re PR c++/51299 ([C++11] erroneous nullptr warning on dynamic cast)

/cp
2011-11-30  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/51299
	* rtti.c (ifnonnull): Use nullptr_node.
	(build_dynamic_cast_1): Call cp_truthvalue_conversion instead
	of c_common_truthvalue_conversion.

/testsuite
2011-11-30  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/51299
	* g++.dg/warn/Wzero-as-null-pointer-constant-4.C: New.

From-SVN: r181854