Output the Ada task name in more messages.

With this patch, we e.g. get:
      [Switching to task 2 "task_list(1)"]
      [Current task is 2 "task_list(1)"]
    instead of
      [Switching to task 2]
      [Current task is 2]

The logic to produce the taskno optionally followed
by the task name has been factorized in the task_to_str function.

Task names are output between double quotes in the new messages,
similarly to what GDB does for thread names.
However, no quotes are put around task names in 'info tasks' Name column.
This was discussed with Tom, that preferred no quotes there, while I
was more in favour of visual consistency.
I discussed with a few more users, which led to (exactly) 50% preferring
quotes and 50% preferring no quotes :).
To arrive to the decision to remove the quotes, the following "killing args"
were used:
 * To have quotes or to not have quotes, that is the question; yes
   but not *THE* question :).
 * If there is not a clear majority that prefers quotes, better to
   not disturb the existing user basis for a (somewhat) irrelevant
   aspect.
 * The opinion of the reviewer has more weight.

So, compared to the previous version, this version remotes the quotes
in 'info tasks'.

It improves the alignement of 'info tasks' output.
With this patch, we get:
      (gdb) info task
         ID           TID P-ID Pri State                  Name
      *   1  555555759030       48 Runnable               main_task
          2  555555759e30    1  48 Selective Wait         mit
      (gdb)
   instead of
      (gdb) info task
         ID       TID P-ID Pri State                  Name
      *   1 555555759030       48 Runnable               main_task
          2 555555759e30    1  48 Selective Wait         mit
      (gdb)
(e.g. the first one properly shows parent and priority under the
correct header).

This is version 4 of the 'task name' patch.
Compared to version 3, the changes are:
   output task names between quotes but not in 'info tasks'

gdb/ChangeLog
2019-09-12  Philippe Waroquiers  <philippe.waroquiers@skynet.be>

	* NEWS: Announce that Ada task names are now shown at more places,
	and between quotes (except in info task output).
	* gdb/ada-tasks.c (task_to_str): New function.
	(display_current_task_id): Call task_to_str.
	(task_command_1): Likewise.
	(print_ada_task_info): In non-mi mode, Properly align headers and data
	when task-id length is > 9 (9 is the default for a 32 bits CORE_ADDR).

gdb/doc/ChangeLog
2019-09-12  Philippe Waroquiers  <philippe.waroquiers@skynet.be>

	* gdb.texinfo (Ada Tasks): Tell the task name is printed, update
	examples.

gdb/testsuite/ChangeLog
2019-09-12  Philippe Waroquiers  <philippe.waroquiers@skynet.be>

	* gdb.ada/rdv_wait.exp: Update to new task names.
	* gdb.base/task_switch_in_core.exp: Likewise.
	* gdb.base/info_sources_base.c: Likewise.

1 files changed, 54 insertions, 12 deletions

diff --git a/gdb/ada-tasks.c b/gdb/ada-tasks.c
index 99458aa..34da786 100644
--- a/gdb/ada-tasks.c
+++ b/gdb/ada-tasks.c
@@ -240,6 +240,18 @@ struct ada_tasks_inferior_data
 static const struct inferior_key<ada_tasks_inferior_data>
   ada_tasks_inferior_data_handle;
 
+/* Return a string with TASKNO followed by the task name if TASK_INFO
+   contains a name.  */
+
+static std::string
+task_to_str (int taskno, const ada_task_info *task_info)
+{
+  if (task_info->name[0] == '\0')
+    return string_printf ("%d", taskno);
+  else
+    return string_printf ("%d \"%s\"", taskno, task_info->name);
+}
+
 /* Return the ada-tasks module's data for the given program space (PSPACE).
    If none is found, add a zero'ed one now.
 
@@ -1047,7 +1059,26 @@ print_ada_task_info (struct ui_out *uiout,
   ui_out_emit_table table_emitter (uiout, nb_columns, nb_tasks, "tasks");
   uiout->table_header (1, ui_left, "current", "");
   uiout->table_header (3, ui_right, "id", "ID");
-  uiout->table_header (9, ui_right, "task-id", "TID");
+  {
+    size_t tid_width = 9;
+    /* Grown below in case the largest entry is bigger.  */
+
+    if (!uiout->is_mi_like_p ())
+      {
+	for (taskno = 1; taskno <= data->task_list.size (); taskno++)
+	  {
+	    const struct ada_task_info *const task_info
+	      = &data->task_list[taskno - 1];
+
+	    gdb_assert (task_info != NULL);
+
+	    tid_width = std::max (tid_width,
+				  1 + strlen (phex_nz (task_info->task_id,
+						       sizeof (CORE_ADDR))));
+	  }
+      }
+    uiout->table_header (tid_width, ui_right, "task-id", "TID");
+  }
   /* The following column is provided in GDB/MI mode only because
      it is only really useful in that mode, and also because it
      allows us to keep the CLI output shorter and more compact.  */
@@ -1129,10 +1160,12 @@ print_ada_task_info (struct ui_out *uiout,
       else
 	uiout->field_string ("state", task_states[task_info->state]);
 
