Add hir lowering of closure expressions

In the AST we have ClosureExprInner and ClosureExprInnerTyped the first
is the closure expression of the form:

    let closure_inferred  = |i| i + 1;

The second is of the form:

    let closure_annotated = |i: i32| -> i32 { i + 1 };

Both of these can be seguared into a single HIR::ClosureExpr with an
optional return type and parameter types.

Addresses #195

23 files changed, 206 insertions, 207 deletions

diff --git a/gcc/rust/ast/rust-expr.h b/gcc/rust/ast/rust-expr.h
index c764f9c..c58fae5 100644
--- a/gcc/rust/ast/rust-expr.h
+++ b/gcc/rust/ast/rust-expr.h
@@ -2134,8 +2134,6 @@ struct ClosureParam
 private:
   std::vector<Attribute> outer_attrs;
   std::unique_ptr<Pattern> pattern;
-
-  // bool has_type_given;
   std::unique_ptr<Type> type;
   Location locus;
 
@@ -2202,19 +2200,19 @@ public:
   const std::vector<Attribute> &get_outer_attrs () const { return outer_attrs; }
   std::vector<Attribute> &get_outer_attrs () { return outer_attrs; }
 
-  // TODO: is this better? Or is a "vis_block" better?
   std::unique_ptr<Pattern> &get_pattern ()
   {
     rust_assert (pattern != nullptr);
     return pattern;
   }
 
-  // TODO: is this better? Or is a "vis_block" better?
   std::unique_ptr<Type> &get_type ()
   {
     rust_assert (has_type_given ());
     return type;
   }
+
+  Location get_locus () const { return locus; }
 };
 
 // Base closure definition expression AST node - abstract
@@ -2248,6 +2246,8 @@ public:
   {
     outer_attrs = std::move (new_attrs);
   }
+
+  bool get_has_move () const { return has_move; }
 };
 
 // Represents a non-type-specified closure expression AST node
@@ -2307,7 +2307,6 @@ public:
     return closure_inner == nullptr;
   }
 
-  // TODO: is this better? Or is a "vis_block" better?
   std::unique_ptr<Expr> &get_definition_expr ()
   {
     rust_assert (closure_inner != nullptr);
diff --git a/gcc/rust/backend/rust-compile-block.h b/gcc/rust/backend/rust-compile-block.h
index cdd17f1..8f62f45 100644
--- a/gcc/rust/backend/rust-compile-block.h
+++ b/gcc/rust/backend/rust-compile-block.h
@@ -57,8 +57,7 @@ public:
   // Empty visit for unused Expression HIR nodes.
   void visit (HIR::PathInExpression &) override {}
   void visit (HIR::QualifiedPathInExpression &) override {}
-  void visit (HIR::ClosureExprInner &) override {}
-  void visit (HIR::ClosureExprInnerTyped &) override {}
+  void visit (HIR::ClosureExpr &) override {}
   void visit (HIR::StructExprFieldIdentifier &) override {}
   void visit (HIR::StructExprFieldIdentifierValue &) override {}
   void visit (HIR::StructExprFieldIndexValue &) override {}
@@ -146,8 +145,7 @@ public:
   // Empty visit for unused Expression HIR nodes.
   void visit (HIR::PathInExpression &) override {}
   void visit (HIR::QualifiedPathInExpression &) override {}
-  void visit (HIR::ClosureExprInner &) override {}
-  void visit (HIR::ClosureExprInnerTyped &) override {}
+  void visit (HIR::ClosureExpr &) override {}
   void visit (HIR::StructExprFieldIdentifier &) override {}
   void visit (HIR::StructExprFieldIdentifierValue &) override {}
   void visit (HIR::StructExprFieldIndexValue &) override {}
diff --git a/gcc/rust/backend/rust-compile-expr.cc b/gcc/rust/backend/rust-compile-expr.cc
index 9ff2be6..d66aa5d 100644
--- a/gcc/rust/backend/rust-compile-expr.cc
+++ b/gcc/rust/backend/rust-compile-expr.cc
@@ -2798,5 +2798,11 @@ CompileExpr::visit (HIR::ArrayIndexExpr &expr)
 						   expr.get_locus ());
 }
 
+void
+CompileExpr::visit (HIR::ClosureExpr &expr)
+{
+  gcc_unreachable ();
+}
+
 } // namespace Compile
 } // namespace Rust
diff --git a/gcc/rust/backend/rust-compile-expr.h b/gcc/rust/backend/rust-compile-expr.h
index f5cb06d..fee2ba7 100644
--- a/gcc/rust/backend/rust-compile-expr.h
+++ b/gcc/rust/backend/rust-compile-expr.h
@@ -67,10 +67,9 @@ public:
   void visit (HIR::RangeToExpr &expr) override;
   void visit (HIR::RangeFullExpr &expr) override;
   void visit (HIR::RangeFromToInclExpr &expr) override;
+  void visit (HIR::ClosureExpr &expr) override;
 
