c-macro-expand isn't part of CC Mode [Was: cpp use in cc-mode is broken]

c-macro-expand isn't part of CC Mode [Was: cpp use in cc-mode is broken]

[Alan Mackenzie]

Hi Tim, Hi Nick, Hi Emacs, Hi Martin!

On Fri, 29 Apr 2005, Tim Van Holder wrote:

>As of a few days ago, the cc-mode in cvs emacs seems to preprocess the
>source file in order to determine the C macros present.

Please Note: `c-macro-expand', despite its name, is _NOT_ part of CC
Mode.  Its name prefix "c-" is misleading here.  That, and the fact that
it has a binding in some of the CC Mode keymaps, is its only connection
with CC Mode.  (If you look carefully, you'll find it's not in the CC
Mode manual.  ;-)

`c-macro-expand' actually lives in the file
.../list/progmodes/cmacexp.el.  This file was last updated 3 years 8
months ago by Eli.

There seem to have been a lot of patches to cc-mode.el and friends for
c-macro-expand in the last week.  Would somebody please take all these
changes out of the CC Mode files and put them into cmacexp.el instead.
Otherwise, there's going to be confusion and significant lack of
happiness when the time comes to merge the upcoming version of CC Mode
(5.31) into savannah.

Thanks in Advance!

[ .... ]

>The patches below resolve the immediate problem, just not optimally.

I couldn't have put it better myself.  ;-)

>Index: cc-vars.el
>===================================================================
>RCS file: /cvsroot/emacs/emacs/lisp/progmodes/cc-vars.el,v
>retrieving revision 1.37
>diff -u -u -p -d -r1.37 cc-vars.el
>--- cc-vars.el	31 Dec 2004 14:52:17 -0000	1.37
>+++ cc-vars.el	29 Apr 2005 14:11:11 -0000

[ .... ]

>Index: cc-mode.el
>===================================================================
>RCS file: /cvsroot/emacs/emacs/lisp/progmodes/cc-mode.el,v
>retrieving revision 1.34
>diff -u -u -p -d -r1.34 cc-mode.el
>--- cc-mode.el	27 Apr 2005 21:59:43 -0000	1.34
>+++ cc-mode.el	29 Apr 2005 14:11:39 -0000

-- 
Alan Mackenzie (Munich, Germany)





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c-macro-expand isn't part of CC Mode [Was: cpp use in cc-mode is broken]

[Nick Roberts]

Alan Mackenzie writes:
 > >As of a few days ago, the cc-mode in cvs emacs seems to preprocess the
 > >source file in order to determine the C macros present.

Actually to generate a list of #define directives.

 > Please Note: `c-macro-expand', despite its name, is _NOT_ part of CC
 > Mode.  Its name prefix "c-" is misleading here.  That, and the fact that
 > it has a binding in some of the CC Mode keymaps, is its only connection
 > with CC Mode.  (If you look carefully, you'll find it's not in the CC
 > Mode manual.  ;-)

Within Emacs CVS, I think both cc-mode.el and cmacexp.el are part of
Emacs.

 > `c-macro-expand' actually lives in the file
 > .../list/progmodes/cmacexp.el.  This file was last updated 3 years 8
 > months ago by Eli.

Thats why I'm interested in updating the variable c-macro-preprocessor.

 > There seem to have been a lot of patches to cc-mode.el and friends for
 > c-macro-expand in the last week.  Would somebody please take all these
 > changes out of the CC Mode files and put them into cmacexp.el instead.
 > Otherwise, there's going to be confusion and significant lack of
 > happiness when the time comes to merge the upcoming version of CC Mode
 > (5.31) into savannah.

They wouldn't work in cmacexp.el because they were part of c-mode. I've
already moved them now into gud.el and gdb-ui.el, anyway. Not because
cc-mode.el is part of CC Mode but because they were bad changes. If someone
makes good changes to cc-*.el files in Emacs CVS, then they would presumably
become part of your merge.

Nick


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Re: c-macro-expand isn't part of CC Mode [Was: cpp use in cc-mode is broken]

[Eli Zaretskii]

> Date: Tue, 3 May 2005 21:00:50 +0000 (GMT)
> From: Alan Mackenzie <acm@muc.de>
> Cc: bug-cc-mode@gnu.org, emacs-pretest-bug@gnu.org, emacs-devel@gnu.org
> 
> `c-macro-expand' actually lives in the file
> .../list/progmodes/cmacexp.el.  This file was last updated 3 years 8
> months ago by Eli.

Yes, that's when I fixed a similar problem in cmacexp.el with
invoking cpp.


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Re: c-macro-expand isn't part of CC Mode [Was: cpp use in cc-mode is broken]

[Richard Stallman]

    Please Note: `c-macro-expand', despite its name, is _NOT_ part of CC
    Mode.  Its name prefix "c-" is misleading here.

It has this name because it is specifically for C code and C mode.
This function and its name antedate CC Mode.


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Re: c-macro-expand isn't part of CC Mode

[Martin Stjernholm]

Nick Roberts <nickrob@snap.net.nz> wrote:

> Within Emacs CVS, I think both cc-mode.el and cmacexp.el are part of
> Emacs.

Maybe so, but it's more relevant to note what the respective
maintainers are inclined to support. If the CC Mode maintainers aren't
prepared to support a certain feature then it's better to not add that
feature to the cc-*.el files. That avoids confusion with bug reports
sent to the wrong places, bitrot and possible lossage in merges.

In this particular case the added feature was outside the scope of CC
Mode, so it's good that it was taken out again (although I'm sure the
feature in itself is very neat). The scope of CC Mode isn't spelled
out anywhere, so I don't blame anyone for missing it. Anyway, it is
something like this:

o  Provide functionality for syntax parsing in the supported
   languages.
o  Implement basic major mode operations for the supported languages,
   meaning buffer setup, movement/mark commands and miscellaneous
   simple tools for handling language constructs (e.g. aligning the
   backslashes in cpp macros).
o  Implement syntactically sensitive indentation and font locking.

Some noteworthy things that are outside the scope:

o  Tracking of symbols, e.g. for providing tooltips containing symbol
   docs and type info etc, or for locating symbol definitions.
o  Stuff that requires knowledge of the compilation environment, e.g.
   pulling in include files, expand macros, tracking cross file
   references.
o  Templates for source constructs, e.g. to quickly insert a more or
   less complete class or method.

These are not left out just because I personally don't consider them
nice features (I do), but because implementing those things well is
nontrivial and requires quite a bit of dedicated effort. I, and I
probably speak for Alan Mackenzie as well here, have enough with
getting the things inside the current scope to work as well as we
would like. Also, there's no particular reason why stuff like that
can't be in separate packages.


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