[Bug libstdc++/109568] [12/13/14 Regression] Spurious "potential null pointer dereference" in shared_ptr_base.h with "-O1"

[jakub at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109568

--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Plus, because dynamic_cast<Derived*>((Base*)nullptr) is valid and has to return
(Derived*)nullptr, the emitted code effective has to use
if (var)
  var_ref = ...
else
  var_ref = nullptr;
if (var_ref->empty ())
and so again, for the case where var is nullptr and is tested in the IL it is
clearly invoking empty method on nullptr.