[ clisp-Bugs-1731469 ] loop expansion: spurious LET twice

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Bugs item #1731469, was opened at 2007-06-05 11:04
Message generated for change (Comment added) made by sds
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Category: clisp
Group: None
Status: Closed
Resolution: Fixed
Priority: 3
Private: No
Submitted By: Jörg Höhle (hoehle)
Assigned to: Sam Steingold (sds)
Summary: loop expansion: spurious LET twice

Initial Comment:
Hi,

Looking at CLISP macroexpansions after my (gensym "NAME-") patches made me discover the following irregularity.

The pattern variable for loop destructuring is bound twice.  I don't think the reason for duplication is special tricks with shadowing, I rather believe it's a small bug, producing no known error.

(loop for nil on '(1 2 . 3) count t)
(MACROLET ((LOOP-FINISH NIL (SYSTEM::LOOP-FINISH-ERROR)))
 (BLOCK NIL
  (LET ((#:PATTERN-6274 NIL))        ; here
   (LET ((#:LIST-6273 '(1 2 . 3)))
    (PROGN
     (LET ((#:PATTERN-6274 NIL))     ; here
      (LET ((#:ACCUNUM-VAR-6275 0))
       (MACROLET ((LOOP-FINISH NIL '(GO SYSTEM::END-LOOP)))
        (TAGBODY SYSTEM::BEGIN-LOOP (WHEN (ATOM #:LIST-6273) (LOOP-FINISH))
         (SETQ #:PATTERN-6274 #:LIST-6273)
         (PROGN (WHEN T (INCF #:ACCUNUM-VAR-6275)))
         (PSETQ #:LIST-6273 (CDR #:LIST-6273)) (GO SYSTEM::BEGIN-LOOP)
         SYSTEM::END-LOOP
         (MACROLET
          ((LOOP-FINISH NIL (SYSTEM::LOOP-FINISH-WARN) '(GO SYSTEM::END-LOOP)))
          (RETURN-FROM NIL #:ACCUNUM-VAR-6275)))))))))))

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>Comment By: Sam Steingold (sds)
Date: 2011-08-05 15:36

Message:
fixed differently...

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Comment By: Sam Steingold (sds)
Date: 2011-08-05 15:18

Message:
my "fix" broke 
(loop with nil = (return t) return nil)

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Comment By: Sam Steingold (sds)
Date: 2011-03-31 15:21

Message:
thank you for your bug report.
the bug has been fixed in the source tree (mercurial/hg).
you can either wait for the next release (recommended)
or check out the current mercurial tree (see http://clisp.org)
and build CLISP from the sources (be advised that between
releases the source tree is very unstable and may not even build
on your platform).

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You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=101355&aid=1731469&group_id=1355