   // TODO
-  void visit (HIR::ClosureExprInner &) override {}
-  void visit (HIR::ClosureExprInnerTyped &) override {}
   void visit (HIR::ErrorPropagationExpr &) override {}
   void visit (HIR::RangeToInclExpr &) override {}
   void visit (HIR::ForLoopExpr &) override {}
diff --git a/gcc/rust/checks/errors/privacy/rust-privacy-reporter.cc b/gcc/rust/checks/errors/privacy/rust-privacy-reporter.cc
index 35fde40..a828058 100644
--- a/gcc/rust/checks/errors/privacy/rust-privacy-reporter.cc
+++ b/gcc/rust/checks/errors/privacy/rust-privacy-reporter.cc
@@ -408,7 +408,7 @@ PrivacyReporter::visit (HIR::FieldAccessExpr &expr)
 }
 
 void
-PrivacyReporter::visit (HIR::ClosureExprInner &expr)
+PrivacyReporter::visit (HIR::ClosureExpr &expr)
 {
   // Not handled yet
 }
@@ -425,12 +425,6 @@ PrivacyReporter::visit (HIR::BlockExpr &expr)
 }
 
 void
-PrivacyReporter::visit (HIR::ClosureExprInnerTyped &expr)
-{
-  // Not handled yet
-}
-
-void
 PrivacyReporter::visit (HIR::ContinueExpr &expr)
 {}
 
diff --git a/gcc/rust/checks/errors/privacy/rust-privacy-reporter.h b/gcc/rust/checks/errors/privacy/rust-privacy-reporter.h
index 546b108..38a5f08 100644
--- a/gcc/rust/checks/errors/privacy/rust-privacy-reporter.h
+++ b/gcc/rust/checks/errors/privacy/rust-privacy-reporter.h
@@ -83,8 +83,7 @@ types
 
   virtual void visit (HIR::QualifiedPathInExpression &expr);
   virtual void visit (HIR::PathInExpression &expr);
-  virtual void visit (HIR::ClosureExprInnerTyped &);
-  virtual void visit (HIR::ClosureExprInner &expr);
+  virtual void visit (HIR::ClosureExpr &expr);
   virtual void visit (HIR::StructExprStructFields &);
   virtual void visit (HIR::StructExprStruct &);
   virtual void visit (HIR::LiteralExpr &expr);
diff --git a/gcc/rust/checks/errors/rust-const-checker.cc b/gcc/rust/checks/errors/rust-const-checker.cc
index a2a6dc2..4b4350e 100644
--- a/gcc/rust/checks/errors/rust-const-checker.cc
+++ b/gcc/rust/checks/errors/rust-const-checker.cc
@@ -382,7 +382,7 @@ ConstChecker::visit (FieldAccessExpr &expr)
 }
 
 void
-ConstChecker::visit (ClosureExprInner &expr)
+ConstChecker::visit (ClosureExpr &expr)
 {}
 
 void
@@ -396,10 +396,6 @@ ConstChecker::visit (BlockExpr &expr)
 }
 
 void
-ConstChecker::visit (ClosureExprInnerTyped &expr)
-{}
-
-void
 ConstChecker::visit (ContinueExpr &expr)
 {}
 
diff --git a/gcc/rust/checks/errors/rust-const-checker.h b/gcc/rust/checks/errors/rust-const-checker.h
index 90b675b..f0175df 100644
--- a/gcc/rust/checks/errors/rust-const-checker.h
+++ b/gcc/rust/checks/errors/rust-const-checker.h
@@ -111,9 +111,8 @@ private:
   virtual void visit (CallExpr &expr) override;
   virtual void visit (MethodCallExpr &expr) override;
   virtual void visit (FieldAccessExpr &expr) override;
-  virtual void visit (ClosureExprInner &expr) override;
+  virtual void visit (ClosureExpr &expr) override;
   virtual void visit (BlockExpr &expr) override;
-  virtual void visit (ClosureExprInnerTyped &expr) override;
   virtual void visit (ContinueExpr &expr) override;
   virtual void visit (BreakExpr &expr) override;
   virtual void visit (RangeFromToExpr &expr) override;
diff --git a/gcc/rust/checks/errors/rust-unsafe-checker.cc b/gcc/rust/checks/errors/rust-unsafe-checker.cc
index e3f3253..8dff50b 100644
--- a/gcc/rust/checks/errors/rust-unsafe-checker.cc
+++ b/gcc/rust/checks/errors/rust-unsafe-checker.cc
@@ -453,7 +453,7 @@ UnsafeChecker::visit (FieldAccessExpr &expr)
 }
 
