gdb/

	* exceptions.h (NOT_AVAILABLE_ERROR): New error.
	* value.c: Include "exceptions.h".
	(require_available): Throw NOT_AVAILABLE_ERROR instead of a
	generic error.
	* cp-abi.c: Include gdb_assert.h.
	(baseclass_offset): Add `embedded_offset' and `val' parameters.
	Assert the method is implemented.  Wrap NOT_AVAILABLE_ERROR
	errors.
	* cp-abi.h (baseclass_offset): Add `embedded_offset' and `val'
	parameters.  No longer returns -1 on error.
	(struct cp_abi_ops) <baseclass_offset>: Add `embedded_offset' and
	`val' parameters.
	* cp-valprint.c: Include exceptions.h.
	(cp_print_value): Handle NOT_AVAILABLE_ERROR errors when fetching
	the baseclass_offset.  Handle unavailable base classes.  Use
	val_print_invalid_address.
	* p-valprint.c: Include exceptions.h.
	(pascal_object_print_value): Handle NOT_AVAILABLE_ERROR errors
	when fetching the baseclass_offset.  No longer expect
	baseclass_offset returning -1.  Handle unavailable base classes.
	Use val_print_invalid_address.
	* valops.c (dynamic_cast_check_1): Rename `contents' parameter to
	`valaddr' parameter, and change its type to gdb_byte pointer.  Add
	`embedded_offset' and `val' parameters.  Adjust.
	(dynamic_cast_check_2): Rename `contents' parameter to `valaddr'
	parameter, and change its type to gdb_byte pointer.  Add
	`embedded_offset' and `val' parameters.  Adjust.  No longer expect
	baseclass_offset returning -1.
	(value_dynamic_cast): Use value_contents_for_printing rather than
	value_contents.  Adjust.
	(search_struct_field): No longer expect baseclass_offset returning
	-1.
	(search_struct_method): If reading memory from the target is
	necessary, wrap it in a new value to pass to baseclass_offset.  No
	longer expect baseclass_offset returning -1.
	(find_method_list): No longer expect baseclass_offset returning
	-1.  Use value_contents_for_printing rather than value_contents.
	* valprint.c (val_print_invalid_address): New function.
	* valprint.h (val_print_invalid_address): Declare.
	* gdbtypes.c (is_unique_ancestor_worker): New `embedded_offset'
	and `val' parameters.  No longer expect baseclass_offset returning
	-1.  Adjust.
	* gnu-v2-abi.c: Include "exceptions.h".
	(gnuv2_baseclass_offset): Add `embedded_offset' and `val'
	parameters.  Handle unavailable memory.  Recurse through
	gnuv2_baseclass_offset directly, rather than through
	baseclass_offset.  No longer returns -1 on not found, instead
	throw an error.
	* gnu-v3-abi.c (gnuv3_baseclass_offset): Add `embedded_offset' and
	`val' parameters.  Adjust.

	gdb/testsuite/
	* gdb.trace/unavailable.cc (class Base, class Middle, class
	Derived): New types.
	(derived_unavail, derived_partial, derived_whole): New globals.
	(virtual_partial): New global.
	(virtualp): Point at virtual_partial.
	* gdb.trace/unavailable.exp (gdb_collect_globals_test): Add tests
	related to unavailable vptr.