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implement readonly checker on HIR
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‎gcc/rust/Make-lang.in‎

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@@ -205,6 +205,7 @@ GRS_OBJS = \
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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-readonly-check.o \
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rust/rust-readonly-check2.o \
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rust/rust-hir-type-check-path.o \
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rust/rust-unsafe-checker.o \
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rust/rust-hir-pattern-analysis.o \

‎gcc/rust/checks/errors/rust-readonly-check2.cc‎

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// Copyright (C) 2020-2025 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-readonly-check2.h"
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#include "rust-hir-expr-abstract.h"
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#include "rust-hir-node.h"
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#include "rust-hir-path.h"
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#include "rust-hir-map.h"
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#include "rust-hir-pattern.h"
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#include "rust-mapping-common.h"
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#include "rust-system.h"
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namespace Rust {
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namespace HIR {
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static std::map<HirId, int> assignment_map = {};
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ReadonlyChecker::ReadonlyChecker ()
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: resolver (*Resolver::Resolver::get ()),
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mappings (Analysis::Mappings::get ()), in_mutable_context (false)
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{}
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void
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ReadonlyChecker::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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ReadonlyChecker::visit (AssignmentExpr &expr)
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{
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Expr &lhs = expr.get_lhs ();
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in_mutable_context = true;
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lhs.accept_vis (*this);
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in_mutable_context = false;
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}
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void
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ReadonlyChecker::visit (PathInExpression &expr)
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{
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if (!in_mutable_context)
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return;
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NodeId id = expr.get_mappings ().get_nodeid ();
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NodeId def_id;
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if (!resolver.lookup_resolved_name (id, &def_id))
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return;
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auto hir_id = mappings.lookup_node_to_hir (def_id);
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if (!hir_id)
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return;
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if (assignment_map.find (*hir_id) == assignment_map.end ())
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return;
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assignment_map[*hir_id]++;
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// Check if the local variable is mutable.
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auto maybe_pattern = mappings.lookup_hir_pattern (*hir_id);
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if (maybe_pattern
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&& maybe_pattern.value ()->get_pattern_type ()
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== HIR::Pattern::PatternType::IDENTIFIER)
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{
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auto ident_pattern
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= static_cast<HIR::IdentifierPattern *> (*maybe_pattern);
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if (!ident_pattern->is_mut () && assignment_map[*hir_id] > 1)
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rust_error_at (expr.get_locus (),
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"cannot assign to immutable variable");
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}
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// Check if the static variable is mutable.
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auto maybe_static_item = mappings.lookup_hir_item (*hir_id);
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if (maybe_static_item
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&& maybe_static_item.value ()->get_item_kind ()
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== HIR::Item::ItemKind::Static)
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{
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auto static_item = static_cast<HIR::StaticItem *> (*maybe_static_item);
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if (!static_item->is_mut () && assignment_map[*hir_id] > 1)
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rust_error_at (expr.get_locus (),
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"cannot assign to mutable static variable");
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}
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}
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// Check if the variables are initialized in the let statement.
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// If the pattern is a tuple, we need to check each element.
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void
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ReadonlyChecker::visit (LetStmt &stmt)
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{
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HIR::Pattern &pattern = stmt.get_pattern ();
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HirId pattern_id = pattern.get_mappings ().get_hirid ();
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assignment_map.insert ({pattern_id, 0});
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if (stmt.has_init_expr ())
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{
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assignment_map[pattern_id]++;
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}
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}
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void
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ReadonlyChecker::visit (FieldAccessExpr &expr)
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{
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if (in_mutable_context)
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{
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// TODO: Add check for field access
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}
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}
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void
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ReadonlyChecker::visit (TupleIndexExpr &expr)
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{
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if (in_mutable_context)
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{
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// TODO: Add check for tuple index
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}
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}
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void
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ReadonlyChecker::visit (ArrayIndexExpr &expr)
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{
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if (in_mutable_context)
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{
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// TODO: Add check for array index
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}
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}
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void
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ReadonlyChecker::visit (TupleExpr &expr)
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{
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if (in_mutable_context)
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{
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// TODO: Add check for tuple expression
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}
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}
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} // namespace HIR
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} // namespace Rust

‎gcc/rust/checks/errors/rust-readonly-check2.h‎

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// Copyright (C) 2020-2025 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-full-decls.h"
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#include "rust-hir-path.h"
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#include "rust-hir-visitor.h"
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#include "rust-name-resolver.h"
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namespace Rust {
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namespace HIR {
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class ReadonlyChecker : public DefaultHIRVisitor
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{
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public:
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ReadonlyChecker ();
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void go (HIR::Crate &crate);
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private:
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Resolver::Resolver &resolver;
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Analysis::Mappings &mappings;
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// TODO: Replace with a stacked context.
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bool in_mutable_context;
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void visit (AssignmentExpr &expr) override;
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void visit (PathInExpression &expr) override;
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void visit (FieldAccessExpr &expr) override;
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void visit (ArrayIndexExpr &expr) override;
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void visit (TupleExpr &expr) override;
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void visit (TupleIndexExpr &expr) override;
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void visit (LetStmt &stmt) override;
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};
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} // namespace HIR
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} // namespace Rust

‎gcc/rust/rust-session-manager.cc‎

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#include "rust-borrow-checker.h"
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#include "rust-ast-validation.h"
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#include "rust-tyty-variance-analysis.h"
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#include "rust-readonly-check2.h"
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#include "input.h"
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#include "selftest.h"
@@ -738,6 +739,7 @@ Session::compile_crate (const char *filename)
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Analysis::ScanDeadcode::Scan (hir);
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Analysis::UnusedVariables::Lint (ctx);
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Analysis::ReadonlyCheck::Lint (ctx);
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HIR::ReadonlyChecker ().go (hir);
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// metadata
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bool specified_emit_metadata

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