Constify some parameters in the varobj code

To make it clear that some functions should not modify the variable
object, this patch adds the const qualifier where it makes sense to some
struct varobj * parameters. Most getters should take a const pointer to
guarantee they don't modify the object.

Unfortunately, I couldn't add it to some callbacks (such as name_of_child).
In the C implementation, they call c_describe_child, which calls
varobj_get_path_expr. varobj_get_path_expr needs to modify the object in
order to cache the computed value. It therefore can't take a const
pointer, and it affects the whole call chain. I suppose that's where you
would use a "mutable" in C++.

I did that to make sure there was no other cases like the one fixed in
the previous patch. I don't think it can hurt.

gdb/ChangeLog:

	* ada-varobj.c (ada_number_of_children): Constify struct varobj *
	parameter.
	(ada_name_of_variable): Same.
	(ada_path_expr_of_child): Same.
	(ada_value_of_variable): Same.
	(ada_value_is_changeable_p): Same.
	(ada_value_has_mutated): Same.
	* c-varobj.c (varobj_is_anonymous_child): Same.
	(c_is_path_expr_parent): Same.
	(c_number_of_children): Same.
	(c_name_of_variable): Same.
	(c_path_expr_of_child): Same.
	(get_type): Same.
	(c_value_of_variable): Same.
	(cplus_number_of_children): Same.
	(cplus_name_of_variable): Same.
	(cplus_path_expr_of_child): Same.
	(cplus_value_of_variable): Same.
	* jv-varobj.c (java_number_of_children): Same.
	(java_name_of_variable): Same.
	(java_path_expr_of_child): Same.
	(java_value_of_variable): Same.
	* varobj.c (number_of_children): Same.
	(name_of_variable): Same.
	(is_root_p): Same.
	(varobj_ensure_python_env): Same.
	(varobj_get_objname): Same.
	(varobj_get_expression): Same.
	(varobj_get_display_format): Same.
	(varobj_get_display_hint): Same.
	(varobj_has_more): Same.
	(varobj_get_thread_id): Same.
	(varobj_get_frozen): Same.
	(dynamic_varobj_has_child_method): Same.
	(varobj_get_gdb_type): Same.
	(is_path_expr_parent): Same.
	(varobj_default_is_path_expr_parent): Same.
	(varobj_get_language): Same.
	(varobj_get_attributes): Same.
	(varobj_is_dynamic_p): Same.
	(varobj_get_child_range): Same.
	(varobj_value_has_mutated): Same.
	(varobj_get_value_type): Same.
	(number_of_children): Same.
	(name_of_variable): Same.
	(check_scope): Same.
	(varobj_editable_p): Same.
	(varobj_value_is_changeable_p): Same.
	(varobj_floating_p): Same.
	(varobj_default_value_is_changeable_p): Same.
	* varobj.h (struct lang_varobj_ops): Consitfy some struct varobj *
	parameters.
	(varobj_get_objname): Constify struct varobj * parameter.
	(varobj_get_expression): Same.
	(varobj_get_thread_id): Same.
	(varobj_get_frozen): Same.
	(varobj_get_child_range): Same.
	(varobj_get_display_hint): Same.
	(varobj_get_gdb_type): Same.
	(varobj_get_language): Same.
	(varobj_get_attributes): Same.
	(varobj_editable_p): Same.
	(varobj_floating_p): Same.
	(varobj_has_more): Same.
	(varobj_is_dynamic_p): Same.
	(varobj_ensure_python_env): Same.
	(varobj_default_value_is_changeable_p): Same.
	(varobj_value_is_changeable_p): Same.
	(varobj_get_value_type): Same.
	(varobj_is_anonymous_child): Same.
	(varobj_value_get_print_value): Same.
	(varobj_default_is_path_expr_parent): Same.

1 files changed, 30 insertions, 28 deletions

diff --git a/gdb/varobj.h b/gdb/varobj.h
index 796b940..750660a 100644
--- a/gdb/varobj.h
+++ b/gdb/varobj.h
@@ -167,17 +167,17 @@ struct varobj
 struct lang_varobj_ops
 {
   /* The number of children of PARENT.  */
-  int (*number_of_children) (struct varobj *parent);
+  int (*number_of_children) (const struct varobj *parent);
 
   /* The name (expression) of a root varobj.  */
-  char *(*name_of_variable) (struct varobj *parent);
+  char *(*name_of_variable) (const struct varobj *parent);
 
   /* The name of the INDEX'th child of PARENT.  */
   char *(*name_of_child) (struct varobj *parent, int index);
 
   /* Returns the rooted expression of CHILD, which is a variable
      obtain that has some parent.  */
-  char *(*path_expr_of_child) (struct varobj *child);
+  char *(*path_expr_of_child) (const struct varobj *child);
 
   /* The ``struct value *'' of the INDEX'th child of PARENT.  */
   struct value *(*value_of_child) (struct varobj *parent, int index);
@@ -186,7 +186,7 @@ struct lang_varobj_ops
   struct type *(*type_of_child) (struct varobj *parent, int index);
 
   /* The current value of VAR.  */
-  char *(*value_of_variable) (struct varobj *var,
+  char *(*value_of_variable) (const struct varobj *var,
 			      enum varobj_display_formats format);
 
   /* Return non-zero if changes in value of VAR must be detected and
@@ -197,7 +197,7 @@ struct lang_varobj_ops
 
      Return value of 0 means that gdb need not call value_fetch_lazy
      for the value of this variable object.  */
-  int (*value_is_changeable_p) (struct varobj *var);
+  int (*value_is_changeable_p) (const struct varobj *var);
 
   /* Return nonzero if the type of VAR has mutated.
 
