bug#7351: 24.0.50; next-error no longer takes into account buffer modifications

bug#7351: 24.0.50; next-error no longer takes into account buffer modifications

[Paul Pogonyshev]

When hitting C-x ` (next-error) the point is positioned correctly only
if the buffer is not modified.  If number of lines before the target
position is changed, point is positioned wrongly.

For instance, say 'test.txt' contains these lines:

    foo
    bar
    baz

I then run 'grep' from Emacs like this:

    grep -nH -e ba test.txt

Results:

    -*- mode: grep; default-directory: "/home/paul/test/" -*-
    Grep started at Sun Nov  7 01:25:17

    grep -nH -e ba test.txt
    test.txt:2:bar
    test.txt:3:baz

    Grep finished (matches found) at Sun Nov  7 01:25:17

Then I insert a few more lines in 'test.txt' buffer:

    foo
    bar
    spam
    ham
    baz

Now if I hit C-x ` the first time point is moved to line 2 --
correctly.  The second time, however, the point is moved to line 3,
i.e. the original location of 'baz'.  However, 'baz' is now at line 5
and that's where I expect C-x ` to move point to.  Note that at no
point I closed the buffer, so Emacs should be able to track changes
between 'grep' run and current buffer/file contents.

This is especially unhelpful with compilation errors.  Often, you'd go
through errors fixing them in process, sometimes adding or removing
lines.  However, any such change makes finding subsequent errors
difficult as C-x ` will no longer locate errors correctly.

I believe this used to work fine in past.

Paul

bug#7351: 24.0.50; next-error no longer takes into account buffer modifications

[Glenn Morris]

Paul Pogonyshev wrote:

> I believe this used to work fine in past.

Could you give a release of Emacs in which this works?

I tried 21.4, 22.1, 22.2, 22.3, 23.1, and 23.2; and it didn't seem to
work in any of them.

bug#7351: 24.0.50; next-error no longer takes into account buffer modifications

[Paul Pogonyshev]

Glenn Morris wrote:
> Paul Pogonyshev wrote:
> 
> > I believe this used to work fine in past.
> 
> Could you give a release of Emacs in which this works?
> 
> I tried 21.4, 22.1, 22.2, 22.3, 23.1, and 23.2; and it didn't seem to
> work in any of them.

No.  I seem to recollect that at some point (certainly before 24.x
development, maybe even before 23) I could fix a compilation error in
a C file by adding/removing lines, and subsequent errors would still
be found correctly, without any line offset.  Maybe it depends on
actual error source, i.e. gcc vs. grep?  Then again, maybe I invented
this whole story and my memory is failing...

In the latter case, can this be requalified as a feature request?

Paul

bug#7351: 24.0.50; next-error no longer takes into account buffer modifications

[Jan Djärv]

FWIW, I remember this feature also from 5-10 years ago.  But I hadn't noticed 
that it was gone now.

	Jan D.


Paul Pogonyshev skrev 2010-11-11 20.31:
> Glenn Morris wrote:
>> Paul Pogonyshev wrote:
>>
>>> I believe this used to work fine in past.
>>
>> Could you give a release of Emacs in which this works?
>>
>> I tried 21.4, 22.1, 22.2, 22.3, 23.1, and 23.2; and it didn't seem to
>> work in any of them.
>
> No.  I seem to recollect that at some point (certainly before 24.x
> development, maybe even before 23) I could fix a compilation error in
> a C file by adding/removing lines, and subsequent errors would still
> be found correctly, without any line offset.  Maybe it depends on
> actual error source, i.e. gcc vs. grep?  Then again, maybe I invented
> this whole story and my memory is failing...
>
> In the latter case, can this be requalified as a feature request?
>
> Paul
>
>

Re: bug#7351: 24.0.50; next-error no longer takes into account buffer modifications

[Ted Zlatanov]

On Thu, 11 Nov 2010 21:31:56 +0200 Paul Pogonyshev <pogonyshev@gmx.net> wrote: 

PP> Glenn Morris wrote:
>> Paul Pogonyshev wrote:
>> 
>> > I believe this used to work fine in past.
>> 
>> Could you give a release of Emacs in which this works?
>> 
>> I tried 21.4, 22.1, 22.2, 22.3, 23.1, and 23.2; and it didn't seem to
>> work in any of them.

PP> No.  I seem to recollect that at some point (certainly before 24.x
PP> development, maybe even before 23) I could fix a compilation error in
PP> a C file by adding/removing lines, and subsequent errors would still
PP> be found correctly, without any line offset.  Maybe it depends on
PP> actual error source, i.e. gcc vs. grep?  Then again, maybe I invented
PP> this whole story and my memory is failing...

PP> In the latter case, can this be requalified as a feature request?

compilation-mode and the other providers of `next-error' set it up
differently (see `compilation-next-error-function').  I know that `M-x
occur' will track occurrences through add/delete changes, for instance,
but it has access to the original buffer.  compilation-mode only has
access to line numbers at the time of the compilation.

Ted