PR c++/18001

	PR c++/18001
	* c-common.h (lvalue_use): Move here from c-ctypeck.c.
	(lvalue_or_else): Declare.
	* c-common.c (lvalue_or_else): Move here from c-typeck.c.
	* c-typeck.c (lvalue_use): Remove.
	(lvalue_or_else): Remove.

	PR c++/18556
	* toplev.c (check_global_declarations): Set DECL_IGNORED_P on
	unemitted variables with static storage duration.

	PR c++/18445
	* class.c (instantiate_type): Treat NON_DEPENDENT_EXPRs with
	unknown_type as non matching.  Tidy up.
	* pt.c (build_non_dependent_expr): Do not build a
	NON_DEPENDENT_EXPR for a VAR_DECL.

	PR c++/18001
	* cp-tree.h (lvalue_or_else): Remove declaration.
	* tree.c (lvalue_or_else): Remove.
	* typeck.c (build_unary_op): Adjust call to lvalue_or_else.
	(build_modify_expr): Likewise.

	PR c++/18625
	* decl.c (duplicate_decls): Return error_mark_node on error, as
	specified.

	PR c++/18466
	* decl.c (grokvardecl): Keep track of whether or not a there was
	explicit qualification.
	* name-lookup.c (set_decl_namespace): Complain about explicit
	qualification of a name within its own namespace.

	PR c++/18545
	* typeck.c (check_return_expr): Robustify.

	PR c++/18445
	* g++.dg/template/crash28.C: Likewise.

	PR c++/18001
	* g++.dg/expr/unary2.C: Adjust lvalue messages.
	* g++.dg/ext/lvaddr.C: Likewise.
	* g++.dg/opt/pr7503-3.C: Likewise.

	PR c++/18466
	* g++.dg/parse/qualified3.C: New test.
	* g++.old-deja/g++.other/friend7.C: Remove bogus qualification.

	PR c++/18545
	* g++.dg/expr/return1.C: New test.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@91301 138bc75d-0d04-0410-961f-82ee72b054a4