Re: [PATCH] Finish constification of varobj interface

[Simon Marchi <simon dot marchi at ericsson dot com>]

On 02/10/2015 11:27 AM, Simon Marchi wrote:
> This completes the constification of the struct varobj pointers in the
> lang_varobj_ops interface partially done in
> b09e2c591f9221d865bfe8425990a6bf9fab24e3. As suggested by Pedro,
> varobj_get_path_expr casts away the const to assign the "mutable" struct
> member.
> 
> gdb/ChangeLog:
> 
> 	* ada-varobj.c (ada_name_of_child): Constify parent.
> 	(ada_path_expr_of_child): Same.
> 	(ada_value_of_child): Same.
> 	(ada_type_of_child): Same.
> 	* c-varobj.c (c_is_path_expr_parent): Same.
> 	(c_describe_child): Same.
> 	(c_name_of_child): Same.
> 	(c_value_of_child): Same.
> 	(c_type_of_child): Same.
> 	(cplus_number_of_children): Same.
> 	(cplus_describe_child): Constify var.
> 	(cplus_name_of_child): Constify parent.
> 	(cplus_value_of_child): Same.
> 	(cplus_type_of_child): Same.
> 	* jv-varobj.c (java_name_of_child): Same.
> 	(java_value_of_child): Same.
> 	(java_type_of_child): Same.
> 	* varobj.c (value_of_child): Same.
> 	(varobj_default_is_path_expr_parent): Constify var, parent and return
> 	value.
> 	(varobj_get_path_expr): Constify var, modify path_expr through
> 	mutable_var.
> 	(install_new_value): Constify parent.
> 	(value_of_child): Same.
> 	* varobj.h (struct varobj): Same.
> 	(struct lang_varobj_ops): Constify name_of_child, value_of_child and
> 	type_of_child.
> 	(varobj_get_path_expr): Constify var.
> 	(varobj_get_path_expr_parent): Constify var and return value.
> ---
>  gdb/ada-varobj.c |  8 ++++----
>  gdb/c-varobj.c   | 22 +++++++++++-----------
>  gdb/jv-varobj.c  |  6 +++---
>  gdb/varobj.c     | 17 +++++++++--------
>  gdb/varobj.h     | 13 +++++++------
>  5 files changed, 34 insertions(+), 32 deletions(-)
> 
> diff --git a/gdb/ada-varobj.c b/gdb/ada-varobj.c
> index 7407af4..83d0707 100644
> --- a/gdb/ada-varobj.c
> +++ b/gdb/ada-varobj.c
> @@ -918,7 +918,7 @@ ada_name_of_variable (const struct varobj *parent)
>  }
>  
>  static char *
> -ada_name_of_child (struct varobj *parent, int index)
> +ada_name_of_child (const struct varobj *parent, int index)
>  {
>    return ada_varobj_get_name_of_child (parent->value, parent->type,
>  				       parent->name, index);
> @@ -927,7 +927,7 @@ ada_name_of_child (struct varobj *parent, int index)
>  static char*
>  ada_path_expr_of_child (const struct varobj *child)
>  {
> -  struct varobj *parent = child->parent;
> +  const struct varobj *parent = child->parent;
>    const char *parent_path_expr = varobj_get_path_expr (parent);
>  
>    return ada_varobj_get_path_expr_of_child (parent->value,
> @@ -938,14 +938,14 @@ ada_path_expr_of_child (const struct varobj *child)
>  }
>  
>  static struct value *
> -ada_value_of_child (struct varobj *parent, int index)
> +ada_value_of_child (const struct varobj *parent, int index)
>  {
>    return ada_varobj_get_value_of_child (parent->value, parent->type,
>  					parent->name, index);
>  }
>  
>  static struct type *
> -ada_type_of_child (struct varobj *parent, int index)
> +ada_type_of_child (const struct varobj *parent, int index)
>  {
>    return ada_varobj_get_type_of_child (parent->value, parent->type,
>  				       index);
> diff --git a/gdb/c-varobj.c b/gdb/c-varobj.c
> index 9394d7c..363a356 100644
> --- a/gdb/c-varobj.c
> +++ b/gdb/c-varobj.c
> @@ -146,7 +146,7 @@ c_is_path_expr_parent (const struct varobj *var)
>        && TYPE_NAME (type) == NULL
>        && TYPE_TAG_NAME (type) == NULL)
>      {
> -      struct varobj *parent = var->parent;
> +      const struct varobj *parent = var->parent;
>  
>        while (parent != NULL && CPLUS_FAKE_CHILD (parent))
>  	parent = parent->parent;
> @@ -282,7 +282,7 @@ value_struct_element_index (struct value *value, int type_index)
>     to NULL.  */
>  
>  static void 
> -c_describe_child (struct varobj *parent, int index,
> +c_describe_child (const struct varobj *parent, int index,
>  		  char **cname, struct value **cvalue, struct type **ctype,
>  		  char **cfull_expression)
>  {
> @@ -422,7 +422,7 @@ c_describe_child (struct varobj *parent, int index,
