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binutils-gdb/gdb/varobj.h
Andrew Burgess 9a9a760829 Improve MI -var-info-path-expression for nested struct/union case. 
https://sourceware.org/ml/gdb-patches/2014-05/msg00383.html

The MI command -var-info-path-expression currently does not handle
non-anonymous structs / unions nested within other structs / unions,
it will skip parts of the expression.  Consider this example:

  ## START EXAMPLE ##
  $ cat ex.c
  #include <string.h>

  int
  main ()
  {
    struct s1
    {
      int a;
    };

    struct ss
    {
      struct s1 x;
    };

    struct ss an_ss;
    memset (&an_ss, 0, sizeof (an_ss));
    return 0;
  }
  $ gcc -g -o ex.x ex.c
  $ gdb ex.x
  (gdb) break 18
  Breakpoint 1 at 0x80483ba: file ex.c, line 18.
  (gdb) run
  Starting program: /home/user/ex.x

  Breakpoint 1, main () at ex.c:18
  18	  return 0;
  (gdb) interpreter-exec mi "-var-create an_ss * an_ss"
  (gdb) interpreter-exec mi "-var-list-children an_ss"
  ^done,numchild="1",children=[child={name="an_ss.x",exp="x",numchild="1",type="struct s1",thread-id="1"}],has_more="0"
  (gdb) interpreter-exec mi "-var-list-children an_ss.x"
  ^done,numchild="1",children=[child={name="an_ss.x.a",exp="a",numchild="0",type="int",thread-id="1"}],has_more="0"
  (gdb) interpreter-exec mi "-var-list-children an_ss.x.a"
  ^done,numchild="0",has_more="0"
  (gdb) interpreter-exec mi "-var-info-path-expression an_ss.x.a"
  ^done,path_expr="(an_ss).a"
  (gdb) print (an_ss).a
  There is no member named a.
  ## END EXAMPLE ##

Notice that the path expression returned is wrong, and as a result
the print command fails.

This patch adds a new method to the varobj_ops structure called
is_path_expr_parent, to allow language specific control over finding
the parent varobj, the current logic becomes the C/C++ version and is
extended to handle the nested cases.  No other language currently uses
this code, so all other languages just get a default method.

With this patch, the above example now finishes like this:

  ## START EXAMPLE ##
  $ gdb ex.x
  (gdb) break 18
  Breakpoint 1 at 0x80483ba: file ex.c, line 18.
  (gdb) run
  Starting program: /home/user/ex.x

  Breakpoint 1, main () at ex.c:18
  18	  return 0;
  (gdb) interpreter-exec mi "-var-list-children an_ss"
  ^done,numchild="1",children=[child={name="an_ss.x",exp="x",numchild="1",type="struct s1",thread-id="1"}],has_more="0"
  (gdb) interpreter-exec mi "-var-list-children an_ss.x"
  ^done,numchild="1",children=[child={name="an_ss.x.a",exp="a",numchild="0",type="int",thread-id="1"}],has_more="0"
  (gdb) interpreter-exec mi "-var-list-children an_ss.x.a"
  ^done,numchild="0",has_more="0"
  (gdb) interpreter-exec mi "-var-info-path-expression an_ss.x.a"
  ^done,path_expr="((an_ss).x).a"
  (gdb) print ((an_ss).x).a
  $1 = 0
  ## END EXAMPLE ##

Notice that the path expression is now correct, and the print is a
success.

gdb/ChangeLog:

	* ada-varobj.c (ada_varobj_ops): Fill in is_path_expr_parent
	field.
	* c-varobj.c (c_is_path_expr_parent): New function, moved core
	from varobj.c, with additional checks.
	(c_varobj_ops): Fill in is_path_expr_parent field.
	(cplus_varobj_ops): Fill in is_path_expr_parent field.
	* jv-varobj.c (java_varobj_ops): Fill in is_path_expr_parent
	field.
	* varobj.c (is_path_expr_parent): Call is_path_expr_parent varobj
	ops method.
	(varobj_default_is_path_expr_parent): New function.
	* varobj.h (lang_varobj_ops): Add is_path_expr_parent field.
	(varobj_default_is_path_expr_parent): Declare new function.

gdb/testsuite/ChangeLog:

