[Bug c++/51299] New: [C++11] erroneous nullptr warning on dynamic cast

[jarrydb at cse dot unsw.edu.au]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51299

             Bug #: 51299
           Summary: [C++11] erroneous nullptr warning on dynamic cast
    Classification: Unclassified
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassig...@gcc.gnu.org
        ReportedBy: jarr...@cse.unsw.edu.au


The below code compiled with -Wzero-as-null-pointer-constant produces an
erroneous warning on a dynamic cast.

g++ -std=gnu++11 nullcast.cpp -c -Wzero-as-null-pointer-constant
nullcast.cpp: In function ‘void foo(Base*)’:
nullcast.cpp:13:40: warning: zero as null pointer constant
[-Wzero-as-null-pointer-constant]
nullcast.cpp:13:40: warning: zero as null pointer constant
[-Wzero-as-null-pointer-constant]

class Base
{
  public:
  virtual ~Base() = default;
};

class Derived : public Base
{
};

void foo(Base *b)
{
  Derived *d = dynamic_cast<Derived*>(b);
}

gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/home/jarrydb/current/soft/install-latest/libexec/gcc/x86_64-unknown-linux-gnu/4.7.0/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: /home/jarrydb/current/soft/src/gcc-git/configure
--prefix=/home/jarrydb/current/soft/install-latest --disable-multilib
--enable-languages=c,c++
Thread model: posix
gcc version 4.7.0 20111125 (experimental) (GCC)