re PR c++/27471 (ICE within build_c_cast cp/typeck.c:5434)

re PR c++/27471 (ICE within build_c_cast cp/typeck.c:5434)

	PR c++/27471
	PR c++/27506
	* typeck.c (decay_conversion): Convert bitfields to their declared
	types here.  Improve documentation.  Avoid use of cp_convert.
	(default_conversion): Make it static.  Perform integral promotions
	before lvalue-to-rvalue, function-to-pointer, and array-to-pointer
	conversions.
	* init.c (build_init): Remove.
	(expand_default_init): Do not call rvalue.
	* call.c (null_ptr_cst_p): Robustify.
	(build_conditional_expr): Tidy.
	* except.c (build_throw): Do not perform lvalue-to-rvalue
	conversion on operand before initializing temporary.
	* tree.c (convert.h): Include it.
	(convert_bitfield_to_declared_type): Use convert_to_integer, not
	cp_convert.
	(rvalue): Don't convert bitfields to their declared type here.
	* cp-tree.h (build_init): Remove.
	(default_conversion): Likewise.
	* typeck2.c (build_m_component_ref): Do not perform
	lvalue-to-rvalue, function-to-pointer, or array-to-pointer
	conversions here.  Correct error message.
	PR c++/27471
	PR c++/27506
	* g++.dg/conversion/bitfield5.C: New test.
	* g++.dg/conversion/bitfield6.C: New test.

From-SVN: r113902