	* gdb.mi/var-cmd.c (do_nested_struct_union_tests): New function
	setting up test structures.
	(main): Call new test function.
	* gdb.mi/mi2-var-child.exp: Create additional breakpoint in new
	test function, continue into test function and walk test
	structures.
2014-07-09 14:47:47 +01:00

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/* GDB variable objects API.
Copyright (C) 1999-2014 Free Software Foundation, Inc.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
#ifndef VAROBJ_H
#define VAROBJ_H 1
#include "symtab.h"
#include "gdbtypes.h"
#include "vec.h"
/* Enumeration for the format types */
enum varobj_display_formats
{
FORMAT_NATURAL, /* What gdb actually calls 'natural' */
FORMAT_BINARY, /* Binary display */
FORMAT_DECIMAL, /* Decimal display */
FORMAT_HEXADECIMAL, /* Hex display */
FORMAT_OCTAL /* Octal display */
};
enum varobj_type
{
USE_SPECIFIED_FRAME, /* Use the frame passed to varobj_create. */
USE_CURRENT_FRAME, /* Use the current frame. */
USE_SELECTED_FRAME /* Always reevaluate in selected frame. */
};
/* Enumerator describing if a variable object is in scope. */
enum varobj_scope_status
{
VAROBJ_IN_SCOPE = 0, /* Varobj is scope, value available. */
VAROBJ_NOT_IN_SCOPE = 1, /* Varobj is not in scope, value not
available, but varobj can become in
scope later. */
VAROBJ_INVALID = 2, /* Varobj no longer has any value, and never
will. */
};
/* String representations of gdb's format codes (defined in varobj.c). */
extern char *varobj_format_string[];
/* Struct thar describes a variable object instance. */
struct varobj;
typedef struct varobj *varobj_p;
DEF_VEC_P (varobj_p);
typedef struct varobj_update_result_t
{
struct varobj *varobj;
int type_changed;
int children_changed;
int changed;
enum varobj_scope_status status;
/* This variable is used internally by varobj_update to indicate if the
new value of varobj is already computed and installed, or has to
be yet installed. Don't use this outside varobj.c. */
int value_installed;
/* This will be non-NULL when new children were added to the varobj.
It lists the new children (which must necessarily come at the end
of the child list) added during an update. The caller is
responsible for freeing this vector. */
VEC (varobj_p) *new;
} varobj_update_result;
DEF_VEC_O (varobj_update_result);
struct varobj_root;
struct varobj_dynamic;
/* Every variable in the system has a structure of this type defined
for it. This structure holds all information necessary to manipulate
a particular object variable. Members which must be freed are noted. */
struct varobj
{
/* Alloc'd name of the variable for this object. If this variable is a
child, then this name will be the child's source name.
(bar, not foo.bar). */
/* NOTE: This is the "expression". */
char *name;
/* Alloc'd expression for this child. Can be used to create a
root variable corresponding to this child. */
char *path_expr;
/* The alloc'd name for this variable's object. This is here for
convenience when constructing this object's children. */
char *obj_name;
/* Index of this variable in its parent or -1. */
int index;
/* The type of this variable. This can be NULL
for artifial variable objects -- currently, the "accessibility"
variable objects in C++. */
struct type *type;
/* The value of this expression or subexpression. A NULL value
indicates there was an error getting this value.
Invariant: if varobj_value_is_changeable_p (this) is non-zero,
the value is either NULL, or not lazy. */
struct value *value;
/* The number of (immediate) children this variable has. */
int num_children;
/* If this object is a child, this points to its immediate parent. */
struct varobj *parent;
/* Children of this object. */
VEC (varobj_p) *children;
/* Description of the root variable. Points to root variable for
children. */
struct varobj_root *root;
/* The format of the output for this object. */
enum varobj_display_formats format;
/* Was this variable updated via a varobj_set_value operation. */
int updated;
/* Last print value. */
char *print_value;
/* Is this variable frozen. Frozen variables are never implicitly
updated by -var-update *
or -var-update <direct-or-indirect-parent>. */
int frozen;
/* Is the value of this variable intentionally not fetched? It is
not fetched if either the variable is frozen, or any parents is
frozen. */
int not_fetched;
/* Sub-range of children which the MI consumer has requested. If
FROM < 0 or TO < 0, means that all children have been
requested. */
int from;
int to;
/* Dynamic part of varobj. */
struct varobj_dynamic *dynamic;
};
/* Is the variable X one of our "fake" children? */
#define CPLUS_FAKE_CHILD(x) \
((x) != NULL && (x)->type == NULL && (x)->value == NULL)
/* The language specific vector */