 void
-UnsafeChecker::visit (ClosureExprInner &expr)
+UnsafeChecker::visit (ClosureExpr &expr)
 {}
 
 void
@@ -467,10 +467,6 @@ UnsafeChecker::visit (BlockExpr &expr)
 }
 
 void
-UnsafeChecker::visit (ClosureExprInnerTyped &expr)
-{}
-
-void
 UnsafeChecker::visit (ContinueExpr &expr)
 {}
 
diff --git a/gcc/rust/checks/errors/rust-unsafe-checker.h b/gcc/rust/checks/errors/rust-unsafe-checker.h
index ae1eb509..fe564a2 100644
--- a/gcc/rust/checks/errors/rust-unsafe-checker.h
+++ b/gcc/rust/checks/errors/rust-unsafe-checker.h
@@ -88,9 +88,8 @@ private:
   virtual void visit (CallExpr &expr) override;
   virtual void visit (MethodCallExpr &expr) override;
   virtual void visit (FieldAccessExpr &expr) override;
-  virtual void visit (ClosureExprInner &expr) override;
+  virtual void visit (ClosureExpr &expr) override;
   virtual void visit (BlockExpr &expr) override;
-  virtual void visit (ClosureExprInnerTyped &expr) override;
   virtual void visit (ContinueExpr &expr) override;
   virtual void visit (BreakExpr &expr) override;
   virtual void visit (RangeFromToExpr &expr) override;
diff --git a/gcc/rust/hir/rust-ast-lower-base.h b/gcc/rust/hir/rust-ast-lower-base.h
index 5479e63..16fe13c8 100644
--- a/gcc/rust/hir/rust-ast-lower-base.h
+++ b/gcc/rust/hir/rust-ast-lower-base.h
@@ -313,6 +313,8 @@ protected:
   HIR::Literal lower_literal (const AST::Literal &literal);
 
   HIR::ExternBlock *lower_extern_block (AST::ExternBlock &extern_block);
+
+  HIR::ClosureParam lower_closure_param (AST::ClosureParam &param);
 };
 
 } // namespace HIR
diff --git a/gcc/rust/hir/rust-ast-lower-expr.cc b/gcc/rust/hir/rust-ast-lower-expr.cc
index c148308..df4ba9d 100644
--- a/gcc/rust/hir/rust-ast-lower-expr.cc
+++ b/gcc/rust/hir/rust-ast-lower-expr.cc
@@ -753,5 +753,58 @@ ASTLoweringExpr::visit (AST::RangeFromToInclExpr &expr)
 				    expr.get_locus ());
 }
 
+void
+ASTLoweringExpr::visit (AST::ClosureExprInner &expr)
+{
+  HIR::Expr *closure_expr
+    = ASTLoweringExpr::translate (expr.get_definition_expr ().get ());
+
+  std::vector<HIR::ClosureParam> closure_params;
+  for (auto &param : expr.get_params ())
+    {
+      HIR::ClosureParam p = lower_closure_param (param);
+      closure_params.push_back (std::move (p));
+    }
+
+  auto crate_num = mappings->get_current_crate ();
+  Analysis::NodeMapping mapping (crate_num, expr.get_node_id (),
+				 mappings->get_next_hir_id (crate_num),
+				 mappings->get_next_localdef_id (crate_num));
+
+  translated
+    = new HIR::ClosureExpr (mapping, std::move (closure_params),
+			    nullptr /* closure_return_type */,
+			    std::unique_ptr<HIR::Expr> (closure_expr),
+			    expr.get_has_move (), expr.get_outer_attrs (),
+			    expr.get_locus ());
+}
+
+void
+ASTLoweringExpr::visit (AST::ClosureExprInnerTyped &expr)
+{
+  HIR::Type *closure_return_type = nullptr;
+  HIR::Expr *closure_expr
+    = ASTLoweringExpr::translate (expr.get_definition_block ().get ());
+
+  std::vector<HIR::ClosureParam> closure_params;
+  for (auto &param : expr.get_params ())
+    {
+      HIR::ClosureParam p = lower_closure_param (param);
+      closure_params.push_back (std::move (p));
+    }
+
+  auto crate_num = mappings->get_current_crate ();
+  Analysis::NodeMapping mapping (crate_num, expr.get_node_id (),
+				 mappings->get_next_hir_id (crate_num),
+				 mappings->get_next_localdef_id (crate_num));
+
+  translated
+    = new HIR::ClosureExpr (mapping, std::move (closure_params),
+			    std::unique_ptr<HIR::Type> (closure_return_type),
+			    std::unique_ptr<HIR::Expr> (closure_expr),
+			    expr.get_has_move (), expr.get_outer_attrs (),
+			    expr.get_locus ());
+}
+
 } // namespace HIR
 } // namespace Rust
diff --git a/gcc/rust/hir/rust-ast-lower-expr.h b/gcc/rust/hir/rust-ast-lower-expr.h
index 315bca3..0963e40 100644
--- a/gcc/rust/hir/rust-ast-lower-expr.h
+++ b/gcc/rust/hir/rust-ast-lower-expr.h
@@ -116,6 +116,8 @@ public:
   void visit (AST::RangeToExpr &expr) override;
   void visit (AST::RangeFullExpr &expr) override;
   void visit (AST::RangeFromToInclExpr &expr) override;
+  void visit (AST::ClosureExprInner &expr) override;
+  void visit (AST::ClosureExprInnerTyped &expr) override;
 
