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PR libstdc++/90388 fix std::hash<unique_ptr<T,D>> bugs 

A disabled specialization should not be callable, so move the function
call operator into a new base class which correctly implements the
disabled hash semantics. For the versioned namespace configuration do
not derive from __poison_hash in the enabled case, as the empty base
class serves no purpose but potentially increases the object size. For
the default configuration that base class must be kept, to preserve
layout.

An enabled specialization should not be unconditionally noexcept,
because the underlying hash object might throw.

	PR libstdc++/90388
	* include/bits/unique_ptr.h (default_delete, default_delete<T[]>):
	Use _Require for constraints.
	(operator>(nullptr_t, const unique_ptr<T,D>&)): Implement exactly as
	per the standard.
	(__uniq_ptr_hash): New base class with conditionally-disabled call
	operator.
	(hash<unique_ptr<T,D>>): Derive from __uniq_ptr_hash.
	* testsuite/20_util/default_delete/48631_neg.cc: Adjust dg-error line.
	* testsuite/20_util/unique_ptr/hash/90388.cc: New test.

From-SVN: r271078
This commit is contained in:
Jonathan Wakely 2019-05-10 22:41:16 +01:00 committed by Jonathan Wakely
parent 302b699607
commit 7fb65a8759
4 changed files with 138 additions and 23 deletions
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11
libstdc++-v3/ChangeLog
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@ -1,5 +1,16 @@
2019-05-10 Jonathan Wakely <jwakely@redhat.com>
PR libstdc++/90388
* include/bits/unique_ptr.h (default_delete, default_delete<T[]>):
Use _Require for constraints.
(operator>(nullptr_t, const unique_ptr<T,D>&)): Implement exactly as
per the standard.
(__uniq_ptr_hash): New base class with conditionally-disabled call
operator.
(hash<unique_ptr<T,D>>): Derive from __uniq_ptr_hash.
* testsuite/20_util/default_delete/48631_neg.cc: Adjust dg-error line.
* testsuite/20_util/unique_ptr/hash/90388.cc: New test.
* include/bits/shared_ptr.h: Improve docs.
* include/bits/shared_ptr_base.h: Likewise.
* include/bits/stl_uninitialized.h: Likewise.

58
libstdc++-v3/include/bits/unique_ptr.h
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@ -66,8 +66,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
* Allows conversion from a deleter for objects of another type, `_Up`,
* only if `_Up*` is convertible to `_Tp*`.
*/
template<typename _Up, typename = typename
enable_if<is_convertible<_Up*, _Tp*>::value>::type>
template<typename _Up,
typename = _Require<is_convertible<_Up*, _Tp*>>>
default_delete(const default_delete<_Up>&) noexcept { }
/// Calls `delete __ptr`
@ -102,19 +102,19 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
* it is undefined to `delete[]` an array of derived types through a
* pointer to the base type.
*/
template<typename _Up, typename = typename
enable_if<is_convertible<_Up(*)[], _Tp(*)[]>::value>::type>
template<typename _Up,
typename = _Require<is_convertible<_Up(*)[], _Tp(*)[]>>>
default_delete(const default_delete<_Up[]>&) noexcept { }
/// Calls `delete[] __ptr`
template<typename _Up>
typename enable_if<is_convertible<_Up(*)[], _Tp(*)[]>::value>::type
typename enable_if<is_convertible<_Up(*)[], _Tp(*)[]>::value>::type
operator()(_Up* __ptr) const
{
static_assert(sizeof(_Tp)>0,
"can't delete pointer to incomplete type");
delete [] __ptr;
}
{
static_assert(sizeof(_Tp)>0,
"can't delete pointer to incomplete type");
delete [] __ptr;
}
};
/// @cond undocumented
@ -712,7 +712,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
unique_ptr<_Tp, _Dp>&) = delete;
#endif
/// Equality operator for unique_ptr objects, compares the owned pointers.
/// Equality operator for unique_ptr objects, compares the owned pointers
template<typename _Tp, typename _Dp,
typename _Up, typename _Ep>
_GLIBCXX_NODISCARD inline bool
@ -848,23 +848,37 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
_GLIBCXX_NODISCARD inline bool
operator>=(nullptr_t, const unique_ptr<_Tp, _Dp>& __x)
{ return !(nullptr < __x); }
// @} relates unique_ptr
/// @cond undocumented
template<typename _Up, typename _Ptr = typename _Up::pointer,
bool = __poison_hash<_Ptr>::__enable_hash_call>
struct __uniq_ptr_hash
#if ! _GLIBCXX_INLINE_VERSION
: private __poison_hash<_Ptr>
#endif
{
size_t
operator()(const _Up& __u) const
noexcept(noexcept(std::declval<hash<_Ptr>>()(std::declval<_Ptr>())))
{ return hash<_Ptr>()(__u.get()); }
};
template<typename _Up, typename _Ptr>
struct __uniq_ptr_hash<_Up, _Ptr, false>
: private __poison_hash<_Ptr>
{ };
/// @endcond
/// std::hash specialization for unique_ptr.
template<typename _Tp, typename _Dp>
struct hash<unique_ptr<_Tp, _Dp>>
: public __hash_base<size_t, unique_ptr<_Tp, _Dp>>,
private __poison_hash<typename unique_ptr<_Tp, _Dp>::pointer>
{
size_t
operator()(const unique_ptr<_Tp, _Dp>& __u) const noexcept
{
typedef unique_ptr<_Tp, _Dp> _UP;
return std::hash<typename _UP::pointer>()(__u.get());
}
};
public __uniq_ptr_hash<unique_ptr<_Tp, _Dp>>
{ };
#if __cplusplus > 201103L
/// @relates unique_ptr @{
#define __cpp_lib_make_unique 201304
/// @cond undocumented
@ -899,9 +913,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _Tp, typename... _Args>
inline typename _MakeUniq<_Tp>::__invalid_type
make_unique(_Args&&...) = delete;
// @} relates unique_ptr
#endif
// @} relates unique_ptr
// @} group pointer_abstractions
#if __cplusplus >= 201703L

