Patch for parse error in operand scanning

[Ben Elliston]

This patch has been tested and is self-documenting. :-) Okay to
commit?


2001-03-21  Ben Elliston  <bje@redhat.com>

	* opc-itab.scm (compute-syntax): Emit a parse error if an operand
	name is empty or invalid -- eg. "$(rs)" instead of "($rs)".

Index: opc-itab.scm
===================================================================
RCS file: /cvs/cvsfiles/devo/cgen/opc-itab.scm,v
retrieving revision 1.21
diff -u -c -r1.21 opc-itab.scm
*** opc-itab.scm	2001/03/20 19:49:10	1.21
--- opc-itab.scm	2001/03/21 04:37:59
***************
*** 162,167 ****
--- 162,169 ----
  						  (substring syn 2 n)))
  						"), ")))))
  		 (let ((n (id-len (string-drop1 syn))))
+ 		   (if (= n 0)
+ 		       (parse-error context "empty or invalid operand name" syntax))
  		   (loop (string-drop (1+ n) syn)
  			 (string-append result op-macro " ("
  					(string-upcase