 private:
   ASTLoweringExpr ();
diff --git a/gcc/rust/hir/rust-ast-lower.cc b/gcc/rust/hir/rust-ast-lower.cc
index fa3a83d..52b7003 100644
--- a/gcc/rust/hir/rust-ast-lower.cc
+++ b/gcc/rust/hir/rust-ast-lower.cc
@@ -22,9 +22,12 @@
 #include "rust-ast-lower-expr.h"
 #include "rust-ast-lower-block.h"
 #include "rust-ast-lower-type.h"
+#include "rust-ast-lower-pattern.h"
+#include "rust-ast-lower-struct-field-expr.h"
 
 namespace Rust {
 namespace HIR {
+using HIR::ClosureParam;
 
 Visibility
 translate_visibility (const AST::Visibility &vis)
@@ -473,5 +476,25 @@ ASTLowerQualPathInExpression::visit (AST::QualifiedPathInExpression &expr)
 						   expr.get_locus (),
 						   expr.get_outer_attrs ());
 }
+
+ClosureParam
+ASTLoweringBase::lower_closure_param (AST::ClosureParam &param)
+{
+  HIR::Pattern *param_pattern
+    = ASTLoweringPattern::translate (param.get_pattern ().get ());
+
+  HIR::Type *param_type
+    = param.has_type_given ()
+	? ASTLoweringType::translate (param.get_type ().get ())
+	: nullptr;
+
+  return HIR::ClosureParam (std::unique_ptr<HIR::Pattern> (param_pattern),
+			    param.get_locus (),
+			    param.has_type_given ()
+			      ? std::unique_ptr<HIR::Type> (param_type)
+			      : nullptr,
+			    param.get_outer_attrs ());
+}
+
 } // namespace HIR
 } // namespace Rust
diff --git a/gcc/rust/hir/rust-hir-dump.cc b/gcc/rust/hir/rust-hir-dump.cc
index bb139a7..11d4cd1 100644
--- a/gcc/rust/hir/rust-hir-dump.cc
+++ b/gcc/rust/hir/rust-hir-dump.cc
@@ -197,7 +197,7 @@ void
 Dump::visit (FieldAccessExpr &)
 {}
 void
-Dump::visit (ClosureExprInner &)
+Dump::visit (ClosureExpr &)
 {}
 void
 Dump::visit (BlockExpr &block_expr)
@@ -212,9 +212,7 @@ Dump::visit (BlockExpr &block_expr)
   stream << "]";
   indent--;
 }
-void
-Dump::visit (ClosureExprInnerTyped &)
-{}
+
 void
 Dump::visit (ContinueExpr &)
 {}
diff --git a/gcc/rust/hir/rust-hir-dump.h b/gcc/rust/hir/rust-hir-dump.h
index 8b9e893..1953efe 100644
--- a/gcc/rust/hir/rust-hir-dump.h
+++ b/gcc/rust/hir/rust-hir-dump.h
@@ -78,9 +78,8 @@ private:
   virtual void visit (CallExpr &) override;
   virtual void visit (MethodCallExpr &) override;
   virtual void visit (FieldAccessExpr &) override;
-  virtual void visit (ClosureExprInner &) override;
+  virtual void visit (ClosureExpr &) override;
   virtual void visit (BlockExpr &) override;
-  virtual void visit (ClosureExprInnerTyped &) override;
   virtual void visit (ContinueExpr &) override;
   virtual void visit (BreakExpr &) override;
   virtual void visit (RangeFromToExpr &) override;
diff --git a/gcc/rust/hir/tree/rust-hir-expr.h b/gcc/rust/hir/tree/rust-hir-expr.h
index e173d37..c3180d8 100644
--- a/gcc/rust/hir/tree/rust-hir-expr.h
+++ b/gcc/rust/hir/tree/rust-hir-expr.h
@@ -1985,21 +1985,22 @@ protected:
 struct ClosureParam
 {
 private:
+  std::vector<AST::Attribute> outer_attrs;
   std::unique_ptr<Pattern> pattern;
-
-  // bool has_type_given;
   std::unique_ptr<Type> type;
-
-  // TODO: should this store location data?
+  Location locus;
 
 public:
   // Returns whether the type of the parameter has been given.
   bool has_type_given () const { return type != nullptr; }
 
