From 4a6161c0db78e4739433377861c0fa89b92619be Mon Sep 17 00:00:00 2001
From: Luke Lau <luke_lau@icloud.com>
Date: Mon, 29 Jul 2019 14:20:47 +0100
Subject: [PATCH] Fix graph not considering original binds when recursing

---
 tests.scm     | 18 ++++++++++++++++++
 typecheck.scm |  6 ++++--
 2 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/tests.scm b/tests.scm
index a198dd4..67d8b30 100644
--- a/tests.scm
+++ b/tests.scm
@@ -50,6 +50,24 @@
 		    bar))
 	    '(abs a a))
 
+(test-types (typecheck '(let ([foo 3]
+			      [bar (+ foo baz)]
+			      [baz (- bar 1)])
+			  bar))
+	    'int)
+
+(test-types (typecheck '(let ([foo 3]
+			      [bar (baz foo)]
+			      [baz (lambda (x) x)])
+			  baz))
+	    '(abs a a))
+
+(test-types (typecheck '(let ([foo 3]
+			      [bar (baz foo)]
+			      [baz (lambda (x) x)])
+			  bar))
+	    'int)
+
 (test-prog '(+ 1 2) 3)
 (test-prog '((lambda (x) ((lambda (y) (+ x y)) 42)) 100) 142)
 
diff --git a/typecheck.scm b/typecheck.scm
index 219b010..e96f694 100644
--- a/typecheck.scm
+++ b/typecheck.scm
@@ -339,12 +339,13 @@
 					; input: a list of binds ((x . y) (y . 3))
 					; returns: pair of verts, edges ((x y) . (x . y))
 (define (graph bs)
+  (define (go bs orig-bs)
     (define (find-refs prog)
       (ast-collect
        (lambda (x)
 	 (case (ast-type x)
 					; only count a reference if its a binding
-	 ['var (if (assoc x bs) (list x) '())]
+	   ['var (if (assoc x orig-bs) (list x) '())]
 	   [else '()]))
        prog))
     (if (null? bs)
@@ -358,10 +359,11 @@
 
 	       (rest (if (null? (cdr bs))
 			 (cons '() '())
-		       (graph (cdr bs))))
+			 (go (cdr bs) orig-bs)))
 	       (total-verts (cons vert (car rest)))
 	       (total-edges (append edges (cdr rest)))]
 	  (cons total-verts total-edges))))
+  (go bs bs))
 
 (define (successors graph v)
   (define (go v E)
-- 
2.30.2