[gcc/devel/omp/gcc-9] PR libstdc++/90220 fix experimental::any_cast for non-object types
Tobias Burnus
burnus@gcc.gnu.org
Thu Mar 5 13:52:00 GMT 2020
https://gcc.gnu.org/g:8e355a1c3b292256605180e55b71296f7c13be6b
commit 8e355a1c3b292256605180e55b71296f7c13be6b
Author: Jonathan Wakely <jwakely@redhat.com>
Date: Thu May 23 15:18:13 2019 +0100
PR libstdc++/90220 fix experimental::any_cast for non-object types
This corresponds to the fixes done for std::any_cast, but has to be done
without if-constexpr. The dummy specialization of _Manager_internal<_Op>
is used to avoid instantiating the real _Manager_internal<T>::_S_manage
function just to compare its address.
Backport from mainline
2019-05-23 Jonathan Wakely <jwakely@redhat.com>
PR libstdc++/90220
* include/experimental/any (__any_caster): Constrain to only be
callable for object types. Use remove_cv_t instead of decay_t.
If the type decays or isn't copy constructible, compare the manager
function to a dummy specialization.
(__any_caster): Add overload constrained for non-object types.
(any::_Manager_internal<_Op>): Add dummy specialization.
* testsuite/experimental/any/misc/any_cast.cc: Test function types
and array types.
From-SVN: r271558
Diff:
---
libstdc++-v3/ChangeLog | 15 ++++++
libstdc++-v3/include/experimental/any | 38 +++++++++++++--
.../testsuite/experimental/any/misc/any_cast.cc | 56 ++++++++++++++++++++--
3 files changed, 101 insertions(+), 8 deletions(-)
diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index 91bd18d..494cf37 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,18 @@
+2019-05-23 Jonathan Wakely <jwakely@redhat.com>
+
+ Backport from mainline
+ 2019-05-23 Jonathan Wakely <jwakely@redhat.com>
+
+ PR libstdc++/90220
+ * include/experimental/any (__any_caster): Constrain to only be
+ callable for object types. Use remove_cv_t instead of decay_t.
+ If the type decays or isn't copy constructible, compare the manager
+ function to a dummy specialization.
+ (__any_caster): Add overload constrained for non-object types.
+ (any::_Manager_internal<_Op>): Add dummy specialization.
+ * testsuite/experimental/any/misc/any_cast.cc: Test function types
+ and array types.
+
2019-05-22 Jonathan Wakely <jwakely@redhat.com>
Backport from mainline
diff --git a/libstdc++-v3/include/experimental/any b/libstdc++-v3/include/experimental/any
index ed7a115..1ba29c7 100644
--- a/libstdc++-v3/include/experimental/any
+++ b/libstdc++-v3/include/experimental/any
@@ -300,7 +300,8 @@ inline namespace fundamentals_v1
_Storage _M_storage;
template<typename _Tp>
- friend void* __any_caster(const any* __any);
+ friend enable_if_t<is_object<_Tp>::value, void*>
+ __any_caster(const any* __any);
// Manage in-place contained object.
template<typename _Tp>
@@ -410,12 +411,24 @@ inline namespace fundamentals_v1
}
// @}
+ /// @cond undocumented
template<typename _Tp>
- void* __any_caster(const any* __any)
+ enable_if_t<is_object<_Tp>::value, void*>
+ __any_caster(const any* __any)
{
- struct _None { };
- using _Up = decay_t<_Tp>;
- using _Vp = conditional_t<is_copy_constructible<_Up>::value, _Up, _None>;
+ // any_cast<T> returns non-null if __any->type() == typeid(T) and
+ // typeid(T) ignores cv-qualifiers so remove them:
+ using _Up = remove_cv_t<_Tp>;
+ // The contained value has a decayed type, so if decay_t<U> is not U,
+ // then it's not possible to have a contained value of type U.
+ using __does_not_decay = is_same<decay_t<_Up>, _Up>;
+ // Only copy constructible types can be used for contained values.
