From 6cc10cdb181e88a8fd1bc2958314c44e086fe8e3 Mon Sep 17 00:00:00 2001
From: Eric Dobson <eric.n.dobson@gmail.com>
Date: Sun, 18 May 2014 15:03:28 -0700
Subject: [PATCH] Remove unused code in subst-gen, and remove internal error.

---
 .../typed-racket/infer/infer-unit.rkt         | 45 +++++--------------
 .../typed-racket/unit-tests/infer-tests.rkt   |  4 +-
 2 files changed, 13 insertions(+), 36 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 e977fd510b..a02b9df0da 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
@@ -716,39 +716,18 @@
   ;; was found.  If we're at this point and had no other constraints, then adding the
   ;; equivalent of the constraint (dcon null (c Bot X Top)) is okay.
   (define (extend-idxs S)
-    (define fi-R (fi R))
-    ;; If the index variable v is not used in the type, then
-    ;; we allow it to be replaced with the empty list of types;
-    ;; otherwise we error, as we do not yet know what an appropriate
-    ;; lower bound is.
-    (define (demote/check-free v)
-      (if (memq v fi-R)
-          (int-err "attempted to demote dotted variable")
-          (i-subst null)))
-    ;; absent-entries is #f if there's an error in the substitution, otherwise
-    ;; it's a list of variables that don't appear in the substitution
-    (define absent-entries
-      (for/fold ([no-entry null]) ([v (in-list Y)])
-        (let ([entry (hash-ref S v #f)])
-          ;; Make sure we got a subst entry for an index var
-          ;; (i.e. a list of types for the fixed portion
-          ;;  and a type for the starred portion)
-          (cond
-            [(not no-entry) no-entry]
-            [(not entry) (cons v no-entry)]
-            [(or (i-subst? entry) (i-subst/starred? entry) (i-subst/dotted? entry)) no-entry]
-            [else #f]))))
-    (and absent-entries
-         (hash-union
-          (for/hash ([missing (in-list absent-entries)])
-            (let ([var (hash-ref idx-hash missing Constant)])
-              (values missing
-                      (evcase var
-                              [Constant (demote/check-free missing)]
-                              [Covariant (demote/check-free missing)]
-                              [Contravariant (i-subst/starred null Univ)]
-                              [Invariant (demote/check-free missing)]))))
-          S)))
+    (hash-union
+     (for/hash ([v (in-list Y)]
+                #:unless (hash-has-key? S v))
+       (let ([var (hash-ref idx-hash v Constant)])
+         (values v
+                 (evcase var
+                         [Constant (i-subst null)]
+                         [Covariant (i-subst null)]
+                         [Contravariant (i-subst/starred null Univ)]
+                         ;; TODO figure out if there is a better subst here
+                         [Invariant (i-subst null)]))))
+     S))
   (match (car (cset-maps C))
     [(cons cmap (dmap dm))
      (let ([subst (hash-union
diff --git a/pkgs/typed-racket-pkgs/typed-racket-test/tests/typed-racket/unit-tests/infer-tests.rkt b/pkgs/typed-racket-pkgs/typed-racket-test/tests/typed-racket/unit-tests/infer-tests.rkt
index 71734745ae..4c36f491b4 100644
--- a/pkgs/typed-racket-pkgs/typed-racket-test/tests/typed-racket/unit-tests/infer-tests.rkt
+++ b/pkgs/typed-racket-pkgs/typed-racket-test/tests/typed-racket/unit-tests/infer-tests.rkt
@@ -109,9 +109,7 @@
     (infer-t (-v a) (-v b) #:vars '(b))
 
     (infer-t (make-ListDots -Symbol 'b) (-lst -Symbol) #:indices '(b)
-             ;; TODO Figure out why this doesnt' work
-             #;#;
-             #:result [(make-ListDots (-v b) 'b) (-lst Univ)])
+             #:result [(make-ListDots (-v b) 'b) -Null])
     (infer-t (make-ListDots (-v a) 'b) (-lst -Symbol) #:vars '(a) #:indices '(b)
              #:result [(-lst* (make-ListDots (-v b) 'b) (-v a))
                        (-lst* (-lst -Bottom) -Bottom)])