>  }
>  
>  static char *
> -c_name_of_child (struct varobj *parent, int index)
> +c_name_of_child (const struct varobj *parent, int index)
>  {
>    char *name;
>  
> @@ -441,7 +441,7 @@ c_path_expr_of_child (const struct varobj *child)
>  }
>  
>  static struct value *
> -c_value_of_child (struct varobj *parent, int index)
> +c_value_of_child (const struct varobj *parent, int index)
>  {
>    struct value *value = NULL;
>  
> @@ -450,7 +450,7 @@ c_value_of_child (struct varobj *parent, int index)
>  }
>  
>  static struct type *
> -c_type_of_child (struct varobj *parent, int index)
> +c_type_of_child (const struct varobj *parent, int index)
>  {
>    struct type *type = NULL;
>  
> @@ -614,7 +614,7 @@ cplus_number_of_children (const struct varobj *var)
>        /* It is necessary to access a real type (via RTTI).  */
>        if (opts.objectprint)
>          {
> -	  struct varobj *parent = var->parent;
> +	  const struct varobj *parent = var->parent;
>  
>  	  value = parent->value;
>  	  lookup_actual_type = (TYPE_CODE (parent->type) == TYPE_CODE_REF
> @@ -697,7 +697,7 @@ match_accessibility (struct type *type, int index, enum accessibility acc)
>  }
>  
>  static void
> -cplus_describe_child (struct varobj *parent, int index,
> +cplus_describe_child (const struct varobj *parent, int index,
>  		      char **cname, struct value **cvalue, struct type **ctype,
>  		      char **cfull_expression)
>  {
> @@ -706,7 +706,7 @@ cplus_describe_child (struct varobj *parent, int index,
>    int was_ptr;
>    int lookup_actual_type = 0;
>    char *parent_expression = NULL;
> -  struct varobj *var;
> +  const struct varobj *var;
>    struct value_print_options opts;
>  
>    if (cname)
> @@ -898,7 +898,7 @@ cplus_describe_child (struct varobj *parent, int index,
>  }
>  
>  static char *
> -cplus_name_of_child (struct varobj *parent, int index)
> +cplus_name_of_child (const struct varobj *parent, int index)
>  {
>    char *name = NULL;
>  
> @@ -917,7 +917,7 @@ cplus_path_expr_of_child (const struct varobj *child)
>  }
>  
>  static struct value *
> -cplus_value_of_child (struct varobj *parent, int index)
> +cplus_value_of_child (const struct varobj *parent, int index)
>  {
>    struct value *value = NULL;
>  
> @@ -926,7 +926,7 @@ cplus_value_of_child (struct varobj *parent, int index)
>  }
>  
>  static struct type *
> -cplus_type_of_child (struct varobj *parent, int index)
> +cplus_type_of_child (const struct varobj *parent, int index)
>  {
>    struct type *type = NULL;
>  
> diff --git a/gdb/jv-varobj.c b/gdb/jv-varobj.c
> index dbd92a6..69e88fb 100644
> --- a/gdb/jv-varobj.c
> +++ b/gdb/jv-varobj.c
> @@ -47,7 +47,7 @@ java_name_of_variable (const struct varobj *parent)
>  }
>  
>  static char *
> -java_name_of_child (struct varobj *parent, int index)
> +java_name_of_child (const struct varobj *parent, int index)
>  {
>    char *name, *p;
>  
> @@ -72,13 +72,13 @@ java_path_expr_of_child (const struct varobj *child)
>  }
>  
>  static struct value *
> -java_value_of_child (struct varobj *parent, int index)
> +java_value_of_child (const struct varobj *parent, int index)
>  {
>    return cplus_varobj_ops.value_of_child (parent, index);
>  }
>  
>  static struct type *
> -java_type_of_child (struct varobj *parent, int index)
> +java_type_of_child (const struct varobj *parent, int index)
>  {
>    return cplus_varobj_ops.type_of_child (parent, index);
>  }
> diff --git a/gdb/varobj.c b/gdb/varobj.c
> index 268ba3c..43ea96f 100644
> --- a/gdb/varobj.c
> +++ b/gdb/varobj.c
> @@ -201,7 +201,7 @@ static char *name_of_child (struct varobj *, int);
>  
>  static struct value *value_of_root (struct varobj **var_handle, int *);
>  
> -static struct value *value_of_child (struct varobj *parent, int index);
> +static struct value *value_of_child (const struct varobj *parent, int index);
>  
>  static char *my_value_of_variable (struct varobj *var,
>  				   enum varobj_display_formats format);
> @@ -1019,10 +1019,10 @@ varobj_default_is_path_expr_parent (const struct varobj *var)
>  
>  /* Return the path expression parent for VAR.  */
