1 files changed, 78 insertions, 0 deletions
diff --git a/gcc/rust/expand/rust-macro-builtins-offset-of.cc b/gcc/rust/expand/rust-macro-builtins-offset-of.cc
new file mode 100644
index 0000000..53efe74
--- /dev/null
+++ b/gcc/rust/expand/rust-macro-builtins-offset-of.cc
@@ -0,0 +1,78 @@
+// Copyright (C) 2020-2025 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 "optional.h"
+#include "rust-ast-fragment.h"
+#include "rust-ast.h"
+#include "rust-builtin-ast-nodes.h"
+#include "rust-diagnostics.h"
+#include "rust-macro-builtins-helpers.h"
+#include "rust-macro-builtins.h"
+#include "rust-macro-invoc-lexer.h"
+#include "rust-parse.h"
+
+namespace Rust {
+
+tl::optional<AST::Fragment>
+MacroBuiltin::offset_of_handler (location_t invoc_locus,
+				 AST::MacroInvocData &invoc,
+				 AST::InvocKind semicolon)
+{
+  MacroInvocLexer lex (invoc.get_delim_tok_tree ().to_token_stream ());
+  Parser<MacroInvocLexer> parser (lex);
+
+  auto last_token = macro_end_token (invoc.get_delim_tok_tree (), parser);
+
+  auto type = parser.parse_type ();
+
+  // if we don't see a type, there might be an eager macro expansion missing
+  // FIXME: handle that
+  if (!type)
+    {
+      rust_error_at (invoc_locus, "could not parse type argument for %qs",
+		     "offset_of");
+
+      // we skip so we can still parse the field arg and check if it is correct
+      while (parser.peek_current_token ()->get_id () != COMMA
+	     && parser.peek_current_token ()->get_id () != last_token)
+	parser.skip_token ();
+    }
+
+  parser.skip_token (COMMA);
+
+  auto field_tok = parser.parse_identifier_or_keyword_token ();
+  auto invalid_field = !field_tok || !field_tok->has_str ();
+
+  if (invalid_field)
+    rust_error_at (invoc_locus, "could not parse field argument for %qs",
+		   "offset_of");
+
+  if (!type || invalid_field)
+    return tl::nullopt;
+
+  auto field = Identifier (field_tok->get_str ());
+
+  // FIXME: Do we need to do anything to handle the optional comma at the end?
+  parser.maybe_skip_token (COMMA);
+
+  return AST::Fragment ({AST::SingleASTNode (std::make_unique<AST::OffsetOf> (
+			  std::move (type), field, invoc_locus))},
+			invoc.get_delim_tok_tree ().to_token_stream ());
+}
+
+} // namespace Rust