Re: [PATCH v4 2/4] gdb/cli: add '.' as an argument for 'list' command

[Andrew Burgess <aburgess@redhat.com>]

Bruno Larsen via Gdb-patches <gdb-patches@sourceware.org> writes:

> On 14/07/2023 19:50, Pedro Alves wrote:
>> Hi,
>>
>> Sorry for coming late to the party here, but while trying to catch up on the
>> list I spotted a few things that I think should be fixed.  See below.
> I forgot to send the email, but I've already pushed this patch... I'll 
> fix up the things you pointed in a moment and send a new patch, I just 
> have a few questions.
>>
>> BTW, I think the feature is cool!
>>
>> On 2023-07-13 11:24, Bruno Larsen via Gdb-patches wrote:
>>> Currently, after the user has used the list command once, there is no
>>> self-contained way to ask GDB to print the location where the inferior is
>>> stopped.  The current best options require either using a separate
>>> command to scope out where the inferior is stopped, or using "list *$pc"
>>> requiring knowledge of GDB standard registers.  This commit adds a way
>>> to do that using '.' as a new argument for the 'list' command.  If the
>>> inferior isn't running, the command prints around the main function.
>>>
>>> Because this necessitated having the inferior running and the test was
>>> (seemingly unnecessarily) using printf in a non-essential way and it
>>> would make the resulting log harder to read for no benefit, it was
>>> replaced by a differen t statement.
>>> ---
>>>   gdb/NEWS                        |  4 ++++
>>>   gdb/cli/cli-cmds.c              | 31 ++++++++++++++++++++++++--
>>>   gdb/doc/gdb.texinfo             |  5 +++++
>>>   gdb/testsuite/gdb.base/list.exp | 39 +++++++++++++++++++++++++++++++++
>>>   gdb/testsuite/gdb.base/list1.c  |  2 +-
>>>   5 files changed, 78 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/gdb/NEWS b/gdb/NEWS
>>> index b924834d3d7..eef440a5242 100644
>>> --- a/gdb/NEWS
>>> +++ b/gdb/NEWS
>>> @@ -84,6 +84,10 @@
>>>     is 64k.  To print longer strings you should increase
>>>     'max-value-size'.
>>>   
>>> +* The 'list' command now accepts '.' as an argument, which tells GDB to
>>> +  print the location where the inferior is stopped.  If the inferior hasn't
>>> +  started yet, the command will print around the main function.
>> It would be more accurate to say that it's where the current thread is stopped.
>>
>> Say you run to breakpoint hit in thread 1, and then switch to thread 2, and then do
>> "list .".  That will show you the current frame of thread 2, while "where the
>> inferior is stopped" could very well be interpreted as "thread 1".
>
> The wording does need changing, I agree. I think using the wording that 
> already exists in the documentation is the best way to go: "prints 
> around the last solitary line printed as part of displaying a stack 
> frame". The wording I originally used (and the improvement you 
> suggested) could make it sound like I would always print the lowermost 
> frame, when that is not the point I wanted. What I wanted was to re-do 
> what the first usage of "list" does without needing to know the lines.
>
> My big question: Can I change the NEWS entry, or is that some taboo 
> that's best avoided?

It's fine to change the section of the NEWS file for the next release,
that is, the part currently under the 'Changes since GDB 13' heading.

We shouldn't change anything under a 'Change in GDB xxx' heading, as
that describes content that has already been released.

Thanks,
Andrew