gccrs: Refactor HIR to reduce the amount of raw pointers

Attempt to use references and smart pointers whenever possible.

gcc/rust/ChangeLog:

	* backend/rust-compile-base.cc (HIRCompileBase::compile_function_body):
	Remove usage of get function to retrieve a raw pointer.
	* backend/rust-compile-base.h:
	Change API usage from raw pointer to a reference.
	* backend/rust-compile-block.cc (CompileBlock::compile): Likewise.
	(CompileBlock::visit): Likewise.
	(CompileConditionalBlocks::visit): Likewise.
	* backend/rust-compile-block.h: Likewise.
	* backend/rust-compile-expr.cc (CompileExpr::Compile): Likewise.
	(CompileExpr::visit): Likewise.
	(check_match_scrutinee): Likewise.
	(CompileExpr::array_value_expr): Likewise.
	(CompileExpr::array_copied_expr): Likewise.
	(CompileExpr::generate_closure_function): Likewise.
	(CompileExpr::generate_possible_fn_trait_call): Likewise.
	* backend/rust-compile-expr.h: Likewise.
	* backend/rust-compile-fnparam.cc (CompileFnParam::compile): Likewise.
	(CompileFnParam::visit): Likewise.
	* backend/rust-compile-fnparam.h: Likewise.
	* backend/rust-compile-implitem.cc (CompileTraitItem::visit): Likewise.
	* backend/rust-compile-intrinsic.cc (compile_fn_params): Likewise.
	* backend/rust-compile-item.cc (CompileItem::visit): Likewise.
	* backend/rust-compile-pattern.cc (CompilePatternCheckExpr::visit):
	Likewise.
	(compile_range_pattern_bound): Likewise.
	(CompilePatternBindings::visit): Likewise.
	(CompilePatternLet::visit): Likewise.
	* backend/rust-compile-pattern.h: Likewise.
	* backend/rust-compile-resolve-path.cc (ResolvePathRef::resolve):
	Likewise.
	(HIRCompileBase::query_compile): Likewise.
	* backend/rust-compile-stmt.cc (CompileStmt::visit): Likewise.
	* backend/rust-compile-struct-field-expr.cc (CompileStructExprField::Compile):
	Likewise.
	(CompileStructExprField::visit): Likewise.
	* backend/rust-compile-struct-field-expr.h: Likewise.
	* backend/rust-compile-type.cc (TyTyResolveCompile::visit): Likewise.
	* backend/rust-compile-var-decl.h: Likewise.
	* backend/rust-compile.cc: Likewise.
	* backend/rust-mangle-v0.cc (v0_inherent_or_trait_impl_path): Likewise.
	* checks/errors/borrowck/rust-bir-builder-expr-stmt.cc (ExprStmtBuilder::visit):
	Likewise.
	* checks/errors/borrowck/rust-bir-builder-lazyboolexpr.h: Likewise.
	* checks/errors/borrowck/rust-bir-builder-pattern.h: Likewise.
	* checks/errors/borrowck/rust-bir-builder-struct.h: Likewise.
	* checks/errors/borrowck/rust-bir-builder.h: Likewise.
	* checks/errors/borrowck/rust-function-collector.h: Likewise.
	* checks/errors/privacy/rust-privacy-reporter.cc (PrivacyReporter::check_type_privacy):
	Likewise.
	(PrivacyReporter::visit): Likewise.
	* checks/errors/privacy/rust-privacy-reporter.h: Likewise.
	* checks/errors/privacy/rust-reachability.cc (ReachabilityVisitor::visit):
	Likewise.
	* checks/errors/rust-const-checker.cc (ConstChecker::visit): Likewise.
	* checks/errors/rust-unsafe-checker.cc (UnsafeChecker::visit):
	Likewise.
	* checks/lints/rust-lint-marklive.cc (MarkLive::visit): Likewise.
	* checks/lints/rust-lint-marklive.h: Likewise.
	* hir/rust-hir-dump.cc (Dump::visit): Likewise.
	* hir/tree/rust-hir-expr.h: Likewise.
	* hir/tree/rust-hir-item.h: Likewise.
	* hir/tree/rust-hir-path.h: Likewise.
	* hir/tree/rust-hir-pattern.h: Likewise.
	* hir/tree/rust-hir-stmt.h: Likewise.
	* hir/tree/rust-hir-type.h: Likewise.
	* hir/tree/rust-hir.h: Likewise.
	* typecheck/rust-autoderef.cc: Likewise.
	* typecheck/rust-hir-dot-operator.cc (MethodResolver::select):
	Likewise.
	* typecheck/rust-hir-inherent-impl-overlap.h: Likewise.
	* typecheck/rust-hir-path-probe.cc (PathProbeType::process_impl_item_candidate):
	Likewise.
	(PathProbeImplTrait::process_trait_impl_items_for_candidates): Likewise.
	* typecheck/rust-hir-trait-resolve.cc (TraitResolver::resolve_trait):
	Likewise.
	(TraitItemReference::resolve_item): Likewise.
	* typecheck/rust-hir-type-check-base.cc: Likewise.
	* typecheck/rust-hir-type-check-base.h: Likewise.
	* typecheck/rust-hir-type-check-enumitem.cc (TypeCheckEnumItem::Resolve):
	Likewise.
	(TypeCheckEnumItem::visit): Likewise.
	* typecheck/rust-hir-type-check-enumitem.h: Likewise.
	* typecheck/rust-hir-type-check-expr.cc (TypeCheckExpr::Resolve):
	Likewise.
	(TypeCheckExpr::visit): Likewise.
	(TypeCheckExpr::resolve_fn_trait_call): Likewise.
	* typecheck/rust-hir-type-check-expr.h: Likewise.
	* typecheck/rust-hir-type-check-implitem.cc (TypeCheckTopLevelExternItem::Resolve):
	Likewise.
	(TypeCheckTopLevelExternItem::visit): Likewise.
	(TypeCheckImplItem::visit): Likewise.
	(TypeCheckImplItemWithTrait::visit): Likewise.
	* typecheck/rust-hir-type-check-implitem.h: Likewise.
	* typecheck/rust-hir-type-check-item.cc (TypeCheckItem::visit): Likewise.
	(TypeCheckItem::resolve_impl_item): Likewise.
	(TypeCheckItem::resolve_impl_block_substitutions): Likewise.
	(TypeCheckItem::resolve_impl_block_self): Likewise.
	* typecheck/rust-hir-type-check-path.cc (TypeCheckExpr::visit): Likewise.
	(TypeCheckExpr::resolve_segments): Likewise.
	* typecheck/rust-hir-type-check-pattern.cc (TypeCheckPattern::Resolve):
	Likewise.
	(TypeCheckPattern::visit): Likewise.
	(ClosureParamInfer::Resolve): Likewise.
	(ClosureParamInfer::visit): Likewise.
	* typecheck/rust-hir-type-check-pattern.h: Likewise.
	* typecheck/rust-hir-type-check-stmt.cc (TypeCheckStmt::Resolve):
	Likewise.
	(TypeCheckStmt::visit): Likewise.
	* typecheck/rust-hir-type-check-stmt.h: Likewise.
	* typecheck/rust-hir-type-check-struct-field.h: Likewise.
	* typecheck/rust-hir-type-check-struct.cc (TypeCheckStructExpr::TypeCheckStructExpr):
	Likewise.
	(TypeCheckStructExpr::Resolve): Likewise.
	(TypeCheckStructExpr::resolve): Likewise.
	(TypeCheckStructExpr::visit): Likewise.
	* typecheck/rust-hir-type-check-type.cc (TypeCheckResolveGenericArguments::resolve):
	Likewise.
	(TypeCheckType::Resolve): Likewise.
	(TypeCheckType::visit): Likewise.
	(TypeCheckType::resolve_root_path): Likewise.
	(TypeResolveGenericParam::Resolve): Likewise.
	(TypeResolveGenericParam::visit): Likewise.
	(ResolveWhereClauseItem::visit): Likewise.
	* typecheck/rust-hir-type-check-type.h: Likewise.
	* typecheck/rust-hir-type-check.cc (TraitItemReference::get_type_from_fn):
	Likewise.
	* typecheck/rust-hir-type-check.h: Likewise.
	* typecheck/rust-type-util.cc (query_type): Likewise.
	* typecheck/rust-typecheck-context.cc (TypeCheckContextItem::TypeCheckContextItem):
	Likewise.
	* typecheck/rust-tyty-bounds.cc (TypeBoundsProbe::scan): Likewise.
	(TypeCheckBase::get_predicate_from_bound): Likewise.
	* typecheck/rust-tyty-call.cc (TypeCheckCallExpr::visit): Likewise.
	(TypeCheckMethodCallExpr::go): Likewise.
	(TypeCheckMethodCallExpr::check): Likewise.
	* typecheck/rust-tyty-subst.cc: Likewise.
	* typecheck/rust-tyty.cc (BaseType::monomorphized_clone): Likewise.
	(VariantDef::VariantDef): Remove copy constructor.
	(VariantDef::operator=): Change to move operator.
	(VariantDef::get_discriminant): Replace return type to a reference
	instead of a reference to a unique pointer.
	(VariantDef::clone): Change to references.
	(VariantDef::monomorphized_clone): Likewise.
	(FnType::as_string): Likewise.
	(FnType::clone): Likewise.
	* typecheck/rust-tyty.h: Likewise.
	* util/rust-hir-map.cc (Mappings::insert_hir_impl_block): Likewise.
	* backend/rust-compile-asm.cc: Use a reference instead of the raw
	pointer value.
	* checks/errors/borrowck/rust-bir-builder-pattern.cc: Use references.
	* checks/errors/rust-hir-pattern-analysis.cc: Likewise.

