[2/4] gdb: remove use of iterate_over_inferiors in mi/mi-interp.c

From: Simon Marchi <simon.marchi@efficios.com>

  On 2020-01-16 4:01 a.m., Aktemur, Tankut Baris wrote:
>> @@ -140,8 +138,22 @@ mi_interp::init (bool top_level)
>>        /* The initial inferior is created before this function is
>>  	 called, so we need to report it explicitly.  Use iteration in
>>  	 case future version of GDB creates more than one inferior
>> -	 up-front.  */
>> -      iterate_over_inferiors (report_initial_inferior, mi);
>> +	 up-front.
>> +
>> +         This function is called from mi_interpreter_init, and since
> 
> There is an 8-spaces/tab issue above.  And also, the comment piece "This
> function is called from mi_interpreter_init, and" seems obsolete now.

Thanks for spotting these.

That made me realize there are many issues with that comment.

- The part about not being able to use mi_inferior_added because top_level_interpreter_data
  is not set is stale.  That was true before the interps were made into C++ classes.  Back
  then, the mi_interpreter_init function would return the pointer to be used as interpreter
  data, which the caller (the interp_set function) would assign to interp->data.  So it was
  indeed not possible to call mi_inferior_added, because it required interp->data to be set.

- It is still not possible today to use mi_inferior_added, because it iterates over all MI UIs
  and to print the event on all of them.  So if you do:

  1. Start GDB with `-i mi`
  2. Add some inferiors
  3. Create a new MI UI, with `new-ui mi /dev/pts/X`

  When initializing the new MI UI, it will print the inferior-added events on both MI UIs.

- It is necessary to use iteration, not only in case GDB creates more than one inferior
  up front, but also because there might be multiple inferiors when initializing a secondary
  MI UI, as shown above.

I don't know if it is by design, that the =inferior-added events are sent to a new MI UI added
with new-ui, but in any case I don't want to change the behavior with this patch.

Also, when testing this, I realized it was wrong to put the gdb_flush out of the loop.  It's not
a simple flush as in "make sure the data is all sent to the underlying device", it's also what
adds the final \n!  So with the gdb_flush outside the loop, all the events were printed on the same
line.  I've put the terminal setting calls and the gdb_flush back into the loop, to minimize the
changes.

The patch would now look like this:

From cb845a4f28d1761feb463914c13b0a45c97d9974 Mon Sep 17 00:00:00 2001
From: Simon Marchi <simon.marchi@efficios.com>
Date: Wed, 15 Jan 2020 14:12:20 -0500
Subject: [PATCH] gdb: remove use of iterate_over_inferiors in mi/mi-interp.c

Replace it with a range-based for.  I've updated the comment in
mi_interp::init, which was a bit stale.

gdb/ChangeLog:

	* mi/mi-interp.c (report_initial_inferior): Remove.
	(mi_interp::init): Use range-based for to iterate over inferiors.
---
 gdb/mi/mi-interp.c | 49 ++++++++++++++++++++--------------------------
 1 file changed, 21 insertions(+), 28 deletions(-)

[2/4] gdb: remove use of iterate_over_inferiors in mi/mi-interp.c

Commit Message

Comments

Patch