Summary:
This patch fixes bugs.llvm.org/PR32979.
[util.smartptr.shared.const] says:
> In the constructor definitions below, enables shared_from_this with p, for a pointer p of type Y*, means
> that if Y has an unambiguous and accessible base class that is a specialization of enable_shared_from_-
> this.
This means that libc++ needs to respect the access specifier of the base class, and not attempt to construct
and enabled_shared_from_this base if it is private. However access specifiers don't affect overload resolution
so our current implementation will attempt to construct the private base.
This patch uses SFINAE to correctly detect if the shared_ptr input has an accessible enable_shared_from_this
base class.
Reviewers: mclow.lists
Reviewed By: mclow.lists
Subscribers: cfe-commits
Differential Revision: https://reviews.llvm.org/D33033
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@302709 91177308-0d34-0410-b5e6-96231b3b80d8
See https://llvm.org/bugs/show_bug.cgi?id=27115
The problem was that the conversion from
'const enable_shared_from_this<T>*' to 'const T*' didn't work if
T inherited enable_shared_from_this as a virtual base class. The fix
is to take the original pointer passed to shared_ptr's constructor in the
__enable_weak_this method and perform an upcast to 'const T*' instead of
performing a downcast from the enable_shared_from_this base.
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@273835 91177308-0d34-0410-b5e6-96231b3b80d8