Signed-off-by: Pierre-Emmanuel Patry <pierre-emmanuel.patry@embecosm.com>

7 files changed, 123 insertions, 125 deletions

diff --git a/gcc/rust/hir/tree/rust-hir-expr.h b/gcc/rust/hir/tree/rust-hir-expr.h
index 0155e25..692b9b4 100644
--- a/gcc/rust/hir/tree/rust-hir-expr.h
+++ b/gcc/rust/hir/tree/rust-hir-expr.h
@@ -209,7 +209,7 @@ protected:
 public:
   location_t get_locus () const override final { return locus; }
 
-  std::unique_ptr<Expr> &get_expr () { return main_or_left_expr; }
+  Expr &get_expr () { return *main_or_left_expr; }
 
   ExprType get_expression_type () const override final
   {
@@ -423,8 +423,8 @@ public:
   void visit_lhs (HIRFullVisitor &vis) { main_or_left_expr->accept_vis (vis); }
   void visit_rhs (HIRFullVisitor &vis) { right_expr->accept_vis (vis); }
 
-  std::unique_ptr<Expr> &get_lhs () { return main_or_left_expr; }
-  std::unique_ptr<Expr> &get_rhs () { return right_expr; }
+  Expr &get_lhs () { return *main_or_left_expr; }
+  Expr &get_rhs () { return *right_expr; }
 
   std::string get_operator_str () const;
 
@@ -497,8 +497,8 @@ public:
   void accept_vis (HIRFullVisitor &vis) override;
   void accept_vis (HIRExpressionVisitor &vis) override;
 
-  std::unique_ptr<Expr> &get_lhs () { return main_or_left_expr; }
-  std::unique_ptr<Expr> &get_rhs () { return right_expr; }
+  Expr &get_lhs () { return *main_or_left_expr; }
+  Expr &get_rhs () { return *right_expr; }
 
   ExprType get_kind () { return expr_type; }
 
@@ -571,8 +571,8 @@ public:
   void accept_vis (HIRFullVisitor &vis) override;
   void accept_vis (HIRExpressionVisitor &vis) override;
 
