Move gdbsupport to the top level

This patch moves the gdbsupport directory to the top level.  This is
the next step in the ongoing project to move gdbserver to the top
level.

The bulk of this patch was created by "git mv gdb/gdbsupport gdbsupport".

This patch then adds a build system to gdbsupport and wires it into
the top level.  Then it changes gdb to use the top-level build.

gdbserver, on the other hand, is not yet changed.  It still does its
own build of gdbsupport.

ChangeLog
2020-01-14  Tom Tromey  <tom@tromey.com>

	* src-release.sh (GDB_SUPPORT_DIRS): Add gdbsupport.
	* MAINTAINERS: Add gdbsupport.
	* configure: Rebuild.
	* configure.ac (configdirs): Add gdbsupport.
	* gdbsupport: New directory, move from gdb/gdbsupport.
	* Makefile.def (host_modules, dependencies): Add gnulib.
	* Makefile.in: Rebuild.

gdb/ChangeLog
2020-01-14  Tom Tromey  <tom@tromey.com>

	* nat/x86-linux-dregs.c: Include configh.h.
	* nat/linux-ptrace.c: Include configh.h.
	* nat/linux-btrace.c: Include configh.h.
	* defs.h: Include config.h, bfd.h.
	* configure.ac: Don't source common.host.
	(CONFIG_OBS, CONFIG_SRCS): Remove gdbsupport files.
	* configure: Rebuild.
	* acinclude.m4: Update path.
	* Makefile.in (SUPPORT, LIBSUPPORT, INCSUPPORT): New variables.
	(CONFIG_SRC_SUBDIR): Remove gdbsupport.
	(INTERNAL_CFLAGS_BASE): Add INCSUPPORT.
	(CLIBS): Add LIBSUPPORT.
	(CDEPS): Likewise.
	(COMMON_SFILES): Remove gdbsupport files.
	(HFILES_NO_SRCDIR): Likewise.
	(stamp-version): Update path to create-version.sh.
	(ALLDEPFILES): Remove gdbsupport files.

gdb/gdbserver/ChangeLog
2020-01-14  Tom Tromey  <tom@tromey.com>

	* server.h: Include config.h.
	* gdbreplay.c: Include config.h.
	* configure: Rebuild.
	* configure.ac: Don't source common.host.
	* acinclude.m4: Update path.
	* Makefile.in (INCSUPPORT): New variable.
	(INCLUDE_CFLAGS): Add INCSUPPORT.
	(SFILES): Update paths.
	(version-generated.c): Update path to create-version.sh.
	(gdbsupport/%-ipa.o, gdbsupport/%.o): Update paths.

gdbsupport/ChangeLog
2020-01-14  Tom Tromey  <tom@tromey.com>

	* common-defs.h: Add GDBSERVER case.  Update includes.
	* acinclude.m4, aclocal.m4, config.in, configure, configure.ac,
	Makefile.am, Makefile.in, README: New files.
	* Moved from ../gdb/gdbsupport/

