GNU bug report logs - #6978
show-paren-mode doesn't match when scope "::" operator is used : emacs 32.1.97

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

From: "Bob" <purchasebyemail1 <at> comcast.net>
To: <bug-gnu-emacs <at> gnu.org>
Subject: show-paren-mode doesn't match when scope "::" operator is used :
	emacs 32.1.97
Date: Fri, 3 Sep 2010 09:05:11 -0700

[Message part 1 (text/plain, inline)]

 

Emacs 23.1.97:

 

When using the C++ scope operator "::", show-paren-mode gets confused:

 

------  Foo.cpp ------------------------------------

struct Foo1 {};

 

namespace X

{

  struct Foo2 {};

 

  template<class _Y>

  struct Bar;

 

  template<>

  struct Bar<::Foo1>         // "(show-paren-mode)" does not match `>` to
`<`

  {

  };

 

  template<>

  struct Bar<Foo2>           // "(show-paren-mode)" correctly matches `>` to
`<` 

  {

  };

}

---------------------------------------------

[Message part 2 (text/html, inline)]

Message #10 received at 6978 <at> debbugs.gnu.org (full text, mbox):

From: Stefan Kangas <stefan <at> marxist.se>
To: Bob <purchasebyemail1 <at> comcast.net>
Cc: 6978 <at> debbugs.gnu.org
Subject: Re: bug#6978: show-paren-mode doesn't match when scope "::" operator
 is used : emacs 32.1.97
Date: Sun, 6 Oct 2019 13:39:24 +0200

severity 6978 minor
found 6978 27.0.50
quit

"Bob" <purchasebyemail1 <at> comcast.net> writes:

>
>
> Emacs 23.1.97:
>
>
>
> When using the C++ scope operator "::", show-paren-mode gets confused:
>
>
>
> ------  Foo.cpp ------------------------------------
>
> struct Foo1 {};
>
>
>
> namespace X
>
> {
>
>   struct Foo2 {};
>
>
>
>   template<class _Y>
>
>   struct Bar;
>
>
>
>   template<>
>
>   struct Bar<::Foo1>         // "(show-paren-mode)" does not match `>` to `<`
>
>   {
>
>   };
>
>
>
>   template<>
>
>   struct Bar<Foo2>           // "(show-paren-mode)" correctly matches `>` to `<`
>
>   {
>
>   };
>
> }
>
> ---------------------------------------------

I can reproduce this on current master.

Best regards,
Stefan Kangas

Message #17 received at 6978 <at> debbugs.gnu.org (full text, mbox):

From: Alan Mackenzie <acm <at> muc.de>
To: Stefan Kangas <stefan <at> marxist.se>
Cc: 6978 <at> debbugs.gnu.org
Subject: Re: bug#6978: show-paren-mode doesn't match when scope "::" operator
 is used : emacs 32.1.97
Date: 6 Oct 2019 17:38:50 -0000

In article <mailman.1087.1570362019.2651.bug-gnu-emacs <at> gnu.org> you wrote:
> severity 6978 minor
> found 6978 27.0.50
> quit

> "Bob" <purchasebyemail1 <at> comcast.net> writes:

>>
>>
>> Emacs 23.1.97:
>>
>>
>>
>> When using the C++ scope operator "::", show-paren-mode gets confused:
>>
>>
>>
>> ------  Foo.cpp ------------------------------------
>>
>> struct Foo1 {};
>>
>>
>>
>> namespace X
>>
>> {
>>
>>   struct Foo2 {};
>>
>>
>>
>>   template<class _Y>
>>
>>   struct Bar;
>>
>>
>>
>>   template<>
>>
>>   struct Bar<::Foo1>         // "(show-paren-mode)" does not match `>` to `<`
>>
>>   {
>>
>>   };
>>
>>
>>
>>   template<>
>>
>>   struct Bar<Foo2>           // "(show-paren-mode)" correctly matches `>` to `<`
>>
>>   {
>>
>>   };
>>
>> }
>>
>> ---------------------------------------------

> I can reproduce this on current master.

This is a CC Mode bug.  The pertinent < and > are not being marked with
syntax-table text properties, hence can't be recognised as parens.

I'll be looking into this.

> Best regards,
> Stefan Kangas

-- 
Alan Mackenzie (Nuremberg, Germany).

Message #20 received at 6978 <at> debbugs.gnu.org (full text, mbox):

From: Richard Copley <rcopley <at> gmail.com>
To: Alan Mackenzie <acm <at> muc.de>
Cc: 6978 <at> debbugs.gnu.org, Stefan Kangas <stefan <at> marxist.se>
Subject: Re: bug#6978: show-paren-mode doesn't match when scope "::" operator
 is used : emacs 32.1.97
Date: Sun, 6 Oct 2019 19:56:19 +0100

[Message part 1 (text/plain, inline)]

On Sun, 6 Oct 2019 at 18:39, Alan Mackenzie <acm <at> muc.de> wrote:

> In article <mailman.1087.1570362019.2651.bug-gnu-emacs <at> gnu.org> you wrote:
> > "Bob" <purchasebyemail1 <at> comcast.net> writes:
> >>   struct Bar<::Foo1>         // "(show-paren-mode)" does not match `>`
> to `<`
> The pertinent < and > are not being marked with
> syntax-table text properties, hence can't be recognised as parens.
>

Digraphs? (Just a thought.)

Best,
Richard.

[Message part 2 (text/html, inline)]

Message #23 received at 6978 <at> debbugs.gnu.org (full text, mbox):

From: Alan Mackenzie <acm <at> muc.de>
To: Richard Copley <rcopley <at> gmail.com>
Cc: 6978 <at> debbugs.gnu.org
Subject: Re: bug#6978: show-paren-mode doesn't match when scope "::" operator
 is used : emacs 32.1.97
Date: 6 Oct 2019 19:16:07 -0000

Hello, Richard.

