From: Philip Herron <philip.herron@embecosm.com>
This is a simple walk_tree which acts on the monomorphized code by walking
the compiled translation unit of functions.
---
gcc/rust/checks/lints/rust-lint-unused-var.cc | 98 +++++++++++++++++++
gcc/rust/checks/lints/rust-lint-unused-var.h | 36 +++++++
2 files changed, 134 insertions(+)
create mode 100644 gcc/rust/checks/lints/rust-lint-unused-var.cc
create mode 100644 gcc/rust/checks/lints/rust-lint-unused-var.h
new file mode 100644
@@ -0,0 +1,98 @@
+// 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/>.
+
+#include "rust-lint-unused-var.h"
+#include "print-tree.h"
+
+namespace Rust {
+namespace Analysis {
+
+static void
+check_decl (tree *t)
+{
+ rust_assert (TREE_CODE (*t) == VAR_DECL || TREE_CODE (*t) == PARM_DECL
+ || TREE_CODE (*t) == CONST_DECL);
+
+ tree var_name = DECL_NAME (*t);
+ const char *var_name_ptr = IDENTIFIER_POINTER (var_name);
+ bool starts_with_under_score = strncmp (var_name_ptr, "_", 1) == 0;
+
+ bool is_constant = TREE_CODE (*t) == CONST_DECL;
+ // if (!is_constant)
+ // {
+ // debug_tree (*t);
+ // rust_debug ("found var-decl: used %s artifical %s underscore %s name
+ // %s",
+ // TREE_USED (*t) ? "true" : "false",
+ // DECL_ARTIFICIAL (*t) ? "true" : "false",
+ // starts_with_under_score ? "true" : "false", var_name_ptr);
+ // }
+
+ if (!TREE_USED (*t) && !DECL_ARTIFICIAL (*t) && !starts_with_under_score)
+ {
+ warning_at (DECL_SOURCE_LOCATION (*t),
+ is_constant ? OPT_Wunused_const_variable_
+ : OPT_Wunused_variable,
+ "unused name %qE", *t);
+ }
+}
+
+static tree
+unused_var_walk_fn (tree *t, int *walk_subtrees, void *closure)
+{
+ switch (TREE_CODE (*t))
+ {
+ case VAR_DECL:
+ case CONST_DECL:
+ check_decl (t);
+ break;
+
+ default:
+ break;
+ }
+ return NULL_TREE;
+}
+
+void
+UnusedVariables::Lint (Compile::Context &ctx)
+{
+ for (auto &fndecl : ctx.get_func_decls ())
+ {
+ for (tree p = DECL_ARGUMENTS (fndecl); p != NULL_TREE; p = DECL_CHAIN (p))
+ {
+ check_decl (&p);
+ }
+
+ walk_tree_without_duplicates (&DECL_SAVED_TREE (fndecl),
+ &unused_var_walk_fn, &ctx);
+ }
+
+ for (auto &var : ctx.get_var_decls ())
+ {
+ tree t = ctx.get_backend ()->var_expression (var, Location ());
+ check_decl (&t);
+ }
+
+ for (auto &const_decl : ctx.get_const_decls ())
+ {
+ check_decl (&const_decl);
+ }
+}
+
+} // namespace Analysis
+} // namespace Rust
new file mode 100644
@@ -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