,
// istreambuf_iterator
__msg_deref_istreambuf,
__msg_inc_istreambuf,
// forward_list
__msg_insert_after_end,
__msg_erase_after_bad,
__msg_valid_range2,
// unordered container local iterators
__msg_local_iter_compare_bad,
__msg_non_empty_range,
// self move assign (no longer used)
__msg_self_move_assign,
// unordered container buckets
__msg_bucket_index_oob,
__msg_valid_load_factor,
// others
__msg_equal_allocs,
__msg_insert_range_from_self,
__msg_irreflexive_ordering
};
class _Error_formatter
{
// Tags denoting the type of parameter for construction
struct _Is_iterator { };
struct _Is_iterator_value_type { };
struct _Is_sequence { };
struct _Is_instance { };
public:
/// Whether an iterator is constant, mutable, or unknown
enum _Constness
{
__unknown_constness,
__const_iterator,
__mutable_iterator,
__last_constness
};
// The state of the iterator (fine-grained), if we know it.
enum _Iterator_state
{
__unknown_state,
__singular, // singular, may still be attached to a sequence
__begin, // dereferenceable, and at the beginning
__middle, // dereferenceable, not at the beginning
__end, // past-the-end, may be at beginning if sequence empty
__before_begin, // before begin
__rbegin, // dereferenceable, and at the reverse-beginning
__rmiddle, // reverse-dereferenceable, not at the reverse-beginning
__rend, // reverse-past-the-end
__last_state
};
// A parameter that may be referenced by an error message
struct _Parameter
{
enum
{
__unused_param,
__iterator,
__sequence,
__integer,
__string,
__instance,
__iterator_value_type
} _M_kind;
struct _Type
{
const char* _M_name;
const type_info* _M_type;
};
struct _Instance : _Type
{
const void* _M_address;
};
union
{
// When _M_kind == __iterator
struct : _Instance
{
_Constness _M_constness;
_Iterator_state _M_state;
const void* _M_sequence;
const type_info* _M_seq_type;
} _M_iterator;
// When _M_kind == __sequence
_Instance _M_sequence;
// When _M_kind == __integer
struct
{
const char* _M_name;
long _M_value;
} _M_integer;
// When _M_kind == __string
struct
{
const char* _M_name;
const char* _M_value;
} _M_string;
// When _M_kind == __instance
_Instance _M_instance;
// When _M_kind == __iterator_value_type
_Type _M_iterator_value_type;
} _M_variant;
_Parameter() : _M_kind(__unused_param), _M_variant() { }
_Parameter(long __value, const char* __name)
: _M_kind(__integer), _M_variant()
{
_M_variant._M_integer._M_name = __name;
_M_variant._M_integer._M_value = __value;
}
_Parameter(const char* __value, const char* __name)
: _M_kind(__string), _M_variant()
{
_M_variant._M_string._M_name = __name;
_M_variant._M_string._M_value = __value;
}
template<typename _Iterator, typename _Sequence, typename _Category>
_Parameter(_Safe_iterator<_Iterator, _Sequence, _Category> const& __it,
const char* __name, _Is_iterator)
: _M_kind(__iterator), _M_variant()
{
_M_variant._M_iterator._M_name = __name;
_M_variant._M_iterator._M_address = std::__addressof(__it);
_M_variant._M_iterator._M_type = _GLIBCXX_TYPEID(_Iterator);
_M_variant._M_iterator._M_constness =
__it._S_constant() ? __const_iterator : __mutable_iterator;
_M_variant._M_iterator._M_sequence = __it._M_get_sequence();
_M_variant._M_iterator._M_seq_type = _GLIBCXX_TYPEID(_Sequence);
if (__it._M_singular())
_M_variant._M_iterator._M_state = __singular;
else
{
if (__it._M_is_before_begin())
_M_variant._M_iterator._M_state = __before_begin;
else if (__it._M_is_end())
_M_variant._M_iterator._M_state = __end;
else if (__it._M_is_begin())
_M_variant._M_iterator._M_state = __begin;
else
_M_variant._M_iterator._M_state = __middle;
}
}
template<typename _Iterator, typename _Sequence>
_Parameter(_Safe_local_iterator<_Iterator, _Sequence> const& __it,
const char* __name, _Is_iterator)
: _M_kind(__iterator), _M_variant()
{
_M_variant._M_iterator._M_name = __name;
_M_variant._M_iterator._M_address = std::__addressof(__it);
_M_variant._M_iterator._M_type = _GLIBCXX_TYPEID(_Iterator);
_M_variant._M_iterator._M_constness =
__it._S_constant() ? __const_iterator : __mutable_iterator;
_M_variant._M_iterator._M_sequence = __it._M_get_sequence();