2
libstdc++-v3/testsuite/20_util/default_delete/48631_neg.cc
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@ -26,4 +26,4 @@ struct D : B { };
D d;
std::default_delete<B[]> db;
typedef decltype(db(&d)) type; // { dg-error "no match" }
// { dg-error "no type" "" { target *-*-* } 111 }
// { dg-error "no type" "" { target *-*-* } 112 }

90
libstdc++-v3/testsuite/20_util/unique_ptr/hash/90388.cc Normal file
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@ -0,0 +1,90 @@
// Copyright (C) 2019 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.
// You should have received a copy of the GNU General Public License along
// with this library; see the file COPYING3. If not see
// <http://www.gnu.org/licenses/>.
// { dg-do run { target c++11 } }
#include <memory>
template<typename Func, typename Arg, typename = void>
struct is_callable
: std::false_type
{ };
template<typename Func, typename Arg>
struct is_callable<Func, Arg,
decltype((void)(std::declval<Func&>()(std::declval<Arg>())))>
: std::true_type
{ };
void
test01()
{
struct D {
struct pointer { };
void operator()(pointer) const noexcept { }
};
static_assert( !is_callable<std::hash<D::pointer>&, D::pointer>::value );
using UP = std::unique_ptr<int, D>;
// [unord.hash]
// Disabled specializations of hash are not function object types
static_assert( !is_callable<std::hash<UP>&, UP>::value );
static_assert( !is_callable<std::hash<UP>&, UP&>::value );
static_assert( !is_callable<std::hash<UP>&, const UP&>::value );
}
struct D {
struct pointer { };
void operator()(pointer) const noexcept { }
};
bool operator==(D::pointer, std::nullptr_t) { return false; }
bool operator!=(D::pointer, std::nullptr_t) { return true; }
namespace std {
template<> struct hash<D::pointer> {
size_t operator()(D::pointer) const { throw 1; }
};
}
void
test02()
{
using UP = std::unique_ptr<int, D>;
UP p;
std::hash<UP> h;
try {
// [util.smartptr.hash]
// The member functions are not guaranteed to be noexcept.
h(p);
throw "should not reach here";
} catch (int) {
// Should catch exception here, rather than terminating.
}
// Should still be noexcept if the underlying hash object is:
using UP2 = std::unique_ptr<int>;
UP2 p2;
std::hash<UP2> h2;
static_assert( noexcept(h2(p2)), "operator() is noexcept" );
}
int
main()
{
test02();
}