TR: local type inference fails in class bodies, and type error identifies the wrong expression

Originally submitted on: Tue Dec 30 18:04:01 -0500 2014

The error is

Type Checker: missing type for identifier;
consider adding a type annotation with `:'
identifier: self52876 in: dc

The highlighted expression is dc in (define alpha (send dc get-alpha)), which is very confusing.

Uncommenting (: alpha Nonnegative-Real) allows the program to typecheck. But this information is already known: replacing the type declaration with (: alpha String) results in the following error message:

Type Checker: type mismatch
expected: String
given: Nonnegative-Real in: alpha

Steps to Reproduce:

#lang typed/racket

(require typed/racket/draw
         typed/racket/class)

(define foo%
  (class object%
    (init-field [dc : (Instance DC<%>)])
    (super-new)
    ;(: alpha Nonnegative-Real)
    (define alpha (send dc get-alpha))))

Release:

6.1.1.6--2014-12-21(-/f)

Environment:

unix "Linux snoopy 3.13.0-37-generic #64-Ubuntu SMP Mon Sep 22 21:28:38 UTC 2014 x86_64
 x86_64 x86_64 GNU/Linux" (x86_64-linux/3m) (get-display-depth) = 32
Human Language: english
(current-memory-use) 633168392
raco pkg (show):
Installation-wide:
 Package                 Checksum           Source
 disassemble             cf0ee3a5...        catalog...ssemble
 drbayes                                    link...il/drbayes
 main-distribution       67868e03...        catalog...ibution
 main-distribution-test  ca4a870e...        catalog...on-test
 nonplussed              f6c06999...        url.../nonplussed
 optimization-coach      be5f7908...        catalog...n-coach
 pict3d                                     link...eil/pict3d
 plot                    e536986e...        clone...path=plot
 racket-lib                                 static-link...lib
 rsound                  4f5d4d15...        catalog rsound
 slideshow-latex         9275fecb...        catalog...w-latex
 [214 auto-installed packages not shown]
User-specific for installation "development":
 [none]



Collections:
("/home/neil/.racket/development/collects"
 (non-existent-path))
("/home/neil/plt-fresh/racket/collects"
 (".gitignore" "acks" "compiler" "data" "db" "dynext" "ffi" "file" "info" "info-domain"
 "json" "launcher" "net" "openssl" "pkg" "planet" "racket" "raco" "reader" "realm" "s-exp"
 "setup" "syntax" "unstable" "version" "xml"))

Recent Internal Errors: 
Computer Language: (("Determine language from source") (#(#t print mixed-fraction-e #f #t
 none) (default) #() "#lang racket\n" #t #f ((test) (main)) #t))

This bug was converted from Gnats bug 14909.