From 65d804d2867ea66cfdeb61e544f21aa2e835fb7a Mon Sep 17 00:00:00 2001
From: Sam Tobin-Hochstadt <samth@racket-lang.org>
Date: Thu, 1 Oct 2009 18:59:12 +0000
Subject: [PATCH] Add disappeared-use properties for struct ids. Fix bug with
 handling of identifier as second arg to `define-match-expander'

svn: r16201
---
 collects/scheme/match.ss              | 37 +++++++++++++--------------
 collects/scheme/match/parse-helper.ss |  7 ++++-
 2 files changed, 24 insertions(+), 20 deletions(-)

diff --git a/collects/scheme/match.ss b/collects/scheme/match.ss
index e5407b47f4..cfe1cb2c7c 100644
--- a/collects/scheme/match.ss
+++ b/collects/scheme/match.ss
@@ -1,22 +1,21 @@
+#lang scheme/base
+(require scheme/match/match
+         (for-syntax scheme/base))
+(provide (except-out (all-from-out scheme/match/match)
+                     define-match-expander)
+         (rename-out [define-match-expander* define-match-expander]))
 
-(module match scheme/base
-  (require scheme/match/match
-           (for-syntax scheme/base))
-  (provide (except-out (all-from-out scheme/match/match)
-                       define-match-expander)
-           (rename-out [define-match-expander* define-match-expander]))
+(define-for-syntax (no-old-match-form stx)
+  (raise-syntax-error
+   #f
+   "works only for constructor-based `match' form"
+   stx))
 
-  (define-for-syntax (no-old-match-form stx)
-    (raise-syntax-error
-     #f
-     "works only for constructor-based `match' form"
-     stx))
-
-  (define-syntax define-match-expander*
-    (syntax-rules ()
-      [(_ id expr) (define-match-expander id expr)]
-      [(_ id expr expr2) (define-match-expander id
-                           expr
-                           no-old-match-form
-                           expr2)])))
+(define-syntax define-match-expander*
+  (syntax-rules ()
+    [(_ id expr) (define-match-expander id expr)]
+    [(_ id expr expr2) (define-match-expander id
+                         expr
+                         no-old-match-form
+                         (#%expression expr2))]))
 
diff --git a/collects/scheme/match/parse-helper.ss b/collects/scheme/match/parse-helper.ss
index daf6ca64ac..83c30b05d0 100644
--- a/collects/scheme/match/parse-helper.ss
+++ b/collects/scheme/match/parse-helper.ss
@@ -93,7 +93,12 @@
              [acc (cond [(null? acc) acc]
                         [(not (car acc)) (cdr acc)]
                         [else acc])])
-        (make-Struct id pred (get-lineage (cert struct-name)) acc
+        (make-Struct id
+                     (syntax-property 
+                      pred 
+                      'disappeared-use (list struct-name))
+                     (get-lineage (cert struct-name))
+                     acc
                      (cond [(eq? '_ (syntax-e pats))                            
                             (map make-Dummy acc)]
                            [(syntax->list pats)