-      /* Finally, print the task name.  */
+      /* Finally, print the task name, without quotes around it, as mi like
+	 is not expecting quotes, and in non mi-like no need for quotes
+         as there is a specific column for the name.  */
       uiout->field_string ("name",
-			   task_info->name[0] != '\0' ? task_info->name
-			   : _("<no name>"));
+                          task_info->name[0] != '\0' ? task_info->name
+                          : _("<no name>"));
 
       uiout->text ("\n");
     }
@@ -1166,7 +1199,7 @@ info_task (struct ui_out *uiout, const char *taskno_str, struct inferior *inf)
 
   /* Print the name of the task.  */
   if (task_info->name[0] != '\0')
-    printf_filtered (_("Name: %s\n"), task_info->name);
+    printf_filtered (_("Name: \"%s\"\n"), task_info->name);
   else
     printf_filtered (_("<no name>\n"));
 
@@ -1187,7 +1220,7 @@ info_task (struct ui_out *uiout, const char *taskno_str, struct inferior *inf)
 
       printf_filtered (_("Parent: %d"), parent_taskno);
       if (parent->name[0] != '\0')
-        printf_filtered (" (%s)", parent->name);
+        printf_filtered (" (\"%s\")", parent->name);
       printf_filtered ("\n");
     }
   else
@@ -1220,7 +1253,7 @@ info_task (struct ui_out *uiout, const char *taskno_str, struct inferior *inf)
         ada_task_info *target_task_info = &data->task_list[target_taskno - 1];
 
         if (target_task_info->name[0] != '\0')
-          printf_filtered (" (%s)", target_task_info->name);
+          printf_filtered (" (\"%s\")", target_task_info->name);
       }
 
     printf_filtered ("\n");
@@ -1255,7 +1288,14 @@ display_current_task_id (void)
   if (current_task == 0)
     printf_filtered (_("[Current task is unknown]\n"));
   else
-    printf_filtered (_("[Current task is %d]\n"), current_task);
+    {
+      struct ada_tasks_inferior_data *data
+	= get_ada_tasks_inferior_data (current_inferior ());
+      struct ada_task_info *task_info = &data->task_list[current_task - 1];
+
+      printf_filtered (_("[Current task is %s]\n"),
+		       task_to_str (current_task, task_info).c_str ());
+    }
 }
 
 /* Parse and evaluate TIDSTR into a task id, and try to switch to
@@ -1274,7 +1314,8 @@ task_command_1 (const char *taskno_str, int from_tty, struct inferior *inf)
   task_info = &data->task_list[taskno - 1];
 
   if (!ada_task_is_alive (task_info))
-    error (_("Cannot switch to task %d: Task is no longer running"), taskno);
+    error (_("Cannot switch to task %s: Task is no longer running"),
+	   task_to_str (taskno, task_info).c_str ());
    
   /* On some platforms, the thread list is not updated until the user
      performs a thread-related operation (by using the "info threads"
@@ -1295,13 +1336,14 @@ task_command_1 (const char *taskno_str, int from_tty, struct inferior *inf)
      it's nicer for the user to just refuse to perform the task switch.  */
   thread_info *tp = find_thread_ptid (task_info->ptid);
   if (tp == NULL)
-    error (_("Unable to compute thread ID for task %d.\n"
+    error (_("Unable to compute thread ID for task %s.\n"
              "Cannot switch to this task."),
-           taskno);
+           task_to_str (taskno, task_info).c_str ());
 
   switch_to_thread (tp);
   ada_find_printable_frame (get_selected_frame (NULL));
-  printf_filtered (_("[Switching to task %d]\n"), taskno);
+  printf_filtered (_("[Switching to task %s]\n"),
+		   task_to_str (taskno, task_info).c_str ());
   print_stack_frame (get_selected_frame (NULL),
                      frame_relative_level (get_selected_frame (NULL)),
 		     SRC_AND_LOC, 1);