Re: [Emacs-diffs] master e4de91d: Introduce new macros to cover Emacs's new names in cl-lib.el.

Re: [Emacs-diffs] master e4de91d: Introduce new macros to cover Emacs's new names in cl-lib.el.

[Stefan Monnier]

>     Change this back to cc-external-require from an eval-when-compile
>     require.

I haven't been able to figure out what is the difference.  Can you
enlighten us with, ideally, a testcase?


        Stefan

Re: [Emacs-diffs] master e4de91d: Introduce new macros to cover Emacs's new names in cl-lib.el.

[Alan Mackenzie]

Hello, Stefan.

On Wed, Aug 12, 2015 at 10:48:42PM -0400, Stefan Monnier wrote:
> >     Change this back to cc-external-require from an eval-when-compile
> >     require.

> I haven't been able to figure out what is the difference.  Can you
> enlighten us with, ideally, a testcase?

The (eval-when-compile (require 'cl)) was inadequate, because
cl.el (now cl-lib.el) is now required at run-time, too.  Without the
change, the error "cl-mapcan not known" gets thrown when attempting to
visit the first file.c in an Emacs session.

>         Stefan

-- 
Alan Mackenzie (Nuremberg, Germany).

Re: [Emacs-diffs] master e4de91d: Introduce new macros to cover Emacs's new names in cl-lib.el.

[Stefan Monnier]

> The (eval-when-compile (require 'cl)) was inadequate, because
> cl.el (now cl-lib.el) is now required at run-time, too.  Without the
> change, the error "cl-mapcan not known" gets thrown when attempting to
> visit the first file.c in an Emacs session.

Oh, right, sorry, so the question becomes: what is the difference
between `require' and `cc-external-require' here?


        Stefan

Re: [Emacs-diffs] master e4de91d: Introduce new macros to cover Emacs's new names in cl-lib.el.

[Alan Mackenzie]

Hello, Stefan.

On Thu, Aug 13, 2015 at 12:02:20PM -0400, Stefan Monnier wrote:
> > The (eval-when-compile (require 'cl)) was inadequate, because
> > cl.el (now cl-lib.el) is now required at run-time, too.  Without the
> > change, the error "cl-mapcan not known" gets thrown when attempting to
> > visit the first file.c in an Emacs session.

> Oh, right, sorry, so the question becomes: what is the difference
> between `require' and `cc-external-require' here?

Not a great deal, to be honest.  The main difference is that symbols
whose function cell has been given a placeholder value to inhibit
compiler warnings have these function cells restored to their correct
values in `cc-external-require' around the actual `require'.

An example of an XEmacs function which gets this treatment is
`buffer-syntactic-context'.  An example of an Emacs function is
`string-to-syntax'.

>         Stefan

-- 
Alan Mackenzie (Nuremberg, Germany).

Re: [Emacs-diffs] master e4de91d: Introduce new macros to cover Emacs's new names in cl-lib.el.

[Stefan Monnier]

>> > The (eval-when-compile (require 'cl)) was inadequate, because
>> > cl.el (now cl-lib.el) is now required at run-time, too.  Without the
>> > change, the error "cl-mapcan not known" gets thrown when attempting to
>> > visit the first file.c in an Emacs session.
>> Oh, right, sorry, so the question becomes: what is the difference
>> between `require' and `cc-external-require' here?
> Not a great deal, to be honest.  The main difference is that symbols
> whose function cell has been given a placeholder value to inhibit
> compiler warnings have these function cells restored to their correct
> values in `cc-external-require' around the actual `require'.

Ah, so it tries to restore temporary sanity while loading the file.
That makes sense, thank you.

> An example of an XEmacs function which gets this treatment is
> `buffer-syntactic-context'.  An example of an Emacs function is
> `string-to-syntax'.

BTW, how 'bout using something like the patch below, to try and avoid
messing with function cells when we can?


        Stefan


diff --git a/lisp/progmodes/cc-bytecomp.el b/lisp/progmodes/cc-bytecomp.el
index b63eeb4..fe7cac7 100644
--- a/lisp/progmodes/cc-bytecomp.el
+++ b/lisp/progmodes/cc-bytecomp.el
@@ -377,6 +377,8 @@
 about incorrect number of arguments.  It's dangerous to try to replace
 existing functions since the byte compiler might need the definition
 at compile time, e.g. for macros and inline functions."
+  (if (fboundp 'declare-function)
+      `(declare-function ,fun nil)
   `(eval-when-compile
      (if (fboundp ',fun)
 	 (cc-bytecomp-debug-msg
@@ -393,7 +395,7 @@
 	     (fset ',fun (intern (concat "cc-bytecomp-ignore-fun:"
 					 (symbol-name ',fun))))
 	     (cc-bytecomp-debug-msg
-	      "cc-bytecomp-defun: Covered function %s" ',fun))))))
+		"cc-bytecomp-defun: Covered function %s" ',fun)))))))
 
 (defmacro cc-bytecomp-put (symbol propname value)
   "Set a property on a symbol during compilation (and evaluation) of
@@ -428,13 +428,15 @@
 the compilation.  This is the same as using `fboundp' but additionally
 exclude any functions that have been bound during compilation with
 `cc-bytecomp-defun'."
+  (if (fboundp 'declare-function)
+      `(fboundp ,symbol)
   (let (fun-elem)
     (if (and (cc-bytecomp-is-compiling)
 	     (setq fun-elem (assq (car (cdr symbol))
 				  cc-bytecomp-original-functions))
 	     (eq (elt fun-elem 2) 'unbound))
 	nil
-      `(fboundp ,symbol))))
+	`(fboundp ,symbol)))))
 
 \f
 (provide 'cc-bytecomp)