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sakupan102lucasly-ba
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Implement unused variable checker on HIR.
gcc/rust/ChangeLog: * Make-lang.in: New file. * lang.opt: Add new flag. * rust-session-manager.cc (Session::compile_crate): Execute new variable checker. * checks/lints/unused-var/rust-unused-var-checker.cc (UnusedVarChecker): Implement unused variable checker. * checks/lints/unused-var/rust-unused-var-checker.h (UnusedVarChecker): Implement unused variable checker. * checks/lints/unused-var/rust-unused-var-collector.cc (UnusedVarCollector): Implement unused variable collector. * checks/lints/unused-var/rust-unused-var-collector.h (UnusedVarCollector): Implement unused variable collector. * checks/lints/unused-var/rust-unused-var-context.cc (UnusedVarContext): Implement unused variable context. * checks/lints/unused-var/rust-unused-var-context.h (UnusedVarContext): Implement unused variable context. gcc/testsuite/ChangeLog: * rust/compile/static_item_0.rs: New test. * rust/compile/template_function_0.rs: New test. Signed-off-by: Lucas Ly Ba <lucas.ly-ba@outlook.com>
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‎gcc/rust/Make-lang.in‎

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@@ -200,6 +200,9 @@ GRS_OBJS = \
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rust/rust-const-checker.o \
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rust/rust-lint-marklive.o \
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rust/rust-lint-unused-var.o \
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rust/rust-unused-var-checker.o \
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rust/rust-unused-var-collector.o \
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rust/rust-unused-var-context.o \
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rust/rust-readonly-check.o \
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rust/rust-hir-type-check-path.o \
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rust/rust-unsafe-checker.o \
@@ -432,6 +435,7 @@ RUST_INCLUDES = -I $(srcdir)/rust \
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-I $(srcdir)/rust/typecheck \
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-I $(srcdir)/rust/checks/lints \
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-I $(srcdir)/rust/checks/errors \
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-I $(srcdir)/rust/checks/lints/unused-var \
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-I $(srcdir)/rust/checks/errors/privacy \
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-I $(srcdir)/rust/checks/errors/borrowck \
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-I $(srcdir)/rust/checks/errors/feature \
@@ -502,6 +506,11 @@ rust/%.o: rust/checks/lints/%.cc
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$(COMPILE) $(RUST_CXXFLAGS) $(RUST_INCLUDES) $<
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$(POSTCOMPILE)
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# build unused variable checking pass files in rust folder
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rust/%.o: rust/checks/lints/unused-var/%.cc
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$(COMPILE) $(RUST_CXXFLAGS) $(RUST_INCLUDES) $<
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$(POSTCOMPILE)
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# build rust/checks/errors files in rust folder
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rust/%.o: rust/checks/errors/%.cc
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$(COMPILE) $(RUST_CXXFLAGS) $(RUST_INCLUDES) $<

‎gcc/rust/checks/lints/unused-var/rust-unused-var-checker.cc‎

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// Copyright (C) 2025 Free Software Foundation, Inc.
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// This file is part of GCC.
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// GCC is free software; you can redistribute it and/or modify it under
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// the terms of the GNU General Public License as published by the Free
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// Software Foundation; either version 3, or (at your option) any later
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// version.
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// GCC is distributed in the hope that it will be useful, but WITHOUT ANY
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// WARRANTY; without even the implied warranty of MERCHANTABILITY or
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// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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// for more details.
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// You should have received a copy of the GNU General Public License
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// along with GCC; see the file COPYING3. If not see
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// <http://www.gnu.org/licenses/>.
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#include "rust-unused-var-checker.h"
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#include "rust-hir-item.h"
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#include "options.h"
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namespace Rust {
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namespace Analysis {
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UnusedVarChecker::UnusedVarChecker ()
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: nr_context (
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Resolver2_0::ImmutableNameResolutionContext::get ().resolver ()),
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mappings (Analysis::Mappings::get ()),
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unused_var_context (std::make_unique<UnusedVarContext> ())
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{}
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void
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UnusedVarChecker::go (HIR::Crate &crate)
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{
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UnusedVarCollector collector (*unused_var_context);
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collector.go (crate);
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for (auto &item : crate.get_items ())
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item->accept_vis (*this);
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}
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void
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UnusedVarChecker::visit (HIR::ConstantItem &item)
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{
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std::string var_name = item.get_identifier ().as_string ();
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bool starts_with_under_score = var_name.compare (0, 1, "_") == 0;
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auto id = item.get_mappings ().get_hirid ();
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if (!unused_var_context->is_variable_used (id) && !starts_with_under_score)
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rust_warning_at (item.get_locus (), OPT_Wunused_variable,
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"unused name '%s'",
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item.get_identifier ().as_string ().c_str ());
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}
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void
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UnusedVarChecker::visit (HIR::StaticItem &item)
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{
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std::string var_name = item.get_identifier ().as_string ();
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bool starts_with_under_score = var_name.compare (0, 1, "_") == 0;
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auto id = item.get_mappings ().get_hirid ();
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if (!unused_var_context->is_variable_used (id) && !starts_with_under_score)
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rust_warning_at (item.get_locus (), OPT_Wunused_variable,
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"unused name '%s'",
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item.get_identifier ().as_string ().c_str ());
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}
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void
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UnusedVarChecker::visit (HIR::TraitItemFunc &item)
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{
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// TODO: check trait item functions if they are not derived.
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}
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void
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UnusedVarChecker::visit (HIR::IdentifierPattern &pattern)
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{
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std::string var_name = pattern.get_identifier ().as_string ();
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bool starts_with_under_score = var_name.compare (0, 1, "_") == 0;
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auto id = pattern.get_mappings ().get_hirid ();
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if (!unused_var_context->is_variable_used (id) && var_name != "self"
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&& !starts_with_under_score)
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rust_warning_at (pattern.get_locus (), OPT_Wunused_variable,
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"unused name '%s'",
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pattern.get_identifier ().as_string ().c_str ());
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}
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} // namespace Analysis
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} // namespace Rust

