Eliminate catch_errors

If you want to use catch_errors with a function with parameters, then
currently you have to manually write a "capture" struct wrapping the
arguments and marshall/unmarshall that.

https://sourceware.org/ml/gdb-patches/2017-09/msg00834.html proposed
adjusting catch_errors to use gdb::function_view, which would allow
passing lambdas with automatic captures.  However, it seems like using
TRY/CATCH directly instead ends up producing clearer and easier to
debug code.  This is what this commit does.

Note that removing catch_errors exposes further cleanup opportunities
around no longer having to follow catch_errors callback type, and also
removes a few cleanups.

I didn't do anything to save/restore current_uiout because I think
that should be the responsibility of the code that changes
current_uiout in the first place.

(Another approach could be to make catch_errors a variadic template
like:

  template<typename Function, typename... Args>
  int catch_errors (const char *errstring, return_mask mask,
		    Function &&func, Args... args);

and then with:

  extern void function_with_args (int, int);
  extern void function_with_no_args ();

calls to the above functions would be wrapped like this:

  catch_errors ("some error happened", RETURN_MASK_ERROR,
                function_with_args, arg1, arg2);

  catch_errors ("some error happened", RETURN_MASK_ERROR,
                function_with_no_args);

but I'm thinking that that doesn't improve much if at all either.)

gdb/ChangeLog
2017-10-10  Pedro Alves  <palves@redhat.com>
	    Tom Tromey  <tom@tromey.com>

	* breakpoint.c (breakpoint_cond_eval): Change return type to bool
	and reverse logic.
	(WP_DELETED, WP_VALUE_CHANGED, WP_VALUE_NOT_CHANGED, WP_IGNORE):
	No longer macros.  Instead ...
	(enum wp_check_result): They're now values of this new
	enumeration.
	(watchpoint_check): Change return type to wp_check_result and
	parameter type to bpstat.
	(bpstat_check_watchpoint): Use TRY/CATCH instead of catch_errors.
	(bpstat_check_breakpoint_conditions): Use TRY/CATCH instead of
	catch_errors.  Reverse logic of watchpoint_check call.
	(breakpoint_re_set_one): Now returns void and takes a breakpoint
	pointer as parameter.
	(breakpoint_re_set): Use TRY/CATCH instead of catch_errors.
	* common/common-exceptions.c (throw_exception_sjlj): Update
	comments to avoid mentioning catch_errors.
	* exceptions.c (catch_errors): Delete.
	* exceptions.h: Update comments to avoid mentioning catch_errors.
	(catch_errors_ftype, catch_errors): Delete.
	* infrun.c (normal_stop): Use TRY/CATCH instead of catch_errors.
	(hook_stop_stub): Delete.
	(restore_selected_frame): Change return type to void, and
	parameter type to const frame_id &.
	(restore_infcall_control_state): Use TRY/CATCH instead of
	catch_errors.
	* main.c (captured_command_loop): Return void and remove
	parameter.  Remove references to catch_errors.
	(captured_main): Use TRY/CATCH instead of catch_errors.
	* objc-lang.c (objc_submethod_helper_data)
	(find_objc_msgcall_submethod_helper): Delete.
	(find_objc_msgcall_submethod): Use TRY/CATCH instead of
	catch_errors.
	* record-full.c (record_full_message): Return void.
	(record_full_message_args, record_full_message_wrapper): Delete.
	(record_full_message_wrapper_safe): Return bool and use TRY/CATCH
	instead of catch_errors.
	* solib-aix.c (solib_aix_open_symbol_file_object): Change
	parameter type to int.
	* solib-darwin.c (open_symbol_file_object): Ditto.
	* solib-dsbt.c (open_symbol_file_object): Ditto.
	* solib-frv.c (open_symbol_file_object): Ditto.
	* solib-svr4.c (open_symbol_file_object): Ditto.
	* solib-target.c (solib_target_open_symbol_file_object): Ditto.
	* solib.c (update_solib_list): Use TRY/CATCH instead of
	catch_errors.
	* solist.h (struct target_so_ops) <open_symbol_file_object>:
	Change type.
	* symmisc.c (struct print_symbol_args): Remove.
	(dump_symtab_1): Use TRY/CATCH instead of catch_errors.
	(print_symbol): Change type.
	* windows-nat.c (handle_load_dll, handle_unload_dll): Return void
	and remove parameters.
	(catch_errors): New.
	(get_windows_debug_event): Adjust.

gdb/testsuite/ChangeLog:
2017-10-10  Pedro Alves  <palves@redhat.com>

	* lib/selftest-support.exp (selftest_setup): Update for
	captured_command_loop's prototype change.

