GNU bug report logs - #13865
redefinition of +

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Ian Price <ianprice90 <at> googlemail.com>
To: bug-guile <at> gnu.org
Cc: ioliveira <at> id.uff.br
Subject: redefinition of +
Date: Mon, 04 Mar 2013 00:42:12 +0000

Hi guys,
On #guile, euiuer (CCed) reported this, though he was to shy to report
this himself. In guile 1.8.7

<euiuer> (define (foo) (+ 1 1))
<euiuer> (define (+ a b) (- a b))
<euiuer> (display (foo))
<euiuer> (display (+ 1 1))
<euiuer> it evails like 0 and 0.
<euiuer> but..
<euiuer> (define (foo) (+ 1 1))
<euiuer> (display (foo))
<euiuer> (define (+ a b) (- a b))
<euiuer> (display (foo))
<euiuer> (display (+ 1 1))
<euiuer> it evails like 2 2 0
<euiuer> it is kind of odd.

He confirms he gets these when he runs these from a script.

I get the same on my 1.8.8 install, both at the repl and from a script.

Since it evaluates correct if we run (bar) _after_ redefining + I think
it's a safe bet to assume that 1.8 cached the reference to +, but not
having been around for 1.8, this is a conjecture only.


Now, 1.8 is the old series, how about 2? Running a recent master
(9b977c836bf147d386944c401113aba32776fa68)[0].

From the repl:
scheme@(guile−user)> (define (foo) (+ 1 1))
scheme@(guile−user)> (define (+ a b) (- a b))
scheme@(guile−user)> (foo)
$2 = 2
scheme@(guile−user)> (+ 1 1)
$3 = 0

and

scheme@(guile−user)> (define (foo) (+ 1 1))
scheme@(guile−user)> (foo)
$2 = 2
scheme@(guile−user)> (define (+ a b) (- a b))
scheme@(guile−user)> (foo)
$3 = 2
scheme@(guile−user)> (+ 1 1)
$4 = 0


From a script
$ guile -q -s /tmp/file1.scm
22
$ guile -q -s /tmp/file2.scm
222


This behaviour can be "blamed" on guile 2's more aggressive
optimisation. Indeed, 

scheme@(guile−user)> ,disassemble foo
Disassembly of #<procedure foo ()>:

   0    (assert−nargs−ee/locals 0)      ;; 0 args, 0 locals
   2    (make−int8 2)                   ;; 2                  at (unknown file):5:14
   4    (return)      

is pretty much what we want usually. And I'm inclined to say NOTABUG for
the repl when optimisation is turned on. However, in a script, this is a
bug IMO, since we shouldn't really be optimising + if our top-level
binding for + is not the builtin one, and we can certainly detect a
redefinition of + within a file.

Just to be sure, I tried turning off cse and peal, but ran into a
different optimisation

scheme@(guile−user)> ,option compile-options (#:partial-eval? #f #:cse? #f)
scheme@(guile−user)> ,option compile-options
(#:partial−eval? #f #:cse? #f)
scheme@(guile−user)> (foo)
$2 = 2
scheme@(guile−user)> (+ )
$3 = 0
scheme@(guile−user)> (define (+ a b) (- a b))
scheme@(guile−user)> (foo)
$4 = 2
scheme@(guile−user)> (+ 1 1)
$5 = 0

Have you guessed what it was?

scheme@(guile−user)> ,disassemble foo
Disassembly of #<procedure foo ()>:

   0    (assert−nargs−ee/locals 0)      ;; 0 args, 0 locals
   2    (make−int8:1)                   ;; 1
   3    (add1)                                                at (unknown file):44:14
   4    (return)                        

So, you can't win on this one :)

[0] I have not got a stable-2.0 install at the moment to compare, but I
suspect it will be similar.

-- 
Ian Price -- shift-reset.com

"Programming is like pinball. The reward for doing it well is
the opportunity to do it again" - from "The Wizardy Compiled"

Message #8 received at 13865 <at> debbugs.gnu.org (full text, mbox):

From: ludo <at> gnu.org (Ludovic Courtès)
To: Ian Price <ianprice90 <at> googlemail.com>
Cc: 13865 <at> debbugs.gnu.org, control <at> debbugs.gnu.org, ioliveira <at> id.uff.br
Subject: Re: bug#13865: redefinition of +
Date: Mon, 04 Mar 2013 14:34:37 +0100

close 13865
tag 13865 notabug
thanks

Ian Price <ianprice90 <at> googlemail.com> skribis:

> is pretty much what we want usually. And I'm inclined to say NOTABUG for
> the repl when optimisation is turned on. However, in a script, this is a
> bug IMO, since we shouldn't really be optimising + if our top-level
> binding for + is not the builtin one, and we can certainly detect a
> redefinition of + within a file.

The REPL is different from a “real” program.

In a stand-alone file like this:

--8<---------------cut here---------------start------------->8---
(define (+ a b) (- a b))
(pk (+ 1 1))
--8<---------------cut here---------------end--------------->8---

You get the expected behavior, because top-level ‘define’ is like
‘letrec*’.

So closing it as not-a-bug.  Let us know if you think of actions to be
taken.

Thanks,
Ludo’.

