GNU bug report logs - #8712
24.0.50; getting the "Forgot to expand macro XXXX" error - problem? solution?

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

From: "Drew Adams" <drew.adams <at> oracle.com>
To: <bug-gnu-emacs <at> gnu.org>
Subject: 24.0.50;
	getting the "Forgot to expand macro XXXX" error - problem? solution?
Date: Sat, 21 May 2011 14:00:49 -0700

When byte-compiling I'm getting the famous "Forgot to expand macro XXXX"
error.
 
AFAICT, the email threads about that error just said, in effect:
 
1. Stefan thinks he found a bug that caused this, and fixed it, but he
isn't sure.
 
2. Concerning Emacs sources, just do a make -k clean and then try again.
 

But I'm seeing this for my own code.  I guess I need to understand the
solution (what to do) and, preferably, the cause of the problem.
 
I put the source files in a new directory, load the file with the
defmacros, and try to byte-compile a file that uses them.  I get the
above error, with XXXX = `push'.
 
These are the files: icicles-mac.el has the macros; icicles-cmd1.el is
the file whose byte-compiling raises the error.
 
With the source files (only) in new directory foo, cd to foo,
(add-to-list 'load-path "."), then M-x load-library icicles.
Then try to byte-compile icicles-cmd1.el.
 
The files you will need are here:
http://www.emacswiki.org/cgi-bin/wiki?action=index;match=%5C.(el%7Ctar)(%5C.gz)%
3F%24
 
You will need these files, in order to load library `icicles':
 
hexrgb.el
icicles-cmd1.el
icicles-cmd2.el
icicles-face.el
icicles-fn.el
icicles-mac.el
icicles-mcmd.el
icicles-mode.el
icicles-opt.el
icicles-var.el
icicles.el
 
To reproduce, after loading those source files try to byte-compile
icicles-cmd1.el.  You'll get this error:
 
icicles-cmd1.el:3066:91:Error: Wrong type argument: listp, "Forgot to
expand macro push"
 
I really don't understand.  Please advise.  Is this an Emacs bug that
has been fixed or will be fixed?  Is there something that I need to do
to make the code compatible with lexbind?  What's the story?  Thx.
 
In GNU Emacs 24.0.50.1 (i386-mingw-nt5.1.2600)
 of 2011-05-16 on 3249CTO
Windowing system distributor `Microsoft Corp.', version 5.1.2600
configured using `configure --with-gcc (4.5) --no-opt --cflags
-Ic:/build/include'
 

Message #8 received at 8712 <at> debbugs.gnu.org (full text, mbox):

From: "Drew Adams" <drew.adams <at> oracle.com>
To: <8712 <at> debbugs.gnu.org>
Subject: RE: bug#8712: 24.0.50;
	getting the "Forgot to expand macro XXXX" error - problem? solution?
Date: Sat, 21 May 2011 14:06:37 -0700

Forgot to mention that the same problem occurs when trying to byte-compile
icicles-cmd2.el.  In that case the error message is:

icicles-cmd2.el:3033:11:Error: Wrong type argument: listp, "Forgot to expand
macro push"

So the same problem appears in icicles-cmd1.el and icicles-cmd2.el.

Message #11 received at 8712 <at> debbugs.gnu.org (full text, mbox):

From: Stefan Monnier <monnier <at> iro.umontreal.ca>
To: "Drew Adams" <drew.adams <at> oracle.com>
Cc: 8712 <at> debbugs.gnu.org
Subject: Re: bug#8712: 24.0.50;
	getting the "Forgot to expand macro XXXX" error - problem? solution?
Date: Sun, 22 May 2011 15:14:20 -0300

> icicles-cmd1.el:3066:91:Error: Wrong type argument: listp, "Forgot to
> expand macro push"

I think the patch below fixes your problem, thanks.  Please confirm.


        Stefan


=== modified file 'lisp/emacs-lisp/bytecomp.el'
--- lisp/emacs-lisp/bytecomp.el	2011-05-12 02:36:05 +0000
+++ lisp/emacs-lisp/bytecomp.el	2011-05-22 17:36:39 +0000
@@ -2892,8 +2892,8 @@
 That command is designed for interactive use only" fn))
         (if (and (fboundp (car form))
                  (eq (car-safe (symbol-function (car form))) 'macro))
-            (byte-compile-report-error
-             (format "Forgot to expand macro %s" (car form))))
+            (byte-compile-log-warning
+             (format "Forgot to expand macro %s" (car form)) nil :error))
         (if (and handler
                  ;; Make sure that function exists.  This is important
                  ;; for CL compiler macros since the symbol may be
@@ -2991,7 +2991,7 @@
     (cond
      ((<= (+ alen alen) fmax2)
       ;; Add missing &optional (or &rest) arguments.
-      (dotimes (i (- (/ (1+ fmax2) 2) alen))
+      (dotimes (_ (- (/ (1+ fmax2) 2) alen))
         (byte-compile-push-constant nil)))
      ((zerop (logand fmax2 1))
       (byte-compile-log-warning "Too many arguments for inlined function"