>  
> -struct varobj *
> -varobj_get_path_expr_parent (struct varobj *var)
> +const struct varobj *
> +varobj_get_path_expr_parent (const struct varobj *var)
>  {
> -  struct varobj *parent = var;
> +  const struct varobj *parent = var;
>  
>    while (!is_root_p (parent) && !is_path_expr_parent (parent))
>      parent = parent->parent;
> @@ -1033,16 +1033,17 @@ varobj_get_path_expr_parent (struct varobj *var)
>  /* Return a pointer to the full rooted expression of varobj VAR.
>     If it has not been computed yet, compute it.  */
>  char *
> -varobj_get_path_expr (struct varobj *var)
> +varobj_get_path_expr (const struct varobj *var)
>  {
>    if (var->path_expr == NULL)
>      {
>        /* For root varobjs, we initialize path_expr
>  	 when creating varobj, so here it should be
>  	 child varobj.  */
> +      struct varobj *mutable_var = (struct varobj *) var;
>        gdb_assert (!is_root_p (var));
>  
> -      var->path_expr = (*var->root->lang_ops->path_expr_of_child) (var);
> +      mutable_var->path_expr = (*var->root->lang_ops->path_expr_of_child) (var);
>      }
>  
>    return var->path_expr;
> @@ -1378,7 +1379,7 @@ install_new_value (struct varobj *var, struct value *value, int initial)
>       will be lazy, which means we've lost that old value.  */
>    if (need_to_fetch && value && value_lazy (value))
>      {
> -      struct varobj *parent = var->parent;
> +      const struct varobj *parent = var->parent;
>        int frozen = var->frozen;
>  
>        for (; !frozen && parent; parent = parent->parent)
> @@ -2483,7 +2484,7 @@ value_of_root (struct varobj **var_handle, int *type_changed)
>  
>  /* What is the ``struct value *'' for the INDEX'th child of PARENT?  */
>  static struct value *
> -value_of_child (struct varobj *parent, int index)
> +value_of_child (const struct varobj *parent, int index)
>  {
>    struct value *value;
>  
> diff --git a/gdb/varobj.h b/gdb/varobj.h
> index 30c31ef..bb4fbfa 100644
> --- a/gdb/varobj.h
> +++ b/gdb/varobj.h
> @@ -120,7 +120,7 @@ struct varobj
>    int num_children;
>  
>    /* If this object is a child, this points to its immediate parent.  */
> -  struct varobj *parent;
> +  const struct varobj *parent;
>  
>    /* Children of this object.  */
>    VEC (varobj_p) *children;
> @@ -175,7 +175,7 @@ struct lang_varobj_ops
>  
>    /* The name of the INDEX'th child of PARENT.  The returned value must be
>       freed by the caller.  */
> -  char *(*name_of_child) (struct varobj *parent, int index);
> +  char *(*name_of_child) (const struct varobj *parent, int index);
>  
>    /* Returns the rooted expression of CHILD, which is a variable
>       obtain that has some parent.  The returned value must be freed by the
> @@ -183,10 +183,10 @@ struct lang_varobj_ops
>    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);
> +  struct value *(*value_of_child) (const struct varobj *parent, int index);
>  
>    /* The type of the INDEX'th child of PARENT.  */
> -  struct type *(*type_of_child) (struct varobj *parent, int index);
> +  struct type *(*type_of_child) (const struct varobj *parent, int index);
>  
>    /* The current value of VAR.  The returned value must be freed by the
>       caller.  */
> @@ -285,7 +285,7 @@ extern char *varobj_get_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 char *varobj_get_path_expr (const struct varobj *var);
>  
>  extern const struct language_defn *
>    varobj_get_language (const struct varobj *var);
> @@ -329,7 +329,8 @@ extern struct type *varobj_get_value_type (const struct varobj *var);
>  
>  extern int varobj_is_anonymous_child (const struct varobj *child);
>  
> -extern struct varobj *varobj_get_path_expr_parent (struct varobj *var);
> +extern const struct varobj *varobj_get_path_expr_parent (
> +    const struct varobj *var);

Hmm, to be consistent the rest of the file (varobj_get_language), I think this should be

extern const struct varobj *
  varobj_get_path_expr_parent (const struct varobj *var);

>  
>  extern char *varobj_value_get_print_value (struct value *value,
>  					   enum varobj_display_formats format,
>