struct lang_varobj_ops
{
/* The number of children of PARENT. */
int (*number_of_children) (struct varobj *parent);
/* The name (expression) of a root varobj. */
char *(*name_of_variable) (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);
/* The ``struct value *'' of the INDEX'th child of PARENT. */
struct value *(*value_of_child) (struct varobj *parent, int index);
/* The type of the INDEX'th child of PARENT. */
struct type *(*type_of_child) (struct varobj *parent, int index);
/* The current value of VAR. */
char *(*value_of_variable) (struct varobj *var,
enum varobj_display_formats format);
/* Return non-zero if changes in value of VAR must be detected and
reported by -var-update. Return zero if -var-update should never
report changes of such values. This makes sense for structures
(since the changes in children values will be reported separately),
or for artifical objects (like 'public' pseudo-field in C++).
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);
/* Return nonzero if the type of VAR has mutated.
VAR's value is still the varobj's previous value, while NEW_VALUE
is VAR's new value and NEW_TYPE is the var's new type. NEW_VALUE
may be NULL indicating that there is no value available (the varobj
may be out of scope, of may be the child of a null pointer, for
instance). NEW_TYPE, on the other hand, must never be NULL.
This function should also be able to assume that var's number of
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,
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);
};
extern const struct lang_varobj_ops c_varobj_ops;
extern const struct lang_varobj_ops cplus_varobj_ops;
extern const struct lang_varobj_ops java_varobj_ops;
extern const struct lang_varobj_ops ada_varobj_ops;
#define default_varobj_ops c_varobj_ops
/* API functions */
extern struct varobj *varobj_create (char *objname,
char *expression, CORE_ADDR frame,
enum varobj_type type);
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_expression (struct varobj *var);
extern int varobj_delete (struct varobj *var, char ***dellist,
int only_children);
extern enum varobj_display_formats varobj_set_display_format (
struct varobj *var,
enum varobj_display_formats format);
extern enum varobj_display_formats varobj_get_display_format (
struct varobj *var);
extern int varobj_get_thread_id (struct varobj *var);
extern void varobj_set_frozen (struct varobj *var, int frozen);
extern int varobj_get_frozen (struct varobj *var);
extern void varobj_get_child_range (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 int varobj_get_num_children (struct varobj *var);
/* Return the list of children of VAR. The returned vector should not
be modified in any way. FROM and TO are in/out parameters
indicating the range of children to return. If either *FROM or *TO
is less than zero on entry, then all children will be returned. On
return, *FROM and *TO will be updated to indicate the real range
that was returned. The resulting VEC will contain at least the
children from *FROM to just before *TO; it might contain more
children, depending on whether any more were available. */
extern VEC (varobj_p)* varobj_list_children (struct varobj *var,
int *from, int *to);
extern char *varobj_get_type (struct varobj *var);
extern struct type *varobj_get_gdb_type (struct varobj *var);
extern char *varobj_get_path_expr (struct varobj *var);
extern const struct language_defn *varobj_get_language (struct varobj *var);
extern int varobj_get_attributes (struct varobj *var);
extern char *varobj_get_formatted_value (struct varobj *var,
enum varobj_display_formats format);
extern char *varobj_get_value (struct varobj *var);
extern int varobj_set_value (struct varobj *var, char *expression);
extern void all_root_varobjs (void (*func) (struct varobj *var, void *data),
void *data);
extern VEC(varobj_update_result) *varobj_update (struct varobj **varp,
int explicit);
extern void varobj_invalidate (void);
extern int varobj_editable_p (struct varobj *var);
extern int varobj_floating_p (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_is_dynamic_p (struct varobj *var);
extern struct cleanup *varobj_ensure_python_env (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 struct type *varobj_get_value_type (struct varobj *var);
extern int varobj_is_anonymous_child (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);
extern void varobj_formatted_print_options (struct value_print_options *opts,
enum varobj_display_formats format);
extern void varobj_restrict_range (VEC (varobj_p) *children, int *from,
int *to);
extern int varobj_default_is_path_expr_parent (struct varobj *var);
#endif /* VAROBJ_H */
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