Remove old unused code pass this was too generic

This now uses the TREE_USED fields on GCC tree's to track the usage of
VAR_DECLS, PARM_DECLS and CONST_DECLS. The code does a pass over the body
and parameters of functions as a lint pass.

Fixes #676

1 files changed, 36 insertions, 0 deletions

diff --git a/gcc/rust/lint/rust-lint-unused-var.h b/gcc/rust/lint/rust-lint-unused-var.h
new file mode 100644
index 0000000..6fabfef
--- /dev/null
+++ b/gcc/rust/lint/rust-lint-unused-var.h
@@ -0,0 +1,36 @@
+// Copyright (C) 2021-2022 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_LINT_UNUSED_VAR
+#define RUST_LINT_UNUSED_VAR
+
+#include "rust-compile-context.h"
+
+namespace Rust {
+namespace Analysis {
+
+class UnusedVariables
+{
+public:
+  static void Lint (Compile::Context &ctx);
+};
+
+} // namespace Analysis
+} // namespace Rust
+
+#endif // RUST_LINT_UNUSED_VAR