‎gcc/rust/checks/lints/unused-var/rust-unused-var-checker.h‎

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// Copyright (C) 2025 Free Software Foundation, Inc.
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// This file is part of GCC.
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// GCC is free software; you can redistribute it and/or modify it under
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// the terms of the GNU General Public License as published by the Free
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// Software Foundation; either version 3, or (at your option) any later
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// version.
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// GCC is distributed in the hope that it will be useful, but WITHOUT ANY
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// WARRANTY; without even the implied warranty of MERCHANTABILITY or
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// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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// for more details.
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// You should have received a copy of the GNU General Public License
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// along with GCC; see the file COPYING3. If not see
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// <http://www.gnu.org/licenses/>.
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#include "rust-hir-item.h"
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#include "rust-hir-pattern.h"
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#include "rust-hir-visitor.h"
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#include "rust-immutable-name-resolution-context.h"
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#include "rust-unused-var-collector.h"
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namespace Rust {
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namespace Analysis {
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class UnusedVarChecker : public HIR::DefaultHIRVisitor
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{
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public:
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UnusedVarChecker ();
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void go (HIR::Crate &crate);
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private:
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const Resolver2_0::NameResolutionContext &nr_context;
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Analysis::Mappings &mappings;
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std::unique_ptr<UnusedVarContext> unused_var_context;
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using HIR::DefaultHIRVisitor::visit;
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virtual void visit (HIR::TraitItemFunc &decl) override;
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virtual void visit (HIR::ConstantItem &item) override;
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virtual void visit (HIR::StaticItem &item) override;
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virtual void visit (HIR::IdentifierPattern &identifier) override;
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};
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} // namespace Analysis
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} // namespace Rust

‎gcc/rust/checks/lints/unused-var/rust-unused-var-collector.cc‎

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// Copyright (C) 2025 Free Software Foundation, Inc.
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// This file is part of GCC.
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// GCC is free software; you can redistribute it and/or modify it under
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// the terms of the GNU General Public License as published by the Free
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// Software Foundation; either version 3, or (at your option) any later
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// version.
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// GCC is distributed in the hope that it will be useful, but WITHOUT ANY
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// WARRANTY; without even the implied warranty of MERCHANTABILITY or
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// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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// for more details.
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// You should have received a copy of the GNU General Public License
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// along with GCC; see the file COPYING3. If not see
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// <http://www.gnu.org/licenses/>.
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#include "rust-unused-var-collector.h"
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#include "rust-hir-full-decls.h"
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#include "rust-hir-item.h"
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#include "rust-hir-path.h"
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#include "rust-hir-pattern.h"
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#include "rust-immutable-name-resolution-context.h"
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namespace Rust {
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namespace Analysis {
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UnusedVarCollector::UnusedVarCollector (UnusedVarContext &context)
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: nr_context (
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Resolver2_0::ImmutableNameResolutionContext::get ().resolver ()),
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mappings (Analysis::Mappings::get ()), unused_var_context (context)
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{}
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void
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UnusedVarCollector::go (HIR::Crate &crate)
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{
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for (auto &item : crate.get_items ())
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item->accept_vis (*this);
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}
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void
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UnusedVarCollector::visit (HIR::ConstantItem &item)
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{
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unused_var_context.add_variable (item.get_mappings ().get_hirid ());
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walk (item);
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}
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void
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UnusedVarCollector::visit (HIR::StaticItem &item)
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{
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unused_var_context.add_variable (item.get_mappings ().get_hirid ());
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walk (item);
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}
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void
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UnusedVarCollector::visit (HIR::IdentifierPattern &pattern)
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{
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auto id = pattern.get_mappings ().get_hirid ();
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unused_var_context.add_variable (id);
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}
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void
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UnusedVarCollector::visit (HIR::PathInExpression &expr)
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{
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mark_path_used (expr);
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}
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void
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UnusedVarCollector::visit (HIR::QualifiedPathInExpression &expr)
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{
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mark_path_used (expr);
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}
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void
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UnusedVarCollector::visit (HIR::StructExprFieldIdentifier &ident)
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{
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mark_path_used (ident);
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}
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} // namespace Analysis
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} // namespace Rust

