Fixes #434 (Type of literal char is not the literal char itself) using solution from Alex Knauth.

typed-racket-lib/typed-racket/typecheck/tc-literal.rkt

@@ -28,7 +28,7 @@
 ;; tc-literal: racket-value-syntax [type] -> type
 (define (tc-literal v-stx [expected #f])
   (define-syntax-class exp
-    (pattern (~and i (~or :number :str :bytes))
+    (pattern (~and i (~or :number :str :bytes :char))
              #:fail-unless expected #f
              #:fail-unless (let ([n (syntax-e #'i)])
                              (subtype (-val n) expected #:obj (if (exact-integer? n) (-lexp n) -empty-obj))) #f))

typed-racket-test/succeed/literal-char-gh-issue-434.rkt

@@ -0,0 +1,22 @@
+#lang typed/racket
+;; The precise type for chars should be the char itself:
+(ann #\nul #\nul)
+(ann #\a #\a)
+(ann #\b '#\b)
+;; Up-casting as Char should still work:
+(ann #\nul Char)
+(ann #\a Char)
+(ann (ann #\b '#\b) Char)
+
+;; Check that the inferred type is still implicitly widened to Char by default,
+;; for backwards compatibility (previously, all chars had the type Char):
+;; * Check that when passed as a #:∀ type, the inferred type is Char
+(ann (let #:∀ (C) ([c : C #\a])
+         (λ ([x : C]) x))
+       (→ Char Char))
+;; * Check that loops which rely on the first iteration having the wider Char
+;;   type still work:
+(let loop : Void ([c #\a])
+    (if (equal? c #\a)
+        (loop #\b)
+        (void)))