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diff --git a/gcc/rust/expand/rust-macro-builtins-helpers.cc b/gcc/rust/expand/rust-macro-builtins-helpers.cc
new file mode 100644
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+++ b/gcc/rust/expand/rust-macro-builtins-helpers.cc
@@ -0,0 +1,284 @@
+// Copyright (C) 2020-2024 Free Software Foundation, Inc.
+
+// This file is part of GCC.
+
+// GCC 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.
+
+// GCC 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 GCC; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+#include "rust-macro-builtins-helpers.h"
+
+namespace Rust {
+
+std::string
+make_macro_path_str (BuiltinMacro kind)
+{
+  auto str = MacroBuiltin::builtins.lookup (kind);
+  rust_assert (str.has_value ());
+
+  return str.value ();
+}
+
+std::vector<std::unique_ptr<AST::MacroInvocation>>
+check_for_eager_invocations (
+  std::vector<std::unique_ptr<AST::Expr>> &expressions)
+{
+  std::vector<std::unique_ptr<AST::MacroInvocation>> pending;
+
+  for (auto &expr : expressions)
+    if (expr->get_ast_kind () == AST::Kind::MACRO_INVOCATION)
+      pending.emplace_back (std::unique_ptr<AST::MacroInvocation> (
+	static_cast<AST::MacroInvocation *> (expr->clone_expr ().release ())));
+
+  return pending;
+}
+
+//
+// Shorthand function for creating unique_ptr tokens
+//
+std::unique_ptr<AST::Token>
+make_token (const TokenPtr tok)
+{
+  return std::unique_ptr<AST::Token> (new AST::Token (tok));
+}
+
+std::unique_ptr<AST::Expr>
+make_string (location_t locus, std::string value)
+{
+  return std::unique_ptr<AST::Expr> (
+    new AST::LiteralExpr (value, AST::Literal::STRING,
+			  PrimitiveCoreType::CORETYPE_STR, {}, locus));
+}
+
+// TODO: Is this correct?
+AST::Fragment
+make_eager_builtin_invocation (
+  BuiltinMacro kind, location_t locus, AST::DelimTokenTree arguments,
+  std::vector<std::unique_ptr<AST::MacroInvocation>> &&pending_invocations)
+{
+  auto path_str = make_macro_path_str (kind);
+
+  std::unique_ptr<AST::Expr> node = AST::MacroInvocation::Builtin (
+    kind,
+    AST::MacroInvocData (AST::SimplePath (
+			   {AST::SimplePathSegment (path_str, locus)}),
+			 std::move (arguments)),
+    {}, locus, std::move (pending_invocations));
+
+  return AST::Fragment ({AST::SingleASTNode (std::move (node))},
+			arguments.to_token_stream ());
+}
+
+/* Match the end token of a macro given the start delimiter of the macro */
+TokenId
+macro_end_token (AST::DelimTokenTree &invoc_token_tree,
+		 Parser<MacroInvocLexer> &parser)
+{
+  auto last_token_id = TokenId::RIGHT_CURLY;
+  switch (invoc_token_tree.get_delim_type ())
+    {
+    case AST::DelimType::PARENS:
+      last_token_id = TokenId::RIGHT_PAREN;
+      rust_assert (parser.skip_token (LEFT_PAREN));
+      break;
+
+    case AST::DelimType::CURLY:
+      rust_assert (parser.skip_token (LEFT_CURLY));
+      break;
+
+    case AST::DelimType::SQUARE:
+      last_token_id = TokenId::RIGHT_SQUARE;
+      rust_assert (parser.skip_token (LEFT_SQUARE));
+      break;
+    }
+
+  return last_token_id;
+}
+
+// Expand and then extract a string literal from the macro
+std::unique_ptr<AST::LiteralExpr>
+try_extract_string_literal_from_fragment (const location_t &parent_locus,
+					  std::unique_ptr<AST::Expr> &node)
+{
+  auto maybe_lit = static_cast<AST::LiteralExpr *> (node.get ());
+  if (!node || !node->is_literal ()
+      || maybe_lit->get_lit_type () != AST::Literal::STRING)
+    {
+      rust_error_at (parent_locus, "argument must be a string literal");
+      if (node)
+	rust_inform (node->get_locus (), "expanded from here");
+      return nullptr;
+    }
+  return std::unique_ptr<AST::LiteralExpr> (
+    static_cast<AST::LiteralExpr *> (node->clone_expr ().release ()));
+}
+
+std::vector<std::unique_ptr<AST::Expr>>
+try_expand_many_expr (Parser<MacroInvocLexer> &parser,
+		      const TokenId last_token_id, MacroExpander *expander,
+		      bool &has_error)
+{
+  auto restrictions = Rust::ParseRestrictions ();
+  // stop parsing when encountered a braces/brackets
+  restrictions.expr_can_be_null = true;
+  // we can't use std::optional, so...
