Speed up and improve tc-literal. Now uses expected types more, and more sensibly.

Closes PR 12586.

collects/tests/typed-racket/unit-tests/typecheck-tests.rkt

@@ -1398,6 +1398,8 @@
         
         [tc-e (vector-append #(1) #(2))
               (-vec -Integer)]
+	[tc-e/t (ann #() (Vectorof Integer))
+                (-vec -Integer)]
         )
   (test-suite
    "check-type tests"

collects/typed-racket/infer/restrict.rkt

@@ -9,29 +9,30 @@
 (import infer^)
 (export restrict^)
 
-
-;; NEW IMPL
-;; restrict t1 to be a subtype of t2
-;; if `f' is 'new, use t2 when giving up, otherwise use t1
-(define (restrict* t1 t2 [f 'new])
 ;; we don't use union map directly, since that might produce too many elements
   (define (union-map f l)
     (match l
       [(Union: es)
        (let ([l (map f es)])
          (apply Un l))]))
-  (match* (t1 t2) 
-    [(_ (? (lambda _ (subtype t1 t2)))) t1] ;; already a subtype
-    [(_ (Poly: vars t))
+
+;; NEW IMPL
+;; restrict t1 to be a subtype of t2
+;; if `f' is 'new, use t2 when giving up, otherwise use t1
+(define (restrict* t1 t2 [f 'new])  
+  (cond
+    [(subtype t1 t2) t1] ;; already a subtype
+    [(match t2 
+       [(Poly: vars t)
         (let ([subst (infer vars null (list t1) (list t) t1)])
           (and subst (restrict* t1 (subst-all subst t1) f)))]
-    [((Union: _) _) (union-map (lambda (e) (restrict* e t2 f)) t1)]
-    [(_ (Union: _)) (union-map (lambda (e) (restrict* t1 e f)) t2)]
-    [((? needs-resolving?) _) (restrict* (resolve-once t1) t2 f)]
-    [(_ (? needs-resolving?)) (restrict* t1 (resolve-once t2) f)]
-    [(_ _)
-     (cond [(subtype t2 t1) t2] ;; we don't actually want this - want something that's a part of t1
+       [_ #f])]
+    [(Union? t1) (union-map (lambda (e) (restrict* e t2 f)) t1)]
+    [(Union? t2) (union-map (lambda (e) (restrict* t1 e f)) t2)]
+    [(needs-resolving? t1) (restrict* (resolve-once t1) t2 f)]
+    [(needs-resolving? t2) (restrict* t1 (resolve-once t2) f)]
+    [(subtype t2 t1) t2] ;; we don't actually want this - want something that's a part of t1
     [(not (overlap t1 t2)) (Un)] ;; there's no overlap, so the restriction is empty
-           [else (if (eq? f 'new) t2 t1)])])) ;; t2 and t1 have a complex relationship, so we punt
+    [else (if (eq? f 'new) t2 t1)])) ;; t2 and t1 have a complex relationship, so we punt
     
 (define restrict restrict*)

collects/typed-racket/typecheck/tc-app.rkt

@@ -153,7 +153,8 @@
 
 (define (type->list t)
   (match t
-    [(Pair: (Value: (? keyword? k)) b) (cons k (type->list b))]
+    [(Pair: (Value: (? keyword? k)) b)
+     (cons k (type->list b))]
     [(Value: '()) null]
     [_ (int-err "bad value in type->list: ~a" t)]))
 

collects/typed-racket/typecheck/tc-expr-unit.rkt

@@ -23,15 +23,10 @@
 (export tc-expr^)
 
 ;; return the type of a literal value
-;; scheme-value -> type
+;; scheme-value [type] -> type
 (define (tc-literal v-stx [expected #f])
-  (define-syntax-class exp
-    (pattern i
-             #:fail-unless expected #f
-             #:attr datum (syntax-e #'i)
-             #:fail-unless (subtype (-val (attribute datum)) expected) #f))
+  (define r
     (syntax-parse v-stx
-    [i:exp expected]
       [i:boolean (-val (syntax-e #'i))]
       [i:identifier (-val (syntax-e #'i))]
       
@@ -78,20 +73,23 @@
       [i:byte-regexp -Byte-Regexp]
       [i:pregexp -PRegexp]
       [i:regexp  -Regexp]
-    [(i ...)
-     (match expected
-       [(Mu: var (Union: (list (Value: '()) (Pair: elem-ty (F: var)))))
-        (-Tuple
-         (for/list ([l (in-list (syntax->list #'(i ...)))])
-           (tc-literal l elem-ty)))]
+      [(~and i ()) (-val '())]
+      [(i . r)
+       (match (and expected (restrict expected (-pair Univ Univ) 'orig))
+         [(Pair: a-ty d-ty)
+          (-pair
+           (tc-literal #'i a-ty)
+           (tc-literal #'r d-ty))]
+         [(Union: '())
+          (tc-error/expr "expected ~a, but got" expected #:return expected)]
          ;; errors are handled elsewhere
-       [_ (-Tuple
-           (for/list ([l (in-list (syntax->list #'(i ...)))])
-             (tc-literal l #f)))])]
+         [t 
+          (-pair (tc-literal #'i) (tc-literal #'r))])]
       [(~var i (3d vector?))
-     (match expected
+       (match (and expected (restrict expected (-vec Univ) 'orig))
          [(Vector: t)
           (make-Vector (apply Un
+                              t ;; so that this isn't (Un) when we get no elems
                               (for/list ([l (in-vector (syntax-e #'i))])
                                 (tc-literal l t))))]
          [(HeterogenousVector: ts)
@@ -113,9 +111,12 @@
                    [ks (hash-map h (lambda (x y) (tc-literal x)))]
                    [vs (hash-map h (lambda (x y) (tc-literal y)))])
               (make-Hashtable (generalize (apply Un ks)) (generalize (apply Un vs))))])]
-    [(a . b) (-pair (tc-literal #'a) (tc-literal #'b))]
       [_ Univ]))
   
+  (if expected
+      (check-below r expected)
+      r))
+
 
 ;; do-inst : syntax type -> type
 (define (do-inst stx ty)