   // Constructor for closure parameter
-  ClosureParam (std::unique_ptr<Pattern> param_pattern,
-		std::unique_ptr<Type> param_type = nullptr)
-    : pattern (std::move (param_pattern)), type (std::move (param_type))
+  ClosureParam (std::unique_ptr<Pattern> param_pattern, Location locus,
+		std::unique_ptr<Type> param_type = nullptr,
+		std::vector<AST::Attribute> outer_attrs = {})
+    : outer_attrs (std::move (outer_attrs)),
+      pattern (std::move (param_pattern)), type (std::move (param_type)),
+      locus (locus)
   {}
 
   // Copy constructor required due to cloning as a result of unique_ptrs
@@ -2007,6 +2008,8 @@ public:
     : pattern (other.pattern->clone_pattern ())
   {
     // guard to protect from null pointer dereference
+    if (other.pattern != nullptr)
+      pattern = other.pattern->clone_pattern ();
     if (other.type != nullptr)
       type = other.type->clone_type ();
   }
@@ -2016,8 +2019,17 @@ public:
   // Assignment operator must be overloaded to clone as well
   ClosureParam &operator= (ClosureParam const &other)
   {
-    pattern = other.pattern->clone_pattern ();
-    type = other.type->clone_type ();
+    outer_attrs = other.outer_attrs;
+
+    // guard to protect from null pointer dereference
+    if (other.pattern != nullptr)
+      pattern = other.pattern->clone_pattern ();
+    else
+      pattern = nullptr;
+    if (other.type != nullptr)
+      type = other.type->clone_type ();
+    else
+      type = nullptr;
 
     return *this;
   }
@@ -2026,31 +2038,79 @@ public:
   ClosureParam (ClosureParam &&other) = default;
   ClosureParam &operator= (ClosureParam &&other) = default;
 
-  // Returns whether closure parameter is in an error state.
-  bool is_error () const { return pattern == nullptr; }
+  std::string as_string () const;
 
-  // Creates an error state closure parameter.
-  static ClosureParam create_error () { return ClosureParam (nullptr); }
+  const std::vector<AST::Attribute> &get_outer_attrs () const
+  {
+    return outer_attrs;
+  }
+  std::vector<AST::Attribute> &get_outer_attrs () { return outer_attrs; }
 
-  std::string as_string () const;
+  std::unique_ptr<Pattern> &get_pattern ()
+  {
+    rust_assert (pattern != nullptr);
+    return pattern;
+  }
+
+  std::unique_ptr<Type> &get_type ()
+  {
+    rust_assert (has_type_given ());
+    return type;
+  }
+
+  Location get_locus () const { return locus; }
 };
 
 // Base closure definition expression HIR node - abstract
 class ClosureExpr : public ExprWithoutBlock
 {
+private:
   bool has_move;
   std::vector<ClosureParam> params;
   Location locus;
+  std::unique_ptr<Type> return_type;
+  std::unique_ptr<Expr> expr;
 
-protected:
+public:
   ClosureExpr (Analysis::NodeMapping mappings,
-	       std::vector<ClosureParam> closure_params, bool has_move,
+	       std::vector<ClosureParam> closure_params,
+	       std::unique_ptr<Type> closure_return_type,
+	       std::unique_ptr<Expr> closure_expr, bool has_move,
 	       AST::AttrVec outer_attribs, Location locus)
     : ExprWithoutBlock (std::move (mappings), std::move (outer_attribs)),
-      has_move (has_move), params (std::move (closure_params)), locus (locus)
+      has_move (has_move), params (std::move (closure_params)), locus (locus),
+      return_type (std::move (closure_return_type)),
+      expr (std::move (closure_expr))
   {}
 
