Delete gdb::unique_ptr/gdb::move

Now that we require C++11 and all uses of gdb::unique_ptr and
gdb::move are gone, let's remove their definitions...

With my lazy hat on, I repurposed the header for "generally useful
unique_ptr specializations", and left gdb::unique_xmalloc_ptr in
there.  Not sure whether we it'd be better move it out of the gdb
namespace or leave it be.  I left it because it's less work and avoids
disrupting yet-unmerged patches that use it.

gdb/ChangeLog:
2016-11-15  Pedro Alves  <palves@redhat.com>

	* common/common-defs.h: Update comment.
	* common/gdb_unique_ptr.h: Update header comment and copyright
	year.
	(gdb::unique_ptr, gdb::move): Delete.

2 files changed, 7 insertions, 348 deletions

diff --git a/gdb/common/common-defs.h b/gdb/common/common-defs.h
index 8fbb4bf..69254c8 100644
--- a/gdb/common/common-defs.h
+++ b/gdb/common/common-defs.h
@@ -87,7 +87,7 @@
 #define EXTERN_C_PUSH extern "C" {
 #define EXTERN_C_POP }
 
-/* Pull in gdb::unique_ptr and gdb::unique_xmalloc_ptr.  */
+/* Pull in gdb::unique_xmalloc_ptr.  */
 #include "common/gdb_unique_ptr.h"
 
 #endif /* COMMON_DEFS_H */
diff --git a/gdb/common/gdb_unique_ptr.h b/gdb/common/gdb_unique_ptr.h
index e881e38..86a0d2f 100644
--- a/gdb/common/gdb_unique_ptr.h
+++ b/gdb/common/gdb_unique_ptr.h
@@ -1,6 +1,6 @@
-/* gdb::unique_ptr, a simple std::unique_ptr replacement for C++03.
+/* std::unique_ptr specializations for GDB.
 
-   Copyright (C) 2007-2016 Free Software Foundation, Inc.
+   Copyright (C) 2016 Free Software Foundation, Inc.
 
    This file is part of GDB.
 
@@ -17,60 +17,6 @@
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
-/* gdb::unique_ptr defines a C++ owning smart pointer that exposes a
-   subset of the std::unique_ptr API.
-
-   In fact, when compiled with a C++11 compiler, gdb::unique_ptr
-   actually _is_ std::unique_ptr.  When compiled with a C++03 compiler
-   OTOH, it's an hand coded std::unique_ptr emulation that assumes
-   code is correct and doesn't try to be too smart.
-
-   This supports custom deleters, but not _stateful_ deleters, so you
-   can't use those in C++11 mode either.  Only the managed pointer is
-   stored in the smart pointer.  That could be changed; it simply
-   wasn't found necessary.
-
-   At the end of the file you'll find a gdb::unique_ptr partial
-   specialization that uses a custom (stateless) deleter:
-   gdb::unique_xmalloc_ptr.  That is used to manage pointers to
-   objects allocated with xmalloc.
-
-   The C++03 version was originally based on GCC 7.0's std::auto_ptr
-   and then heavily customized to behave more like C++11's
-   std::unique_ptr, but at this point, it no longer shares much at all
-   with the original file.  But, that's the history and the reason for
-   the copyright's starting year.
-
-   The C++03 version lets you shoot yourself in the foot, since
-   similarly to std::auto_ptr, the copy constructor and assignment
-   operators actually move.  Also, in the name of simplicity, no
-   effort is spent on using SFINAE to prevent invalid conversions,
-   etc.  This is not really a problem, because the goal here is to
-   allow code that would be correct using std::unique_ptr to be
-   equally correct in C++03 mode, and, just as efficient.  If client
-   code compiles correctly with a C++11 (or newer) compiler, we know
-   we're not doing anything invalid by mistake.
-
-   Usage notes:
-
-   - Putting gdb::unique_ptr in standard containers is not supported,
-     since C++03 containers are not move-aware (and our emulation
-     relies on copy actually moving).
-
-   - Since there's no nullptr in C++03, gdb::unique_ptr allows
-     implicit initialization and assignment from NULL instead.
-
-   - To check whether there's an associated managed object, all these
-     work as expected:
-
-      if (ptr)
-      if (!ptr)
-      if (ptr != NULL)
-      if (ptr == NULL)
-      if (NULL != ptr)
-      if (NULL == ptr)
-*/
-
 #ifndef GDB_UNIQUE_PTR_H
 #define GDB_UNIQUE_PTR_H 1
 
