bug#38749: 27.0.50; objc-mode: wrong imenu item

bug#38749: 27.0.50; objc-mode: wrong imenu item

[HaiJun Zhang]

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In GNU Emacs 27.0.50 (build 1, x86_64-apple-darwin17.7.0, NS appkit-1561.61 Version 10.13.6 (Build 17G10021))
 of 2019-12-23 built on jundeMac
Repository revision: 3ee8ee8476fef2a5e8159f7597e36e0953295ce2
Repository branch: mod
Windowing system distributor ‘Apple', version 10.3.1561
System Description: Mac OS X 10.13.6

Open file nsfns.m in emacs source(src/nsfns.m). Many imenu items are invalid.
For example, “C/Copyright” and some more are in the header comment.


Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.
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Configured using:
 ‘configure —with-ns '--enable-locallisppath=/Library/Application
 Support/Emacs/${version}/site-lisp:/Library/Application
 Support/Emacs/site-lisp’ --with-modules --disable-acl
 —without-makeinfo CFLAGS=-O2’

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bug#38749: 27.0.50; objc-mode: wrong imenu item

[Alan Mackenzie]

Hello, HaiJun.

On Thu, Dec 26, 2019 at 18:31:55 +0800, HaiJun Zhang wrote:
> In GNU Emacs 27.0.50 (build 1, x86_64-apple-darwin17.7.0, NS appkit-1561.61 Version 10.13.6 (Build 17G10021))
>  of 2019-12-23 built on jundeMac
> Repository revision: 3ee8ee8476fef2a5e8159f7597e36e0953295ce2
> Repository branch: mod
> Windowing system distributor ‘Apple', version 10.3.1561
> System Description: Mac OS X 10.13.6

> Open file nsfns.m in emacs source(src/nsfns.m). Many imenu items are invalid.
> For example, “C/Copyright” and some more are in the header comment.

I've just spent some time fixing a more serious bug in the Objective-C
imenu mechanism.  This only occurs when I invoke imenu through the
keyboard (e.g. with M-x imenu), which might explain why it's survived so
long without detection.  If I invoke imenu with a mouse click, it works.

Anyhow, with nsfns.m, do M-x imenu <tab> C <tab> and select any item.
This works.  Now do M-x imenu.  This throws the error "Wrong type
argument: stringp, nil".

I've fixed this now, but haven't committed the fix yet.

Back to your bug - clearly what is happening is that the regular
expression search for functions is finding things in comments (such as
"Copyright (C)") which look like functions but aren't.  This is easy
enough to fix, by checking for comments and strings, but comes with a
fairly stiff time penalty.  On my 2½ year old Ryzen machine, scanning
the freshly visited Objc buffer currently takes 0.0196s.  With the check
for comments/strings, it takes 0.0650s.

That's a factor of ~3.25 slower.  On a slower machine (factor 3) with a
larger file (factor 3) this could mean the scanning would take 0.6s
rather than 0.2s.  This might be slow enough to annoy somebody a little.

Getting spurious entries in the index, like "Copyright" also is clearly
annoying, otherwise you wouldn't have submitted the bug report.  So
please give me a little time to decide which annoyance is the more
important.  Sorry!

-- 
Alan Mackenzie (Nuremberg, Germany).

bug#38749: 27.0.50; objc-mode: wrong imenu item

[HaiJun Zhang]

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在 2020年1月7日 +0800 AM2:08，Alan Mackenzie <acm@muc.de>，写道：
> I've just spent some time fixing a more serious bug in the Objective-C
> imenu mechanism. This only occurs when I invoke imenu through the
> keyboard (e.g. with M-x imenu), which might explain why it's survived so
> long without detection. If I invoke imenu with a mouse click, it works.
>
> Anyhow, with nsfns.m, do M-x imenu <tab> C <tab> and select any item.
> This works. Now do M-x imenu. This throws the error "Wrong type
> argument: stringp, nil".
>
> I've fixed this now, but haven't committed the fix yet.
>

Thanks.

> Back to your bug - clearly what is happening is that the regular
> expression search for functions is finding things in comments (such as
> "Copyright (C)") which look like functions but aren't. This is easy
> enough to fix, by checking for comments and strings, but comes with a
> fairly stiff time penalty. On my 2½ year old Ryzen machine, scanning
> the freshly visited Objc buffer currently takes 0.0196s. With the check
> for comments/strings, it takes 0.0650s.
>
> That's a factor of ~3.25 slower. On a slower machine (factor 3) with a
> larger file (factor 3) this could mean the scanning would take 0.6s
> rather than 0.2s. This might be slow enough to annoy somebody a little.
>

I'm not familiar with objc. What about searching the char '{' after the current pattern? But then I see the following snippet in nsfns.m:

static Lisp_Object
interpret_services_menu (NSMenu *menu, Lisp_Object prefix, Lisp_Object old)
/* —————————————————————————————————————
   Turn the input menu (an NSMenu) into a lisp list for tracking on lisp side.
   ————————————————————————————————————— */
{



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bug#38749: 27.0.50; objc-mode: wrong imenu item

[Alan Mackenzie]

Hello, HaiJun.

On Tue, Jan 07, 2020 at 10:09:49 +0800, HaiJun Zhang wrote:
> 在 2020年1月7日 +0800 AM2:08，Alan Mackenzie <acm@muc.de>，写道：
> > I've just spent some time fixing a more serious bug in the
> > Objective-C imenu mechanism. This only occurs when I invoke imenu
> > through the keyboard (e.g. with M-x imenu), which might explain why
> > it's survived so long without detection. If I invoke imenu with a
> > mouse click, it works.