-public:
+  // Copy constructor requires cloning
+  ClosureExpr (ClosureExpr const &other)
+    : ExprWithoutBlock (other.get_mappings (), other.get_outer_attrs ())
+  {
+    return_type
+      = other.has_return_type () ? other.return_type->clone_type () : nullptr;
+    expr = other.expr->clone_expr ();
+    params = other.params;
+    has_move = other.has_move;
+  }
+
+  // Overload assignment operator to clone unique_ptrs
+  ClosureExpr &operator= (ClosureExpr const &other)
+  {
+    mappings = other.mappings;
+    return_type
+      = other.has_return_type () ? other.return_type->clone_type () : nullptr;
+    expr = other.expr->clone_expr ();
+    params = other.params;
+    has_move = other.has_move;
+
+    return *this;
+  }
+
+  // move constructors
+  ClosureExpr (ClosureExpr &&other) = default;
+  ClosureExpr &operator= (ClosureExpr &&other) = default;
+
   std::string as_string () const override;
 
   Location get_locus () const override final { return locus; }
@@ -2059,47 +2119,17 @@ public:
   {
     return ExprType::Closure;
   }
-};
 
-// Represents a non-type-specified closure expression HIR node
-class ClosureExprInner : public ClosureExpr
-{
-  std::unique_ptr<Expr> closure_inner;
+  bool get_has_move () const { return has_move; }
 
-public:
-  std::string as_string () const override;
+  bool has_return_type () const { return return_type != nullptr; }
 
-  // Constructor for a ClosureExprInner
-  ClosureExprInner (Analysis::NodeMapping mappings,
-		    std::unique_ptr<Expr> closure_inner_expr,
-		    std::vector<ClosureParam> closure_params, Location locus,
-		    bool is_move = false,
-		    AST::AttrVec outer_attribs = AST::AttrVec ())
-    : ClosureExpr (std::move (mappings), std::move (closure_params), is_move,
-		   std::move (outer_attribs), locus),
-      closure_inner (std::move (closure_inner_expr))
-  {}
-
-  // Copy constructor must be defined to allow copying via cloning of unique_ptr
-  ClosureExprInner (ClosureExprInner const &other)
-    : ClosureExpr (other), closure_inner (other.closure_inner->clone_expr ())
-  {}
-
-  // Overload assignment operator to clone closure_inner
-  ClosureExprInner &operator= (ClosureExprInner const &other)
+  std::unique_ptr<Type> &get_return_type ()
   {
-    ClosureExpr::operator= (other);
-    closure_inner = other.closure_inner->clone_expr ();
-    // params = other.params;
-    // has_move = other.has_move;
-    // outer_attrs = other.outer_attrs;
-
-    return *this;
-  }
-
-  // move constructors
-  ClosureExprInner (ClosureExprInner &&other) = default;
-  ClosureExprInner &operator= (ClosureExprInner &&other) = default;
+    rust_assert (has_return_type ());
+    return return_type;
+  };
+  std::unique_ptr<Expr> &get_expr () { return expr; }
 
   void accept_vis (HIRFullVisitor &vis) override;
   void accept_vis (HIRExpressionVisitor &vis) override;
@@ -2107,16 +2137,16 @@ public:
 protected:
   /* Use covariance to implement clone function as returning this object rather
    * than base */
-  ClosureExprInner *clone_expr_impl () const override
+  ClosureExpr *clone_expr_impl () const override
   {
-    return new ClosureExprInner (*this);
+    return new ClosureExpr (*this);
   }
 
   /* Use covariance to implement clone function as returning this object rather
    * than base */
-  ClosureExprInner *clone_expr_without_block_impl () const override
+  ClosureExpr *clone_expr_without_block_impl () const override
   {
-    return new ClosureExprInner (*this);
+    return new ClosureExpr (*this);
   }
 };
 
@@ -2239,71 +2269,6 @@ protected:
   }
 };
 