1 files changed, 28 insertions, 30 deletions

diff --git a/gdb/infrun.c b/gdb/infrun.c
index 113add6..d00c5f6 100644
--- a/gdb/infrun.c
+++ b/gdb/infrun.c
@@ -80,10 +80,6 @@ static void sig_print_header (void);
 
 static void resume_cleanups (void *);
 
-static int hook_stop_stub (void *);
-
-static int restore_selected_frame (void *);
-
 static int follow_fork (void);
 
 static int follow_fork_inferior (int follow_child, int detach_fork);
@@ -8314,8 +8310,16 @@ normal_stop (void)
       struct cleanup *old_chain
 	= make_cleanup (release_stop_context_cleanup, saved_context);
 
-      catch_errors (hook_stop_stub, stop_command,
-		    "Error while running hook_stop:\n", RETURN_MASK_ALL);
+      TRY
+	{
+	  execute_cmd_pre_hook (stop_command);
+	}
+      CATCH (ex, RETURN_MASK_ALL)
+	{
+	  exception_fprintf (gdb_stderr, ex,
+			     "Error while running hook_stop:\n");
+	}
+      END_CATCH
 
       /* If the stop hook resumes the target, then there's no point in
 	 trying to notify about the previous stop; its context is
@@ -8356,13 +8360,6 @@ normal_stop (void)
 
   return 0;
 }
-
-static int
-hook_stop_stub (void *cmd)
-{
-  execute_cmd_pre_hook ((struct cmd_list_element *) cmd);
-  return (0);
-}
 
 int
 signal_stop_state (int signo)
@@ -8983,25 +8980,20 @@ save_infcall_control_state (void)
   return inf_status;
 }
 
-static int
-restore_selected_frame (void *args)
+static void
+restore_selected_frame (const frame_id &fid)
 {
-  struct frame_id *fid = (struct frame_id *) args;
-  struct frame_info *frame;
-
-  frame = frame_find_by_id (*fid);
+  frame_info *frame = frame_find_by_id (fid);
 
   /* If inf_status->selected_frame_id is NULL, there was no previously
      selected frame.  */
   if (frame == NULL)
     {
       warning (_("Unable to restore previously selected frame."));
-      return 0;
+      return;
     }
 
   select_frame (frame);
-
-  return (1);
 }
 
 /* Restore inferior session state to INF_STATUS.  */
@@ -9031,16 +9023,22 @@ restore_infcall_control_state (struct infcall_control_state *inf_status)
 
   if (target_has_stack)
     {
-      /* The point of catch_errors is that if the stack is clobbered,
+      /* The point of the try/catch is that if the stack is clobbered,
          walking the stack might encounter a garbage pointer and
          error() trying to dereference it.  */
-      if (catch_errors
-	  (restore_selected_frame, &inf_status->selected_frame_id,
-	   "Unable to restore previously selected frame:\n",
-	   RETURN_MASK_ERROR) == 0)
-	/* Error in restoring the selected frame.  Select the innermost
-	   frame.  */
-	select_frame (get_current_frame ());
+      TRY
+	{
+	  restore_selected_frame (inf_status->selected_frame_id);
+	}
+      CATCH (ex, RETURN_MASK_ERROR)
+	{
+	  exception_fprintf (gdb_stderr, ex,
+			     "Unable to restore previously selected frame:\n");
+	  /* Error in restoring the selected frame.  Select the
+	     innermost frame.  */
+	  select_frame (get_current_frame ());
+	}
+      END_CATCH
     }
 
   xfree (inf_status);