c++-mode does not support C-h S?

c++-mode does not support C-h S?

[Sergey Organov]

Hello,

In a buffer with c++-mode major mode, pressing C-h S causes appearance
of the prompt "Use symbol help mode: " in the minibuffer that, according
to the manual, means c++-mode does not support info-lookup-symbol?:

 If you use C-h S in a major mode that does not support it, it asks you
 to specify the symbol help mode. You should enter a command such as
 c-mode that would select a major mode which C-h S does support.

How do I configure c++-mode to use c-mode to lookup symbols, and why
it's not configured this way by default?

Thanks,
-- Sergey Organov

Re: c++-mode does not support C-h S?

[Eli Zaretskii]

> From: Sergey Organov <sorganov@gmail.com>
> Date: Mon, 06 Mar 2023 00:11:02 +0300
> 
> In a buffer with c++-mode major mode, pressing C-h S causes appearance
> of the prompt "Use symbol help mode: " in the minibuffer that, according
> to the manual, means c++-mode does not support info-lookup-symbol?:
> 
>  If you use C-h S in a major mode that does not support it, it asks you
>  to specify the symbol help mode. You should enter a command such as
>  c-mode that would select a major mode which C-h S does support.

If you type "c-mode RET" at the prompt, does the feature work then?

> How do I configure c++-mode to use c-mode to lookup symbols

Copy the two info-lookup-maybe-add-help blocks in info-look.el that
reference c-mode and make them reference c++-mode.

> and why it's not configured this way by default?

Because the _real_ documentation of C++ is usually not installed on
the end-user systems.

Re: c++-mode does not support C-h S?

[Sergey Organov]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Sergey Organov <sorganov@gmail.com>
>> Date: Mon, 06 Mar 2023 00:11:02 +0300
>> 
>> In a buffer with c++-mode major mode, pressing C-h S causes appearance
>> of the prompt "Use symbol help mode: " in the minibuffer that, according
>> to the manual, means c++-mode does not support info-lookup-symbol?:
>> 
>>  If you use C-h S in a major mode that does not support it, it asks you
>>  to specify the symbol help mode. You should enter a command such as
>>  c-mode that would select a major mode which C-h S does support.
>
> If you type "c-mode RET" at the prompt, does the feature work then?

Yes, it does. It finds symbols in GNU C library info files alright then.

>
>> How do I configure c++-mode to use c-mode to lookup symbols
>
> Copy the two info-lookup-maybe-add-help blocks in info-look.el that
> reference c-mode and make them reference c++-mode.

Thanks for the hint, will try.

>
>> and why it's not configured this way by default?
>
> Because the _real_ documentation of C++ is usually not installed on
> the end-user systems.

GNU Standard C++ Library v3 (documentation files) are likely to be
installed on Linux hosts, I think.

Also, C library is still accessible from C++, so search in GNU C info
files what was not found in C++ seems to be a good idea as well.

Thanks,
-- Sergey Organov

Re: c++-mode does not support C-h S?

[Eli Zaretskii]

> From: Sergey Organov <sorganov@gmail.com>
> Cc: help-gnu-emacs@gnu.org
> Date: Mon, 06 Mar 2023 16:13:35 +0300
> 
> >> and why it's not configured this way by default?
> >
> > Because the _real_ documentation of C++ is usually not installed on
> > the end-user systems.
> 
> GNU Standard C++ Library v3 (documentation files) are likely to be
> installed on Linux hosts, I think.

In Info format?  I could only find it in HTML format.

> Also, C library is still accessible from C++, so search in GNU C info
> files what was not found in C++ seems to be a good idea as well.

Maybe, not sure.  Feel free to file a feature-request bug report to
that effect.

Re: c++-mode does not support C-h S?

[Sergey Organov]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Sergey Organov <sorganov@gmail.com>
>> Cc: help-gnu-emacs@gnu.org
>> Date: Mon, 06 Mar 2023 16:13:35 +0300
>> 
>> >> and why it's not configured this way by default?
>> >
>> > Because the _real_ documentation of C++ is usually not installed on
>> > the end-user systems.
>> 
>> GNU Standard C++ Library v3 (documentation files) are likely to be
>> installed on Linux hosts, I think.
>
> In Info format?  I could only find it in HTML format.

You are right. Entirely unexpected from a GNU project.

Thanks,
-- Sergey

Re: c++-mode does not support C-h S?

[Arsen Arsenović]

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Sergey Organov <sorganov@gmail.com> writes:

>>> GNU Standard C++ Library v3 (documentation files) are likely to be
>>> installed on Linux hosts, I think.
>>
>> In Info format?  I could only find it in HTML format.
>
> You are right. Entirely unexpected from a GNU project.

The GNU standard C++ library, like many other C++ libraries, provide
in-header documentation with Doxygen.  It would likely be nice to parse
those in C and C++ mode both, as it's commonly used in both.

When you do file a request, maybe include that suggestion.
-- 
Arsen Arsenović

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