// Copyright (C) 2020-2021 Free Software Foundation, Inc.

// This file is part of GCC.

// GCC is free software; you can redistribute it and/or modify it under
// the terms of the GNU General Public License as published by the Free
// Software Foundation; either version 3, or (at your option) any later
// version.

// GCC is distributed in the hope that it will be useful, but WITHOUT ANY
// WARRANTY; without even the implied warranty of MERCHANTABILITY or
// FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
// for more details.

// You should have received a copy of the GNU General Public License
// along with GCC; see the file COPYING3.  If not see
// <http://www.gnu.org/licenses/>.

#include "rust-compile.h"
#include "rust-compile-item.h"
#include "rust-compile-expr.h"
#include "rust-compile-struct-field-expr.h"
#include "rust-hir-trait-resolve.h"
#include "rust-hir-path-probe.h"
#include "rust-hir-type-bounds.h"
#include "rust-hir-dot-operator.h"
#include "rust-compile-pattern.h"

#include "fold-const.h"

namespace Rust {
namespace Compile {

void
CompileExpr::visit (HIR::ArithmeticOrLogicalExpr &expr)
{
  auto op = expr.get_expr_type ();
  auto lhs = CompileExpr::Compile (expr.get_lhs (), ctx);
  auto rhs = CompileExpr::Compile (expr.get_rhs (), ctx);

  // this might be an operator overload situation lets check
  TyTy::FnType *fntype;
  bool is_op_overload = ctx->get_tyctx ()->lookup_operator_overload (
    expr.get_mappings ().get_hirid (), &fntype);
  if (is_op_overload)
    {
      auto lang_item_type
	= Analysis::RustLangItem::OperatorToLangItem (expr.get_expr_type ());
      translated = resolve_operator_overload (lang_item_type, expr, lhs, rhs,
					      expr.get_lhs (), expr.get_rhs ());
      return;
    }

  translated
    = ctx->get_backend ()->arithmetic_or_logical_expression (op, lhs, rhs,
							     expr.get_locus ());
}

void
CompileExpr::visit (HIR::CompoundAssignmentExpr &expr)
{
  fncontext fn = ctx->peek_fn ();

  auto op = expr.get_expr_type ();
  auto lhs = CompileExpr::Compile (expr.get_left_expr ().get (), ctx);
  auto rhs = CompileExpr::Compile (expr.get_right_expr ().get (), ctx);

  // this might be an operator overload situation lets check
  TyTy::FnType *fntype;
  bool is_op_overload = ctx->get_tyctx ()->lookup_operator_overload (
    expr.get_mappings ().get_hirid (), &fntype);
  if (is_op_overload)
    {
      auto lang_item_type
	= Analysis::RustLangItem::CompoundAssignmentOperatorToLangItem (
	  expr.get_expr_type ());
      auto compound_assignment
	= resolve_operator_overload (lang_item_type, expr, lhs, rhs,
				     expr.get_left_expr ().get (),
				     expr.get_right_expr ().get ());
      auto assignment
	= ctx->get_backend ()->expression_statement (fn.fndecl,
						     compound_assignment);
      ctx->add_statement (assignment);

      return;
    }

  auto operator_expr
    = ctx->get_backend ()->arithmetic_or_logical_expression (op, lhs, rhs,
							     expr.get_locus ());
  tree assignment
    = ctx->get_backend ()->assignment_statement (fn.fndecl, lhs, operator_expr,
						 expr.get_locus ());
  ctx->add_statement (assignment);
}

void
CompileExpr::visit (HIR::NegationExpr &expr)
{
  auto op = expr.get_expr_type ();
  auto negated_expr = CompileExpr::Compile (expr.get_expr ().get (), ctx);
  auto location = expr.get_locus ();

