Avi Kivity 8628d98542 shared_ptr: fix reference count loss when creating a derived type with e_s_f_t ...

make_shared() has a special case for detecting a created class deriving
from enable_shared_from_this<>, so it can point the refcount pointer into
the object's data area instead of creating a shared_ptr_count_base for it.

The code, however, fails to detect a creating class deriving indirectly
from enable_shared_from_this:

   struct base : enable_shared_from_this<base> {};

   struct derived : base {};

   make_shared<derived>();  // <- allocates independent refcount

The result is that the object reference counter lives in two locations.

Fix by detecting the derived class case as well.

2015-03-10 10:56:10 +02:00

16 KiB

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