Subject: Re: bug#5754: Bytecomp Arithmetic test failed

From: Juri Linkov <[email-masked]>
Date: Sun, 04 Apr 2010 01:18:17 +0300

> For this test the different order of arguments changes
> the returned value:
>
> (funcall '* 5e-324 8 0.125)
> => 5e-324
>
> (funcall '* 5e-324 0.125 8)
> => 0.0

`byte-optimize-plus' and `byte-optimize-minus' avoid this problem
by not using `byte-optimize-delay-constants-math' (see how its call
is commented out in `byte-opt.el').  Maybe `byte-optimize-multiply'
and `byte-optimize-divide' should do the same?

=== modified file 'lisp/emacs-lisp/byte-opt.el'
--- lisp/emacs-lisp/byte-opt.el	2010-01-13 08:35:10 +0000
+++ lisp/emacs-lisp/byte-opt.el	2010-04-03 22:16:20 +0000
@@ -806,7 +806,8 @@ (defun byte-optimize-minus (form)
   (byte-optimize-predicate form))
 
 (defun byte-optimize-multiply (form)
-  (setq form (byte-optimize-delay-constants-math form 1 '*))
+  ;; Don't call `byte-optimize-delay-constants-math' (bug#1334, bug#5754).
+  ;; (setq form (byte-optimize-delay-constants-math form 1 '*))
   ;; For (* constants..), byte-optimize-predicate does the work.
   (when (memq nil (mapcar 'numberp (cdr form)))
     ;; After `byte-optimize-predicate', if there is a INTEGER constant
@@ -823,7 +824,8 @@ (defun byte-optimize-multiply (form)
   (byte-optimize-predicate form))
 
 (defun byte-optimize-divide (form)
-  (setq form (byte-optimize-delay-constants-math form 2 '*))
+  ;; Don't call `byte-optimize-delay-constants-math' (bug#1334, bug#5754).
+  ;; (setq form (byte-optimize-delay-constants-math form 2 '*))
   ;; After `byte-optimize-predicate', if there is a INTEGER constant
   ;; in FORM, it is in the last element.
   (let ((last (car (reverse (cdr (cdr form))))))

-- 
Juri Linkov
http://www.jurta.org/emacs/