`assert' macro

`assert' macro

[Johan Bockgård]

The `assert' macro from cl-macs is used in several files in Emacs. It
expands into the following code.

    (macroexpand '(assert x))
     =>
    (progn (or x (signal 'cl-assertion-failed (list 'x))) nil)

Unless cl is loaded `cl-assertion-failed' is not a known error symbol
though, so if the assertion fails it will produce a "peculiar error"
that is impossible to catch. It should signal a known condition.

-- 
Johan Bockgård

Re: `assert' macro

[John Paul Wallington]

bojohan+news@dd.chalmers.se (Johan Bockgård) writes:

> The `assert' macro from cl-macs is used in several files in Emacs. It
> expands into the following code.
>
>     (macroexpand '(assert x))
>      =>
>     (progn (or x (signal 'cl-assertion-failed (list 'x))) nil)
>
> Unless cl is loaded `cl-assertion-failed' is not a known error symbol
> though, so if the assertion fails it will produce a "peculiar error"
> that is impossible to catch. It should signal a known condition.

A minimal impact fix is to move the definition of that condition from
cl.el to subr.el.  Any objections ?


Index: lisp/subr.el
===================================================================
RCS file: /sources/emacs/emacs/lisp/subr.el,v
retrieving revision 1.494
diff -u -r1.494 subr.el
--- lisp/subr.el	26 Jan 2006 17:54:27 -0000	1.494
+++ lisp/subr.el	29 Jan 2006 19:09:26 -0000
@@ -1831,6 +1831,12 @@
 This variable is meaningful on MS-DOG and Windows NT.
 On those systems, it is automatically local in every buffer.
 On other systems, this variable is normally always nil.")
+
+;; The `assert' macro from the cl package signals
+;; `cl-assertion-failed' at runtime so always define it.
+(put 'cl-assertion-failed 'error-conditions '(error))
+(put 'cl-assertion-failed 'error-message "Assertion failed")
+
 \f
 ;;;; Misc. useful functions.

Index: lisp/emacs-lisp/cl.el
===================================================================
RCS file: /sources/emacs/emacs/lisp/emacs-lisp/cl.el,v
retrieving revision 1.46
diff -u -r1.46 cl.el
--- lisp/emacs-lisp/cl.el	6 Aug 2005 17:08:59 -0000	1.46
+++ lisp/emacs-lisp/cl.el	29 Jan 2006 19:09:27 -0000
@@ -580,9 +580,6 @@
 
 ;;; Miscellaneous.
 
-(put 'cl-assertion-failed 'error-conditions '(error))
-(put 'cl-assertion-failed 'error-message "Assertion failed")
-
 (defvar cl-fake-autoloads nil
   "Non-nil means don't make CL functions autoload.")
 

Re: `assert' macro

[Richard M. Stallman]

    A minimal impact fix is to move the definition of that condition from
    cl.el to subr.el.  Any objections ?

It seems good to me.