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[patch] value_change_enclosing_type -> set_value_enclosing_type


Hi.

The comment for value_change_enclosing_type has this:

"The return value is a pointer to the new version of this value structure."

which is not true, the input value is modified as a side-effect.

Most callers essentially expect this side-effect. Sure they use the
result, but they always (except in one case) have just made a new value
so there's no need to create a new value object.

The exception is value_full_object.
It also has a similar comment:

"... if that is different from the enclosing type, create a new value ..."

This patch does two things:
- rename value_change_enclosing_type to set_value_enclosing_type,
  and make the result void, for clarity and consistency with other
  set_value_foo functions
- have value_full_object always return a new value if it needs to
  modify the input value

I will check it in in a few days if there are no objections.

Tested on amd64-linux, no regressions.

2010-11-06  Doug Evans  <dje@google.com>

	* value.c (set_value_enclosing_type): Renamed from
	value_change_enclosing_type.  All callers updated.
	* value.h (set_value_enclosing_type): Update.
	* valops.c (value_full_object): Always return a copy if we need to
	make changes to the input value.

Index: valops.c
===================================================================
RCS file: /cvs/src/src/gdb/valops.c,v
retrieving revision 1.256
diff -u -p -r1.256 valops.c
--- valops.c	4 Nov 2010 20:26:23 -0000	1.256
+++ valops.c	6 Nov 2010 18:38:16 -0000
@@ -335,7 +335,7 @@ value_cast_pointers (struct type *type, 
   /* No superclass found, just change the pointer type.  */
   arg2 = value_copy (arg2);
   deprecated_set_value_type (arg2, type);
-  arg2 = value_change_enclosing_type (arg2, type);
+  set_value_enclosing_type (arg2, type);
   set_value_pointed_to_offset (arg2, 0);	/* pai: chk_val */
   return arg2;
 }
@@ -569,7 +569,7 @@ value_cast (struct type *type, struct va
 
       arg2 = value_copy (arg2);
       deprecated_set_value_type (arg2, type);
-      arg2 = value_change_enclosing_type (arg2, type);
+      set_value_enclosing_type (arg2, type);
       set_value_pointed_to_offset (arg2, 0);	/* pai: chk_val */
       return arg2;
     }
@@ -1139,11 +1139,9 @@ value_assign (struct value *toval, struc
     case lval_internalvar:
       set_internalvar (VALUE_INTERNALVAR (toval), fromval);
       val = value_copy (fromval);
-      val = value_change_enclosing_type (val, 
-					 value_enclosing_type (fromval));
+      set_value_enclosing_type (val, value_enclosing_type (fromval));
       set_value_embedded_offset (val, value_embedded_offset (fromval));
-      set_value_pointed_to_offset (val, 
-				   value_pointed_to_offset (fromval));
+      set_value_pointed_to_offset (val, value_pointed_to_offset (fromval));
       return val;
 
     case lval_internalvar_component:
@@ -1334,8 +1332,7 @@ value_assign (struct value *toval, struc
   memcpy (value_contents_raw (val), value_contents (fromval),
 	  TYPE_LENGTH (type));
   deprecated_set_value_type (val, type);
-  val = value_change_enclosing_type (val, 
-				     value_enclosing_type (fromval));
+  set_value_enclosing_type (val, value_enclosing_type (fromval));
   set_value_embedded_offset (val, value_embedded_offset (fromval));
   set_value_pointed_to_offset (val, value_pointed_to_offset (fromval));
 
@@ -1583,7 +1580,8 @@ value_addr (struct value *arg1)
 
   /* This may be a pointer to a base subobject; so remember the
      full derived object's type ...  */
-  arg2 = value_change_enclosing_type (arg2, lookup_pointer_type (value_enclosing_type (arg1)));
+  set_value_enclosing_type (arg2,
+			    lookup_pointer_type (value_enclosing_type (arg1)));
   /* ... and also the relative position of the subobject in the full
      object.  */
   set_value_pointed_to_offset (arg2, value_embedded_offset (arg1));
@@ -1644,7 +1642,7 @@ value_ind (struct value *arg1)
       /* Re-adjust type.  */
       deprecated_set_value_type (arg2, TYPE_TARGET_TYPE (base_type));
       /* Add embedding info.  */
-      arg2 = value_change_enclosing_type (arg2, enc_type);
+      set_value_enclosing_type (arg2, enc_type);
       set_value_embedded_offset (arg2, value_pointed_to_offset (arg1));
 
       /* We may be pointing to an object of some derived type.  */
@@ -3413,7 +3411,8 @@ value_full_object (struct value *argp, 
   /* pai: FIXME -- sounds iffy */
   if (full)
     {
-      argp = value_change_enclosing_type (argp, real_type);
+      argp = value_copy (argp);
+      set_value_enclosing_type (argp, real_type);
       return argp;
     }
 
Index: value.c
===================================================================
RCS file: /cvs/src/src/gdb/value.c,v
retrieving revision 1.114
diff -u -p -r1.114 value.c
--- value.c	3 Nov 2010 13:49:37 -0000	1.114
+++ value.c	6 Nov 2010 18:38:16 -0000
@@ -1933,21 +1933,20 @@ value_static_field (struct type *type, i
   return retval;
 }
 
-/* Change the enclosing type of a value object VAL to NEW_ENCL_TYPE.  
-   You have to be careful here, since the size of the data area for the value 
-   is set by the length of the enclosing type.  So if NEW_ENCL_TYPE is bigger 
-   than the old enclosing type, you have to allocate more space for the data.  
-   The return value is a pointer to the new version of this value structure. */
+/* Change the enclosing type of a value object VAL to NEW_ENCL_TYPE.
+   You have to be careful here, since the size of the data area for the value
+   is set by the length of the enclosing type.  So if NEW_ENCL_TYPE is bigger
+   than the old enclosing type, you have to allocate more space for the
+   data.  */
 
-struct value *
-value_change_enclosing_type (struct value *val, struct type *new_encl_type)
+void
+set_value_enclosing_type (struct value *val, struct type *new_encl_type)
 {
   if (TYPE_LENGTH (new_encl_type) > TYPE_LENGTH (value_enclosing_type (val))) 
     val->contents =
       (gdb_byte *) xrealloc (val->contents, TYPE_LENGTH (new_encl_type));
 
   val->enclosing_type = new_encl_type;
-  return val;
 }
 
 /* Given a value ARG1 (offset by OFFSET bytes)
Index: value.h
===================================================================
RCS file: /cvs/src/src/gdb/value.h,v
retrieving revision 1.163
diff -u -p -r1.163 value.h
--- value.h	3 Nov 2010 13:49:37 -0000	1.163
+++ value.h	6 Nov 2010 18:38:16 -0000
@@ -136,8 +136,9 @@ extern void deprecated_set_value_modifia
    normally.  */
 
 extern struct type *value_enclosing_type (struct value *);
-extern struct value *value_change_enclosing_type (struct value *val,
-						  struct type *new_type);
+extern void set_value_enclosing_type (struct value *val,
+				      struct type *new_type);
+
 extern int value_pointed_to_offset (struct value *value);
 extern void set_value_pointed_to_offset (struct value *value, int val);
 extern int value_embedded_offset (struct value *value);


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