> > Anyhow, with nsfns.m, do M-x imenu <tab> C <tab> and select any
> > item.  This works. Now do M-x imenu. This throws the error "Wrong
> > type argument: stringp, nil".

> > I've fixed this now, but haven't committed the fix yet.

It turns out, that bug had been fixed in the Emacs core version of CC
Mode back in 2012.  ;-)

> Thanks.

> > Back to your bug - clearly what is happening is that the regular
> > expression search for functions is finding things in comments (such as
> > "Copyright (C)") which look like functions but aren't. This is easy
> > enough to fix, by checking for comments and strings, but comes with a
> > fairly stiff time penalty. On my 2½ year old Ryzen machine, scanning
> > the freshly visited Objc buffer currently takes 0.0196s. With the check
> > for comments/strings, it takes 0.0650s.

> > That's a factor of ~3.25 slower. On a slower machine (factor 3) with a
> > larger file (factor 3) this could mean the scanning would take 0.6s
> > rather than 0.2s. This might be slow enough to annoy somebody a little.

I tried the timings again this evening, and I no longer see this factor
of ~3 slowdown.  In fact just a few 10s of percent.

So I've committed this fix, both to standalone CC Mode and the emacs-27
branch at savannah (from where it will soon find its way to the master
branch).

> I'm not familiar with objc. What about searching the char '{' after
> the current pattern? But then I see the following snippet in nsfns.m:

This isn't needed any more

> static Lisp_Object
> interpret_services_menu (NSMenu *menu, Lisp_Object prefix, Lisp_Object old)
> /* —————————————————————————————————————
>    Turn the input menu (an NSMenu) into a lisp list for tracking on lisp side.
>    ————————————————————————————————————— */
> {

Could I ask you to try out the new code, and if everything's OK, we can
close the bug as fixed.

Thanks!

-- 
Alan Mackenzie (Nuremberg, Germany).

bug#38749: 27.0.50; objc-mode: wrong imenu item

[HaiJun Zhang]

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I tried. It is fixed. Thanks.
在 2020年1月8日 +0800 AM4:54，Alan Mackenzie <acm@muc.de>，写道：
> Hello, HaiJun.
>
> On Tue, Jan 07, 2020 at 10:09:49 +0800, HaiJun Zhang wrote:
> > 在 2020年1月7日 +0800 AM2:08，Alan Mackenzie <acm@muc.de>，写道：
> > > I've just spent some time fixing a more serious bug in the
> > > Objective-C imenu mechanism. This only occurs when I invoke imenu
> > > through the keyboard (e.g. with M-x imenu), which might explain why
> > > it's survived so long without detection. If I invoke imenu with a
> > > mouse click, it works.
>
> > > Anyhow, with nsfns.m, do M-x imenu <tab> C <tab> and select any
> > > item. This works. Now do M-x imenu. This throws the error "Wrong
> > > type argument: stringp, nil".
>
> > > I've fixed this now, but haven't committed the fix yet.
>
> It turns out, that bug had been fixed in the Emacs core version of CC
> Mode back in 2012. ;-)
>
> > Thanks.
>
> > > Back to your bug - clearly what is happening is that the regular
> > > expression search for functions is finding things in comments (such as
> > > "Copyright (C)") which look like functions but aren't. This is easy
> > > enough to fix, by checking for comments and strings, but comes with a
> > > fairly stiff time penalty. On my 2½ year old Ryzen machine, scanning
> > > the freshly visited Objc buffer currently takes 0.0196s. With the check
> > > for comments/strings, it takes 0.0650s.
>
> > > That's a factor of ~3.25 slower. On a slower machine (factor 3) with a
> > > larger file (factor 3) this could mean the scanning would take 0.6s
> > > rather than 0.2s. This might be slow enough to annoy somebody a little.
>
> I tried the timings again this evening, and I no longer see this factor
> of ~3 slowdown. In fact just a few 10s of percent.
>
> So I've committed this fix, both to standalone CC Mode and the emacs-27
> branch at savannah (from where it will soon find its way to the master
> branch).
>
> > I'm not familiar with objc. What about searching the char '{' after
> > the current pattern? But then I see the following snippet in nsfns.m:
>
> This isn't needed any more
>
> > static Lisp_Object
> > interpret_services_menu (NSMenu *menu, Lisp_Object prefix, Lisp_Object old)
> > /* —————————————————————————————————————
> >    Turn the input menu (an NSMenu) into a lisp list for tracking on lisp side.
> >    ————————————————————————————————————— */
> > {
>
> Could I ask you to try out the new code, and if everything's OK, we can
> close the bug as fixed.
>
> Thanks!
>
> --
> Alan Mackenzie (Nuremberg, Germany).

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bug#38749: 27.0.50; objc-mode: wrong imenu item

[Alan Mackenzie]

Hello, HaiJun.

On Wed, Jan 08, 2020 at 12:03:32 +0800, HaiJun Zhang wrote:
> I tried. It is fixed. Thanks.

OK, Thanks!  I'm closing the bug with this post.

> 在 2020年1月8日 +0800 AM4:54，Alan Mackenzie <acm@muc.de>，写道：
> > Hello, HaiJun.

[ .... ]

> > Could I ask you to try out the new code, and if everything's OK, we can
> > close the bug as fixed.

--
Alan Mackenzie (Nuremberg, Germany).