Change-Id: I07632e7798635c1bab389bf885971e584fb4bb78

1 files changed, 219 insertions, 0 deletions

diff --git a/gdbsupport/gdb_optional.h b/gdbsupport/gdb_optional.h
new file mode 100644
index 00000000000..02a87f6ee48
--- /dev/null
+++ b/gdbsupport/gdb_optional.h
@@ -0,0 +1,219 @@
+/* An optional object.
+
+   Copyright (C) 2017-2020 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   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 COMMON_GDB_OPTIONAL_H
+#define COMMON_GDB_OPTIONAL_H
+
+#include "gdbsupport/traits.h"
+
+namespace gdb
+{
+
+struct in_place_t
+{
+  explicit in_place_t () = default;
+};
+
+constexpr gdb::in_place_t in_place {};
+
+/* This class attempts to be a compatible subset of std::optional,
+   which is slated to be available in C++17.  This class optionally
+   holds an object of some type -- by default it is constructed not
+   holding an object, but later the object can be "emplaced".  This is
+   similar to using std::unique_ptr, but in-object allocation is
+   guaranteed.
+
+   Unlike std::optional, we currently only support copy/move
+   construction/assignment of an optional<T> from either exactly
+   optional<T> or T.  I.e., we don't support copy/move
+   construction/assignment from optional<U> or U, when U is a type
+   convertible to T.  Making that work depending on the definitions of
+   T and U is somewhat complicated, and currently the users of this
+   class don't need it.  */
+
+template<typename T>
+class optional
+{
+public:
+
+  constexpr optional ()
+    : m_dummy ()
+  {}
+
+  template<typename... Args>
+  constexpr optional (in_place_t, Args &&... args)
+    : m_item (std::forward<Args> (args)...),
+      m_instantiated (true)
+  {}
+
+  ~optional ()
+  { this->reset (); }
+
+  /* Copy and move constructors.  */
+
+  optional (const optional &other)
+  {
+    if (other.m_instantiated)
+      this->emplace (other.get ());
+  }
+
+  optional (optional &&other)
+    noexcept(std::is_nothrow_move_constructible<T> ())
+  {
+    if (other.m_instantiated)
+      this->emplace (std::move (other.get ()));
+  }
+
+  constexpr optional (const T &other)
+    : m_item (other),
+      m_instantiated (true)
+  {}
+
+  constexpr optional (T &&other)
+    noexcept (std::is_nothrow_move_constructible<T> ())
+    : m_item (std::move (other)),
+      m_instantiated (true)
+  {}
+
+  /* Assignment operators.  */
+
+  optional &
+  operator= (const optional &other)
+  {
+    if (m_instantiated && other.m_instantiated)
+      this->get () = other.get ();
+    else
+      {
+	if (other.m_instantiated)
+	  this->emplace (other.get ());
+	else
+	  this->reset ();
+      }
+
+    return *this;
+  }
+
+  optional &
+  operator= (optional &&other)
+    noexcept (And<std::is_nothrow_move_constructible<T>,
+	      std::is_nothrow_move_assignable<T>> ())
+  {
+    if (m_instantiated && other.m_instantiated)
+      this->get () = std::move (other.get ());
+    else
+      {
+	if (other.m_instantiated)
+	  this->emplace (std::move (other.get ()));
+	else
+	  this->reset ();
+      }
+    return *this;
+  }
+
+  optional &
+  operator= (const T &other)
+  {
+    if (m_instantiated)
+      this->get () = other;
+    else
+      this->emplace (other);
+    return *this;
+  }
+
+  optional &
+  operator= (T &&other)
+    noexcept (And<std::is_nothrow_move_constructible<T>,
+	      std::is_nothrow_move_assignable<T>> ())
+  {
+    if (m_instantiated)
+      this->get () = std::move (other);
+    else
+      this->emplace (std::move (other));
+    return *this;
+  }
+
+  template<typename... Args>
+  T &emplace (Args &&... args)
+  {
+    this->reset ();
+    new (&m_item) T (std::forward<Args>(args)...);
+    m_instantiated = true;
+    return this->get ();
+  }
+
+  /* Observers.  */
+  constexpr const T *operator-> () const
+  { return std::addressof (this->get ()); }
+
+  T *operator-> ()
+  { return std::addressof (this->get ()); }
+
+  constexpr const T &operator* () const &
+  { return this->get (); }
+
+  T &operator* () &
+  { return this->get (); }
+
+  T &&operator* () &&
+  { return std::move (this->get ()); }
+
+  constexpr const T &&operator* () const &&
+  { return std::move (this->get ()); }
+
+  constexpr explicit operator bool () const noexcept
+  { return m_instantiated; }
+
+  constexpr bool has_value () const noexcept
+  { return m_instantiated; }
+
+  /* 'reset' is a 'safe' operation with no precondition.  */
+  void reset () noexcept
+  {
+    if (m_instantiated)
+      this->destroy ();
+  }
+
+private:
+
+  /* Destroy the object.  */
+  void destroy ()
+  {
+    gdb_assert (m_instantiated);
+    m_instantiated = false;
+    m_item.~T ();
+  }
+
+  /* The get operations have m_instantiated as a precondition.  */
+  T &get () noexcept { return m_item; }
+  constexpr const T &get () const noexcept { return m_item; }
+
+  /* The object.  */
+  union
+  {
+    struct { } m_dummy;
+    T m_item;
+  };
+
+  /* True if the object was ever emplaced.  */
+  bool m_instantiated = false;
+};
+
+}
+
+#endif /* COMMON_GDB_OPTIONAL_H */