'struct expression *' -> gdb::unique_xmalloc_ptr<expression>

This patch makes parse_expression and friends return a unique_ptr
instead of raw pointer [1]:

  typedef gdb::unique_malloc_ptr<expression> expression_up;

and then adjusts the codebase throughout to stop using cleanups to
manage lifetime of expression pointers.

Whenever I found a structure owning an expression pointer, I made it
store a unique_ptr instead of a raw pointer, which then requires using
new/delete of the holding structure, instead of XNEW/xfree.

[1] - I'd like to set the rule that types named with an "_up" suffix
      are unique_ptr typedefs.

Note I used gdb::unique_xmalloc_ptr instead of gdb::unique_ptr, simply
because we still use xmalloc instead of new to allocate expression
objects.  Once that's changed, all we need to do is change the
expression_up typedef and the smart pointer will then call delete
instead of xfree.

gdb/ChangeLog:
2016-11-08  Pedro Alves  <palves@redhat.com>

	* ada-lang.c (ada_read_renaming_var_value): Use expression_up.
	(struct ada_catchpoint_location) <excep_cond_expr>: Now an
	expression_up.
	(ada_catchpoint_location_dtor): Reset excep_cond_expr instead of
	using xfree.
	(create_excep_cond_exprs): Use expression_up and gdb::move.
	(allocate_location_exception): Use new instead of XNEW.
	(should_stop_exception): Likewise.  Adjust to use expression_up.
	(create_ada_exception_catchpoint): Use new instead of XNEW.
	* ax-gdb.c (agent_eval_command_one): Use expression_up instead of
	cleanups.
	(maint_agent_printf_command): Use expression_up.
	* break-catch-sig.c (create_signal_catchpoint): Use new instead of
	XNEW.
	* break-catch-syscall.c (create_syscall_event_catchpoint):
	Likewise.
	* break-catch-throw.c (handle_gnu_v3_exceptions): Use new instead
	of XCNEW.  Use gdb::unique_ptr instead of cleanups.
	* breakpoint.c (set_breakpoint_condition, update_watchpoint)
	(parse_cmd_to_aexpr, watchpoint_check)
	(bpstat_check_breakpoint_conditions, watchpoint_locations_match):
	Adjust to use expression_up.
	(init_bp_location): Adjust.
	(free_bp_location): Use delete instead of xfree.
	(set_raw_breakpoint_without_location, set_raw_breakpoint)
	(add_solib_catchpoint, create_fork_vfork_event_catchpoint)
	(new_single_step_breakpoint, create_breakpoint_sal): Use new
	instead of XNEW.
	(find_condition_and_thread): Adjust to use expression_up.
	(create_breakpoint): Use new instead of XNEW.
	(dtor_watchpoint): Don't xfree expression pointers, they're
	unique_ptr's now.
	(insert_watchpoint, remove_watchpoint): Adjust.
	(watch_command_1): Use expression_up.  Use new instead of XCNEW.
	(catch_exec_command_1): Use new instead of XNEW.
	(bp_location_dtor): Don't xfree expression pointers, they're
	unique_ptr's now.
	(base_breakpoint_allocate_location)
	(strace_marker_create_breakpoints_sal): Use new instead of XNEW.
	(delete_breakpoint): Use delete instead of xfree.
	* breakpoint.h (struct bp_location) <cond>: Now an
	unique_ptr<expression> instead of a raw pointer.
	(struct watchpoint) <exp, cond_exp>: Likewise.
	* cli/cli-script.c (execute_control_command): Use expression_up
	instead of cleanups.
	* dtrace-probe.c (dtrace_process_dof_probe): Use expression_up.
	* eval.c (parse_and_eval_address, parse_and_eval_long)
	(parse_and_eval, parse_to_comma_and_eval, parse_and_eval_type):
	Use expression_up instead of cleanups.
	* expression.h (expression_up): New typedef.
	(parse_expression, parse_expression_with_language, parse_exp_1):
	Change return type to expression_up.
	* mi/mi-main.c (mi_cmd_data_evaluate_expression)
	(print_variable_or_computed): Use expression_up.
	* objc-lang.c (print_object_command): Use expression_up instead of
	cleanups.
	* parse.c (parse_exp_1, parse_exp_in_context)
	(parse_exp_in_context_1, parse_expression)
	(parse_expression_with_language): Return an expression_up instead
	of a raw pointer.
	(parse_expression_for_completion): Use expression_up.
	* printcmd.c (struct display) <exp>: Now an expression_up instead
	of a raw pointer.
	(print_command_1, output_command_const, set_command, x_command):
	Use expression_up instead of cleanups.
	(display_command): Likewise.  Use new instead of XNEW.
	(free_display): Use delete instead of xfree.
	(do_one_display): Adjust to use expression_up.
	* remote.c (remote_download_tracepoint): Likewise.
	* stack.c (return_command): Likewise.
	* tracepoint.c (validate_actionline, encode_actions_1): Use
	expression_up instead of cleanups.
	* typeprint.c (whatis_exp, maintenance_print_type): Likewise.
	* value.c (init_if_undefined_command): Likewise.
	* varobj.c (struct varobj_root) <exp>: Now an expression_up
	instead of a raw pointer.
	(varobj_create): Adjust.
	(varobj_set_value): Use an expression_up instead of cleanups.
	(new_root_variable): Use new instead of XNEW.
	(free_variable): Use delete instead of xfree.
	(value_of_root_1): Use std::swap.