@@ -78,309 +24,22 @@
 
 namespace gdb
 {
-
-#if __cplusplus >= 201103
-
-/* In C++11 mode, all we need is import the standard
-   std::unique_ptr.  */
-template<typename T> using unique_ptr = std::unique_ptr<T>;
-
-/* Pull in move as well.  */
-using std::move;
-
-#else /* C++11 */
-
-/* Default destruction policy used by gdb::unique_ptr when no deleter
-   is specified.  Uses delete.  */
-
-template<typename T>
-struct default_delete
-{
-  void operator () (T *ptr) const { delete ptr; }
-};
-
-/* Specialization for arrays.  Uses delete[].  */
-
-template<typename T>
-struct default_delete<T[]>
-{
-  void operator () (T *ptr) const { delete [] ptr; }
-};
-
-namespace detail
-{
-/* Type used to support implicit construction from NULL:
-
-     gdb::unique_ptr<foo> func (....)
-     {
-        return NULL;
-     }
-
-   and assignment from NULL:
-
-     gdb::unique_ptr<foo> ptr (....);
-     ...
-     ptr = NULL;
-
-  It is intentionally not defined anywhere.  */
-struct nullptr_t;
-
-/* Base class of our unique_ptr emulation.  Contains code common to
-   both unique_ptr<T, D> and unique_ptr<T[], D>.  */
-
-template<typename T, typename D>
-class unique_ptr_base
-{
-public:
-  typedef T *pointer;
-  typedef T element_type;
-  typedef D deleter_type;
-
-  /* Takes ownership of a pointer.  P is a pointer to an object of
-     element_type type.  Defaults to NULL.  */
-  explicit unique_ptr_base (element_type *p = NULL) throw () : m_ptr (p) {}
-
-  /* The "move" constructor.  Really a copy constructor that actually
-     moves.  Even though std::unique_ptr is not copyable, our little
-     simpler emulation allows it, because:
-
-       - There are no rvalue references in C++03.  Our move emulation
-         instead relies on copy/assignment moving, like std::auto_ptr.
-       - RVO/NRVO requires an accessible copy constructor
-  */
-  unique_ptr_base (const unique_ptr_base &other) throw ()
-    : m_ptr (const_cast<unique_ptr_base &> (other).release ()) {}
-
-  /* Converting "move" constructor.  Really an lvalue ref converting
-     constructor that actually moves.  This allows constructs such as:
-
-      unique_ptr<Derived> func_returning_unique_ptr (.....);
-      ...
-      unique_ptr<Base> ptr = func_returning_unique_ptr (.....);
-  */
-  template<typename T1, typename D1>
-  unique_ptr_base (const unique_ptr_base<T1, D1> &other) throw ()
-    : m_ptr (const_cast<unique_ptr_base<T1, D1> &> (other).release ()) {}
-
-  /* The "move" assignment operator.  Really an lvalue ref copy
-     assignment operator that actually moves.  See comments above.  */
-  unique_ptr_base &operator= (const unique_ptr_base &other) throw ()
-  {
-    reset (const_cast<unique_ptr_base &> (other).release ());
-    return *this;
-  }
-
-  /* Converting "move" assignment.  Really an lvalue ref converting
-     copy assignment operator that moves.  See comments above.  */
-  template<typename T1, typename D1>
-  unique_ptr_base &operator= (const unique_ptr_base<T1, D1> &other) throw ()
-  {
-    reset (const_cast<unique_ptr_base<T1, D1> &> (other).release ());
-    return *this;
-  }
-
-  /* std::unique_ptr does not allow assignment, except from nullptr.
-     nullptr doesn't exist in C++03, so we allow assignment from NULL
-     instead [ptr = NULL;].
-  */
-  unique_ptr_base &operator= (detail::nullptr_t *) throw ()
-  {
-    reset ();
-    return *this;
-  }
-
-  ~unique_ptr_base () { call_deleter (); }
-
-  /* "explicit operator bool ()" emulation using the safe bool
-     idiom.  */
-private:
-  typedef void (unique_ptr_base::*explicit_operator_bool) () const;
-  void this_type_does_not_support_comparisons () const {}
-
-public:
-  operator explicit_operator_bool () const
-  {
-    return (m_ptr != NULL
-	    ? &unique_ptr_base::this_type_does_not_support_comparisons
-	    : 0);
-  }
-
-  element_type *get () const throw () { return m_ptr; }
-
-  element_type *release () throw ()
-  {
-    pointer tmp = m_ptr;
-    m_ptr = NULL;
-    return tmp;
-  }
-
-  void reset (element_type *p = NULL) throw ()
-  {
-    if (p != m_ptr)
-      {
-	call_deleter ();
-	m_ptr = p;
-      }
-  }
-
-private:
-
-  /* Call the deleter.  Note we assume the deleter is "stateless".  */
-  void call_deleter ()
-  {
-    D d;
-
-    d (m_ptr);
-  }
-
-  element_type *m_ptr;
-};
-
-} /* namespace detail */
-
-/* Macro used to create a unique_ptr_base "partial specialization" --
-   a subclass that uses a specific deleter.  Basically this re-defines
-   the necessary constructors.  This is necessary because C++03
-   doesn't support inheriting constructors with "using".  While at it,
-   we inherit the assignment operator.  TYPE is the name of the type
-   being defined.  Assumes that 'base_type' is a typedef of the
-   baseclass TYPE is inheriting from.  */
-#define DEFINE_GDB_UNIQUE_PTR(TYPE)						\
-public:									\
-  explicit TYPE (T *p = NULL) throw ()					\
-    : base_type (p) {}							\
-									\
-  TYPE (const TYPE &other) throw () : base_type (other) {}		\
-									\
-  TYPE (detail::nullptr_t *) throw () : base_type (NULL) {}		\
-									\
-  template<typename T1, typename D1>					\
-  TYPE (const detail::unique_ptr_base<T1, D1> &other) throw ()		\
-    : base_type (other) {}						\
-									\
-  using base_type::operator=;
-
-/* Define single-object gdb::unique_ptr.  */
-
-template <typename T, typename D = default_delete<T> >
-class unique_ptr : public detail::unique_ptr_base<T, D>
-{
-  typedef detail::unique_ptr_base<T, D> base_type;
-
-  DEFINE_GDB_UNIQUE_PTR (unique_ptr)
-
-public:
-  /* Dereferencing.  */
-  T &operator* () const throw () { return *this->get (); }
-  T *operator-> () const throw () { return this->get (); }
-};
-
-/* Define gdb::unique_ptr specialization for T[].  */
-
-template <typename T, typename D>
-class unique_ptr<T[], D> : public detail::unique_ptr_base<T, D>
-{
-  typedef detail::unique_ptr_base<T, D> base_type;
-
-  DEFINE_GDB_UNIQUE_PTR (unique_ptr)
-
-public:
-  /* Indexing operator.  */
-  T &operator[] (size_t i) const { return this->get ()[i]; }
-};
-
-/* Comparison operators.  */
-
-template <typename T, typename D,
-	  typename U, typename E>
-inline bool
-operator== (const detail::unique_ptr_base<T, D> &x,
-	    const detail::unique_ptr_base<U, E> &y)
-{ return x.get() == y.get(); }
-
-template <typename T, typename D,
-	  typename U, typename E>
-inline bool
-operator!= (const detail::unique_ptr_base<T, D> &x,
-	    const detail::unique_ptr_base<U, E> &y)
-{ return x.get() != y.get(); }
-
-template<typename T, typename D,
-	 typename U, typename E>
-inline bool
-operator< (const detail::unique_ptr_base<T, D> &x,
-	   const detail::unique_ptr_base<U, E> &y)
-{ return x.get() < y.get (); }
-
-template<typename T, typename D,
-	 typename U, typename E>
-inline bool
-operator<= (const detail::unique_ptr_base<T, D> &x,
-	    const detail::unique_ptr_base<U, E> &y)
-{ return !(y < x); }
-
-template<typename T, typename D,
-	 typename U, typename E>
-inline bool
-operator> (const detail::unique_ptr_base<T, D> &x,
-	   const detail::unique_ptr_base<U, E> &y)
-{ return y < x; }
-
-template<typename T, typename D,
-	 typename U, typename E>
-inline bool
-operator>= (const detail::unique_ptr_base<T, D> &x,
-	    const detail::unique_ptr_base<U, E> &y)
-{ return !(x < y); }
-
-/* std::move "emulation".  This is as simple as it can be -- no
-   attempt is made to emulate rvalue references.  Instead relies on
-   the fact that gdb::unique_ptr has move semantics like
-   std::auto_ptr.  I.e., copy/assignment actually moves.  */
-
-template<typename T, typename D>
-unique_ptr<T, D>
-move (unique_ptr<T, D> v)
-{
-  return v;
-}
-
-#endif /* C++11 */
-
-/* Define gdb::unique_xmalloc_ptr, a gdb::unique_ptr that manages
+/* Define gdb::unique_xmalloc_ptr, a std::unique_ptr that manages
    xmalloc'ed memory.  */
 
