I'm seeing the following error:
In function int main():
cc1plus: warning: dereferencing pointer <anonymous> does break
strict-aliasing
rules
/usr/lib/gcc/i386-redhat-linux/4.4.0/../../../../include/c++/4.4.0/bits/stl_tree.h:184:
note: initialized from here
I'm unsure of these are legitimate warnings i.e. if stl_tree.h is genuinely
faulty or if it's a false positive from g++. This appears to be similar to
issue 39207.
This problem was originally encountered in chromium (dev.chromium.org) but I
have produced a much reduced test case below. I'm not expecting the reduced
test case to run of course but compilation would be nice :)
Compile with -O2 -Wall
[begin main.cc]
#include <list>
#include <map>
class MyClass {
public:
typedef std::list<int> MyList;
typedef std::map<int, MyList::iterator> MyMap;
MyClass() {}
~MyClass() {}
void Fail(const int key) {
MyMap::iterator map_iter = map_.find(key);
// this doesn't fail
MyList::iterator list_iter = map_iter->second;
// this does
list_.erase(map_iter->second);
}
MyList list_;
MyMap map_;
};
int main(void)
{
MyClass myclass;
myclass.Fail(5);
return 0;
}
[end main.cc]
Please let me know if you need a save-temps version too.
Thank you!
$ gcc -v
Using built-in specs.
Target: i386-redhat-linux
Configured with: ../configure --prefix=/usr --mandir=/usr/share/man
--infodir=/usr/share/info --with-bugurl=http://bugzilla.redhat.com/bugzilla
--enable-bootstrap --enable-shared --enable-threads=posix
--enable-checking=release --with-system-zlib --enable-__cxa_atexit
--disable-libunwind-exceptions
--enable-languages=c,c++,objc,obj-c++,java,fortran --disable-libgcj
--with-tune=generic --with-arch=i586 --build=i386-redhat-linux
Thread model: posix
gcc version 4.4.0 20090310 (Red Hat 4.4.0-0.24) (GCC)
--
Summary: Aliasing errors in stl_tree.h
Product: gcc
Version: 4.4.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: craig dot schlenter at gmail dot com
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42032
