From 25f92f8e9ead040b602dffc0066bd85df8e1869a Mon Sep 17 00:00:00 2001
From: Robby Findler <robby@racket-lang.org>
Date: Sat, 2 Feb 2013 19:34:20 -0600
Subject: [PATCH] fix a problem with the way that check syntax's interval map
 tracks information about the program

---
 collects/drracket/private/syncheck/gui.rkt | 17 ++++++++---------
 collects/tests/drracket/syncheck-test.rkt  | 15 ++++++++++++++-
 2 files changed, 22 insertions(+), 10 deletions(-)

diff --git a/collects/drracket/private/syncheck/gui.rkt b/collects/drracket/private/syncheck/gui.rkt
index 9e870f615e..29591a0e78 100644
--- a/collects/drracket/private/syncheck/gui.rkt
+++ b/collects/drracket/private/syncheck/gui.rkt
@@ -811,11 +811,12 @@ If the namespace does not, they are colored the unbound color.
                 ;;    the last test in the above and is because some syntax objects
                 ;;    appear to be from the original source, but can have bogus information.
 
-                ;; Use (add1 end) below, because interval-maps use half-open intervals
-                ;; ie, [start, end] = [start, end+1)
+                ;; interval-maps use half-open intervals which works out well for positions
+                ;; in the editor, since the interval [0,3) covers the characters just after
+                ;; positions 0, 1, and 2, but not the character at position 3 (positions are
+                ;; between characters)
                 (cond [use-key?
-                       (interval-map-update*! arrow-record
-                                              start (add1 end)
+                       (interval-map-update*! arrow-record start end
                                               (lambda (old)
                                                 (if (for/or ([x (in-list old)])
                                                       (and (pair? x) (car x) (eq? (car x) key)))
@@ -823,9 +824,8 @@ If the namespace does not, they are colored the unbound color.
                                                     (cons (cons key to-add) old)))
                                               null)]
                       [else
-                       (interval-map-cons*! arrow-record
-                                            start (add1 end) 
-                                            to-add null)])))
+                       (interval-map-cons*!
+                        arrow-record start end to-add null)])))
             
             (define/private (add-identifier-to-range text/start/ends name-dup?)
               (define id-set (apply set text/start/ends))
@@ -835,8 +835,7 @@ If the namespace does not, they are colored the unbound color.
                 (define arrow-record (get-arrow-record arrow-records (list-ref text/start/span 0)))
                 (define start (list-ref text/start/span 1))
                 (define end (list-ref text/start/span 2))
-                (interval-map-update*! arrow-record
-                                       start (add1 end)
+                (interval-map-update*! arrow-record start end
                                        (lambda (curr-val)
                                          (define this-uf-set
                                            (for/or ([thing (in-list curr-val)])
diff --git a/collects/tests/drracket/syncheck-test.rkt b/collects/tests/drracket/syncheck-test.rkt
index 5337a51a63..a56c80be55 100644
--- a/collects/tests/drracket/syncheck-test.rkt
+++ b/collects/tests/drracket/syncheck-test.rkt
@@ -1149,7 +1149,20 @@
        "  x x x x x x x x x x x x x x x x x x x x x x x x\n"
        "  x x x x x x x x x x x x x x x x x x x x x x x x\n"
        "  x x x x x x x x x x x x x x x x x x x x x x x x)\n"))
-     ))
+     (build-rename-test
+      (string-append
+       "#lang racket\n"
+       "(let ([x 1])\n"
+       "  x`1\n"
+       "  `2)\n")
+      20
+      "x"
+      "y"
+      (string-append
+       "#lang racket\n"
+       "(let ([y 1])\n"
+       "  y`1\n"
+       "  `2)\n"))))
                   
   
   (define (main)