-// Represents a type-specified closure expression HIR node
-class ClosureExprInnerTyped : public ClosureExpr
-{
-  std::unique_ptr<Type> return_type;
-  std::unique_ptr<BlockExpr>
-    expr; // only used because may be polymorphic in future
-
-public:
-  std::string as_string () const override;
-
-  // Constructor potentially with a move
-  ClosureExprInnerTyped (Analysis::NodeMapping mappings,
-			 std::unique_ptr<Type> closure_return_type,
-			 std::unique_ptr<BlockExpr> closure_expr,
-			 std::vector<ClosureParam> closure_params,
-			 Location locus, bool is_move = false,
-			 AST::AttrVec outer_attribs = AST::AttrVec ())
-    : ClosureExpr (std::move (mappings), std::move (closure_params), is_move,
-		   std::move (outer_attribs), locus),
-      return_type (std::move (closure_return_type)),
-      expr (std::move (closure_expr))
-  {}
-
-  // Copy constructor requires cloning
-  ClosureExprInnerTyped (ClosureExprInnerTyped const &other)
-    : ClosureExpr (other), return_type (other.return_type->clone_type ()),
-      expr (other.expr->clone_block_expr ())
-  {}
-
-  // Overload assignment operator to clone unique_ptrs
-  ClosureExprInnerTyped &operator= (ClosureExprInnerTyped const &other)
-  {
-    ClosureExpr::operator= (other);
-    return_type = other.return_type->clone_type ();
-    expr = other.expr->clone_block_expr ();
-    // params = other.params;
-    // has_move = other.has_move;
-    // outer_attrs = other.outer_attrs;
-
-    return *this;
-  }
-
-  // move constructors
-  ClosureExprInnerTyped (ClosureExprInnerTyped &&other) = default;
-  ClosureExprInnerTyped &operator= (ClosureExprInnerTyped &&other) = default;
-
-  void accept_vis (HIRFullVisitor &vis) override;
-  void accept_vis (HIRExpressionVisitor &vis) override;
-
-protected:
-  /* Use covariance to implement clone function as returning this object rather
-   * than base */
-  ClosureExprInnerTyped *clone_expr_impl () const override
-  {
-    return new ClosureExprInnerTyped (*this);
-  }
-
-  /* Use covariance to implement clone function as returning this object rather
-   * than base */
-  ClosureExprInnerTyped *clone_expr_without_block_impl () const override
-  {
-    return new ClosureExprInnerTyped (*this);
-  }
-};
-
 // HIR node representing continue expression within loops
 class ContinueExpr : public ExprWithoutBlock
 {
diff --git a/gcc/rust/hir/tree/rust-hir-full-decls.h b/gcc/rust/hir/tree/rust-hir-full-decls.h
index 2798ba9..717facf 100644
--- a/gcc/rust/hir/tree/rust-hir-full-decls.h
+++ b/gcc/rust/hir/tree/rust-hir-full-decls.h
@@ -94,9 +94,7 @@ class MethodCallExpr;
 class FieldAccessExpr;
 struct ClosureParam;
 class ClosureExpr;
-class ClosureExprInner;
 class BlockExpr;
-class ClosureExprInnerTyped;
 class ContinueExpr;
 class BreakExpr;
 class RangeExpr;
diff --git a/gcc/rust/hir/tree/rust-hir-full-test.cc b/gcc/rust/hir/tree/rust-hir-full-test.cc
index 4e25532..7e5b49d 100644
--- a/gcc/rust/hir/tree/rust-hir-full-test.cc
+++ b/gcc/rust/hir/tree/rust-hir-full-test.cc
@@ -1133,15 +1133,8 @@ ClosureExpr::as_string () const
 	}
     }
 
-  return str;
-}
-
-std::string
-ClosureExprInnerTyped::as_string () const
-{
-  std::string str = ClosureExpr::as_string ();
-
-  str += "\n Return type: " + return_type->as_string ();
+  str += "\n Return type: "
+	 + (has_return_type () ? return_type->as_string () : "none");
 
   str += "\n Body: " + expr->as_string ();
 
@@ -1516,16 +1509,6 @@ UnsafeBlockExpr::as_string () const
 }
 
 std::string
-ClosureExprInner::as_string () const
-{
-  std::string str = ClosureExpr::as_string ();
-
-  str += "\n Expression: " + closure_inner->as_string ();
-
-  return str;
-}
-
-std::string
 IfExpr::as_string () const
 {
   std::string str ("IfExpr: ");
@@ -4038,7 +4021,7 @@ FieldAccessExpr::accept_vis (HIRFullVisitor &vis)
 }
 
 void
-ClosureExprInner::accept_vis (HIRFullVisitor &vis)
+ClosureExpr::accept_vis (HIRFullVisitor &vis)
 {
   vis.visit (*this);
 }
@@ -4050,12 +4033,6 @@ BlockExpr::accept_vis (HIRFullVisitor &vis)
 }
 
 void
-ClosureExprInnerTyped::accept_vis (HIRFullVisitor &vis)
-{
-  vis.visit (*this);
-}
-
-void
 ContinueExpr::accept_vis (HIRFullVisitor &vis)
 {
   vis.visit (*this);
@@ -4986,7 +4963,7 @@ IfExpr::accept_vis (HIRExpressionVisitor &vis)
 }
 
 void
-ClosureExprInner::accept_vis (HIRExpressionVisitor &vis)
+ClosureExpr::accept_vis (HIRExpressionVisitor &vis)
 {
   vis.visit (*this);
 }
@@ -5076,12 +5053,6 @@ QualifiedPathInExpression::accept_vis (HIRPatternVisitor &vis)
 }
 
