Jason Rhinelander 14e70650fe Fix downcasting of base class pointers ... When we are returned a base class pointer (either directly or via shared_from_this()) we detect its runtime type (using `typeid`), then end up essentially reinterpret_casting the pointer to the derived type. This is invalid when the base class pointer was a non-first base, and we end up with an invalid pointer. We could dynamic_cast to the most-derived type, but if *that* type isn't pybind11-registered, the resulting pointer given to the base `cast` implementation isn't necessarily valid to be reinterpret_cast'ed back to the backup type. This commit removes the "backup" type argument from the many-argument `cast(...)` and instead does the derived-or-pointer type decision and type lookup in type_caster_base, where the dynamic_cast has to be to correctly get the derived pointer, but also has to do the type lookup to ensure that we don't pass the wrong (derived) pointer when the backup type (i.e. the type caster intrinsic type) pointer is needed. Since the lookup is needed before calling the base cast(), this also changes the input type to a detail::type_info rather than doing a (second) lookup in cast().		2017-04-27 09:12:41 -04:00
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pybind11	Fix downcasting of base class pointers	2017-04-27 09:12:41 -04:00