_M_variant._M_iterator._M_seq_type = _GLIBCXX_TYPEID(_Sequence);
if (__it._M_singular())
_M_variant._M_iterator._M_state = __singular;
else
{
if (__it._M_is_end())
_M_variant._M_iterator._M_state = __end;
else if (__it._M_is_begin())
_M_variant._M_iterator._M_state = __begin;
else
_M_variant._M_iterator._M_state = __middle;
}
}
template<typename _Type>
_Parameter(const _Type* const& __it, const char* __name, _Is_iterator)
: _M_kind(__iterator), _M_variant()
{
_M_variant._M_iterator._M_name = __name;
_M_variant._M_iterator._M_address = std::__addressof(__it);
_M_variant._M_iterator._M_type = _GLIBCXX_TYPEID(__it);
_M_variant._M_iterator._M_constness = __const_iterator;
_M_variant._M_iterator._M_state = __it ? __unknown_state : __singular;
_M_variant._M_iterator._M_sequence = 0;
_M_variant._M_iterator._M_seq_type = 0;
}
template<typename _Type>
_Parameter(_Type* const& __it, const char* __name, _Is_iterator)
: _M_kind(__iterator), _M_variant()
{
_M_variant._M_iterator._M_name = __name;
_M_variant._M_iterator._M_address = std::__addressof(__it);
_M_variant._M_iterator._M_type = _GLIBCXX_TYPEID(__it);
_M_variant._M_iterator._M_constness = __mutable_iterator;
_M_variant._M_iterator._M_state = __it ? __unknown_state : __singular;
_M_variant._M_iterator._M_sequence = 0;
_M_variant._M_iterator._M_seq_type = 0;
}
template<typename _Iterator>
_Parameter(_Iterator const& __it, const char* __name, _Is_iterator)
: _M_kind(__iterator), _M_variant()
{
_M_variant._M_iterator._M_name = __name;
_M_variant._M_iterator._M_address = std::__addressof(__it);
_M_variant._M_iterator._M_type = _GLIBCXX_TYPEID(__it);
_M_variant._M_iterator._M_constness = __unknown_constness;
_M_variant._M_iterator._M_state =
__gnu_debug::__check_singular(__it) ? __singular : __unknown_state;
_M_variant._M_iterator._M_sequence = 0;
_M_variant._M_iterator._M_seq_type = 0;
}
#if __cplusplus >= 201103L
// The following constructors are only defined in C++11 to take
// advantage of the constructor delegation feature.
template<typename _Iterator, typename _Container>
_Parameter(
__gnu_cxx::__normal_iterator<_Iterator, _Container> const& __it,
const char* __name, _Is_iterator)
: _Parameter(__it.base(), __name, _Is_iterator{})
{ _M_variant._M_iterator._M_type = _GLIBCXX_TYPEID(__it); }
template<typename _Iterator>
_Parameter(std::reverse_iterator<_Iterator> const& __it,
const char* __name, _Is_iterator)
: _Parameter(__it.base(), __name, _Is_iterator{})
{
_M_variant._M_iterator._M_type = _GLIBCXX_TYPEID(__it);
_M_variant._M_iterator._M_state
= _S_reverse_state(_M_variant._M_iterator._M_state);
}
template<typename _Iterator, typename _Sequence, typename _Category>
_Parameter(std::reverse_iterator<_Safe_iterator<_Iterator, _Sequence,
_Category>> const& __it,
const char* __name, _Is_iterator)
: _Parameter(__it.base(), __name, _Is_iterator{})
{
_M_variant._M_iterator._M_type
= _GLIBCXX_TYPEID(std::reverse_iterator<_Iterator>);
_M_variant._M_iterator._M_state
= _S_reverse_state(_M_variant._M_iterator._M_state);
}
template<typename _Iterator>
_Parameter(std::move_iterator<_Iterator> const& __it,
const char* __name, _Is_iterator)
: _Parameter(__it.base(), __name, _Is_iterator{})
{ _M_variant._M_iterator._M_type = _GLIBCXX_TYPEID(__it); }
template<typename _Iterator, typename _Sequence, typename _Category>
_Parameter(std::move_iterator<_Safe_iterator<_Iterator, _Sequence,
_Category>> const& __it,
const char* __name, _Is_iterator)
: _Parameter(__it.base(), __name, _Is_iterator{})
{
_M_variant._M_iterator._M_type
= _GLIBCXX_TYPEID(std::move_iterator<_Iterator>);
}
private:
_Iterator_state
_S_reverse_state(_Iterator_state __state)
{
switch (__state)
{
case __begin:
return __rend;
case __middle:
return __rmiddle;
case __end:
return __rbegin;
default:
return __state;
}
}
public:
#endif
template<typename _Sequence>
_Parameter(const _Safe_sequence<_Sequence>& __seq,
const char* __name, _Is_sequence)
: _M_kind(__sequence), _M_variant()
{
