gccrs: proc_macro: Remode function indirection

There was no need to register a function when the value could be
registered directly.

gcc/rust/ChangeLog:

	* expand/rust-proc-macro.cc (available): Remove function.
	(load_macros_array): There was no need for an indirection here.

libgrust/ChangeLog:

	* libproc_macro/proc_macro.cc (not_available): Remove
	function.
	* libproc_macro/proc_macro.h (not_available): Remove
	function prototype.
	* libproc_macro/registration.h: Change symbol type.
	* libproc_macro/bridge.h: New file.

Signed-off-by: Pierre-Emmanuel Patry <pierre-emmanuel.patry@embecosm.com>

gcc/rust/expand/rust-proc-macro.cc

@@ -56,12 +56,6 @@ static_assert (
 	       ProcMacro::from_str_function_t>::value,
   "Registration callback signature not synced, check proc macro internals.");
 
-static bool
-available ()
-{
-  return true;
-}
-
 template <typename Symbol, typename Callback>
 bool
 register_callback (void *handle, Symbol, std::string symbol_name,
@@ -102,7 +96,7 @@ load_macros_array (std::string path)
 			  tokenstream_from_string))
     return nullptr;
   if (!REGISTER_CALLBACK (handle, __gccrs_proc_macro_is_available_fn,
-			  available))
+			  ProcMacro::BridgeState::Available))
     return nullptr;
 
   // FIXME: Add CrateStableId handling, right now all versions may be loaded,

libgrust/libproc_macro/bridge.h

@@ -0,0 +1,35 @@
+// Copyright (C) 2023 Free Software Foundation, Inc.
+//
+// This file is part of the GNU Proc Macro Library.  This library 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, or (at your option)
+// any later version.
+
+// This library 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.
+
+// Under Section 7 of GPL version 3, you are granted additional
+// permissions described in the GCC Runtime Library Exception, version
+// 3.1, as published by the Free Software Foundation.
+
+// You should have received a copy of the GNU General Public License and
+// a copy of the GCC Runtime Library Exception along with this program;
+// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
+// <http://www.gnu.org/licenses/>.
+#ifndef BRIDGE_H
+#define BRIDGE_H
+
+namespace ProcMacro {
+
+enum class BridgeState
+{
+  Available,
+  Unavailable,
+};
+
+}
+
+#endif /* ! BRIDGE_H */

libgrust/libproc_macro/proc_macro.cc

@@ -21,6 +21,7 @@
 // <http://www.gnu.org/licenses/>.
 
 #include "proc_macro.h"
+#include "bridge.h"
 
 namespace ProcMacro {
 
@@ -52,17 +53,12 @@ Procmacro::make_bang (const char *name, BangMacro macro)
 extern "C" bool
 bridge_is_available ()
 {
-  return __gccrs_proc_macro_is_available_fn ();
-}
-
-bool
-not_available ()
-{
-  return false;
+  return __gccrs_proc_macro_is_available_fn
+	 == ProcMacro::BridgeState::Available;
 }
 
 } // namespace ProcMacro
 
 ProcMacro::from_str_function_t __gccrs_proc_macro_from_str_fn = nullptr;
-ProcMacro::is_available_function_t __gccrs_proc_macro_is_available_fn
-  = ProcMacro::not_available;
+ProcMacro::is_available_t __gccrs_proc_macro_is_available_fn
+  = ProcMacro::BridgeState::Unavailable;

libgrust/libproc_macro/proc_macro.h

@@ -99,9 +99,6 @@ struct ProcmacroArray
   Procmacro *macros;
 };
 
-bool
-not_available ();
-
 extern "C" bool
 bridge_is_available ();
 

libgrust/libproc_macro/registration.h

@@ -25,16 +25,16 @@
 
 #include <string>
 #include "tokenstream.h"
+#include "bridge.h"
 
 namespace ProcMacro {
 
 using from_str_function_t = ProcMacro::TokenStream (*) (std::string &, bool &);
-using is_available_function_t = bool (*) ();
+using is_available_t = ProcMacro::BridgeState;
 
 } // namespace ProcMacro
 
 extern "C" ProcMacro::from_str_function_t __gccrs_proc_macro_from_str_fn;
-extern "C" ProcMacro::is_available_function_t
-  __gccrs_proc_macro_is_available_fn;
+extern "C" ProcMacro::is_available_t __gccrs_proc_macro_is_available_fn;
 
 #endif /* !REGISTRATION_H */