gccrs: libproc_macro: Add Literal type

Add the Literal type matching rust ffi definitions.

libgrust/ChangeLog:

	* libproc_macro/proc_macro.h (PROC_MACRO_H): Add
	literal header include directive.
	* libproc_macro/literal.h: New file.

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

libgrust/libproc_macro/literal.h

@@ -0,0 +1,161 @@
+// 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 LITERAL_H
+#define LITERAL_H
+
+#include <cstdint>
+
+enum UnsignedTag
+{
+  UNSIGNED_8,
+  UNSIGNED_16,
+  UNSIGNED_32,
+  UNSIGNED_64,
+  UNSIGNED_128
+};
+
+struct Payload128
+{
+  std::uint64_t low;
+  std::uint64_t high;
+};
+
+union UnsignedPayload
+{
+  std::uint8_t unsigned8;
+  std::uint16_t unsigned16;
+  std::uint32_t unsigned32;
+  std::uint64_t unsigned64;
+  Payload128 unsigned128;
+};
+
+struct Unsigned
+{
+  UnsignedTag tag;
+  UnsignedPayload payload;
+};
+
+enum SignedTag
+{
+  SIGNED_8,
+  SIGNED_16,
+  SIGNED_32,
+  SIGNED_64,
+  SIGNED_128
+};
+
+union SignedPayload
+{
+  std::int8_t signed8;
+  std::int16_t signed16;
+  std::int32_t signed32;
+  std::int64_t signed64;
+};
+
+struct Signed
+{
+  SignedTag tag;
+  SignedPayload payload;
+};
+
+enum LiteralTag
+{
+  STRING,
+  BYTE_STRING,
+  CHAR,
+  UNSIGNED,
+  SIGNED,
+  USIZE,
+  ISIZE,
+  FLOAT32,
+  FLOAT64
+};
+
+struct StringPayload
+{
+  unsigned char *data;
+  std::uint64_t len;
+};
+
+struct ByteStringPayload
+{
+  std::uint8_t *data;
+  std::uint64_t size;
+};
+
+struct UnsignedSuffixPayload
+{
+  Unsigned value;
+  bool suffix;
+};
+
+struct SignedSuffixPayload
+{
+  Signed value;
+  bool suffix;
+};
+
+struct UsizePayload
+{
+  std::uint64_t value;
+  bool suffix;
+};
+
+struct IsizePayload
+{
+  std::int64_t value;
+  bool suffix;
+};
+
+struct Float32Payload
+{
+  float value;
+  bool suffix;
+};
+
+struct Float64Payload
+{
+  double value;
+  bool suffix;
+};
+
+union LiteralPayload
+{
+  StringPayload string_payload;
+  ByteStringPayload byte_string_payload;
+  std::uint32_t char_payload;
+  UnsignedSuffixPayload unsigned_payload;
+  SignedSuffixPayload signed_payload;
+  UsizePayload usize_payload;
+  IsizePayload isize_payload;
+  Float32Payload float32_payload;
+  Float64Payload float64_payload;
+};
+
+struct Literal
+{
+  LiteralTag tag;
+  LiteralPayload payload;
+};
+
+#endif /* ! LITERAL_H */

libgrust/libproc_macro/proc_macro.h

@@ -23,4 +23,6 @@
 #ifndef PROC_MACRO_H
 #define PROC_MACRO_H
 
+#include "literal.h"
+
 #endif /* ! PROC_MACRO_H */