1 files changed, 26 insertions, 10 deletions

diff --git a/gdb/common/scoped_restore.h b/gdb/common/scoped_restore.h
index ae7a49f..e7dbca9 100644
--- a/gdb/common/scoped_restore.h
+++ b/gdb/common/scoped_restore.h
@@ -21,8 +21,23 @@
 #define SCOPED_RESTORE_H
 
 /* Base class for scoped_restore_tmpl.  */
-struct scoped_restore_base
+class scoped_restore_base
 {
+public:
+  /* This informs the (scoped_restore_tmpl<T>) dtor that you no longer
+     want the original value restored.  */
+  void release () const
+  { m_saved_var = NULL; }
+
+protected:
+  scoped_restore_base (void *saved_var)
+    : m_saved_var (saved_var)
+  {}
+
+  /* The type-erased saved variable.  This is here so that clients can
+     call release() on a "scoped_restore" local, which is a typedef to
+     a scoped_restore_base.  See below.  */
+  mutable void *m_saved_var;
 };
 
 /* A convenience typedef.  Users of make_scoped_restore declare the
@@ -40,7 +55,7 @@ class scoped_restore_tmpl : public scoped_restore_base
      of *VAR.  *VAR will be restored when this scoped_restore object
      is destroyed.  */
   scoped_restore_tmpl (T *var)
-    : m_saved_var (var),
+    : scoped_restore_base (var),
       m_saved_value (*var)
   {
   }
@@ -52,14 +67,14 @@ class scoped_restore_tmpl : public scoped_restore_base
      E.g.: T='base'; T2='derived'.  */
   template <typename T2>
   scoped_restore_tmpl (T *var, T2 value)
-    : m_saved_var (var),
+    : scoped_restore_base (var),
       m_saved_value (*var)
   {
     *var = value;
   }
 
   scoped_restore_tmpl (const scoped_restore_tmpl<T> &other)
-    : m_saved_var (other.m_saved_var),
+    : scoped_restore_base {other.m_saved_var},
       m_saved_value (other.m_saved_value)
   {
     other.m_saved_var = NULL;
@@ -67,18 +82,19 @@ class scoped_restore_tmpl : public scoped_restore_base
 
   ~scoped_restore_tmpl ()
   {
-    if (m_saved_var != NULL)
-      *m_saved_var = m_saved_value;
+    if (saved_var () != NULL)
+      *saved_var () = m_saved_value;
   }
 
- private:
+private:
+  /* Return a pointer to the saved variable with its type
+     restored.  */
+  T *saved_var ()
+  { return static_cast<T *> (m_saved_var); }
 
   /* No need for this.  It is intentionally not defined anywhere.  */
   scoped_restore_tmpl &operator= (const scoped_restore_tmpl &);
 
-  /* The saved variable.  */
-  mutable T *m_saved_var;
-
   /* The saved value.  */
   const T m_saved_value;
 };