bug#20629: 25.0.50; Regression: TAGS broken, can't find anything in C++ files.

[Francesco Potortì]

Eli Zaretskii:
>> Francesco Potortì wrote:
>> >> second, if appropriate, match against a tag ::NAME
>> >> third, regex match against a tag .*::NAME$
>> >
>> >Why can we use colons? That implies some sort of knowledge about C++, 
>> >whereas until now etags.el has remained language-agnostic.
>> 
>> Mh.  I had taken it for given that each major-mode in fact added
>> something to the list of functions called when looking for a tag.
>> Doesn't it work that way?
>
>No.
>
>In addition, doing so would not work if I tried to look up a symbol in
>language A from a buffer whose major mode is tailored to language B.
>
>> If not, couldn't it be done for languages where the
>> language-agnostic behaviour of etags.el is not satisfactory?
>
>etags.el relies on etags.c to know languages well enough to do that
>part of the job.  I think we should keep this separation of
>responsibilities.

I see.  Given these constraints, I see no other way than augmenting the
TAGS format to include an arbitrary number of tags per entry...