When casting a const reference of a derived class (which inherits from multiple
classes with virtual methods) to a non-const reference of one of it's base
classes, the resulting non-const base class reference points to an incorrect
address.
system type/gcc build options/version:
Target: x86_64-redhat-linux
Configured with: ../configure --prefix=/usr --mandir=/usr/share/man
--infodir=/u
sr/share/info --enable-shared --enable-threads=posix --enable-checking=release
-
-with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions
--with-gx
x-include-dir=/usr/include/c++/3.4.3 --enable-libgcj-multifile
--enable-language
s=c,c++,java,f95 --enable-java-awt=gtk --disable-dssi
--with-java-home=/usr/lib/
jvm/java-1.4.2-gcj-1.4.2.0/jre --with-cpu=generic --host=x86_64-redhat-linux
Thread model: posix
gcc version 4.1.0 20060515 (Red Hat 4.1.0-18)
command line:
compile code with command /usr/bin/g++4 cast.cpp
execute a.out
compiler output:
no compiler messages
execution of program results in "Segmentation fault"
preprocessed file:
# 1 "cast.cpp"
# 1 "/home/hagin//"
# 1 "<built-in>"
# 1 "<command line>"
# 1 "cast.cpp"
class Shape
{
public:
Shape() {}
virtual ~Shape() {}
};
class Loop
{
public:
Loop() {}
virtual ~Loop() {}
virtual void func() {}
};
class Rect :
public Shape,
public Loop
{
public:
Rect() {}
virtual ~Rect() {}
};
int main ()
{
const Rect* rect = new Rect();
((Loop&)(*rect)).func();
return 0;
}
--
Summary: Reference casting involving multiple inheritance
produces bad pointer
Product: gcc
Version: 4.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: hagin at us dot ibm dot com
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31074