-  std::unique_ptr<Expr> &get_lhs () { return main_or_left_expr; }
-  std::unique_ptr<Expr> &get_rhs () { return right_expr; }
+  Expr &get_lhs () { return *main_or_left_expr; }
+  Expr &get_rhs () { return *right_expr; }
 
 protected:
   /* Use covariance to implement clone function as returning this object rather
@@ -633,12 +633,9 @@ public:
   void accept_vis (HIRExpressionVisitor &vis) override;
 
   // FIXME: isn't it the same as get_expr() from parent?
-  std::unique_ptr<Expr> &get_casted_expr () { return main_or_left_expr; }
+  Expr &get_casted_expr () { return *main_or_left_expr; }
 
-  std::unique_ptr<Type> &get_type_to_convert_to ()
-  {
-    return type_to_convert_to;
-  }
+  Type &get_type_to_convert_to () { return *type_to_convert_to; }
 
 protected:
   /* Use covariance to implement clone function as returning this object rather
@@ -700,8 +697,8 @@ public:
   void visit_lhs (HIRFullVisitor &vis) { main_or_left_expr->accept_vis (vis); }
   void visit_rhs (HIRFullVisitor &vis) { right_expr->accept_vis (vis); }
 
-  std::unique_ptr<Expr> &get_lhs () { return main_or_left_expr; }
-  std::unique_ptr<Expr> &get_rhs () { return right_expr; }
+  Expr &get_lhs () { return *main_or_left_expr; }
+  Expr &get_rhs () { return *right_expr; }
 
 protected:
   /* Use covariance to implement clone function as returning this object rather
@@ -770,9 +767,9 @@ public:
   void accept_vis (HIRFullVisitor &vis) override;
   void accept_vis (HIRExpressionVisitor &vis) override;
 
-  std::unique_ptr<Expr> &get_lhs () { return main_or_left_expr; }
+  Expr &get_lhs () { return *main_or_left_expr; }
 
-  std::unique_ptr<Expr> &get_rhs () { return right_expr; }
+  Expr &get_rhs () { return *right_expr; }
 
   void visit_lhs (HIRFullVisitor &vis) { main_or_left_expr->accept_vis (vis); }
   void visit_rhs (HIRFullVisitor &vis) { right_expr->accept_vis (vis); }
@@ -834,7 +831,7 @@ public:
   void accept_vis (HIRFullVisitor &vis) override;
   void accept_vis (HIRExpressionVisitor &vis) override;
 
-  std::unique_ptr<Expr> &get_expr_in_parens () { return expr_in_parens; }
+  Expr &get_expr_in_parens () { return *expr_in_parens; }
 
   ExprType get_expression_type () const override final
   {
@@ -986,9 +983,9 @@ public:
 
   void accept_vis (HIRFullVisitor &vis) override;
 
-  std::unique_ptr<Expr> &get_elem_to_copy () { return elem_to_copy; }
+  Expr &get_elem_to_copy () { return *elem_to_copy; }
 
-  std::unique_ptr<Expr> &get_num_copies_expr () { return num_copies; }
+  Expr &get_num_copies_expr () { return *num_copies; }
 
   ArrayElems::ArrayExprType get_array_expr_type () const override final
   {
@@ -1056,10 +1053,7 @@ public:
   void accept_vis (HIRFullVisitor &vis) override;
   void accept_vis (HIRExpressionVisitor &vis) override;
 
-  std::unique_ptr<ArrayElems> &get_internal_elements ()
-  {
-    return internal_elements;
-  };
+  ArrayElems &get_internal_elements () { return *internal_elements; };
 
   ExprType get_expression_type () const override final
   {
@@ -1125,8 +1119,8 @@ public:
   void accept_vis (HIRFullVisitor &vis) override;
   void accept_vis (HIRExpressionVisitor &vis) override;
 
-  std::unique_ptr<Expr> &get_array_expr () { return array_expr; }
-  std::unique_ptr<Expr> &get_index_expr () { return index_expr; }
+  Expr &get_array_expr () { return *array_expr; }
+  Expr &get_index_expr () { return *index_expr; }
 
   ExprType get_expression_type () const override final
   {
@@ -1279,7 +1273,7 @@ public:
   void accept_vis (HIRFullVisitor &vis) override;
   void accept_vis (HIRExpressionVisitor &vis) override;
 
-  std::unique_ptr<Expr> &get_tuple_expr () { return tuple_expr; }
+  Expr &get_tuple_expr () { return *tuple_expr; }
 
   ExprType get_expression_type () const override final
   {
@@ -1524,7 +1518,7 @@ protected:
 public:
   std::string as_string () const override;
 
-  std::unique_ptr<Expr> &get_value () { return value; }
+  Expr &get_value () { return *value; }
 };
 
 // Identifier and value variant of StructExprField HIR node
@@ -1797,7 +1791,8 @@ public:
   void accept_vis (HIRFullVisitor &vis) override;
   void accept_vis (HIRExpressionVisitor &vis) override;
 
-  std::unique_ptr<Expr> &get_fnexpr () { return function; }
+  bool has_fnexpr () const { return function != nullptr; }
+  Expr &get_fnexpr () { return *function; }
 
   size_t num_params () const { return params.size (); }
 
@@ -1884,7 +1879,7 @@ public:
   void accept_vis (HIRFullVisitor &vis) override;
   void accept_vis (HIRExpressionVisitor &vis) override;
 
-  std::unique_ptr<Expr> &get_receiver () { return receiver; }
+  Expr &get_receiver () { return *receiver; }
 
   PathExprSegment &get_method_name () { return method_name; };
   const PathExprSegment &get_method_name () const { return method_name; };
@@ -1968,7 +1963,7 @@ public:
   void accept_vis (HIRFullVisitor &vis) override;
   void accept_vis (HIRExpressionVisitor &vis) override;
 
