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PR libstdc++/85184 remove debug assertions from std::variant

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The __glibcxx_assert macro should be used to check preconditions that
users must meet, not to check postconditions that the implementation
must meet. We have tests to verify std::variant meets its
postconditions, users shouldn't pay for those checks at runtime.

	PR libstdc++/85184
	* include/std/variant (_Copy_assign_base, _Move_assign_base, variant):
	Remove assertions.
	(variant::emplace<_Tp>): Remove result of emplace<N> directly.

From-SVN: r270117
This commit is contained in:
Jonathan Wakely 2019-04-03 10:47:51 +01:00 committed by Jonathan Wakely
parent 0cb78ef4bc
commit 59e36c85e7
2 changed files with 14 additions and 19 deletions
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5
libstdc++-v3/ChangeLog
View File

@ -1,5 +1,10 @@
2019-04-03 Jonathan Wakely <jwakely@redhat.com>
PR libstdc++/85184
* include/std/variant (_Copy_assign_base, _Move_assign_base, variant):
Remove assertions.
(variant::emplace<_Tp>): Remove result of emplace<N> directly.
* include/std/string (__hash_string_base): New class template defining
operator() for hashing strings.
(hash<pmr::string>, hash<pmr::u8string>, hash<pmr::u16string>)

28
libstdc++-v3/include/std/variant
View File

@ -612,7 +612,6 @@ namespace __variant
this->_M_reset();
return {};
}, __variant_cast<_Types...>(__rhs));
__glibcxx_assert(this->_M_index == __rhs._M_index);
return *this;
}
@ -670,7 +669,6 @@ namespace __variant
this->_M_reset();
return {};
}, __variant_cast<_Types...>(__rhs));
__glibcxx_assert(this->_M_index == __rhs._M_index);
return *this;
}
@ -1245,7 +1243,7 @@ namespace __variant
noexcept(is_nothrow_constructible_v<__accepted_type<_Tp&&>, _Tp&&>)
: variant(in_place_index<__accepted_index<_Tp&&>>,
std::forward<_Tp>(__t))
{ __glibcxx_assert(holds_alternative<__accepted_type<_Tp&&>>(*this)); }
{ }
template<typename _Tp, typename... _Args,
typename = enable_if_t<__exactly_once<_Tp>
@ -1254,7 +1252,7 @@ namespace __variant
variant(in_place_type_t<_Tp>, _Args&&... __args)
: variant(in_place_index<__index_of<_Tp>>,
std::forward<_Args>(__args)...)
{ __glibcxx_assert(holds_alternative<_Tp>(*this)); }
{ }
template<typename _Tp, typename _Up, typename... _Args,
typename = enable_if_t<__exactly_once<_Tp>
@ -1265,7 +1263,7 @@ namespace __variant
_Args&&... __args)
: variant(in_place_index<__index_of<_Tp>>, __il,
std::forward<_Args>(__args)...)
{ __glibcxx_assert(holds_alternative<_Tp>(*this)); }
{ }
template<size_t _Np, typename... _Args,
typename = enable_if_t<
@ -1274,7 +1272,7 @@ namespace __variant
variant(in_place_index_t<_Np>, _Args&&... __args)
: _Base(in_place_index<_Np>, std::forward<_Args>(__args)...),
_Default_ctor_enabler(_Enable_default_constructor_tag{})
{ __glibcxx_assert(index() == _Np); }
{ }
template<size_t _Np, typename _Up, typename... _Args,
typename = enable_if_t<is_constructible_v<__to_type<_Np>,
@ -1284,7 +1282,7 @@ namespace __variant
_Args&&... __args)
: _Base(in_place_index<_Np>, __il, std::forward<_Args>(__args)...),
_Default_ctor_enabler(_Enable_default_constructor_tag{})
{ __glibcxx_assert(index() == _Np); }
{ }
template<typename _Tp>
enable_if_t<__exactly_once<__accepted_type<_Tp&&>>
@ -1300,7 +1298,6 @@ namespace __variant
std::get<__index>(*this) = std::forward<_Tp>(__rhs);
else
this->emplace<__index>(std::forward<_Tp>(__rhs));
__glibcxx_assert(holds_alternative<__accepted_type<_Tp&&>>(*this));
return *this;
}
@ -1309,10 +1306,8 @@ namespace __variant
_Tp&>
emplace(_Args&&... __args)
{
auto& ret =
this->emplace<__index_of<_Tp>>(std::forward<_Args>(__args)...);
__glibcxx_assert(holds_alternative<_Tp>(*this));
return ret;
constexpr size_t __index = __index_of<_Tp>;
return this->emplace<__index>(std::forward<_Args>(__args)...);
}
template<typename _Tp, typename _Up, typename... _Args>
@ -1321,11 +1316,8 @@ namespace __variant
_Tp&>
emplace(initializer_list<_Up> __il, _Args&&... __args)
{
auto& ret =
this->emplace<__index_of<_Tp>>(__il,
std::forward<_Args>(__args)...);
__glibcxx_assert(holds_alternative<_Tp>(*this));
return ret;
constexpr size_t __index = __index_of<_Tp>;
return this->emplace<__index>(__il, std::forward<_Args>(__args)...);
}
template<size_t _Np, typename... _Args>
@ -1363,7 +1355,6 @@ namespace __variant
this->_M_index = variant_npos;
__throw_exception_again;
}
__glibcxx_assert(index() == _Np);
return std::get<_Np>(*this);
}
@ -1399,7 +1390,6 @@ namespace __variant
this->_M_index = variant_npos;
__throw_exception_again;
}
__glibcxx_assert(index() == _Np);
return std::get<_Np>(*this);
}