  // this might be an operator overload situation lets check
  TyTy::FnType *fntype;
  bool is_op_overload = ctx->get_tyctx ()->lookup_operator_overload (
    expr.get_mappings ().get_hirid (), &fntype);
  if (is_op_overload)
    {
      auto lang_item_type
	= Analysis::RustLangItem::NegationOperatorToLangItem (op);
      translated
	= resolve_operator_overload (lang_item_type, expr, negated_expr,
				     nullptr, expr.get_expr ().get (), nullptr);
      return;
    }

  translated
    = ctx->get_backend ()->negation_expression (op, negated_expr, location);
}

void
CompileExpr::visit (HIR::DereferenceExpr &expr)
{
  TyTy::BaseType *tyty = nullptr;
  if (!ctx->get_tyctx ()->lookup_type (expr.get_mappings ().get_hirid (),
				       &tyty))
    {
      rust_fatal_error (expr.get_locus (),
			"did not resolve type for this TupleExpr");
      return;
    }

  tree main_expr = CompileExpr::Compile (expr.get_expr ().get (), ctx);

  // this might be an operator overload situation lets check
  TyTy::FnType *fntype;
  bool is_op_overload = ctx->get_tyctx ()->lookup_operator_overload (
    expr.get_mappings ().get_hirid (), &fntype);
  if (is_op_overload)
    {
      auto lang_item_type = Analysis::RustLangItem::ItemType::DEREF;
      tree operator_overload_call
	= resolve_operator_overload (lang_item_type, expr, main_expr, nullptr,
				     expr.get_expr ().get (), nullptr);

      // rust deref always returns a reference from this overload then we can
      // actually do the indirection
      main_expr = operator_overload_call;
    }

  tree expected_type = TyTyResolveCompile::compile (ctx, tyty);
  bool known_valid = true;
  translated
    = ctx->get_backend ()->indirect_expression (expected_type, main_expr,
						known_valid, expr.get_locus ());
}

void
CompileExpr::visit (HIR::MatchExpr &expr)
{
  // https://gcc.gnu.org/onlinedocs/gccint/Basic-Statements.html#Basic-Statements
  // TODO
  // SWITCH_ALL_CASES_P is true if the switch includes a default label or the
  // case label ranges cover all possible values of the condition expression

  /* Switch expression.

     TREE_TYPE is the original type of the condition, before any
     language required type conversions.  It may be NULL, in which case
     the original type and final types are assumed to be the same.

     Operand 0 is the expression used to perform the branch,
     Operand 1 is the body of the switch, which probably contains
       CASE_LABEL_EXPRs.  It may also be NULL, in which case operand 2
       must not be NULL.  */
  // DEFTREECODE (SWITCH_EXPR, "switch_expr", tcc_statement, 2)

  /* Used to represent a case label.

     Operand 0 is CASE_LOW.  It may be NULL_TREE, in which case the label
       is a 'default' label.
     Operand 1 is CASE_HIGH.  If it is NULL_TREE, the label is a simple
       (one-value) case label.  If it is non-NULL_TREE, the case is a range.
     Operand 2 is CASE_LABEL, which has the corresponding LABEL_DECL.
     Operand 3 is CASE_CHAIN.  This operand is only used in tree-cfg.c to
       speed up the lookup of case labels which use a particular edge in
       the control flow graph.  */
  // DEFTREECODE (CASE_LABEL_EXPR, "case_label_expr", tcc_statement, 4)

  TyTy::BaseType *scrutinee_expr_tyty = nullptr;
  if (!ctx->get_tyctx ()->lookup_type (
	expr.get_scrutinee_expr ()->get_mappings ().get_hirid (),
	&scrutinee_expr_tyty))
    {
      translated = ctx->get_backend ()->error_expression ();
      return;
    }

  rust_assert (scrutinee_expr_tyty->get_kind () == TyTy::TypeKind::ADT);

  // this will need to change but for now the first pass implementation, lets
  // assert this is the case
  TyTy::ADTType *adt = static_cast<TyTy::ADTType *> (scrutinee_expr_tyty);
  rust_assert (adt->is_enum ());
  rust_assert (adt->number_of_variants () > 0);

