odd code deletion note from lambda as argument to a load-time function call

[Tobias C. Rittweiler]

(defvar *foo*)
(defun bar (f)
  (setf *foo* f))
(bar (formatter "~A"))

; compiling file "/tmp/foo.lisp" (written 02 DEC 2009 09:22:50 AM):

; file: /tmp/foo.lisp
; in: BAR (FORMATTER "~A")
; (BAR (FORMATTER "~A"))
;
; note: deleting unreachable code
;
; compilation unit finished
; printed 1 note

; /tmp/foo.fasl written
; compilation finished in 0:00:00.009

[Tobias C. Rittweiler (tcr)]

Must have something to do with the way the FOP compiler arranges
toplevel calls?

  (defvar *foo*)
  (defun bar (f)
    (setf *foo* f))
  (unless *foo* (bar (formatter "~A"))) ;;; => no note

[Nikodemus Siivola (nikodemus)]

 status confirmed
 importance low
 summary "odd code deletion note from lambda as argument to a load-time function call"

This makes the issue more apparent:

(defvar *foo*)
(defun bar (f)
 (setf *foo* f))
;; LET means this isn't toplevel code
(let ()
 (bar
  (LAMBDA
       (STREAM
        &OPTIONAL
        (FORMAT-ARG1010
         (ERROR 'SB-FORMAT:FORMAT-ERROR :COMPLAINT "required argument missing"
                :CONTROL-STRING "~A" :OFFSET 1))
        &REST SB-FORMAT::ARGS)
     (DECLARE (IGNORABLE STREAM))
     (BLOCK NIL (PRINC FORMAT-ARG1010 STREAM))
     SB-FORMAT::ARGS))

gives

  note:
    deleting unreachable code
    --> LET SB-C::%FUNCALL
    ==>
      STREAM

  note: deleting unreachable code

but

(defun foo ()
  (bar
   (LAMBDA
       (STREAM
        &OPTIONAL
        (FORMAT-ARG1010
         (ERROR 'SB-FORMAT:FORMAT-ERROR :COMPLAINT "required argument missing"
                :CONTROL-STRING "~A" :OFFSET 1))
        &REST SB-FORMAT::ARGS)
     (BLOCK NIL (PRINC FORMAT-ARG1010 STREAM))
     SB-FORMAT::ARGS)))

is silent. (Both under COMPILE-FILE.)

[Douglas Katzman (dougk)]

Fixed. Test case is :dead-code-in-optional-dispatch in compiler.pure.lisp