[RFC 02/17] Move gdb-specific code out of start_event_loop

[Tom Tromey <tom@tromey.com>]

This moves some gdb-specific code out of start_event_loop, into a new
function that must be supplied by the event-loop client.

gdb/ChangeLog
2019-02-24  Tom Tromey  <tom@tromey.com>

	* main.c (handle_event_loop_exception): New function.
	* event-loop.c: Don't include event-top.h or observable.h.
	(start_event_loop): Remove gdb-specific code.  Call
	handle_event_loop_exception.
	* event-loop.h (handle_event_loop_exception): Declare.
---
 gdb/ChangeLog    |  8 ++++++++
 gdb/event-loop.c | 26 ++------------------------
 gdb/event-loop.h |  6 +++++-
 gdb/main.c       | 28 ++++++++++++++++++++++++++++
 4 files changed, 43 insertions(+), 25 deletions(-)

diff --git a/gdb/event-loop.c b/gdb/event-loop.c
index 4d05eb9a243..f41094e9add 100644
--- a/gdb/event-loop.c
+++ b/gdb/event-loop.c
@@ -19,7 +19,6 @@
 
 #include "defs.h"
 #include "event-loop.h"
-#include "event-top.h"
 #include "ser-event.h"
 
 #ifdef HAVE_POLL
@@ -33,7 +32,6 @@
 #include <sys/types.h>
 #include "common/gdb_sys_time.h"
 #include "gdb_select.h"
-#include "observable.h"
 #include "top.h"
 
 /* Tell create_file_handler what events we are interested in.
@@ -355,7 +353,7 @@ gdb_do_one_event (void)
    from the command loop.  */
 
 void
-start_event_loop (void)
+start_event_loop ()
 {
   /* Loop until there is nothing to do.  This is the entry point to
      the event loop engine.  gdb_do_one_event will process one event
@@ -371,27 +369,7 @@ start_event_loop (void)
 	}
       CATCH (ex, RETURN_MASK_ALL)
 	{
-	  exception_print (gdb_stderr, ex);
-
-	  /* If any exception escaped to here, we better enable
-	     stdin.  Otherwise, any command that calls async_disable_stdin,
-	     and then throws, will leave stdin inoperable.  */
-	  async_enable_stdin ();
-	  /* If we long-jumped out of do_one_event, we probably didn't
-	     get around to resetting the prompt, which leaves readline
-	     in a messed-up state.  Reset it here.  */
-	  current_ui->prompt_state = PROMPT_NEEDED;
-	  gdb::observers::command_error.notify ();
-	  /* This call looks bizarre, but it is required.  If the user
-	     entered a command that caused an error,
-	     after_char_processing_hook won't be called from
-	     rl_callback_read_char_wrapper.  Using a cleanup there
-	     won't work, since we want this function to be called
-	     after a new prompt is printed.  */
-	  if (after_char_processing_hook)
-	    (*after_char_processing_hook) ();
-	  /* Maybe better to set a flag to be checked somewhere as to
-	     whether display the prompt or not.  */
+	  handle_event_loop_exception (ex);
 	}
       END_CATCH
 
diff --git a/gdb/event-loop.h b/gdb/event-loop.h
index 99b776618bd..f11b008848d 100644
--- a/gdb/event-loop.h
+++ b/gdb/event-loop.h
@@ -80,7 +80,7 @@ typedef void (timer_handler_func) (gdb_client_data);
 
 /* Exported functions from event-loop.c */
 
-extern void start_event_loop (void);
+extern void start_event_loop ();
 extern int gdb_do_one_event (void);
 extern void delete_file_handler (int fd);
 extern void add_file_handler (int fd, handler_func *proc, 
@@ -131,4 +131,8 @@ extern void clear_async_event_handler (struct async_event_handler *handler);
 
 extern void initialize_async_signal_handlers (void);
 
+/* Must be defined by client.  */
+
+extern void handle_event_loop_exception (const gdb_exception &);
+
 #endif /* EVENT_LOOP_H */
diff --git a/gdb/main.c b/gdb/main.c
index e14dd06fa8c..f60f0d0a092 100644
--- a/gdb/main.c
+++ b/gdb/main.c
@@ -48,6 +48,7 @@
 #include <vector>
 #include "common/pathstuff.h"
 #include "cli/cli-style.h"
+#include "observable.h"
 
 /* The selected interpreter.  This will be used as a set command
    variable, so it should always be malloc'ed - since
@@ -314,6 +315,33 @@ setup_alternate_signal_stack (void)
    here.  */
 static void captured_command_loop () __attribute__((noinline));
 
+/* Called to handle an exception when processing an event.  */
+void
+handle_event_loop_exception (const gdb_exception &ex)
+{
+  exception_print (gdb_stderr, ex);
+
+  /* If any exception escaped to here, we better enable
+     stdin.  Otherwise, any command that calls async_disable_stdin,
+     and then throws, will leave stdin inoperable.  */
+  async_enable_stdin ();
+  /* If we long-jumped out of do_one_event, we probably didn't
+     get around to resetting the prompt, which leaves readline
+     in a messed-up state.  Reset it here.  */
+  current_ui->prompt_state = PROMPT_NEEDED;
+  gdb::observers::command_error.notify ();
+  /* This call looks bizarre, but it is required.  If the user
+     entered a command that caused an error,
+     after_char_processing_hook won't be called from
+     rl_callback_read_char_wrapper.  Using a cleanup there
+     won't work, since we want this function to be called
+     after a new prompt is printed.  */
+  if (after_char_processing_hook)
+    (*after_char_processing_hook) ();
+  /* Maybe better to set a flag to be checked somewhere as to
+     whether display the prompt or not.  */
+}
+
 static void
 captured_command_loop ()
 {
-- 
2.17.2