-  std::unique_ptr<Expr> &get_receiver_expr () { return receiver; }
+  Expr &get_receiver_expr () { return *receiver; }
 
   Identifier get_field_name () const { return field; }
 
@@ -2058,9 +2053,9 @@ public:
   }
   std::vector<AST::Attribute> &get_outer_attrs () { return outer_attrs; }
 
-  std::unique_ptr<Pattern> &get_pattern () { return pattern; }
+  Pattern &get_pattern () { return *pattern; }
 
-  std::unique_ptr<Type> &get_type () { return type; }
+  Type &get_type () { return *type; }
 
   location_t get_locus () const { return locus; }
 };
@@ -2128,8 +2123,8 @@ public:
 
   bool has_return_type () const { return return_type != nullptr; }
 
-  std::unique_ptr<Type> &get_return_type () { return return_type; };
-  std::unique_ptr<Expr> &get_expr () { return expr; }
+  Type &get_return_type () { return *return_type; };
+  Expr &get_expr () { return *expr; }
 
   bool has_params () const { return !params.empty (); }
   std::vector<ClosureParam> &get_params () { return params; }
@@ -2243,7 +2238,7 @@ public:
 
   bool is_final_stmt (Stmt *stmt) { return statements.back ().get () == stmt; }
 
-  std::unique_ptr<Expr> &get_final_expr () { return expr; }
+  Expr &get_final_expr () { return *expr; }
 
   std::vector<std::unique_ptr<Stmt> > &get_statements () { return statements; }
 
@@ -2388,7 +2383,7 @@ public:
 
   Lifetime &get_label () { return label; }
 
-  std::unique_ptr<Expr> &get_expr () { return break_expr; }
+  Expr &get_expr () { return *break_expr; }
 
   ExprType get_expression_type () const override final
   {
@@ -2468,8 +2463,8 @@ public:
   void accept_vis (HIRFullVisitor &vis) override;
   void accept_vis (HIRExpressionVisitor &vis) override;
 
-  std::unique_ptr<Expr> &get_from_expr () { return from; }
-  std::unique_ptr<Expr> &get_to_expr () { return to; }
+  Expr &get_from_expr () { return *from; }
+  Expr &get_to_expr () { return *to; }
 
 protected:
   /* Use covariance to implement clone function as returning this object rather
@@ -2522,7 +2517,7 @@ public:
   void accept_vis (HIRFullVisitor &vis) override;
   void accept_vis (HIRExpressionVisitor &vis) override;
 
-  std::unique_ptr<Expr> &get_from_expr () { return from; }
+  Expr &get_from_expr () { return *from; }
 
 protected:
   /* Use covariance to implement clone function as returning this object rather
@@ -2576,7 +2571,7 @@ public:
   void accept_vis (HIRFullVisitor &vis) override;
   void accept_vis (HIRExpressionVisitor &vis) override;
 
-  std::unique_ptr<Expr> &get_to_expr () { return to; }
+  Expr &get_to_expr () { return *to; }
 
 protected:
   /* Use covariance to implement clone function as returning this object rather
@@ -2666,8 +2661,8 @@ public:
   void accept_vis (HIRFullVisitor &vis) override;
   void accept_vis (HIRExpressionVisitor &vis) override;
 
-  std::unique_ptr<Expr> &get_from_expr () { return from; }
-  std::unique_ptr<Expr> &get_to_expr () { return to; }
+  Expr &get_from_expr () { return *from; }
+  Expr &get_to_expr () { return *to; }
 
 protected:
   /* Use covariance to implement clone function as returning this object rather
@@ -2721,7 +2716,7 @@ public:
   void accept_vis (HIRFullVisitor &vis) override;
   void accept_vis (HIRExpressionVisitor &vis) override;
 
-  std::unique_ptr<Expr> &get_to_expr () { return to; };
+  Expr &get_to_expr () { return *to; };
 
 protected:
   /* Use covariance to implement clone function as returning this object rather
@@ -2790,7 +2785,7 @@ public:
   void accept_vis (HIRFullVisitor &vis) override;
   void accept_vis (HIRExpressionVisitor &vis) override;
 
-  std::unique_ptr<Expr> &get_expr () { return return_expr; }
+  Expr &get_expr () { return *return_expr; }
 
   ExprType get_expression_type () const override final
   {
@@ -2856,7 +2851,7 @@ public:
   void accept_vis (HIRFullVisitor &vis) override;
   void accept_vis (HIRExpressionVisitor &vis) override;
 
-  std::unique_ptr<BlockExpr> &get_block_expr () { return expr; }
+  BlockExpr &get_block_expr () { return *expr; }
 
   ExprType get_expression_type () const override final
   {
@@ -2932,7 +2927,7 @@ public:
 
   location_t get_locus () const override final { return locus; }
 
-  std::unique_ptr<HIR::BlockExpr> &get_loop_block () { return loop_block; };
+  HIR::BlockExpr &get_loop_block () { return *loop_block; };
 
   LoopLabel &get_loop_label () { return loop_label; }
 };
@@ -3010,7 +3005,7 @@ public:
   void accept_vis (HIRFullVisitor &vis) override;
   void accept_vis (HIRExpressionVisitor &vis) override;
 
-  std::unique_ptr<Expr> &get_predicate_expr () { return condition; }
+  Expr &get_predicate_expr () { return *condition; }
 
 protected:
   /* Use covariance to implement clone function as returning this object rather
@@ -3086,7 +3081,7 @@ public:
   void accept_vis (HIRFullVisitor &vis) override;
   void accept_vis (HIRExpressionVisitor &vis) override;
 
-  std::unique_ptr<Expr> &get_cond () { return condition; }
+  Expr &get_cond () { return *condition; }
   std::vector<std::unique_ptr<Pattern> > &get_patterns ()
   {
     return match_arm_patterns;
@@ -3166,8 +3161,8 @@ public:
   void vis_if_condition (HIRFullVisitor &vis) { condition->accept_vis (vis); }
   void vis_if_block (HIRFullVisitor &vis) { if_block->accept_vis (vis); }
 
