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+// Copyright (C) 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/>.
+
+#ifndef RUST_DESUGAR_FOR_LOOPS_H
+#define RUST_DESUGAR_FOR_LOOPS_H
+
+#include "rust-ast-builder.h"
+#include "rust-ast-visitor.h"
+#include "rust-expr.h"
+
+namespace Rust {
+namespace AST {
+
+// Desugar for-loops into a set of other AST nodes. The desugar is of the
+// following form:
+//
+// ```
+// for <pat> in <head> <body>
+// ```
+//
+// becomes:
+//
+// ```
+// {
+//     let result = match ::std::iter::IntoIterator::into_iter(<head>) {
+//         mut iter => {
+//             loop {
+//                 let mut __next;
+//                 match ::std::iter::Iterator::next(&mut iter) {
+//                     ::std::option::Option::Some(val) => __next = val,
+//                     ::std::option::Option::None => break
+//                 };
+//                 let <pat> = __next;
+//
+//                 <body>;
+//             }
+//         }
+//     };
+//     result
+// }
+// ```
+//
+// NOTE: In a perfect world, this would be an immutable visitor which would take
+// ownership of the AST node and return a new one, instead of mutating this one
+// in place. Nevertheless, this isn't Rust, and doing immutable visitors in C++
+// sucks, and the world isn't perfect, so we are impure and sad.
+//
+// NOTE: This class could eventually be removed in favor of
+// an HIR desugar. This would avoid mutating the AST and would be cleaner.
+// However, it requires multiple changes in the way we do typechecking and name
+// resolution, as this desugar creates new bindings. Because of this, these new
+// bindings need to be inserted into the name-resolution context outside of the
+// name resolution pass, which is difficult. Those bindings are needed because
+// of the way the typechecker is currently structured, where it will fetch name
+// resolution information in order to typecheck paths - which technically isn't
+// necessary.
+class DesugarForLoops : public DefaultASTVisitor
+{
+  using DefaultASTVisitor::visit;
+
+public:
+  DesugarForLoops ();
+  void go (AST::Crate &);
+
+private:
+  struct DesugarCtx
+  {
+    DesugarCtx (location_t loc) : builder (Builder (loc)), loc (loc) {}
+
+    Builder builder;
+    location_t loc;
+
+    MatchArm make_match_arm (std::unique_ptr<Pattern> &&pattern);
+    MatchCase make_break_arm ();
+    MatchCase make_continue_arm ();
+    std::unique_ptr<Stmt> statementify (std::unique_ptr<Expr> &&expr);
+
+    constexpr static const char *continue_pattern_id = "#val";
+    constexpr static const char *next_value_id = "#__next";
+    constexpr static const char *iter_id = "#iter";
+    constexpr static const char *result_id = "#result";
+  };
+
+  std::unique_ptr<Expr> desugar (AST::ForLoopExpr &expr);
+  void maybe_desugar_expr (std::unique_ptr<Expr> &expr);
+
+  void visit (AST::BlockExpr &) override;
+};
+
+} // namespace AST
+} // namespace Rust
+
+#endif // ! RUST_DESUGAR_FOR_LOOPS_H