http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56636
Bug #: 56636
Summary: strange interaction of dynamic_cast and unique_ptr
Classification: Unclassified
Product: gcc
Version: 4.7.2
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: gcc-b...@naturalcleaningcalgary.com
The following program produces a segfault at the dynamic_cast. If I change
std::unique_ptr<int> to int*, or if I drop the dynamic_cast, the segfault goes
away.
#include <memory>
struct A
{
void F() const
{
F_impl();
}
virtual std::unique_ptr<int> F_impl() const = 0;
};
template <typename Derived>
struct A_impl : virtual A
{
std::unique_ptr<int> F_impl() const override
{
dynamic_cast<const Derived &>(*this);
return nullptr;
}
};
struct B : virtual A {};
struct C : B, A_impl<C> {};
int main()
{
C().F();
}
$ g++ -std=c++11 -otest test.cpp && ./test.exe
I am using GCC 4.7.2 under MinGW, configured with "--enable-libstdcxx-debug
--enable-languages=c,c++ --build=pentium4-pc-mingw32 --disable-nls
--disable-win32-registry --enable-threads".
(gdb) run
Starting program: c:\devel\page\build/test.exe
[New Thread 2356.0xa10]
Program received signal SIGSEGV, Segmentation fault.
__cxxabiv1::__dynamic_cast (src_ptr=0x4031f4, src_type=0x403180,
dst_type=0x403160, src2dst=4)
at ../../../../gcc-4.7.2/libstdc++-v3/libsupc++/dyncast.cc:56
56 adjust_pointer <void> (src_ptr, prefix->whole_object);
(gdb) bt
#0 __cxxabiv1::__dynamic_cast (src_ptr=0x4031f4, src_type=0x403180,
dst_type=0x403160, src2dst=4)
at ../../../../gcc-4.7.2/libstdc++-v3/libsupc++/dyncast.cc:56
#1 0x00401d04 in A_impl<C>::F_impl() const ()
#2 0x00401cc6 in A::F() const ()
#3 0x00401378 in main ()
