Re: [PATCH RESEND] gdb: remove static buffer in command_line_input

[Simon Marchi <simon.marchi@polymtl.ca>]

On 12/15/22 16:44, Tom Tromey wrote:
>>>>>> "Simon" == Simon Marchi via Gdb-patches <gdb-patches@sourceware.org> writes:
> 
> Simon> [I sent this earlier today, but I don't see it in the archives.
> Simon> Resending it through a different computer / SMTP.]
> 
> I didn't see it either.
> 
> Simon> Fix that by removing the static buffer.
> 
> Wow, I've wanted to remove 'struct buffer' for a while now, this is a
> big step toward that.

Ah yeah, that's a nice side-effect indeed.

> 
> Simon> So, it started with modifying command_line_input as described above, all
> Simon> the other changes derive directly from that.
> 
> It's hard to review / understand a change like this but it seems ok to
> me, as far as I can tell.

I was eager to make more simplifications / C++ifications, but some of
them subtly broke things.  So I opted to keep things the same as much as
possible, really just change the type used to the buffer (use
std::string) and change where it was stored.

After spending a few hours debugging regressions, I am fairly confident
that I understand the code flow and that the change is correct.  I'll go
ahead and push it, to unblock Jan's patch.

> 
> Simon> One slightly shady thing is in handle_line_of_input, where we now pass a
> Simon> pointer to an std::string's internal buffer to readline's history_value
> Simon> function, which takes a `char *`.  I'm pretty sure that this function
> Simon> does not modify the input string, because I was able to change it (with
> Simon> enough massaging) to take a `const char *`.
> 
> I think sending a note to upstream readline would be good.

I forgot to mention, but I did send this message:

  https://lists.gnu.org/archive/html/bug-readline/2022-12/msg00002.html

Simon