From 0b626757bb161b0709deaffe873666f1b2795e68 Mon Sep 17 00:00:00 2001
From: Eric Dobson <eric.n.dobson@gmail.com>
Date: Fri, 9 May 2014 22:03:35 -0700
Subject: [PATCH] Correctly extend tvars in the right place during inference.

Removes wrong extension of tvars in apply as well.

original commit: 1d43b583fb04140f55c290fee98db28467d96c98
---
 .../typed-racket/infer/infer-unit.rkt         | 20 +++++++++++++------
 .../typed-racket/typecheck/tc-apply.rkt       | 18 ++++-------------
 2 files changed, 18 insertions(+), 20 deletions(-)

diff --git a/pkgs/typed-racket-pkgs/typed-racket-lib/typed-racket/infer/infer-unit.rkt b/pkgs/typed-racket-pkgs/typed-racket-lib/typed-racket/infer/infer-unit.rkt
index eeacabe2..9de3ecd8 100644
--- a/pkgs/typed-racket-pkgs/typed-racket-lib/typed-racket/infer/infer-unit.rkt
+++ b/pkgs/typed-racket-pkgs/typed-racket-lib/typed-racket/infer/infer-unit.rkt
@@ -272,7 +272,9 @@
      #:return-when (memq dbound* Y) #f
      (let* ([arg-mapping (cgen/list V X Y ts ss)]
             ;; just add dbound as something that can be constrained
-            [darg-mapping (% move-dotted-rest-to-dmap (cgen V (cons dbound X) Y t-dty s-dty) dbound dbound*)]
+            [darg-mapping
+              (extend-tvars (list dbound*)
+                (% move-dotted-rest-to-dmap (cgen V (cons dbound X) Y t-dty s-dty) dbound dbound*))]
             [ret-mapping (cg s t)])
        (% cset-meet arg-mapping darg-mapping ret-mapping))]
     [((arr: ss s #f (cons s-dty dbound)  '())
@@ -280,7 +282,9 @@
      #:return-unless (= (length ss) (length ts)) #f
      (let* ([arg-mapping (cgen/list V X Y ts ss)]
             ;; just add dbound as something that can be constrained
-            [darg-mapping (% move-dotted-rest-to-dmap (cgen V (cons dbound* X) Y t-dty s-dty) dbound* dbound)]
+            [darg-mapping
+              (extend-tvars (list dbound)
+                (% move-dotted-rest-to-dmap (cgen V (cons dbound* X) Y t-dty s-dty) dbound* dbound))]
             [ret-mapping (cg s t)])
        (% cset-meet arg-mapping darg-mapping ret-mapping))]
     ;; * <: ...
@@ -438,13 +442,15 @@
            #:return-when (memq t-dbound Y) #f
            (% cset-meet
               (cgen/list V X Y ss ts)
-              (% move-dotted-rest-to-dmap (cgen V (cons s-dbound X) Y s-dty t-dty) s-dbound t-dbound))]
+              (extend-tvars (list t-dbound)
+                (% move-dotted-rest-to-dmap (cgen V (cons s-dbound X) Y s-dty t-dty) s-dbound t-dbound)))]
           [((ValuesDots: ss s-dty s-dbound)
             (ValuesDots: ts t-dty (? (λ (db) (memq db Y)) t-dbound)))
            ;; s-dbound can't be in Y, due to previous rule
            (% cset-meet
               (cgen/list V X Y ss ts)
-              (% move-dotted-rest-to-dmap (cgen V (cons t-dbound X) Y s-dty t-dty) t-dbound s-dbound))]
+              (extend-tvars (list s-dbound)
+                (% move-dotted-rest-to-dmap (cgen V (cons t-dbound X) Y s-dty t-dty) t-dbound s-dbound)))]
 
           ;; they're subtypes. easy.
           [(a b) 
@@ -585,10 +591,12 @@
           [((ListDots: s-dty (? (λ (db) (memq db Y)) s-dbound)) (ListDots: t-dty t-dbound))
            ;; What should we do if both are in Y?
            #:return-when (memq t-dbound Y) #f
-           (% move-dotted-rest-to-dmap (cgen V (cons s-dbound X) Y s-dty t-dty) s-dbound t-dbound)]
+           (extend-tvars (list t-dbound)
+             (% move-dotted-rest-to-dmap (cgen V (cons s-dbound X) Y s-dty t-dty) s-dbound t-dbound))]
           [((ListDots: s-dty s-dbound) (ListDots: t-dty (? (λ (db) (memq db Y)) t-dbound)))
            ;; s-dbound can't be in Y, due to previous rule
-           (% move-dotted-rest-to-dmap (cgen V (cons t-dbound X) Y s-dty t-dty) t-dbound s-dbound)]
+           (extend-tvars (list s-dbound)
+             (% move-dotted-rest-to-dmap (cgen V (cons t-dbound X) Y s-dty t-dty) t-dbound s-dbound))]
 
           ;; this constrains `dbound' to be |ts| - |ss|
           [((ListDots: s-dty dbound) (List: ts))
diff --git a/pkgs/typed-racket-pkgs/typed-racket-lib/typed-racket/typecheck/tc-apply.rkt b/pkgs/typed-racket-pkgs/typed-racket-lib/typed-racket/typecheck/tc-apply.rkt
index 40377eb0..18a2735b 100644
--- a/pkgs/typed-racket-pkgs/typed-racket-lib/typed-racket/typecheck/tc-apply.rkt
+++ b/pkgs/typed-racket-pkgs/typed-racket-lib/typed-racket/typecheck/tc-apply.rkt
@@ -98,20 +98,10 @@
            ;; ... function, ... arg
            [(and drest tail-bound
                  (= (length domain) (length arg-tys))
-                 (if (eq? tail-bound (cdr drest))
-                     ;; same bound on the ...s
-                     (infer fixed-vars (list dotted-var)
-                            (cons (make-ListDots tail-ty tail-bound) arg-tys)
-                            (cons (make-ListDots (car drest) (cdr drest)) domain)
-                            range)
-                     ;; different bounds on the ...s
-                     (extend-tvars (list tail-bound (cdr drest))
-                       (extend-indexes (cdr drest)
-                         ;; don't need to add tail-bound - it must already be an index
-                        (infer fixed-vars (list dotted-var)
-                               (cons (make-ListDots tail-ty tail-bound) arg-tys)
-                               (cons (make-ListDots (car drest) (cdr drest)) domain)
-                               range)))))
+                 (infer fixed-vars (list dotted-var)
+                        (cons (make-ListDots tail-ty tail-bound) arg-tys)
+                        (cons (make-ListDots (car drest) (cdr drest)) domain)
+                        range))
             => finish]
            ;; ... function, (Listof A) or (List A B C etc) arg
            [(and drest (not tail-bound)