  TyTy::BaseType *expr_tyty = nullptr;
  if (!ctx->get_tyctx ()->lookup_type (expr.get_mappings ().get_hirid (),
				       &expr_tyty))
    {
      translated = ctx->get_backend ()->error_expression ();
      return;
    }

  fncontext fnctx = ctx->peek_fn ();
  Bvariable *tmp = NULL;
  bool needs_temp = !expr_tyty->is_unit ();
  if (needs_temp)
    {
      tree enclosing_scope = ctx->peek_enclosing_scope ();
      tree block_type = TyTyResolveCompile::compile (ctx, expr_tyty);

      bool is_address_taken = false;
      tree ret_var_stmt = nullptr;
      tmp = ctx->get_backend ()->temporary_variable (
	fnctx.fndecl, enclosing_scope, block_type, NULL, is_address_taken,
	expr.get_locus (), &ret_var_stmt);
      ctx->add_statement (ret_var_stmt);
    }

  // lets compile the scrutinee expression
  tree match_scrutinee_expr
    = CompileExpr::Compile (expr.get_scrutinee_expr ().get (), ctx);

  // need to access the qualifier field, if we use QUAL_UNION_TYPE this would be
  // DECL_QUALIFIER i think. For now this will just access the first record
  // field and its respective qualifier because it will always be set because
  // this is all a big special union
  tree scrutinee_first_record_expr
    = ctx->get_backend ()->struct_field_expression (
      match_scrutinee_expr, 0, expr.get_scrutinee_expr ()->get_locus ());
  tree match_scrutinee_expr_qualifier_expr
    = ctx->get_backend ()->struct_field_expression (
      scrutinee_first_record_expr, 0, expr.get_scrutinee_expr ()->get_locus ());

  // setup the end label so the cases can exit properly
  tree fndecl = fnctx.fndecl;
  Location end_label_locus = expr.get_locus (); // FIXME
  tree end_label
    = ctx->get_backend ()->label (fndecl,
				  "" /* empty creates an artificial label */,
				  end_label_locus);
  tree end_label_decl_statement
    = ctx->get_backend ()->label_definition_statement (end_label);

  // setup the switch-body-block
  Location start_location; // FIXME
  Location end_location;   // FIXME
  tree enclosing_scope = ctx->peek_enclosing_scope ();
  tree switch_body_block
    = ctx->get_backend ()->block (fndecl, enclosing_scope, {}, start_location,
				  end_location);
  ctx->push_block (switch_body_block);

  for (auto &kase : expr.get_match_cases ())
    {
      // for now lets just get single pattern's working
      HIR::MatchArm &kase_arm = kase.get_arm ();
      rust_assert (kase_arm.get_patterns ().size () > 0);

      // generate implicit label
      Location arm_locus = kase_arm.get_patterns ().at (0)->get_locus ();
      tree case_label = ctx->get_backend ()->label (
	fndecl, "" /* empty creates an artificial label */, arm_locus);

      // setup the bindings for the block
      for (auto &kase_pattern : kase_arm.get_patterns ())
	{
	  tree switch_kase_expr
	    = CompilePatternCaseLabelExpr::Compile (kase_pattern.get (),
						    case_label, ctx);
	  ctx->add_statement (switch_kase_expr);

	  CompilePatternBindings::Compile (kase_pattern.get (),
					   match_scrutinee_expr, ctx);
	}

      // compile the expr and setup the assignment if required when tmp != NULL
      tree kase_expr_tree = CompileExpr::Compile (kase.get_expr ().get (), ctx);
      if (tmp != NULL)
	{
	  tree result_reference
	    = ctx->get_backend ()->var_expression (tmp, arm_locus);
	  tree assignment = ctx->get_backend ()->assignment_statement (
	    fnctx.fndecl, result_reference, kase_expr_tree, arm_locus);
	  ctx->add_statement (assignment);
	}

