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Message-ID: <52FE7A37.2020305@duke.edu>
Date: Fri, 14 Feb 2014 20:19:00 -0000
From: Benjamin Redelings <benjamin.redelings@duke.edu>
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To: Jan Hubicka <hubicka@ucw.cz>
CC: gcc-patches@gcc.gnu.org
Subject: pure virtual method called
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Hi Jan,

     I hope to report a bug soon, but in the meantime I wanted to let 
you know that for the last month or so, the 4.9 branch has (I think) a 
bug at O3, where my program gets:

pure virtual method called
terminate called without an active exception
Aborted

4.8 works fine.

     I am guessing this is related to your devirt work.  I haven't been 
able to produce a reduce testcase yet (sorry!), but here is some code 
that illustrates the C++ type for the object whose virtual table is (?) 
messed up.  (Note: this code compiles but does NOT crash.)

     Again, sorry for not having a testcase.  I'll make one soon. 
Hopefully it is helpful to know that bugs still exist.

-BenRI

#include <vector>

class Object
{
   virtual Object* clone() const =0;
};

template <typename T>
class Box: public Object, public T
{
public:
   Box<T>* clone() const {return new Box<T>(*this);}
};

template <typename T>
using Vector = Box<std::vector<T>>;

int main()
{
   Vector<int> v;
   v.clone();
}

-BenRI

P.S. The bug exists in debian gcc snapshots taken on 2014-02-12 and 
2014-01-22, Linux AMD64.