Message #15 received at 13865 <at> debbugs.gnu.org (full text, mbox):

From: Ian Price <ianprice90 <at> googlemail.com>
To: ludo <at> gnu.org (Ludovic Courtès)
Cc: 13865 <at> debbugs.gnu.org, control <at> debbugs.gnu.org, ioliveira <at> id.uff.br
Subject: Re: bug#13865: redefinition of +
Date: Mon, 04 Mar 2013 14:24:26 +0000

ludo <at> gnu.org (Ludovic Court$(D+2(Bs) writes:

> close 13865
> tag 13865 notabug
> thanks
>
> Ian Price <ianprice90 <at> googlemail.com> skribis:
>
>> is pretty much what we want usually. And I'm inclined to say NOTABUG for
>> the repl when optimisation is turned on. However, in a script, this is a
>> bug IMO, since we shouldn't really be optimising + if our top-level
>> binding for + is not the builtin one, and we can certainly detect a
>> redefinition of + within a file.
>
> The REPL is different from a $B!H(Breal$B!I(B program.
>
> In a stand-alone file like this:
>
> (define (+ a b) (- a b))
> (pk (+ 1 1))
>
> You get the expected behavior, because top-level $B!F(Bdefine$B!G(B is like
> $B!F(Bletrec*$B!G(B.
>
> So closing it as not-a-bug.  Let us know if you think of actions to be
> taken.

Er, screw the repl, but it happens in a script as well.

(define (foo) (+ 1 1))
(define (+ a b) (- a b))
(display (foo))
(display (+ 1 1))
(newline)

$ guile -s /tmp/file1.scm
;;; note: source file /tmp/file1.scm
;;;       newer than compiled /home/ian/.cache/guile/ccache/2.2-LE-4-3.1/tmp/file1.scm.go
;;; note: auto-compilation is enabled, set GUILE_AUTO_COMPILE=0
;;;       or pass the --no-auto-compile argument to disable.
;;; compiling /tmp/file1.scm
;;; compiled /home/ian/.cache/guile/ccache/2.2-LE-4-3.1/tmp/file1.scm.go
22

  (letrec* ((foo (lambda () (+ 1 1)))
          (+ (lambda (a b) (- a b))))
  (display (foo))
  (display (+ 1 1))
  (newline))
  
$ guile -s /tmp/file1.scm
;;; note: source file /tmp/file1.scm
;;;       newer than compiled /home/ian/.cache/guile/ccache/2.2-LE-4-3.1/tmp/file1.scm.go
;;; note: auto-compilation is enabled, set GUILE_AUTO_COMPILE=0
;;;       or pass the --no-auto-compile argument to disable.
;;; compiling /tmp/file1.scm
;;; compiled /home/ian/.cache/guile/ccache/2.2-LE-4-3.1/tmp/file1.scm.go
00

If top-level module define is supposed to be a letrec*, it certainly
isn't acting like one.

-- 
Ian Price -- shift-reset.com

"Programming is like pinball. The reward for doing it well is
the opportunity to do it again" - from "The Wizardy Compiled"

Message #18 received at 13865 <at> debbugs.gnu.org (full text, mbox):

From: Andy Wingo <wingo <at> pobox.com>
To: Ian Price <ianprice90 <at> googlemail.com>
Cc: 13865 <at> debbugs.gnu.org, Ludovic Courtès <ludo <at> gnu.org>,
	control <at> debbugs.gnu.org, ioliveira <at> id.uff.br
Subject: Re: bug#13865: redefinition of +
Date: Thu, 07 Mar 2013 22:39:05 +0100

On Mon 04 Mar 2013 15:24, Ian Price <ianprice90 <at> googlemail.com> writes:

> Er, screw the repl, but it happens in a script as well.
>
> (define (foo) (+ 1 1))
> (define (+ a b) (- a b))
> (display (foo))
> (display (+ 1 1))
> (newline)
>
> $ guile -s /tmp/file1.scm
> ;;; note: source file /tmp/file1.scm
> ;;;       newer than compiled /home/ian/.cache/guile/ccache/2.2-LE-4-3.1/tmp/file1.scm.go
> ;;; note: auto-compilation is enabled, set GUILE_AUTO_COMPILE=0
> ;;;       or pass the --no-auto-compile argument to disable.
> ;;; compiling /tmp/file1.scm
> ;;; compiled /home/ian/.cache/guile/ccache/2.2-LE-4-3.1/tmp/file1.scm.go
> 22

I see you are on master.  Is this a problem only in master?

    $ ~/src/guile-master/meta/guile /tmp/foo.scm 
    ;;; note: auto-compilation is enabled, set GUILE_AUTO_COMPILE=0
    ;;;       or pass the --no-auto-compile argument to disable.
    ;;; compiling /tmp/foo.scm
    ;;; compiled /home/wingo/src/guile-master/cache/guile/ccache/2.2-LE-8-3.1/tmp/foo.scm.go
    22
    $ ~/src/guile/meta/guile /tmp/foo.scm 
    ;;; note: auto-compilation is enabled, set GUILE_AUTO_COMPILE=0
    ;;;       or pass the --no-auto-compile argument to disable.
    ;;; compiling /tmp/foo.scm
    ;;; compiled /home/wingo/src/guile/cache/guile/ccache/2.0-LE-8-2.0/tmp/foo.scm.go
    00

Andy
-- 
http://wingolog.org/

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