      // go to end label
      tree goto_end_label = build1_loc (arm_locus.gcc_location (), GOTO_EXPR,
					void_type_node, end_label);
      ctx->add_statement (goto_end_label);
    }

  // setup the switch expression
  tree match_body = ctx->pop_block ();
  tree match_expr_stmt
    = build2_loc (expr.get_locus ().gcc_location (), SWITCH_EXPR,
		  TREE_TYPE (match_scrutinee_expr_qualifier_expr),
		  match_scrutinee_expr_qualifier_expr, match_body);
  ctx->add_statement (match_expr_stmt);
  ctx->add_statement (end_label_decl_statement);

  if (tmp != NULL)
    {
      translated = ctx->get_backend ()->var_expression (tmp, expr.get_locus ());
    }
}

void
CompileExpr::visit (HIR::CallExpr &expr)
{
  TyTy::BaseType *tyty = nullptr;
  if (!ctx->get_tyctx ()->lookup_type (
	expr.get_fnexpr ()->get_mappings ().get_hirid (), &tyty))
    {
      rust_error_at (expr.get_locus (), "unknown type");
      return;
    }

  // must be a tuple constructor
  bool is_fn = tyty->get_kind () == TyTy::TypeKind::FNDEF
	       || tyty->get_kind () == TyTy::TypeKind::FNPTR;
  bool is_adt_ctor = !is_fn;
  if (is_adt_ctor)
    {
      rust_assert (tyty->get_kind () == TyTy::TypeKind::ADT);
      TyTy::ADTType *adt = static_cast<TyTy::ADTType *> (tyty);
      tree compiled_adt_type = TyTyResolveCompile::compile (ctx, tyty);

      // what variant is it?
      int union_disriminator = -1;
      TyTy::VariantDef *variant = nullptr;
      if (!adt->is_enum ())
	{
	  rust_assert (adt->number_of_variants () == 1);
	  variant = adt->get_variants ().at (0);
	}
      else
	{
	  HirId variant_id;
	  bool ok = ctx->get_tyctx ()->lookup_variant_definition (
	    expr.get_fnexpr ()->get_mappings ().get_hirid (), &variant_id);
	  rust_assert (ok);

	  ok = adt->lookup_variant_by_id (variant_id, &variant,
					  &union_disriminator);
	  rust_assert (ok);
	}

      // this assumes all fields are in order from type resolution and if a
      // base struct was specified those fields are filed via accesors
      std::vector<tree> arguments;
      for (size_t i = 0; i < expr.get_arguments ().size (); i++)
	{
	  auto &argument = expr.get_arguments ().at (i);
	  auto rvalue = CompileExpr::Compile (argument.get (), ctx);

	  // assignments are coercion sites so lets convert the rvalue if
	  // necessary
	  auto respective_field = variant->get_field_at_index (i);
	  auto expected = respective_field->get_field_type ();

	  TyTy::BaseType *actual = nullptr;
	  bool ok = ctx->get_tyctx ()->lookup_type (
	    argument->get_mappings ().get_hirid (), &actual);
	  rust_assert (ok);

	  // coerce it if required
	  rvalue = coercion_site (rvalue, actual, expected, expr.get_locus ());

	  // add it to the list
	  arguments.push_back (rvalue);
	}

      // the constructor depends on whether this is actually an enum or not if
      // its an enum we need to setup the discriminator
      std::vector<tree> ctor_arguments;
      if (adt->is_enum ())
	{
	  HirId variant_id = variant->get_id ();
	  mpz_t val;
	  mpz_init_set_ui (val, variant_id);

	  tree t = TyTyResolveCompile::get_implicit_enumeral_node_type (ctx);
	  tree qualifier
	    = double_int_to_tree (t, mpz_get_double_int (t, val, true));
	  ctor_arguments.push_back (qualifier);
	}
      for (auto &arg : arguments)
	ctor_arguments.push_back (arg);