‎gcc/rust/checks/lints/unused-var/rust-unused-var-collector.h‎

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// Copyright (C) 2025 Free Software Foundation, Inc.
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// This file is part of GCC.
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// GCC is free software; you can redistribute it and/or modify it under
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// the terms of the GNU General Public License as published by the Free
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// Software Foundation; either version 3, or (at your option) any later
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// version.
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// GCC is distributed in the hope that it will be useful, but WITHOUT ANY
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// WARRANTY; without even the implied warranty of MERCHANTABILITY or
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// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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// for more details.
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// You should have received a copy of the GNU General Public License
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// along with GCC; see the file COPYING3. If not see
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// <http://www.gnu.org/licenses/>.
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#include "rust-hir-expr.h"
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#include "rust-hir-item.h"
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#include "rust-hir-path.h"
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#include "rust-hir-pattern.h"
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#include "rust-hir-visitor.h"
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#include "rust-mapping-common.h"
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#include "rust-name-resolution-context.h"
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#include "rust-unused-var-context.h"
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#include "rust-name-resolver.h"
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namespace Rust {
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namespace Analysis {
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class UnusedVarCollector : public HIR::DefaultHIRVisitor
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{
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public:
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UnusedVarCollector (UnusedVarContext &context);
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void go (HIR::Crate &crate);
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private:
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const Resolver2_0::NameResolutionContext &nr_context;
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Analysis::Mappings &mappings;
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UnusedVarContext &unused_var_context;
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using HIR::DefaultHIRVisitor::visit;
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virtual void visit (HIR::PathInExpression &expr) override;
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virtual void visit (HIR::StructExprFieldIdentifier &ident) override;
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virtual void visit (HIR::ConstantItem &item) override;
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virtual void visit (HIR::StaticItem &item) override;
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virtual void visit (HIR::IdentifierPattern &pattern) override;
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virtual void visit (HIR::QualifiedPathInExpression &expr) override;
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template <typename T> void mark_path_used (T &path_expr)
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{
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NodeId ast_node_id = path_expr.get_mappings ().get_nodeid ();
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NodeId def_id = nr_context.lookup (ast_node_id).value ();
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HirId hir_id = mappings.lookup_node_to_hir (def_id).value ();
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unused_var_context.mark_used (hir_id);
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}
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};
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} // namespace Analysis
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} // namespace Rust

‎gcc/rust/checks/lints/unused-var/rust-unused-var-context.cc‎

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// Copyright (C) 2025 Free Software Foundation, Inc.
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// This file is part of GCC.
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// GCC is free software; you can redistribute it and/or modify it under
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// the terms of the GNU General Public License as published by the Free
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// Software Foundation; either version 3, or (at your option) any later
8+
// version.
9+
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// GCC is distributed in the hope that it will be useful, but WITHOUT ANY
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// WARRANTY; without even the implied warranty of MERCHANTABILITY or
12+
// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13+
// for more details.
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// You should have received a copy of the GNU General Public License
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// along with GCC; see the file COPYING3. If not see
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// <http://www.gnu.org/licenses/>.
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#include "rust-unused-var-context.h"
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namespace Rust {
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namespace Analysis {
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void
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UnusedVarContext::add_variable (HirId id)
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{
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if (is_used.find (id) == is_used.end ())
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is_used.insert ({id, false});
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}
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void
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UnusedVarContext::mark_used (HirId id)
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{
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is_used[id] = true;
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}
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bool
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UnusedVarContext::is_variable_used (HirId id) const
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{
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auto it = is_used.find (id);
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return it != is_used.end () && it->second;
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}
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std::string
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UnusedVarContext::as_string () const
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{
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std::stringstream ss;
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ss << "UnusedVarContext: ";
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for (const auto &pair : is_used)
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{
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ss << "HirId: " << pair.first << " Used: " << (pair.second ? "Yes" : "No")
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<< "\n";
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}
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return ss.str ();
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}
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} // namespace Analysis
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} // namespace Rust

‎gcc/rust/checks/lints/unused-var/rust-unused-var-context.h‎

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// Copyright (C) 2025 Free Software Foundation, Inc.
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// This file is part of GCC.
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// GCC is free software; you can redistribute it and/or modify it under
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// the terms of the GNU General Public License as published by the Free
7+
// Software Foundation; either version 3, or (at your option) any later
8+
// version.
9+
10+
// GCC is distributed in the hope that it will be useful, but WITHOUT ANY
11+
// WARRANTY; without even the implied warranty of MERCHANTABILITY or
12+
// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13+
// for more details.
14+
15+
// You should have received a copy of the GNU General Public License
16+
// along with GCC; see the file COPYING3. If not see
17+
// <http://www.gnu.org/licenses/>.
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#include "rust-mapping-common.h"
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namespace Rust {
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namespace Analysis {
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class UnusedVarContext
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{
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public:
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void add_variable (HirId id);
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void mark_used (HirId id);
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bool is_variable_used (HirId id) const;
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std::string as_string () const;
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private:
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std::map<HirId, bool> is_used;
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};
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} // namespace Analysis
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} // namespace Rust

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