From efb877dbfbc168b4a34cfa085eeb8eab04ad32d5 Mon Sep 17 00:00:00 2001
From: AlexKnauth <alexander@knauth.org>
Date: Sat, 15 Aug 2015 14:36:45 -0500
Subject: [PATCH] fix inference with define-new-subtype

---
 typed-racket-lib/typed-racket/infer/infer-unit.rkt     | 7 +++++++
 typed-racket-test/succeed/define-new-subtype-infer.rkt | 8 ++++++++
 2 files changed, 15 insertions(+)
 create mode 100644 typed-racket-test/succeed/define-new-subtype-infer.rkt

diff --git a/typed-racket-lib/typed-racket/infer/infer-unit.rkt b/typed-racket-lib/typed-racket/infer/infer-unit.rkt
index f841725b..3120a5b4 100644
--- a/typed-racket-lib/typed-racket/infer/infer-unit.rkt
+++ b/typed-racket-lib/typed-racket/infer/infer-unit.rkt
@@ -540,6 +540,13 @@
                         #:when v)
               v))]
 
+          ;; from define-new-subtype
+          [((Distinction: nm1 id1 S) (app resolve (Distinction: nm2 id2 T)))
+           #:when (and (equal? nm1 nm2) (equal? id1 id2))
+           (cg S T)]
+          [((Distinction: _ _ S) T)
+           (cg S T)]
+
           ;; two structs with the same name
           ;; just check pairwise on the fields
           [((Struct: nm _ flds proc _ _) (Struct: nm* _ flds* proc* _ _))
diff --git a/typed-racket-test/succeed/define-new-subtype-infer.rkt b/typed-racket-test/succeed/define-new-subtype-infer.rkt
new file mode 100644
index 00000000..e6f09834
--- /dev/null
+++ b/typed-racket-test/succeed/define-new-subtype-infer.rkt
@@ -0,0 +1,8 @@
+#lang typed/racket
+
+(define-new-subtype T (make-T (List Integer)))
+
+(: f : T -> Integer)
+(define (f t)
+  (define x (car t))
+  (* x 2))