gdb/printcmd.c

@@ -119,7 +119,7 @@ struct display
     char *exp_string;
 
     /* Expression to be evaluated and displayed.  */
-    struct expression *exp;
+    expression_up exp;
 
     /* Item number of this auto-display item.  */
     int number;
@@ -1243,8 +1243,6 @@ print_value (struct value *val, const struct format_data *fmtp)
 static void
 print_command_1 (const char *exp, int voidprint)
 {
-  struct expression *expr;
-  struct cleanup *old_chain = make_cleanup (null_cleanup, NULL);
   struct value *val;
   struct format_data fmt;
 
@@ -1252,9 +1250,8 @@ print_command_1 (const char *exp, int voidprint)
 
   if (exp && *exp)
     {
-      expr = parse_expression (exp);
-      make_cleanup (free_current_contents, &expr);
-      val = evaluate_expression (expr);
+      expression_up expr = parse_expression (exp);
+      val = evaluate_expression (expr.get ());
     }
   else
     val = access_value_history (0);
@@ -1262,8 +1259,6 @@ print_command_1 (const char *exp, int voidprint)
   if (voidprint || (val && value_type (val) &&
 		    TYPE_CODE (value_type (val)) != TYPE_CODE_VOID))
     print_value (val, &fmt);
-
-  do_cleanups (old_chain);
 }
 
 static void
@@ -1292,8 +1287,6 @@ output_command (char *exp, int from_tty)
 void
 output_command_const (const char *exp, int from_tty)
 {
-  struct expression *expr;
-  struct cleanup *old_chain;
   char format = 0;
   struct value *val;
   struct format_data fmt;
@@ -1310,10 +1303,9 @@ output_command_const (const char *exp, int from_tty)
       format = fmt.format;
     }
 
-  expr = parse_expression (exp);
-  old_chain = make_cleanup (free_current_contents, &expr);
+  expression_up expr = parse_expression (exp);
 
-  val = evaluate_expression (expr);
+  val = evaluate_expression (expr.get ());
 
   annotate_value_begin (value_type (val));
 
@@ -1325,16 +1317,12 @@ output_command_const (const char *exp, int from_tty)
 
   wrap_here ("");
   gdb_flush (gdb_stdout);
-
-  do_cleanups (old_chain);
 }
 
 static void
 set_command (char *exp, int from_tty)
 {
-  struct expression *expr = parse_expression (exp);
-  struct cleanup *old_chain =
-    make_cleanup (free_current_contents, &expr);
+  expression_up expr = parse_expression (exp);
 
   if (expr->nelts >= 1)
     switch (expr->elts[0].opcode)
@@ -1352,8 +1340,7 @@ set_command (char *exp, int from_tty)
 	  (_("Expression is not an assignment (and might have no effect)"));
       }
 
