I believe that all defconst's in lao.el should be defvar's.  Several
are changed in the file itself and produce compiler warnings.  I
propose the patch below.  I am not sure what to do about the
Copyright:

;; Copyright (C) 1997 Electrotechnical Laboratory, JAPAN.
;; Licensed to the Free Software Foundation.

===File ~/lao.el-diff=======================================
*** lao.el	01 Sep 2003 16:08:19 -0500	1.8
--- lao.el	14 Nov 2004 12:41:09 -0600	
***************
*** 42,48 ****
  	  (compose-string (quail-lookup-map-and-concat quail-current-key))))
    control-flag)
  
! (defconst lao-key-alist
    '(("!" . "1")
      ("\"" . "=")
      ("#" . "3")
--- 42,48 ----
  	  (compose-string (quail-lookup-map-and-concat quail-current-key))))
    control-flag)
  
! (defvar lao-key-alist
    '(("!" . "1")
      ("\"" . "=")
      ("#" . "3")
***************
*** 148,159 ****
      ("\\9" . "໙")
      ))
  
! (defconst lao-consonant-key-alist nil)
! (defconst lao-semivowel-key-alist nil)
! (defconst lao-vowel-key-alist nil)
! (defconst lao-voweltone-key-alist nil)
! (defconst lao-tone-key-alist nil)
! (defconst lao-other-key-alist nil)
  
  (let ((tail lao-key-alist)
        elt phonetic-type)
--- 148,159 ----
      ("\\9" . "໙")
      ))
  
! (defvar lao-consonant-key-alist nil)
! (defvar lao-semivowel-key-alist nil)
! (defvar lao-vowel-key-alist nil)
! (defvar lao-voweltone-key-alist nil)
! (defvar lao-tone-key-alist nil)
! (defvar lao-other-key-alist nil)
  
  (let ((tail lao-key-alist)
        elt phonetic-type)
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