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, 14 insertions, 9 deletions

diff --git a/gdb/main.c b/gdb/main.c
index 79f14b7..beb8203 100644
--- a/gdb/main.c
+++ b/gdb/main.c
@@ -305,11 +305,10 @@ setup_alternate_signal_stack (void)
 #endif
 }
 
-/* Call command_loop.  If it happens to return, pass that through as a
-   non-zero return status.  */
+/* Call command_loop.  */
 
-static int
-captured_command_loop (void *data)
+static void
+captured_command_loop ()
 {
   struct ui *ui = current_ui;
 
@@ -333,11 +332,9 @@ captured_command_loop (void *data)
      check to detect bad FUNCs code.  */
   do_cleanups (all_cleanups ());
   /* If the command_loop returned, normally (rather than threw an
-     error) we try to quit.  If the quit is aborted, catch_errors()
-     which called this catch the signal and restart the command
-     loop.  */
+     error) we try to quit.  If the quit is aborted, our caller
+     catches the signal and restarts the command loop.  */
   quit_command (NULL, ui->instream == ui->stdin_stream);
-  return 1;
 }
 
 /* Handle command errors thrown from within catch_command_errors.  */
@@ -1145,7 +1142,15 @@ captured_main (void *data)
      change - SET_TOP_LEVEL() - has been eliminated.  */
   while (1)
     {
-      catch_errors (captured_command_loop, 0, "", RETURN_MASK_ALL);
+      TRY
+	{
+	  captured_command_loop ();
+	}
+      CATCH (ex, RETURN_MASK_ALL)
+	{
+	  exception_print (gdb_stderr, ex);
+	}
+      END_CATCH
     }
   /* No exit -- exit is through quit_command.  */
 }