@@ -211,14 +211,14 @@ struct lang_varobj_ops
      children is set (not < 0).
 
      Languages where types do not mutate can set this to NULL.  */
-  int (*value_has_mutated) (struct varobj *var, struct value *new_value,
+  int (*value_has_mutated) (const struct varobj *var, struct value *new_value,
 			    struct type *new_type);
 
   /* Return nonzero if VAR is a suitable path expression parent.
 
      For C like languages with anonymous structures and unions an anonymous
      structure or union is not a suitable parent.  */
-  int (*is_path_expr_parent) (struct varobj *var);
+  int (*is_path_expr_parent) (const struct varobj *var);
 };
 
 extern const struct lang_varobj_ops c_varobj_ops;
@@ -237,9 +237,9 @@ extern char *varobj_gen_name (void);
 
 extern struct varobj *varobj_get_handle (char *name);
 
-extern char *varobj_get_objname (struct varobj *var);
+extern char *varobj_get_objname (const struct varobj *var);
 
-extern char *varobj_get_expression (struct varobj *var);
+extern char *varobj_get_expression (const struct varobj *var);
 
 extern int varobj_delete (struct varobj *var, char ***dellist,
 			  int only_children);
@@ -249,19 +249,20 @@ extern enum varobj_display_formats varobj_set_display_format (
 					enum varobj_display_formats format);
 
 extern enum varobj_display_formats varobj_get_display_format (
-							struct varobj *var);
+						const struct varobj *var);
 
-extern int varobj_get_thread_id (struct varobj *var);
+extern int varobj_get_thread_id (const struct varobj *var);
 
 extern void varobj_set_frozen (struct varobj *var, int frozen);
 
-extern int varobj_get_frozen (struct varobj *var);
+extern int varobj_get_frozen (const struct varobj *var);
 
-extern void varobj_get_child_range (struct varobj *var, int *from, int *to);
+extern void varobj_get_child_range (const struct varobj *var, int *from,
+				    int *to);
 
 extern void varobj_set_child_range (struct varobj *var, int from, int to);
 
-extern char *varobj_get_display_hint (struct varobj *var);
+extern char *varobj_get_display_hint (const struct varobj *var);
 
 extern int varobj_get_num_children (struct varobj *var);
 
@@ -278,13 +279,14 @@ extern VEC (varobj_p)* varobj_list_children (struct varobj *var,
 
 extern char *varobj_get_type (struct varobj *var);
 
-extern struct type *varobj_get_gdb_type (struct varobj *var);
+extern struct type *varobj_get_gdb_type (const struct varobj *var);
 
 extern char *varobj_get_path_expr (struct varobj *var);
 
-extern const struct language_defn *varobj_get_language (struct varobj *var);
+extern const struct language_defn *
+  varobj_get_language (const struct varobj *var);
 
-extern int varobj_get_attributes (struct varobj *var);
+extern int varobj_get_attributes (const struct varobj *var);
 
 extern char *varobj_get_formatted_value (struct varobj *var,
 					 enum varobj_display_formats format);
@@ -301,33 +303,33 @@ extern VEC(varobj_update_result) *varobj_update (struct varobj **varp,
 
 extern void varobj_invalidate (void);
 
-extern int varobj_editable_p (struct varobj *var);
+extern int varobj_editable_p (const struct varobj *var);
 
-extern int varobj_floating_p (struct varobj *var);
+extern int varobj_floating_p (const struct varobj *var);
 
 extern void varobj_set_visualizer (struct varobj *var,
 				   const char *visualizer);
 
 extern void varobj_enable_pretty_printing (void);
 
-extern int varobj_has_more (struct varobj *var, int to);
+extern int varobj_has_more (const struct varobj *var, int to);
 
-extern int varobj_is_dynamic_p (struct varobj *var);
+extern int varobj_is_dynamic_p (const struct varobj *var);
 
-extern struct cleanup *varobj_ensure_python_env (struct varobj *var);
+extern struct cleanup *varobj_ensure_python_env (const struct varobj *var);
 
-extern int varobj_default_value_is_changeable_p (struct varobj *var);
-extern int varobj_value_is_changeable_p (struct varobj *var);
+extern int varobj_default_value_is_changeable_p (const struct varobj *var);
+extern int varobj_value_is_changeable_p (const struct varobj *var);
 
-extern struct type *varobj_get_value_type (struct varobj *var);
+extern struct type *varobj_get_value_type (const struct varobj *var);
 
-extern int varobj_is_anonymous_child (struct varobj *child);
+extern int varobj_is_anonymous_child (const struct varobj *child);
 
 extern struct varobj *varobj_get_path_expr_parent (struct varobj *var);
 
 extern char *varobj_value_get_print_value (struct value *value,
 					   enum varobj_display_formats format,
-					   struct varobj *var);
+					   const struct varobj *var);
 
 extern void varobj_formatted_print_options (struct value_print_options *opts,
 					    enum varobj_display_formats format);
@@ -335,6 +337,6 @@ extern void varobj_formatted_print_options (struct value_print_options *opts,
 extern void varobj_restrict_range (VEC (varobj_p) *children, int *from,
 				   int *to);
 
-extern int varobj_default_is_path_expr_parent (struct varobj *var);
+extern int varobj_default_is_path_expr_parent (const struct varobj *var);
 
 #endif /* VAROBJ_H */