+ using __is_copyable = is_copy_constructible<_Up>;
+ // If the type _Tp could never be stored in an any we don't want to
+ // instantiate _Manager<_Tp>, so use _Manager<any::_Op> instead, which
+ // is explicitly specialized and has a no-op _S_manage function.
+ using _Vp = conditional_t<__and_<__does_not_decay, __is_copyable>::value,
+ _Up, any::_Op>;
if (__any->_M_manager != &any::_Manager<_Vp>::_S_manage)
return nullptr;
any::_Arg __arg;
@@ -423,6 +436,13 @@ inline namespace fundamentals_v1
return __arg._M_obj;
}
+ // This overload exists so that std::any_cast<void(*)()>(a) is well-formed.
+ template<typename _Tp>
+ enable_if_t<!is_object<_Tp>::value, _Tp*>
+ __any_caster(const any*) noexcept
+ { return nullptr; }
+ /// @endcond
+
/**
* @brief Access the contained object.
*
@@ -517,6 +537,14 @@ inline namespace fundamentals_v1
}
}
+ // Dummy specialization used by __any_caster.
+ template<>
+ struct any::_Manager_internal<any::_Op>
+ {
+ static void
+ _S_manage(_Op, const any*, _Arg*) { }
+ };
+
// @} group any
} // namespace fundamentals_v1
} // namespace experimental
diff --git a/libstdc++-v3/testsuite/experimental/any/misc/any_cast.cc b/libstdc++-v3/testsuite/experimental/any/misc/any_cast.cc
index 1875d34..be1e86e 100644
--- a/libstdc++-v3/testsuite/experimental/any/misc/any_cast.cc
+++ b/libstdc++-v3/testsuite/experimental/any/misc/any_cast.cc
@@ -24,6 +24,7 @@
using std::experimental::any;
using std::experimental::any_cast;
+using std::experimental::bad_any_cast;
void test01()
{
@@ -56,7 +57,6 @@ void test01()
void test02()
{
- using std::experimental::bad_any_cast;
any x(1);
auto p = any_cast<double>(&x);
VERIFY(p == nullptr);
@@ -105,7 +105,7 @@ void test03()
MoveDeleted&& md3 = any_cast<MoveDeleted&&>(any(std::move(md)));
}
-void test04()
+void test05()
{
// PR libstdc++/69321
struct noncopyable {
@@ -117,10 +117,60 @@ void test04()
VERIFY( p == nullptr );
}
+void test06()
+{
+ // The contained value of a std::any is always an object type,
+ // but any_cast does not forbid checking for function types.
+
+ any a(1);
+ void (*p1)() = any_cast<void()>(&a);
+ VERIFY( p1 == nullptr );
+ int (*p2)(int) = any_cast<int(int)>(&a);
+ VERIFY( p2 == nullptr );
+ int (*p3)() = any_cast<int()>(&const_cast<const any&>(a));
+ VERIFY( p3 == nullptr );
+
+ try {
+ any_cast<int(&)()>(a);
+ VERIFY( false );
+ } catch (const bad_any_cast&) {
+ }
+
+ try {
+ any_cast<int(&)()>(std::move(a));
+ VERIFY( false );
+ } catch (const bad_any_cast&) {
+ }
+
+ try {
+ any_cast<int(&)()>(const_cast<const any&>(a));
+ VERIFY( false );
+ } catch (const bad_any_cast&) {
+ }
+}
+
+void test07()
+{
+ int arr[3];
+ any a(arr);
+ VERIFY( a.type() == typeid(int*) ); // contained value is decayed
+
+ int (*p1)[3] = any_cast<int[3]>(&a);
+ VERIFY( a.type() != typeid(int[3]) ); // so any_cast should return nullptr
+ VERIFY( p1 == nullptr );
+ int (*p2)[] = any_cast<int[]>(&a);
+ VERIFY( a.type() != typeid(int[]) ); // so any_cast should return nullptr
+ VERIFY( p2 == nullptr );
+ const int (*p3)[] = any_cast<int[]>(&const_cast<const any&>(a));
+ VERIFY( p3 == nullptr );
+}
+
int main()
{
test01();
test02();
test03();
- test04();
+ test05();
+ test06();
+ test07();
}
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