Re: [PATCH 2/3] lisp/progmodes/etags.el don't (forward-char) as it's overriden next line

[Konstantin Kharlamov]

On Пн, Mar 18, 2019 at 06:34:00, Eli Zaretskii <address@hidden> wrote:
> >  Date: Sun, 17 Mar 2019 23:44:28 +0300
> >  From: Konstantin Kharlamov <address@hidden>
> >  Cc: address@hidden
> >
> >  > But that's incorrect: a tag in a tags table always begins at the
> >  > beginning of a line, so it must be a search anchored at the 
> > beginning
> >  > of the line.  And in selective-display mode ^M counts as the 
> > beginning
> >  > of a line.
> >
> >  Great, now that we established that part, to reply your question 
> > why we
> >  don't care about the beginnging of the line let me quote my other 
> > mail:
> >
> >   > The pattern that this functions searches for determines the tag
> >  uniquely. But here's a catch: no programming language creates 
> > distinc
> >  entities (ones that end up in the tag), based only on trailing 
> > space.
> >  I.e. "foo()" and " foo() " always refer to the same thing.
>
> I'm not talking about whitespace.  I'm talking about a tags table file
> that names a symbol 'foobar', say.  If you search for a tag "bar" and
> do not anchor the search at the beginning of a line, you will decide
> that "bar" is present on the "foobar" line, although it really isn't.
> Right?

Not exactly. Here's an alternative bad situation: let's say you do 
anchor the text, and you search for tag 'foo'. And… you still match 
'foobar'!

Actually, it's interesting, that such name clashes are possible right 
now: let's say we have:

        #define FOO
        #define FOO_BAR

If source code is intact, you should get FOO. But if code changed, then 
emacs tries to find where did it go, and may as well stumble upon 
FOO_BAR.

So, I suggest an improvement to my patch: how about we

1. anchor the regexp to the end of the line also
2. replace trailing space with "any whitespace" regex '\s-*'

?