-  std::unique_ptr<Expr> &get_if_condition () { return condition; }
-  std::unique_ptr<BlockExpr> &get_if_block () { return if_block; }
+  Expr &get_if_condition () { return *condition; }
+  BlockExpr &get_if_block () { return *if_block; }
 
   ExprType get_expression_type () const final override { return ExprType::If; }
 
@@ -3230,7 +3225,7 @@ public:
 
   void vis_else_block (HIRFullVisitor &vis) { else_block->accept_vis (vis); }
 
-  std::unique_ptr<ExprWithBlock> &get_else_block () { return else_block; }
+  ExprWithBlock &get_else_block () { return *else_block; }
 
 protected:
   /* Use covariance to implement clone function as returning this object rather
@@ -3330,7 +3325,7 @@ public:
     return match_arm_patterns;
   }
 
-  std::unique_ptr<Expr> &get_guard_expr () { return guard_expr; }
+  Expr &get_guard_expr () { return *guard_expr; }
 
   location_t get_locus () const { return locus; }
 };
@@ -3374,7 +3369,7 @@ public:
   Analysis::NodeMapping get_mappings () const { return mappings; }
 
   MatchArm &get_arm () { return arm; }
-  std::unique_ptr<Expr> &get_expr () { return expr; }
+  Expr &get_expr () { return *expr; }
 };
 
 // Match expression HIR node
@@ -3435,7 +3430,7 @@ public:
   void accept_vis (HIRFullVisitor &vis) override;
   void accept_vis (HIRExpressionVisitor &vis) override;
 
-  std::unique_ptr<Expr> &get_scrutinee_expr () { return branch_value; }
+  Expr &get_scrutinee_expr () { return *branch_value; }
   AST::AttrVec get_inner_attrs () const { return inner_attrs; }
   const std::vector<MatchCase> &get_match_cases () const { return match_arms; }
   std::vector<MatchCase> &get_match_cases () { return match_arms; }
@@ -3499,7 +3494,7 @@ public:
   void accept_vis (HIRFullVisitor &vis) override;
   void accept_vis (HIRExpressionVisitor &vis) override;
 
-  std::unique_ptr<Expr> &get_awaited_expr () { return awaited_expr; }
+  Expr &get_awaited_expr () { return *awaited_expr; }
 
   ExprType get_expression_type () const final override
   {
@@ -3556,7 +3551,7 @@ public:
   location_t get_locus () const override final { return locus; }
 
   bool get_has_move () const { return has_move; }
-  std::unique_ptr<BlockExpr> &get_block_expr () { return block_expr; }
+  BlockExpr &get_block_expr () { return *block_expr; }
 
   void accept_vis (HIRFullVisitor &vis) override;
   void accept_vis (HIRExpressionVisitor &vis) override;
@@ -3581,31 +3576,31 @@ class OperatorExprMeta
 public:
   OperatorExprMeta (HIR::CompoundAssignmentExpr &expr)
     : node_mappings (expr.get_mappings ()),
-      lvalue_mappings (expr.get_expr ()->get_mappings ()),
+      lvalue_mappings (expr.get_expr ().get_mappings ()),
       locus (expr.get_locus ())
   {}
 
   OperatorExprMeta (HIR::ArithmeticOrLogicalExpr &expr)
     : node_mappings (expr.get_mappings ()),
-      lvalue_mappings (expr.get_expr ()->get_mappings ()),
+      lvalue_mappings (expr.get_expr ().get_mappings ()),
       locus (expr.get_locus ())
   {}
 
   OperatorExprMeta (HIR::NegationExpr &expr)
     : node_mappings (expr.get_mappings ()),
-      lvalue_mappings (expr.get_expr ()->get_mappings ()),
+      lvalue_mappings (expr.get_expr ().get_mappings ()),
       locus (expr.get_locus ())
   {}
 
   OperatorExprMeta (HIR::DereferenceExpr &expr)
     : node_mappings (expr.get_mappings ()),
-      lvalue_mappings (expr.get_expr ()->get_mappings ()),
+      lvalue_mappings (expr.get_expr ().get_mappings ()),
       locus (expr.get_locus ())
   {}
 
   OperatorExprMeta (HIR::ArrayIndexExpr &expr)
     : node_mappings (expr.get_mappings ()),
-      lvalue_mappings (expr.get_array_expr ()->get_mappings ()),
+      lvalue_mappings (expr.get_array_expr ().get_mappings ()),
       locus (expr.get_locus ())
   {}
 
diff --git a/gcc/rust/hir/tree/rust-hir-item.h b/gcc/rust/hir/tree/rust-hir-item.h
index 1f53e85..3e98ad4 100644
--- a/gcc/rust/hir/tree/rust-hir-item.h
+++ b/gcc/rust/hir/tree/rust-hir-item.h
@@ -118,7 +118,7 @@ public:
 
   Identifier get_type_representation () const { return type_representation; }
 
-  std::unique_ptr<Type> &get_type () { return type; }
+  Type &get_type () { return *type; }
 
   Analysis::NodeMapping get_type_mappings () const
   {
@@ -277,7 +277,7 @@ public:
 
   std::vector<LifetimeParam> &get_for_lifetimes () { return for_lifetimes; }
 
-  std::unique_ptr<Type> &get_bound_type () { return bound_type; }
+  Type &get_bound_type () { return *bound_type; }
 
   std::vector<std::unique_ptr<TypeParamBound>> &get_type_param_bounds ()
   {
@@ -452,7 +452,7 @@ public:
 
   ImplicitSelfKind get_self_kind () const { return self_kind; }
 
-  std::unique_ptr<Type> &get_type () { return type; }
+  Type &get_type () { return *type; }
 