-/* The deleter for gdb::unique_xmalloc_ptr.  Uses xfree.  */
+/* The deleter for std::unique_xmalloc_ptr.  Uses xfree.  */
 template <typename T>
 struct xfree_deleter
 {
   void operator() (T *ptr) const { xfree (ptr); }
 };
 
-#if __cplusplus >= 201103
-
-/* In C++11, we just import the standard unique_ptr to our namespace
-   with a custom deleter.  */
+/* Import the standard unique_ptr to our namespace with a custom
+   deleter.  */
 
 template<typename T> using unique_xmalloc_ptr
   = std::unique_ptr<T, xfree_deleter<T>>;
 
-#else /* C++11 */
-
-/* In C++03, we don't have template aliases, so we need to define a
-   subclass instead, and re-define the constructors, because C++03
-   doesn't support inheriting constructors either.  */
-
-template <typename T>
-class unique_xmalloc_ptr : public unique_ptr<T, xfree_deleter<T> >
-{
-  typedef unique_ptr<T, xfree_deleter<T> > base_type;
-
-  DEFINE_GDB_UNIQUE_PTR (unique_xmalloc_ptr)
-};
-
-#endif /* C++11 */
-
 } /* namespace gdb */
 
 #endif /* GDB_UNIQUE_PTR_H */