Re: [patch] Print current thread after loading a core file [Re: [patch] Sort threads for thread apply all (bt)]

[Doug Evans <dje at google dot com>]

Jan Kratochvil writes:
 > On Thu, 15 Jan 2015 20:29:07 +0100, Doug Evans wrote:
 > > On Thu, Jan 15, 2015 at 10:33 AM, Jan Kratochvil <jan.kratochvil@redhat.com> wrote:
 > > > Should GDB always print after loading a core file what "thread" command would
 > > > print?
 > > > [Current thread is 1 (Thread 0x7fcbe28fe700 (LWP 15453))]
 > > 
 > > Sounds reasonable to me.
 > > Though there is the concern to not even talk about threads if there are "none".
 > > So maybe only print that if there is more than one thread?
 > 
 > Attached.
 > 
 > BTW I think it will print the thread even when loading single/non-threaded
 > core file when other inferior(s) exist.  But that currently crashes
 > 	[Bug threads/12074] multi-inferior internal error
 > 	https://sourceware.org/bugzilla/show_bug.cgi?id=12074
 > plus I think that would be a correct behavior anyway.
 > 
 > No regressions on {x86_64,x86_64-m32}-fedora22pre-linux-gnu.
 > 
 > 
 > Jan
 > gdb/ChangeLog
 > 2015-01-17  Jan Kratochvil  <jan.kratochvil@redhat.com>
 > 
 > 	* corelow.c (core_open): Call also thread_command.
 > 	* gdbthread.h (thread_command): New prototype moved from ...
 > 	* thread.c (thread_command): ... here.
 > 	(thread_command): Make it global.

Hi.
LGTM with one nit.

 > 
 > diff --git a/gdb/corelow.c b/gdb/corelow.c
 > index a9eadd5..c168d1a 100644
 > --- a/gdb/corelow.c
 > +++ b/gdb/corelow.c
 > @@ -456,6 +456,17 @@ core_open (const char *arg, int from_tty)
 >    /* Now, set up the frame cache, and print the top of stack.  */
 >    reinit_frame_cache ();
 >    print_stack_frame (get_selected_frame (NULL), 1, SRC_AND_LOC, 1);
 > +
 > +  /* Current thread should be NUM 1 but the user does not know that.  */
 > +  if (thread_count () >= 2)

Can you add a comment explaining why the test is >= 2 here?
E.g., something like

  /* Current thread should be NUM 1 but the user does not know that.
     If a program is single threaded gdb in general does not mention
     anything about threads.  That is why the test is >= 2.  */

 > +    {
 > +      TRY_CATCH (except, RETURN_MASK_ERROR)
 > +	{
 > +	  thread_command (NULL, from_tty);
 > +	}
 > +      if (except.reason < 0)
 > +	exception_print (gdb_stderr, except);
 > +    }
 >  }
 >  
 >  static void
 > diff --git a/gdb/gdbthread.h b/gdb/gdbthread.h
 > index 15a979b..a2f378a 100644
 > --- a/gdb/gdbthread.h
 > +++ b/gdb/gdbthread.h
 > @@ -455,6 +455,8 @@ extern void finish_thread_state_cleanup (void *ptid_p);
 >  /* Commands with a prefix of `thread'.  */
 >  extern struct cmd_list_element *thread_cmd_list;
 >  
 > +extern void thread_command (char *tidstr, int from_tty);
 > +
 >  /* Print notices on thread events (attach, detach, etc.), set with
 >     `set print thread-events'.  */
 >  extern int print_thread_events;
 > diff --git a/gdb/thread.c b/gdb/thread.c
 > index ed20fbe..4bce212 100644
 > --- a/gdb/thread.c
 > +++ b/gdb/thread.c
 > @@ -62,7 +62,6 @@ static int highest_thread_num;
 >     spawned new threads we haven't heard of yet.  */
 >  static int threads_executing;
 >  
 > -static void thread_command (char *tidstr, int from_tty);
 >  static void thread_apply_all_command (char *, int);
 >  static int thread_alive (struct thread_info *);
 >  static void info_threads_command (char *, int);
 > @@ -1506,7 +1505,7 @@ thread_apply_command (char *tidlist, int from_tty)
 >  /* Switch to the specified thread.  Will dispatch off to thread_apply_command
 >     if prefix of arg is `apply'.  */
 >  
 > -static void
 > +void
 >  thread_command (char *tidstr, int from_tty)
 >  {
 >    if (!tidstr)