   Analysis::NodeMapping get_mappings () { return mappings; }
 
@@ -547,9 +547,11 @@ public:
 
   location_t get_locus () const { return locus; }
 
-  std::unique_ptr<Pattern> &get_param_name () { return param_name; }
+  Pattern &get_param_name () { return *param_name; }
 
-  std::unique_ptr<Type> &get_type () { return type; }
+  std::unique_ptr<Pattern> take_param_name () { return std::move (param_name); }
+
+  Type &get_type () { return *type; }
 
   const Analysis::NodeMapping &get_mappings () const { return mappings; }
 };
@@ -1056,7 +1058,7 @@ public:
   location_t get_locus () const override final { return locus; }
   ItemKind get_item_kind () const override { return ItemKind::UseDeclaration; }
 
-  std::unique_ptr<UseTree> &get_use_tree () { return use_tree; }
+  UseTree &get_use_tree () { return *use_tree; }
   void accept_vis (HIRFullVisitor &vis) override;
   void accept_vis (HIRStmtVisitor &vis) override;
   void accept_vis (HIRVisItemVisitor &vis) override;
@@ -1210,7 +1212,7 @@ public:
   }
 
   // TODO: is this better? Or is a "vis_block" better?
-  std::unique_ptr<BlockExpr> &get_definition () { return function_body; }
+  BlockExpr &get_definition () { return *function_body; }
 
   const FunctionQualifiers &get_qualifiers () const { return qualifiers; }
 
@@ -1222,7 +1224,7 @@ public:
   bool has_return_type () const { return return_type != nullptr; }
 
   // TODO: is this better? Or is a "vis_block" better?
-  std::unique_ptr<Type> &get_return_type () { return return_type; }
+  Type &get_return_type () { return *return_type; }
 
   bool is_method () const { return !self.is_error (); }
 
@@ -1337,7 +1339,7 @@ public:
 
   WhereClause &get_where_clause () { return where_clause; }
 
-  std::unique_ptr<Type> &get_type_aliased () { return existing_type; }
+  Type &get_type_aliased () { return *existing_type; }
 
   Identifier get_new_type_name () const { return new_type_name; }
 
@@ -1503,7 +1505,7 @@ public:
 
   Identifier get_field_name () const { return field_name; }
 
-  std::unique_ptr<Type> &get_field_type () { return field_type; }
+  Type &get_field_type () { return *field_type; }
 
   Analysis::NodeMapping get_mappings () const { return mappings; }
 
@@ -1640,7 +1642,7 @@ public:
   location_t get_locus () const { return locus; }
 
   AST::AttrVec &get_outer_attrs () { return outer_attrs; }
-  std::unique_ptr<HIR::Type> &get_field_type () { return field_type; }
+  HIR::Type &get_field_type () { return *field_type; }
 };
 
 // Rust tuple declared using struct keyword HIR node
@@ -1855,7 +1857,12 @@ public:
   void accept_vis (HIRFullVisitor &vis) override;
   void accept_vis (HIRStmtVisitor &vis) override;
 
-  std::unique_ptr<Expr> &get_discriminant_expression () { return expression; }
+  Expr &get_discriminant_expression () { return *expression; }
+
+  std::unique_ptr<Expr> take_discriminant_expression ()
+  {
+    return std::move (expression);
+  }
 
 protected:
   // Clone function implementation as (not pure) virtual method
@@ -2126,9 +2133,9 @@ public:
   void accept_vis (HIRImplVisitor &vis) override;
   void accept_vis (HIRVisItemVisitor &vis) override;
 
-  std::unique_ptr<Type> &get_type () { return type; }
+  Type &get_type () { return *type; }
 
-  std::unique_ptr<Expr> &get_expr () { return const_expr; }
+  Expr &get_expr () { return *const_expr; }
 
   Identifier get_identifier () const { return identifier; }
 
@@ -2222,9 +2229,9 @@ public:
 
   bool is_mut () const { return mut == Mutability::Mut; }
 
-  std::unique_ptr<Expr> &get_expr () { return expr; }
+  Expr &get_expr () { return *expr; }
 
-  std::unique_ptr<Type> &get_type () { return type; }
+  Type &get_type () { return *type; }
 
   ItemKind get_item_kind () const override { return ItemKind::Static; }
 
@@ -2324,7 +2331,7 @@ public:
     return generic_params;
   }
 
-  std::unique_ptr<Type> &get_return_type () { return return_type; }
+  Type &get_return_type () { return *return_type; }
 
   std::vector<FunctionParam> &get_function_params () { return function_params; }
 
@@ -2391,7 +2398,7 @@ public:
 
   bool has_block_defined () const { return block_expr != nullptr; }
 
-  std::unique_ptr<BlockExpr> &get_block_expr () { return block_expr; }
+  BlockExpr &get_block_expr () { return *block_expr; }
 
   const std::string trait_identifier () const override final
   {
@@ -2476,9 +2483,9 @@ public:
 
   bool has_expr () const { return expr != nullptr; }
 
-  std::unique_ptr<Type> &get_type () { return type; }
+  Type &get_type () { return *type; }
 
-  std::unique_ptr<Expr> &get_expr () { return expr; }
+  Expr &get_expr () { return *expr; }
 
   const std::string trait_identifier () const override final
   {
@@ -2828,7 +2835,9 @@ public:
 
   location_t get_locus () const override final { return locus; }
 
-  std::unique_ptr<Type> &get_type () { return impl_type; };
+  Type &get_type () { return *impl_type; };
+
+  bool has_type () { return impl_type == nullptr; }
 
   std::vector<std::unique_ptr<GenericParam>> &get_generic_params ()
   {
@@ -2837,7 +2846,7 @@ public:
 
   bool has_trait_ref () const { return trait_ref != nullptr; }
 
-  std::unique_ptr<TypePath> &get_trait_ref () { return trait_ref; }
+  TypePath &get_trait_ref () { return *trait_ref; }
 