+  auto result = std::vector<std::unique_ptr<AST::Expr>> ();
+  auto empty_expr = std::vector<std::unique_ptr<AST::Expr>> ();
+
+  auto first_token = parser.peek_current_token ()->get_id ();
+  if (first_token == COMMA)
+    {
+      rust_error_at (parser.peek_current_token ()->get_locus (),
+		     "expected expression, found %<,%>");
+      has_error = true;
+      return empty_expr;
+    }
+
+  while (parser.peek_current_token ()->get_id () != last_token_id
+	 && parser.peek_current_token ()->get_id () != END_OF_FILE)
+    {
+      auto expr = parser.parse_expr (AST::AttrVec (), restrictions);
+      // something must be so wrong that the expression could not be parsed
+      rust_assert (expr);
+      result.push_back (std::move (expr));
+
+      auto next_token = parser.peek_current_token ();
+      if (!parser.skip_token (COMMA) && next_token->get_id () != last_token_id)
+	{
+	  rust_error_at (next_token->get_locus (), "expected token: %<,%>");
+	  // TODO: is this recoverable? to avoid crashing the parser in the next
+	  // fragment we have to exit early here
+	  has_error = true;
+	  return empty_expr;
+	}
+    }
+
+  return result;
+}
+
+// Parse a single string literal from the given delimited token tree,
+// and return the LiteralExpr for it. Allow for an optional trailing comma,
+// but otherwise enforce that these are the only tokens.
+// FIXME(Arthur): This function needs a rework - it should not emit errors, it
+// should probably be smaller
+std::unique_ptr<AST::Expr>
+parse_single_string_literal (BuiltinMacro kind,
+			     AST::DelimTokenTree &invoc_token_tree,
+			     location_t invoc_locus, MacroExpander *expander)
+{
+  MacroInvocLexer lex (invoc_token_tree.to_token_stream ());
+  Parser<MacroInvocLexer> parser (lex);
+
+  auto last_token_id = macro_end_token (invoc_token_tree, parser);
+
+  std::unique_ptr<AST::LiteralExpr> lit_expr = nullptr;
+  std::unique_ptr<AST::MacroInvocation> macro_invoc = nullptr;
+
+  if (parser.peek_current_token ()->get_id () == STRING_LITERAL)
+    {
+      lit_expr = parser.parse_literal_expr ();
+      parser.maybe_skip_token (COMMA);
+      if (parser.peek_current_token ()->get_id () != last_token_id)
+	{
+	  lit_expr = nullptr;
+	  rust_error_at (invoc_locus, "macro takes 1 argument");
+	}
+    }
+  else if (parser.peek_current_token ()->get_id () == last_token_id)
+    rust_error_at (invoc_locus, "macro takes 1 argument");
+  else
+    {
+      macro_invoc = parser.parse_macro_invocation (AST::AttrVec ());
+
+      parser.maybe_skip_token (COMMA);
+      if (parser.peek_current_token ()->get_id () != last_token_id)
+	{
+	  lit_expr = nullptr;
+	  rust_error_at (invoc_locus, "macro takes 1 argument");
+	}
+
+      if (macro_invoc != nullptr)
+	{
+	  auto path_str = make_macro_path_str (kind);
+
+	  auto pending_invocations
+	    = std::vector<std::unique_ptr<AST::MacroInvocation>> ();
+
+	  pending_invocations.push_back (std::move (macro_invoc));
+
+	  return AST::MacroInvocation::Builtin (
+	    kind,
+	    AST::MacroInvocData (AST::SimplePath ({AST::SimplePathSegment (
+				   path_str, invoc_locus)}),
+				 std::move (invoc_token_tree)),
+	    {}, invoc_locus, std::move (pending_invocations));
+	}
+      else
+	{
+	  rust_error_at (invoc_locus, "argument must be a string literal or a "
+				      "macro which expands to a string");
+	}
+    }
+
+  parser.skip_token (last_token_id);
+
+  return std::unique_ptr<AST::Expr> (std::move (lit_expr));
+}
+
+/* Treat PATH as a path relative to the source file currently being
+   compiled, and return the absolute path for it.  */
+std::string
+source_relative_path (std::string path, location_t locus)
+{
+  std::string compile_fname = LOCATION_FILE (locus);
+
+  auto dir_separator_pos = compile_fname.rfind (file_separator);
+
+  /* If there is no file_separator in the path, use current dir ('.').  */
+  std::string dirname;
+  if (dir_separator_pos == std::string::npos)
+    dirname = std::string (".") + file_separator;
+  else
+    dirname = compile_fname.substr (0, dir_separator_pos) + file_separator;
+
+  return dirname + path;
+}
+
+/* Read the full contents of the file FILENAME and return them in a vector.
+   FIXME: platform specific.  */
+tl::optional<std::vector<uint8_t>>
+load_file_bytes (location_t invoc_locus, const char *filename)
+{
+  RAIIFile file_wrap (filename);
+  if (file_wrap.get_raw () == nullptr)
+    {
+      rust_error_at (invoc_locus, "cannot open filename %s: %m", filename);
+      return tl::nullopt;
+    }
+
+  FILE *f = file_wrap.get_raw ();
+  fseek (f, 0L, SEEK_END);
+  long fsize = ftell (f);
+  fseek (f, 0L, SEEK_SET);
+
+  std::vector<uint8_t> buf (fsize);
+
+  if (fsize > 0 && fread (&buf[0], fsize, 1, f) != 1)
+    {
+      rust_error_at (invoc_locus, "error reading file %s: %m", filename);
+      return std::vector<uint8_t> ();
+    }
+
+  return buf;
+}
+} // namespace Rust
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