-  evaluate_expression (expr);
-  do_cleanups (old_chain);
+  evaluate_expression (expr.get ());
 }
 
 static void
@@ -1676,7 +1663,6 @@ address_info (char *exp, int from_tty)
 static void
 x_command (char *exp, int from_tty)
 {
-  struct expression *expr;
   struct format_data fmt;
   struct cleanup *old_chain;
   struct value *val;
@@ -1698,14 +1684,13 @@ x_command (char *exp, int from_tty)
 
   if (exp != 0 && *exp != 0)
     {
-      expr = parse_expression (exp);
+      expression_up expr = parse_expression (exp);
       /* Cause expression not to be there any more if this command is
          repeated with Newline.  But don't clobber a user-defined
          command's definition.  */
       if (from_tty)
 	*exp = 0;
-      old_chain = make_cleanup (free_current_contents, &expr);
-      val = evaluate_expression (expr);
+      val = evaluate_expression (expr.get ());
       if (TYPE_CODE (value_type (val)) == TYPE_CODE_REF)
 	val = coerce_ref (val);
       /* In rvalue contexts, such as this, functions are coerced into
@@ -1718,7 +1703,6 @@ x_command (char *exp, int from_tty)
 	next_address = value_as_address (val);
 
       next_gdbarch = expr->gdbarch;
-      do_cleanups (old_chain);
     }
 
   if (!next_gdbarch)
@@ -1764,7 +1748,6 @@ static void
 display_command (char *arg, int from_tty)
 {
   struct format_data fmt;
-  struct expression *expr;
   struct display *newobj;
   const char *exp = arg;
 
@@ -1792,12 +1775,12 @@ display_command (char *arg, int from_tty)
     }
 
   innermost_block = NULL;
-  expr = parse_expression (exp);
+  expression_up expr = parse_expression (exp);
 
-  newobj = XNEW (struct display);
+  newobj = new display ();
 
   newobj->exp_string = xstrdup (exp);
-  newobj->exp = expr;
+  newobj->exp = gdb::move (expr);
   newobj->block = innermost_block;
   newobj->pspace = current_program_space;
   newobj->number = ++display_number;
@@ -1826,8 +1809,7 @@ static void
 free_display (struct display *d)
 {
   xfree (d->exp_string);
-  xfree (d->exp);
-  xfree (d);
+  delete d;
 }
 
 /* Clear out the display_chain.  Done when new symtabs are loaded,
@@ -1951,8 +1933,7 @@ do_one_display (struct display *d)
      expression if the current architecture has changed.  */
   if (d->exp != NULL && d->exp->gdbarch != get_current_arch ())
     {
-      xfree (d->exp);
-      d->exp = NULL;
+      d->exp.reset ();
       d->block = NULL;
     }
 
@@ -2025,7 +2006,7 @@ do_one_display (struct display *d)
 	  struct value *val;
 	  CORE_ADDR addr;
 
-	  val = evaluate_expression (d->exp);
+	  val = evaluate_expression (d->exp.get ());
 	  addr = value_as_address (val);
 	  if (d->format.format == 'i')
 	    addr = gdbarch_addr_bits_remove (d->exp->gdbarch, addr);
@@ -2062,7 +2043,7 @@ do_one_display (struct display *d)
         {
 	  struct value *val;
 
-	  val = evaluate_expression (d->exp);
+	  val = evaluate_expression (d->exp.get ());
 	  print_formatted (val, d->format.size, &opts, gdb_stdout);
 	}
       CATCH (ex, RETURN_MASK_ERROR)
@@ -2222,10 +2203,9 @@ clear_dangling_display_expressions (struct objfile *objfile)
 	continue;
 
       if (lookup_objfile_from_block (d->block) == objfile
-	  || (d->exp && exp_uses_objfile (d->exp, objfile)))
+	  || (d->exp != NULL && exp_uses_objfile (d->exp.get (), objfile)))
       {
-	xfree (d->exp);
-	d->exp = NULL;
+	d->exp.reset ();
 	d->block = NULL;
       }
     }