   WhereClause &get_where_clause () { return where_clause; }
 
@@ -2976,7 +2985,7 @@ public:
 
   Mutability get_mut () { return mut; }
 
-  std::unique_ptr<Type> &get_item_type () { return item_type; }
+  Type &get_item_type () { return *item_type; }
 
   ExternKind get_extern_kind () override { return ExternKind::Static; }
 
@@ -3033,7 +3042,7 @@ public:
 
   Identifier get_param_name () const { return name; }
 
-  std::unique_ptr<Type> &get_type () { return param_type; }
+  Type &get_type () { return *param_type; }
 
   Analysis::NodeMapping get_mappings () const { return mappings; }
 };
@@ -3132,7 +3141,7 @@ public:
     return generic_params;
   }
 
-  std::unique_ptr<Type> &get_return_type () { return return_type; }
+  Type &get_return_type () { return *return_type; }
 
   std::vector<NamedFunctionParam> &get_function_params ()
   {
diff --git a/gcc/rust/hir/tree/rust-hir-path.h b/gcc/rust/hir/tree/rust-hir-path.h
index e406d53..1819783 100644
--- a/gcc/rust/hir/tree/rust-hir-path.h
+++ b/gcc/rust/hir/tree/rust-hir-path.h
@@ -107,8 +107,8 @@ public:
   Identifier &get_identifier () { return identifier; }
   const Identifier &get_identifier () const { return identifier; }
 
-  std::unique_ptr<Type> &get_type () { return type; }
-  const std::unique_ptr<Type> &get_type () const { return type; }
+  Type &get_type () { return *type; }
+  const Type &get_type () const { return *type; }
 
   location_t get_locus () const { return locus; }
 };
@@ -574,7 +574,7 @@ public:
   TypePathFunction (TypePathFunction const &other)
   {
     return_type = other.has_return_type ()
-		    ? other.get_return_type ()->clone_type ()
+		    ? other.get_return_type ().clone_type ()
 		    : nullptr;
 
     inputs.reserve (other.inputs.size ());
@@ -588,7 +588,7 @@ public:
   TypePathFunction &operator= (TypePathFunction const &other)
   {
     return_type = other.has_return_type ()
-		    ? other.get_return_type ()->clone_type ()
+		    ? other.get_return_type ().clone_type ()
 		    : nullptr;
 
     inputs.reserve (other.inputs.size ());
@@ -610,8 +610,8 @@ public:
   };
   std::vector<std::unique_ptr<Type> > &get_params () { return inputs; };
 
-  const std::unique_ptr<Type> &get_return_type () const { return return_type; };
-  std::unique_ptr<Type> &get_return_type () { return return_type; };
+  const Type &get_return_type () const { return *return_type; };
+  Type &get_return_type () { return *return_type; };
 };
 
 // Segment used in type path with a function argument
@@ -811,9 +811,9 @@ public:
 
   Analysis::NodeMapping get_mappings () const { return mappings; }
 
-  std::unique_ptr<Type> &get_type () { return type; }
+  Type &get_type () { return *type; }
 
-  std::unique_ptr<TypePath> &get_trait () { return trait; }
+  TypePath &get_trait () { return *trait; }
 
   bool trait_has_generic_args () const
   {
@@ -963,10 +963,7 @@ public:
 
   QualifiedPathType &get_path_type () { return path_type; }
 
-  std::unique_ptr<TypePathSegment> &get_associated_segment ()
-  {
-    return associated_segment;
-  }
+  TypePathSegment &get_associated_segment () { return *associated_segment; }
 
   std::vector<std::unique_ptr<TypePathSegment> > &get_segments ()
   {
diff --git a/gcc/rust/hir/tree/rust-hir-pattern.h b/gcc/rust/hir/tree/rust-hir-pattern.h
index e5d8371..df26a39 100644
--- a/gcc/rust/hir/tree/rust-hir-pattern.h
+++ b/gcc/rust/hir/tree/rust-hir-pattern.h
@@ -132,7 +132,7 @@ public:
 
   bool is_mut () const { return mut == Mutability::Mut; }
   bool get_is_ref () const { return is_ref; }
-  std::unique_ptr<Pattern> &get_to_bind () { return to_bind; }
+  Pattern &get_to_bind () { return *to_bind; }
 
   void accept_vis (HIRFullVisitor &vis) override;
   void accept_vis (HIRPatternVisitor &vis) override;
@@ -405,9 +405,9 @@ public:
     return PatternType::RANGE;
   }
 
-  std::unique_ptr<RangePatternBound> &get_lower_bound () { return lower; }
+  RangePatternBound &get_lower_bound () { return *lower; }
 
-  std::unique_ptr<RangePatternBound> &get_upper_bound () { return upper; }
+  RangePatternBound &get_upper_bound () { return *upper; }
 
 protected:
   /* Use covariance to implement clone function as returning this object rather
@@ -476,7 +476,7 @@ public:
     return PatternType::REFERENCE;
   }
 
-  std::unique_ptr<Pattern> &get_referenced_pattern () { return pattern; }
+  Pattern &get_referenced_pattern () { return *pattern; }
 
 protected:
   /* Use covariance to implement clone function as returning this object rather
@@ -572,7 +572,7 @@ public:
   void accept_vis (HIRFullVisitor &vis) override;
 
   TupleIndex get_index () { return index; }
-  std::unique_ptr<Pattern> &get_tuple_pattern () { return tuple_pattern; }
+  Pattern &get_tuple_pattern () { return *tuple_pattern; }
 
   ItemType get_item_type () const override final { return ItemType::TUPLE_PAT; }
 
@@ -630,7 +630,7 @@ public:
 
   Identifier get_identifier () const { return ident; }
 
-  std::unique_ptr<Pattern> &get_pattern () { return ident_pattern; }
+  Pattern &get_pattern () { return *ident_pattern; }
 
 protected:
   /* Use covariance to implement clone function as returning this object rather
@@ -1002,7 +1002,7 @@ public:
 
