bug#2732: 23.0.91; Please add support for Objective-C++

bug#2732: 23.0.91; Please add support for Objective-C++

[Yavor Doganov]

Package: emacs,cc-mode
Severity: wishlist

I had to edit some ObjC++ files today in my pathetic attempt to port
Dasher [1] to GNUstep.  Emacs opens .mm files in nroff-mode, and
manually switching to c++-mode or objc-mode does not give satisfactory
results.

Objective-C++ is supported by GCC and GNUstep Make, and although there
are currently no free programs written in this language (TTBOMK, apart
from the various free software ported to Mac OS X; but it's unusable
for other reasons), this is likely to change in the near future.

I realize this is Emacs 24 or 25 material; there is no problem about
that.

In GNU Emacs 23.0.91.1 (i486-pc-linux-gnu, GTK+ Version 2.12.9)
 of 2009-03-18 on gana, modified for gNewSense
 (Unofficial gNewSense emacs-snapshot package, version 1:20090318-gns1)
Windowing system distributor `The X.Org Foundation', version 11.0.10400090

[1] http://www.inference.phy.cam.ac.uk/dasher/

bug#29339: 27.0.50; CC-mode doesn't know about .mm and .M suffixes for Objective-C++

[Alan Mackenzie]

In article <mailman.3878.1510925890.27995.bug-gnu-emacs@gnu.org> you wrote:

> GCC uses .mm or .M for Objective-C++,
> cf. https://gcc.gnu.org/onlinedocs/gcc-7.2.0/gcc/Overall-Options.html.
> However, neither `auto-mode-alist' nor `cc-other-file-alist' contain
> these file extensions.

I don't think there's an Objective-C++ mode out there in the wild.  So
what existing mode should be used for *.mm and *.M?  Is that mode a good
enough fit to be able, in good conscience, to use it for Obj-C++?

> In GNU Emacs 27.0.50 (build 17, x86_64-pc-linux-gnu, GTK+ Version 3.10.8)
>  of 2017-11-17 built on localhost
> Repository revision: 345c7d9c7b84c0c03ef1d0f32e9e0f39029be44a
> Windowing system distributor 'The X.Org Foundation', version 11.0.11803000
> System Description:     Ubuntu 14.04.5 LTS

[ .... ]

-- 
Alan Mackenzie (Nuremberg, Germany).

bug#29339: 27.0.50; CC-mode doesn't know about .mm and .M suffixes for Objective-C++

[Philipp Stephani]

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Alan Mackenzie <acm@muc.de> schrieb am Fr., 17. Nov. 2017 um 20:00 Uhr:

> In article <mailman.3878.1510925890.27995.bug-gnu-emacs@gnu.org> you
> wrote:
>
> > GCC uses .mm or .M for Objective-C++,
> > cf. https://gcc.gnu.org/onlinedocs/gcc-7.2.0/gcc/Overall-Options.html.
> > However, neither `auto-mode-alist' nor `cc-other-file-alist' contain
> > these file extensions.
>
> I don't think there's an Objective-C++ mode out there in the wild.  So
> what existing mode should be used for *.mm and *.M?  Is that mode a good
> enough fit to be able, in good conscience, to use it for Obj-C++?
>

According to https://www.emacswiki.org/emacs/ObjectiveCMode#toc2 objc-mode
is the most appropriate mode for now, until a true objc++-mode is added.

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bug#29339: 27.0.50; CC-mode doesn't know about .mm and .M suffixes for Objective-C++

[Alan Mackenzie]

Hello, Philipp.

On Thu, Dec 21, 2017 at 19:22:05 +0000, Philipp Stephani wrote:
> Alan Mackenzie <acm@muc.de> schrieb am Fr., 17. Nov. 2017 um 20:00 Uhr:

> > In article <mailman.3878.1510925890.27995.bug-gnu-emacs@gnu.org> you
> > wrote:

> > > GCC uses .mm or .M for Objective-C++,
> > > cf. https://gcc.gnu.org/onlinedocs/gcc-7.2.0/gcc/Overall-Options.html.
> > > However, neither `auto-mode-alist' nor `cc-other-file-alist' contain
> > > these file extensions.