In article <mailman.1131.1570388227.2651.bug-gnu-emacs <at> gnu.org> you wrote:
> [-- text/plain, encoding 7bit, charset: UTF-8, 15 lines --]

> On Sun, 6 Oct 2019 at 18:39, Alan Mackenzie <acm <at> muc.de> wrote:

>> In article <mailman.1087.1570362019.2651.bug-gnu-emacs <at> gnu.org> you wrote:
>> > "Bob" <purchasebyemail1 <at> comcast.net> writes:
>> >>   struct Bar<::Foo1>         // "(show-paren-mode)" does not match `>`
>> >>   to `<`
>> The pertinent < and > are not being marked with
>> syntax-table text properties, hence can't be recognised as parens.
>>

> Digraphs? (Just a thought.)

Spot on!

I just need to find a way of removing <: from the regexp used to check
the opening <.  Shouldn't be too difficult.

Why on earth are digraphs still an issue?  Why are they still in the C
and C++ standards?  It's been several decades since "complete" character
sets (here, meaning ASCII) superseded incomplete ones.

> Best,
> Richard.

-- 
Alan Mackenzie (Nuremberg, Germany).

Message #26 received at 6978 <at> debbugs.gnu.org (full text, mbox):

From: Alan Mackenzie <acm <at> muc.de>
To: Richard Copley <rcopley <at> gmail.com>, Stefan Kangas <stefan <at> marxist.se>
Cc: 6978 <at> debbugs.gnu.org
Subject: Re: bug#6978: show-paren-mode doesn't match when scope "::" operator
 is used : emacs 32.1.97
Date: Sun, 6 Oct 2019 20:11:36 +0000

Hello, Stefan and Richard.

On Sun, Oct 06, 2019 at 19:16:07 -0000, Alan Mackenzie wrote:
> In article <mailman.1131.1570388227.2651.bug-gnu-emacs <at> gnu.org> you wrote:
> > [-- text/plain, encoding 7bit, charset: UTF-8, 15 lines --]

> > On Sun, 6 Oct 2019 at 18:39, Alan Mackenzie <acm <at> muc.de> wrote:

> >> In article <mailman.1087.1570362019.2651.bug-gnu-emacs <at> gnu.org> you wrote:
> >> > "Bob" <purchasebyemail1 <at> comcast.net> writes:
> >> >>   struct Bar<::Foo1>         // "(show-paren-mode)" does not match `>`
> >> >>   to `<`
> >> The pertinent < and > are not being marked with
> >> syntax-table text properties, hence can't be recognised as parens.

> > Digraphs? (Just a thought.)

> Spot on!

> I just need to find a way of removing <: from the regexp used to check
> the opening <.  Shouldn't be too difficult.

The following seems to fix the bug:



diff -r b0943da37755 cc-langs.el
--- a/cc-langs.el	Thu Oct 03 14:14:45 2019 +0000
+++ b/cc-langs.el	Sun Oct 06 20:08:43 2019 +0000
@@ -1382,11 +1382,11 @@
 
 (c-lang-defconst c-<-op-cont-regexp
   ;; Regexp matching the second and subsequent characters of all
-  ;; multicharacter tokens that begin with "<".
+  ;; multicharacter tokens that begin with "<", apart from digraphs.
   t (c-make-keywords-re nil
       (c-filter-ops (c-lang-const c-all-op-syntax-tokens)
 		    t
-		    "\\`<."
+		    "\\`<[^:]"
 		    (lambda (op) (substring op 1)))))
 (c-lang-defvar c-<-op-cont-regexp (c-lang-const c-<-op-cont-regexp))
 


> > Best,
> > Richard.

-- 
Alan Mackenzie (Nuremberg, Germany).

Message #29 received at 6978 <at> debbugs.gnu.org (full text, mbox):

From: Stefan Kangas <stefan <at> marxist.se>
To: Alan Mackenzie <acm <at> muc.de>
Cc: Richard Copley <rcopley <at> gmail.com>, 6978 <at> debbugs.gnu.org
Subject: Re: bug#6978: show-paren-mode doesn't match when scope "::" operator
 is used : emacs 32.1.97
Date: Sun, 6 Oct 2019 22:21:39 +0200

Hi Alan,

Alan Mackenzie <acm <at> muc.de> writes:

> The following seems to fix the bug:

I can verify that applying your patch to current master fixes the bug
for me.  I think you can push and close this bug.  Thanks for fixing
it.

Best regards,
Stefan Kangas

Message #34 received at 6978-done <at> debbugs.gnu.org (full text, mbox):

From: Alan Mackenzie <acm <at> muc.de>
To: Stefan Kangas <stefan <at> marxist.se>
Cc: Richard Copley <rcopley <at> gmail.com>, 6978-done <at> debbugs.gnu.org
Subject: Re: bug#6978: show-paren-mode doesn't match when scope "::" operator
 is used : emacs 32.1.97
Date: Fri, 11 Oct 2019 19:32:48 +0000

Hello, Stefan.

On Sun, Oct 06, 2019 at 22:21:39 +0200, Stefan Kangas wrote:
> Hi Alan,

> Alan Mackenzie <acm <at> muc.de> writes:

> > The following seems to fix the bug:

> I can verify that applying your patch to current master fixes the bug
> for me.  I think you can push and close this bug.  Thanks for fixing
> it.

I've actually developed a longer, more rigorous patch, which I've
committed.  The C++ standard says that although <:: should be recognised
as a template opener, <::>, and <::: should not be.  The committed patch
follows this.

I'm closing the bug with this post.

> Best regards,
> Stefan Kangas

-- 
Alan Mackenzie (Nuremberg, Germany).

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