   PathInExpression &get_path () { return path; }
 
-  std::unique_ptr<TupleStructItems> &get_items () { return items; }
+  TupleStructItems &get_items () { return *items; }
 
   const Analysis::NodeMapping &get_mappings () const override final
   {
@@ -1221,8 +1221,8 @@ public:
     return PatternType::TUPLE;
   }
 
-  std::unique_ptr<TuplePatternItems> &get_items () { return items; }
-  const std::unique_ptr<TuplePatternItems> &get_items () const { return items; }
+  TuplePatternItems &get_items () { return *items; }
+  const TuplePatternItems &get_items () const { return *items; }
 
 protected:
   /* Use covariance to implement clone function as returning this object rather
diff --git a/gcc/rust/hir/tree/rust-hir-stmt.h b/gcc/rust/hir/tree/rust-hir-stmt.h
index e6e844f..7320bb6 100644
--- a/gcc/rust/hir/tree/rust-hir-stmt.h
+++ b/gcc/rust/hir/tree/rust-hir-stmt.h
@@ -144,11 +144,11 @@ public:
   }
   std::vector<AST::Attribute> &get_outer_attrs () { return outer_attrs; }
 
-  std::unique_ptr<HIR::Type> &get_type () { return type; }
+  HIR::Type &get_type () { return *type; }
 
-  std::unique_ptr<HIR::Expr> &get_init_expr () { return init_expr; }
+  HIR::Expr &get_init_expr () { return *init_expr; }
 
-  std::unique_ptr<HIR::Pattern> &get_pattern () { return variables_pattern; }
+  HIR::Pattern &get_pattern () { return *variables_pattern; }
 
   bool is_item () const override final { return false; }
 
@@ -186,7 +186,7 @@ public:
 
   bool is_item () const override final { return false; }
 
-  std::unique_ptr<Expr> &get_expr () { return expr; }
+  Expr &get_expr () { return *expr; }
 
   // Copy constructor with clone
   ExprStmt (ExprStmt const &other)
diff --git a/gcc/rust/hir/tree/rust-hir-type.h b/gcc/rust/hir/tree/rust-hir-type.h
index e4a9754..26c3d2d 100644
--- a/gcc/rust/hir/tree/rust-hir-type.h
+++ b/gcc/rust/hir/tree/rust-hir-type.h
@@ -271,7 +271,7 @@ public:
      * parenthesised type, it must be in parentheses. */
     return type_in_parens->to_trait_bound (true);
   }
-  std::unique_ptr<Type> &get_type_in_parens () { return type_in_parens; }
+  Type &get_type_in_parens () { return *type_in_parens; }
   void accept_vis (HIRFullVisitor &vis) override;
   void accept_vis (HIRTypeVisitor &vis) override;
 };
@@ -439,7 +439,7 @@ public:
   void accept_vis (HIRFullVisitor &vis) override;
   void accept_vis (HIRTypeVisitor &vis) override;
 
-  std::unique_ptr<Type> &get_type () { return type; }
+  Type &get_type () { return *type; }
 
   Mutability get_mut () const { return mut; }
 
@@ -447,7 +447,7 @@ public:
 
   bool is_const () const { return mut == Mutability::Imm; }
 
-  std::unique_ptr<Type> &get_base_type () { return type; }
+  Type &get_base_type () { return *type; }
 
 protected:
   /* Use covariance to implement clone function as returning this object rather
@@ -520,7 +520,7 @@ public:
 
   Mutability get_mut () const { return mut; }
 
-  std::unique_ptr<Type> &get_base_type () { return type; }
+  Type &get_base_type () { return *type; }
 
 protected:
   /* Use covariance to implement clone function as returning this object rather
@@ -578,9 +578,9 @@ public:
   void accept_vis (HIRFullVisitor &vis) override;
   void accept_vis (HIRTypeVisitor &vis) override;
 
-  std::unique_ptr<Type> &get_element_type () { return elem_type; }
+  Type &get_element_type () { return *elem_type; }
 
-  std::unique_ptr<Expr> &get_size_expr () { return size; }
+  Expr &get_size_expr () { return *size; }
 
 protected:
   /* Use covariance to implement clone function as returning this object rather
@@ -633,7 +633,7 @@ public:
   void accept_vis (HIRFullVisitor &vis) override;
   void accept_vis (HIRTypeVisitor &vis) override;
 
-  std::unique_ptr<Type> &get_element_type () { return elem_type; }
+  Type &get_element_type () { return *elem_type; }
 
 protected:
   /* Use covariance to implement clone function as returning this object rather
@@ -743,7 +743,7 @@ public:
 
   location_t get_locus () const { return locus; }
 
-  std::unique_ptr<Type> &get_type () { return param_type; }
+  Type &get_type () { return *param_type; }
 
   ParamKind get_param_kind () const { return param_kind; }
 
@@ -828,7 +828,7 @@ public:
   }
 
   // TODO: would a "vis_type" be better?
-  std::unique_ptr<Type> &get_return_type () { return return_type; }
+  Type &get_return_type () { return *return_type; }
 
 protected:
   /* Use covariance to implement clone function as returning this object rather
diff --git a/gcc/rust/hir/tree/rust-hir.h b/gcc/rust/hir/tree/rust-hir.h
index 8544d0d..7d133e1 100644
--- a/gcc/rust/hir/tree/rust-hir.h
+++ b/gcc/rust/hir/tree/rust-hir.h
@@ -765,11 +765,8 @@ public:
   bool has_default_expression () { return default_expression != nullptr; }
 
   std::string get_name () { return name; }
-  std::unique_ptr<Type> &get_type () { return type; }
-  std::unique_ptr<Expr> &get_default_expression ()
-  {
-    return default_expression;
-  }
+  Type &get_type () { return *type; }
+  Expr &get_default_expression () { return *default_expression; }
 
 protected:
   /* Use covariance to implement clone function as returning this object rather