pass regression test by modifying 'SearchList.backtrackRange' function. The modification that worked was swapping two if-statements around: first we check if the string position is 0 (and loop to check the previous string if so); in the else case, we check if the searchPos <= 1 (which signals for us to exit backtracking). Swapping the order of the if-statements means that, when we exit the loop, we always exit with string that is at this position.

fcore/search-list.sml

@@ -96,9 +96,7 @@ struct
 
   fun backtrackRange
     (pos, hd, absIdx, tl, acc, searchPos, searchString, finish, prevTl) =
-    if searchPos <= 1 then
-      loopRange (pos, hd, absIdx, tl, acc, 0, searchString, finish, prevTl)
-    else if pos < 0 then
+    if pos < 0 then
       case prevTl of
         prevHd :: prevTl =>
           let
@@ -119,6 +117,8 @@ struct
       | [] =>
           (* Should never be called *)
           raise Fail "SearchList.backtrackRange error: line 120\n"
+    else if searchPos <= 1 then
+      loopRange (pos, hd, absIdx, tl, acc, 0, searchString, finish, prevTl)
     else
       backtrackRange
         ( pos - 1

test/regression.sml

@@ -64,10 +64,6 @@ struct
 
              (* move and then delete twice *)
              val app = TestUtils.updateMany (app, "edede")
-
-             val s = LineGap.toString (#buffer app)
-             val s = String.toCString s ^ "\n"
-             val () = print s
            in
              Expect.isTrue true
            end)