 void
-ClosureExprInnerTyped::accept_vis (HIRExpressionVisitor &vis)
-{
-  vis.visit (*this);
-}
-
-void
 ExprStmtWithBlock::accept_vis (HIRStmtVisitor &vis)
 {
   vis.visit (*this);
diff --git a/gcc/rust/hir/tree/rust-hir-visitor.h b/gcc/rust/hir/tree/rust-hir-visitor.h
index b3c0b93..a922792 100644
--- a/gcc/rust/hir/tree/rust-hir-visitor.h
+++ b/gcc/rust/hir/tree/rust-hir-visitor.h
@@ -63,9 +63,8 @@ public:
   virtual void visit (CallExpr &expr) = 0;
   virtual void visit (MethodCallExpr &expr) = 0;
   virtual void visit (FieldAccessExpr &expr) = 0;
-  virtual void visit (ClosureExprInner &expr) = 0;
   virtual void visit (BlockExpr &expr) = 0;
-  virtual void visit (ClosureExprInnerTyped &expr) = 0;
+  virtual void visit (ClosureExpr &expr) = 0;
   virtual void visit (ContinueExpr &expr) = 0;
   virtual void visit (BreakExpr &expr) = 0;
   virtual void visit (RangeFromToExpr &expr) = 0;
@@ -206,9 +205,8 @@ public:
   virtual void visit (CallExpr &) override {}
   virtual void visit (MethodCallExpr &) override {}
   virtual void visit (FieldAccessExpr &) override {}
-  virtual void visit (ClosureExprInner &) override {}
+  virtual void visit (ClosureExpr &) override {}
   virtual void visit (BlockExpr &) override {}
-  virtual void visit (ClosureExprInnerTyped &) override {}
   virtual void visit (ContinueExpr &) override {}
   virtual void visit (BreakExpr &) override {}
   virtual void visit (RangeFromToExpr &) override {}
@@ -419,8 +417,7 @@ public:
 
   virtual void visit (HIR::QualifiedPathInExpression &expr) = 0;
   virtual void visit (HIR::PathInExpression &expr) = 0;
-  virtual void visit (ClosureExprInnerTyped &) = 0;
-  virtual void visit (ClosureExprInner &expr) = 0;
+  virtual void visit (ClosureExpr &) = 0;
   virtual void visit (StructExprStructFields &) = 0;
   virtual void visit (StructExprStruct &) = 0;
   virtual void visit (LiteralExpr &expr) = 0;
diff --git a/gcc/rust/hir/tree/rust-hir.h b/gcc/rust/hir/tree/rust-hir.h
index 26bf302..97c20c9 100644
--- a/gcc/rust/hir/tree/rust-hir.h
+++ b/gcc/rust/hir/tree/rust-hir.h
@@ -238,6 +238,7 @@ class ExprWithoutBlock;
 // Base expression HIR node - abstract
 class Expr : public Node
 {
+protected:
   AST::AttrVec outer_attrs;
   Analysis::NodeMapping mappings;
 
diff --git a/gcc/rust/typecheck/rust-hir-type-check-expr.cc b/gcc/rust/typecheck/rust-hir-type-check-expr.cc
index 3411a2da..df4ddfa 100644
--- a/gcc/rust/typecheck/rust-hir-type-check-expr.cc
+++ b/gcc/rust/typecheck/rust-hir-type-check-expr.cc
@@ -1418,6 +1418,12 @@ TypeCheckExpr::visit (HIR::MatchExpr &expr)
     }
 }
 
+void
+TypeCheckExpr::visit (HIR::ClosureExpr &expr)
+{
+  gcc_unreachable ();
+}
+
 bool
 TypeCheckExpr::resolve_operator_overload (
   Analysis::RustLangItem::ItemType lang_item_type, HIR::OperatorExprMeta expr,
diff --git a/gcc/rust/typecheck/rust-hir-type-check-expr.h b/gcc/rust/typecheck/rust-hir-type-check-expr.h
index 9e3db00..bf36e19 100644
--- a/gcc/rust/typecheck/rust-hir-type-check-expr.h
+++ b/gcc/rust/typecheck/rust-hir-type-check-expr.h
@@ -69,10 +69,9 @@ public:
   void visit (HIR::RangeFullExpr &expr) override;
   void visit (HIR::RangeFromToInclExpr &expr) override;
   void visit (HIR::WhileLoopExpr &expr) override;
+  void visit (HIR::ClosureExpr &expr) override;
 
   // TODO
-  void visit (HIR::ClosureExprInnerTyped &) override {}
-  void visit (HIR::ClosureExprInner &expr) override {}
   void visit (HIR::ErrorPropagationExpr &expr) override {}
   void visit (HIR::RangeToInclExpr &expr) override {}
   void visit (HIR::WhileLetLoopExpr &expr) override {}