_M_variant._M_sequence._M_name = __name;
_M_variant._M_sequence._M_address =
static_cast<const _Sequence*>(std::__addressof(__seq));
_M_variant._M_sequence._M_type = _GLIBCXX_TYPEID(_Sequence);
}
template<typename _Sequence>
_Parameter(const _Sequence& __seq, const char* __name, _Is_sequence)
: _M_kind(__sequence), _M_variant()
{
_M_variant._M_sequence._M_name = __name;
_M_variant._M_sequence._M_address = std::__addressof(__seq);
_M_variant._M_sequence._M_type = _GLIBCXX_TYPEID(_Sequence);
}
template<typename _Iterator>
_Parameter(const _Iterator& __it, const char* __name,
_Is_iterator_value_type)
: _M_kind(__iterator_value_type), _M_variant()
{
_M_variant._M_iterator_value_type._M_name = __name;
_M_variant._M_iterator_value_type._M_type =
_GLIBCXX_TYPEID(typename std::iterator_traits<_Iterator>::value_type);
}
template<typename _Type>
_Parameter(const _Type& __inst, const char* __name, _Is_instance)
: _M_kind(__instance), _M_variant()
{
_M_variant._M_instance._M_name = __name;
_M_variant._M_instance._M_address = &__inst;
_M_variant._M_instance._M_type = _GLIBCXX_TYPEID(_Type);
}
#if !_GLIBCXX_INLINE_VERSION
void
_M_print_field(const _Error_formatter* __formatter,
const char* __name) const _GLIBCXX_DEPRECATED;
void
_M_print_description(const _Error_formatter* __formatter)
const _GLIBCXX_DEPRECATED;
#endif
};
template<typename _Iterator>
_Error_formatter&
_M_iterator(const _Iterator& __it, const char* __name = 0)
{
if (_M_num_parameters < std::size_t(__max_parameters))
_M_parameters[_M_num_parameters++] = _Parameter(__it, __name,
_Is_iterator());
return *this;
}
template<typename _Iterator>
_Error_formatter&
_M_iterator_value_type(const _Iterator& __it,
const char* __name = 0)
{
if (_M_num_parameters < __max_parameters)
_M_parameters[_M_num_parameters++] =
_Parameter(__it, __name, _Is_iterator_value_type());
return *this;
}
_Error_formatter&
_M_integer(long __value, const char* __name = 0)
{
if (_M_num_parameters < __max_parameters)
_M_parameters[_M_num_parameters++] = _Parameter(__value, __name);
return *this;
}
_Error_formatter&
_M_string(const char* __value, const char* __name = 0)
{
if (_M_num_parameters < __max_parameters)
_M_parameters[_M_num_parameters++] = _Parameter(__value, __name);
return *this;
}
template<typename _Sequence>
_Error_formatter&
_M_sequence(const _Sequence& __seq, const char* __name = 0)
{
if (_M_num_parameters < __max_parameters)
_M_parameters[_M_num_parameters++] = _Parameter(__seq, __name,
_Is_sequence());
return *this;
}
template<typename _Type>
_Error_formatter&
_M_instance(const _Type& __inst, const char* __name = 0)
{
if (_M_num_parameters < __max_parameters)
_M_parameters[_M_num_parameters++] = _Parameter(__inst, __name,
_Is_instance());
return *this;
}
_Error_formatter&
_M_message(const char* __text)
{ _M_text = __text; return *this; }
// Kept const qualifier for backward compatibility, to keep the same
// exported symbol.
_Error_formatter&
_M_message(_Debug_msg_id __id) const throw ();
_GLIBCXX_NORETURN void
_M_error() const;
#if !_GLIBCXX_INLINE_VERSION
template<typename _Tp>
void
_M_format_word(char*, int, const char*, _Tp)
const throw () _GLIBCXX_DEPRECATED;
void
_M_print_word(const char* __word) const _GLIBCXX_DEPRECATED;
void
_M_print_string(const char* __string) const _GLIBCXX_DEPRECATED;
#endif
private:
_Error_formatter(const char* __file, unsigned int __line,
const char* __function)
: _M_file(__file), _M_line(__line), _M_num_parameters(0), _M_text(0)
, _M_function(__function)
{ }
#if !_GLIBCXX_INLINE_VERSION
void
_M_get_max_length() const throw () _GLIBCXX_DEPRECATED;
#endif
enum { __max_parameters = 9 };
const char* _M_file;
unsigned int _M_line;
_Parameter _M_parameters[__max_parameters];
unsigned int _M_num_parameters;
const char* _M_text;
const char* _M_function;
public:
static _Error_formatter&
_S_at(const char* __file, unsigned int __line, const char* __function)
{
static _Error_formatter __formatter(__file, __line, __function);
return __formatter;
}
};
} // namespace __gnu_debug
#undef _GLIBCXX_TYPEID
#endif