Re: [PATCH] gdb: print thread names in thread apply command output

[Luis Machado <luis dot machado at linaro dot org>]

Hi,

Thanks for the patch. Some comments below.

On 2/17/20 7:30 PM, Jérémie Galarneau wrote:
> This makes the thread apply command print the thread's name.  The use
> of target_pid_to_str is replaced by thread_target_id_str, which
> provides the same output as "info threads".

Is this a cosmetic change to the way GDB outputs things? If so, I wonder 
if the current tests expect the old format and thus will start to fail 
with the new output? Have you exercised the testsuite?

> Before:
> (gdb) thread apply 2 bt
>
> Thread 2 (Thread 0x7fd245602700 (LWP 3837)):
> [...]
>
> After:
> (gdb) thread apply 2 bt
>
> Thread 2 (Thread 0x7fd245602700 (LWP 3837) "HT cleanup"):
> [...]
>
> The thread's description header is pre-computed before running the
> command since the command may change the selected inferior. This is
> not permitted by thread_target_id_str as target_thread_name asserts
> that `info->inf == current_inferior ()`.
>
> This situation arises in the `gdb.threads/threadapply.exp` test which
> kills and removes the inferior as part of a "thread apply" command.
>
> gdb/ChangeLog:
>
>          * thread.c (thr_try_catch_cmd): Print thread name.
> ---
>   gdb/ChangeLog |  4 ++++
>   gdb/thread.c  | 16 ++++++++++------
>   2 files changed, 14 insertions(+), 6 deletions(-)
>
> diff --git a/gdb/ChangeLog b/gdb/ChangeLog
> index dafd90ec37..4fce196187 100644
> --- a/gdb/ChangeLog
> +++ b/gdb/ChangeLog
> @@ -1,3 +1,7 @@
> +2020-02-17  Jérémie Galarneau  <jeremie.galarneau@efficios.com>
> +
> +	* thread.c (thr_try_catch_cmd): Print thread name.
> +
>   2020-02-14  Simon Marchi  <simon.marchi@efficios.com>
>   
>   	* aarch64-tdep.c (aarch64_displaced_step_copy_insn): Use
> diff --git a/gdb/thread.c b/gdb/thread.c
> index 54b59e2244..0c1611bdc1 100644
> --- a/gdb/thread.c
> +++ b/gdb/thread.c
> @@ -1563,6 +1563,14 @@ thr_try_catch_cmd (thread_info *thr, const char *cmd, int from_tty,
>   		   const qcs_flags &flags)
>   {
>     switch_to_thread (thr);
> +
> +  /* The thread header is computed before running the command since
> +   * the command can change the inferior, which is not permitted
> +   * by thread_target_id_str.  */

The formatting of the comment block is not right. We don't start 
intermediate lines with *. You can check existing blocks for the format 
that we use.

> +  std::string thr_header = string_printf(_("\nThread %s (%s):\n"),
> +					 print_thread_id (thr),
> +					 thread_target_id_str (thr).c_str ());

Maybe write it as:

std::string thr_header =
  string_printf(_("\nThread %s (%s):\n"), print_thread_id (thr),
                thread_target_id_str (thr).c_str ());

I think it gives it a better alignment. Just a suggestion.

> +
>     try
>       {
>         std::string cmd_result = execute_command_to_string
> @@ -1570,9 +1578,7 @@ thr_try_catch_cmd (thread_info *thr, const char *cmd, int from_tty,
>         if (!flags.silent || cmd_result.length () > 0)
>   	{
>   	  if (!flags.quiet)
> -	    printf_filtered (_("\nThread %s (%s):\n"),
> -			     print_thread_id (thr),
> -			     target_pid_to_str (inferior_ptid).c_str ());
> +	    printf_filtered ("%s", thr_header.c_str ());
>   	  printf_filtered ("%s", cmd_result.c_str ());
>   	}
>       }
> @@ -1581,9 +1587,7 @@ thr_try_catch_cmd (thread_info *thr, const char *cmd, int from_tty,
>         if (!flags.silent)
>   	{
>   	  if (!flags.quiet)
> -	    printf_filtered (_("\nThread %s (%s):\n"),
> -			     print_thread_id (thr),
> -			     target_pid_to_str (inferior_ptid).c_str ());
> +	    printf_filtered ("%s", thr_header.c_str ());
>   	  if (flags.cont)
>   	    printf_filtered ("%s\n", ex.what ());
>   	  else