Re: GDB/MI and ">" prompts

[Eli Zaretskii <eliz at gnu dot org>]

[I moved this to gdb-patches, since I propose a patch below.]

> Date: Thu, 19 Apr 2012 22:24:53 +0300
> From: Eli Zaretskii <eliz@gnu.org>
> Cc: gdb@sourceware.org
> 
> The crux of my question was why non-interactive mode does display a
> prompt while the interactive one doesn't.

To answer my own question, here's why:

  char *
  command_line_input (char *prompt_arg, int repeat, char *annotation_suffix)
  {
    ...
	/* Don't use fancy stuff if not talking to stdin.  */
	if (deprecated_readline_hook && input_from_terminal_p ())
	  {
	    rl = (*deprecated_readline_hook) (local_prompt);
	  }
	else if (command_editing_p && input_from_terminal_p ())
	  {
	    rl = gdb_readline_wrapper (local_prompt);
	  }
	else
	  {
	    rl = gdb_readline (local_prompt);
	  }

Now, the code is clear, but I cannot say I understand the logic.  If
the input is from terminal, we ask (inside gdb_readline_wrapper) the
current interpreter whether to show the prompt.  But if input is _not_
from terminal, we display the prompt unconditionally (inside
gdb_readline).  How does this make sense?

> Date: Thu, 19 Apr 2012 11:53:29 -0700
> From: Joel Brobecker <brobecker@adacore.com>
> Cc: gdb@sourceware.org
> 
> The other thing that occured to me was that, perhaps, we should instead
> be switching the interpreter while executing the console command,

I arrived to the same conclusion, eventually.  See below.

> but I doubt that would be correct.

Why not?  The patch below works for me.

--- gdb/interps.c~0	2012-01-06 06:43:17.000000000 +0200
+++ gdb/interps.c	2012-04-22 08:55:27.056588400 +0300
@@ -253,6 +253,18 @@ interp_ui_out (struct interp *interp)
   return current_interpreter->procs->ui_out_proc (current_interpreter);
 }
 
+/* Temporarily overrides the current interpreter.  */
+struct interp *
+interp_set_temp (const char *name)
+{
+  struct interp *interp = interp_lookup (name);
+  struct interp *old_interp = current_interpreter;
+
+  if (interp)
+    current_interpreter = interp;
+  return old_interp;
+}
+
 /* Returns the interpreter's cookie.  */
 
 void *
--- gdb/interps.h~0	2012-01-06 06:43:17.000000000 +0200
+++ gdb/interps.h	2012-04-22 08:42:05.687879800 +0300
@@ -69,6 +69,7 @@
 extern struct ui_out *interp_ui_out (struct interp *interp);
 extern void *interp_data (struct interp *interp);
 extern const char *interp_name (struct interp *interp);
+extern struct interp *interp_set_temp (const char *name);
 
 extern int current_interp_named_p (const char *name);
 extern int current_interp_display_prompt_p (void);
--- gdb/cli/cli-script.c~0	2012-01-06 06:43:32.000000000 +0200
+++ gdb/cli/cli-script.c	2012-04-22 09:04:23.533807200 +0300
@@ -1178,6 +1178,12 @@ recurse_read_control_structure (char * (
   return ret;
 }
 
+static void
+restore_interp (void *arg)
+{
+  interp_set_temp (interp_name ((struct interp *)arg));
+}
+
 /* Read lines from the input stream and accumulate them in a chain of
    struct command_line's, which is then returned.  For input from a
    terminal, the special command "end" is used to mark the end of the
@@ -1210,8 +1216,21 @@ read_command_lines (char *prompt_arg, in
 	}
     }
 
-  head = read_command_lines_1 (read_next_line, parse_commands,
-			       validator, closure);
+
+  /* Reading commands assumes the CLI behavior, so temporarily
+     override the current interpreter with CLI.  */
+  if (current_interp_named_p (INTERP_CONSOLE))
+    head = read_command_lines_1 (read_next_line, parse_commands,
+				 validator, closure);
+  else
+    {
+      struct interp *old_interp = interp_set_temp (INTERP_CONSOLE);
+      struct cleanup *old_chain = make_cleanup (restore_interp, old_interp);
+
+      head = read_command_lines_1 (read_next_line, parse_commands,
+				   validator, closure);
+      do_cleanups (old_chain);
+    }
 
   if (deprecated_readline_end_hook && from_tty && input_from_terminal_p ())
     {