anchor.diff:  (defun context (results successors)
     (unless (and (listp results)
   	       (every (lambda (result)
  -			(typep result 'sicl-mir:lexical-location))
  +			(typep result 'cleavir-mir:lexical-location))
   		      results))
       (error "illegal results: ~s" results))
     (unless (and (listp successors)
   	       (every (lambda (successor)
  -			(typep successor 'sicl-mir:instruction))
  +			(typep successor 'cleavir-mir:instruction))
   		      successors))
       (error "illegal successors: ~s" results))
     (when (and (null successors) (not (null results)))
  
positive.code: 		ast
  		(context
  		 (list temp)
  		 (list (sicl-mir:make-==-instruction
  			(list temp (sicl-mir:make-constant-input 'nil))
  			successors)))))
  	     (compile-ast
  	      ast
  
negative.code:       context
      (let ((code (compile-function (sicl-ast:body-ast ast))))
        (ecase (length successors)
  	(0 (let ((temp (cleavir-mir:new-temporary)))
  	     (cleavir-mir:make-enclose-instruction
  	      temp
  	      (cleavir-mir:make-return-instruction (list temp))
  	      code)))
  	(1 (if (null results)
  	       (progn (warn "closure compiled in a context with no values")
  		      (car successors))
  	       (cleavir-mir:make-enclose-instruction
  		(car results)
  		(nil-fill (cdr results) (car successors))
  		code)))
  	(2 (if (null results)
  	       (car successors)
  	       (cleavir-mir:make-enclose-instruction
  		(car results)
  		(nil-fill (cdr results) (cadr successors))
  		code)))))))
  