=== modified file 'lisp/emacs-lisp/macroexp.el'
--- lisp/emacs-lisp/macroexp.el	2011-03-12 03:32:43 +0000
+++ lisp/emacs-lisp/macroexp.el	2011-05-22 18:11:30 +0000
@@ -169,14 +169,22 @@
       ;; here, so that any code that cares about the difference will
       ;; see the same transformation.
       ;; First arg is a function:
-      (`(,(and fun (or `apply `mapcar `mapatoms `mapconcat `mapc))
+      (`(,(and fun (or `funcall `apply `mapcar `mapatoms `mapconcat `mapc))
          ',(and f `(lambda . ,_)) . ,args)
+       (byte-compile-log-warning
+        (format "%s quoted with ' rather than with #'"
+                (list 'lambda (nth 1 f) '...))
+        t)
        ;; We don't use `maybe-cons' since there's clearly a change.
        (cons fun
              (cons (macroexpand-all-1 (list 'function f))
                    (macroexpand-all-forms args))))
       ;; Second arg is a function:
       (`(,(and fun (or `sort)) ,arg1 ',(and f `(lambda . ,_)) . ,args)
+       (byte-compile-log-warning
+        (format "%s quoted with ' rather than with #'"
+                (list 'lambda (nth 1 f) '...))
+        t)
        ;; We don't use `maybe-cons' since there's clearly a change.
        (cons fun
              (cons (macroexpand-all-1 arg1)

Message #14 received at 8712 <at> debbugs.gnu.org (full text, mbox):

From: "Drew Adams" <drew.adams <at> oracle.com>
To: "'Stefan Monnier'" <monnier <at> iro.umontreal.ca>
Cc: 8712 <at> debbugs.gnu.org
Subject: RE: bug#8712: 24.0.50;
	getting the "Forgot to expand macro XXXX" error - problem? solution?
Date: Sun, 22 May 2011 13:00:24 -0700

> I think the patch below fixes your problem, thanks.  Please confirm.

I patched the corresponding functions by hand, loaded their original source
files, then loaded the patched functions.  I then byte-compiled
icicles-cmd[12].el.  No byte-compilation errors, so it seems, at least on the
surface, that this is fixed.  The compilation was _very_ slow, but that's no
doubt because I used the source code rather than byte-compiled code.

Thanks for the fix.


I do have a question about the follownig warning, however (which I have not
seen/noticed before):

 (lambda (opt) ...) quoted with ' rather than with #'

That presumably comes from a defmacro that has, in effect, this:

 ` ... (let* (... (something (lambda (opt)...))))

That is, an unquoted lambda inside a backquote.  The backquote expands to (quote
(lambda...)) no doubt.

I have a few such macros, and I use them heavily.  I get this same warning
zillions of times (460 times just for icicles-cmd1.el, 30 times for
icicles-cmd2.el).  This is quite annoying.

What is the suggested/recommended way to write such code, to avoid this warning?
Do I now need to add #' in front of a lambda inside a backquote?

Message #17 received at 8712 <at> debbugs.gnu.org (full text, mbox):

From: Stefan Monnier <monnier <at> iro.umontreal.ca>
To: "Drew Adams" <drew.adams <at> oracle.com>
Cc: 8712 <at> debbugs.gnu.org
Subject: Re: bug#8712: 24.0.50;
	getting the "Forgot to expand macro XXXX" error - problem? solution?
Date: Sun, 22 May 2011 22:36:34 -0300

> I do have a question about the follownig warning, however (which I have not
> seen/noticed before):

>  (lambda (opt) ...) quoted with ' rather than with #'

> That presumably comes from a defmacro that has, in effect, this:

>  ` ... (let* (... (something (lambda (opt)...))))

This is because you pass (lambda (opt) ...) as `function' argument
to a macro that then splices it with

  `(.... ',function ....)

so the expanded code contains '(lambda (opt) ...).
Splice it with #', instead.

> That is, an unquoted lambda inside a backquote.  The backquote expands
> to (quote (lambda...)) no doubt.

No, backquote does not know you're building code, so it can't freely
decide to add `quote' symbols as it sees fit.


        Stefan

Message #20 received at 8712 <at> debbugs.gnu.org (full text, mbox):

From: "Drew Adams" <drew.adams <at> oracle.com>
To: "'Stefan Monnier'" <monnier <at> iro.umontreal.ca>
Cc: 8712 <at> debbugs.gnu.org
Subject: RE: bug#8712: 24.0.50;
	getting the "Forgot to expand macro XXXX" error - problem? solution?
Date: Sun, 22 May 2011 20:55:17 -0700

> > That presumably comes from a defmacro that has, in effect, this:
> >  ` ... (let* (... (something (lambda (opt)...))))
> 
> This is because you pass (lambda (opt) ...) as `function' argument
> to a macro that then splices it with `(.... ',function ....)
> so the expanded code contains '(lambda (opt) ...).

Oh, right; I was looking in the wrong place.  Thx.

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