> > I don't think there's an Objective-C++ mode out there in the wild.  So
> > what existing mode should be used for *.mm and *.M?  Is that mode a good
> > enough fit to be able, in good conscience, to use it for Obj-C++?


> According to https://www.emacswiki.org/emacs/ObjectiveCMode#toc2 objc-mode
> is the most appropriate mode for now, until a true objc++-mode is added.

That only answers the first question, not the second.  If we put .M and
.mm into CC Mode or auto-mode-alist in Emacs, that implies some sort of
commitment to support the language (Objective-C++).  If Objective-C Mode
already almost supports it properly, that is one thing, but if the match
is less good, it could involve a lot of work.

From what I can gather, Objective-C++ is a bit of a mixture between
Objective-C and C++, much as its name implies.  Do these individual
facets fit together (from a CC Mode point of view) without clashing too
much?  According to Wikipedia, the language is not formerly defined in
any standard.  What, then, is the language?

Do you know of anybody working on an Objective-C++ Mode?

-- 
Alan Mackenzie (Nuremberg, Germany).

bug#29339: 27.0.50; CC-mode doesn't know about .mm and .M suffixes for Objective-C++

[Glenn Morris]

Alan Mackenzie wrote:

> That only answers the first question, not the second.  If we put .M and
> .mm into CC Mode or auto-mode-alist in Emacs, that implies some sort of
> commitment to support the language (Objective-C++).  If Objective-C Mode
> already almost supports it properly, that is one thing, but if the match
> is less good, it could involve a lot of work.

8 years ago, the comment was "switching to c++-mode or objc-mode does
not give satisfactory results". I don't know if anything has changed
since. Ref: https://debbugs.gnu.org/2732

bug#2732: 23.0.91; Please add support for Objective-C++

[Lars Ingebrigtsen]

Glenn Morris <rgm@gnu.org> writes:

>> That only answers the first question, not the second.  If we put .M and
>> .mm into CC Mode or auto-mode-alist in Emacs, that implies some sort of
>> commitment to support the language (Objective-C++).  If Objective-C Mode
>> already almost supports it properly, that is one thing, but if the match
>> is less good, it could involve a lot of work.
>
> 8 years ago, the comment was "switching to c++-mode or objc-mode does
> not give satisfactory results". I don't know if anything has changed
> since. Ref: https://debbugs.gnu.org/2732

So it doesn't seem like just mapping .mm to objc-mode would give
satisfactory results, and I'm closing this bug report.

(If somebody wants to add a real mode for Objective-C++, that can, of
course, be done.)

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#2732: 23.0.91; Please add support for Objective-C++

[Philipp]

> 
> (If somebody wants to add a real mode for Objective-C++, that can, of
> course, be done.)

Then why close this bug, which tracks exactly this feature request?

bug#2732: 23.0.91; Please add support for Objective-C++

[Alan Mackenzie]

Hello, Lars.

On Thu, Jun 03, 2021 at 12:07:18 +0200, Lars Ingebrigtsen wrote:
> Glenn Morris <rgm@gnu.org> writes:

> >> That only answers the first question, not the second.  If we put .M and
> >> .mm into CC Mode or auto-mode-alist in Emacs, that implies some sort of
> >> commitment to support the language (Objective-C++).  If Objective-C Mode
> >> already almost supports it properly, that is one thing, but if the match
> >> is less good, it could involve a lot of work.

> > 8 years ago, the comment was "switching to c++-mode or objc-mode does
> > not give satisfactory results". I don't know if anything has changed
> > since. Ref: https://debbugs.gnu.org/2732

> So it doesn't seem like just mapping .mm to objc-mode would give
> satisfactory results, and I'm closing this bug report.

> (If somebody wants to add a real mode for Objective-C++, that can, of
> course, be done.)

Personally, I don't want to spend the time (and the learning effort)
coding up an Objective-C++ Mode.  If anybody else wanted to do this
(most likely as a CC Mode derived mode), which might not be very much
work, I would be prepared to answer questions, and deliver support as
usual.

> -- 
> (domestic pets only, the antidote for overdose, milk.)
>    bloggy blog: http://lars.ingebrigtsen.no

-- 
Alan Mackenzie (Nuremberg, Germany).