* c-tree.h (struct lang_identifier): Remove error_locus field.
(IDENTIFIER_ERROR_LOCUS): Kill.
(record_function_scope_shadow): New prototype.
* c-typeck.c (build_external_ref): Don't complain if
decl is error_mark_node. When not at file scope, bind the
decl's local value to error_mark_node to suppress further
warnings, instead of setting IDENTIFIER_ERROR_LOCUS.
* c-decl.c (get_function_binding_level): New static function.
(record_function_scope_shadow): New exported function.
(c_make_fname_decl): Use get_function_binding_level.