      translated = ctx->get_backend ()->constructor_expression (
	compiled_adt_type, adt->is_enum (), ctor_arguments, union_disriminator,
	expr.get_locus ());

      return;
    }

  auto get_parameter_tyty_at_index
    = [] (const TyTy::BaseType *base, size_t index,
	  TyTy::BaseType **result) -> bool {
    bool is_fn = base->get_kind () == TyTy::TypeKind::FNDEF
		 || base->get_kind () == TyTy::TypeKind::FNPTR;
    rust_assert (is_fn);

    if (base->get_kind () == TyTy::TypeKind::FNPTR)
      {
	const TyTy::FnPtr *fn = static_cast<const TyTy::FnPtr *> (base);
	*result = fn->param_at (index);

	return true;
      }

    const TyTy::FnType *fn = static_cast<const TyTy::FnType *> (base);
    auto param = fn->param_at (index);
    *result = param.second;

    return true;
  };

  bool is_varadic = false;
  if (tyty->get_kind () == TyTy::TypeKind::FNDEF)
    {
      const TyTy::FnType *fn = static_cast<const TyTy::FnType *> (tyty);
      is_varadic = fn->is_varadic ();
    }

  size_t required_num_args;
  if (tyty->get_kind () == TyTy::TypeKind::FNDEF)
    {
      const TyTy::FnType *fn = static_cast<const TyTy::FnType *> (tyty);
      required_num_args = fn->num_params ();
    }
  else
    {
      const TyTy::FnPtr *fn = static_cast<const TyTy::FnPtr *> (tyty);
      required_num_args = fn->num_params ();
    }

  std::vector<tree> args;
  for (size_t i = 0; i < expr.get_arguments ().size (); i++)
    {
      auto &argument = expr.get_arguments ().at (i);
      auto rvalue = CompileExpr::Compile (argument.get (), ctx);

      if (is_varadic && i >= required_num_args)
	{
	  args.push_back (rvalue);
	  continue;
	}

      // assignments are coercion sites so lets convert the rvalue if
      // necessary
      bool ok;
      TyTy::BaseType *expected = nullptr;
      ok = get_parameter_tyty_at_index (tyty, i, &expected);
      rust_assert (ok);

      TyTy::BaseType *actual = nullptr;
      ok = ctx->get_tyctx ()->lookup_type (
	argument->get_mappings ().get_hirid (), &actual);
      rust_assert (ok);

      // coerce it if required
      rvalue = coercion_site (rvalue, actual, expected, expr.get_locus ());

      // add it to the list
      args.push_back (rvalue);
    }

  // must be a call to a function
  auto fn_address = CompileExpr::Compile (expr.get_fnexpr (), ctx);
  auto fncontext = ctx->peek_fn ();
  translated
    = ctx->get_backend ()->call_expression (fncontext.fndecl, fn_address, args,
					    nullptr, expr.get_locus ());
}

void
CompileExpr::visit (HIR::MethodCallExpr &expr)
{
  // method receiver
  tree self = CompileExpr::Compile (expr.get_receiver ().get (), ctx);

  // lookup the resolved name
  NodeId resolved_node_id = UNKNOWN_NODEID;
  if (!ctx->get_resolver ()->lookup_resolved_name (
	expr.get_mappings ().get_nodeid (), &resolved_node_id))
    {
      rust_error_at (expr.get_locus (), "failed to lookup resolved MethodCall");
      return;
    }

  // reverse lookup
  HirId ref;
  if (!ctx->get_mappings ()->lookup_node_to_hir (
	expr.get_mappings ().get_crate_num (), resolved_node_id, &ref))
    {
      rust_fatal_error (expr.get_locus (), "reverse lookup failure");
      return;
    }

  // lookup the expected function type
  TyTy::BaseType *lookup_fntype = nullptr;
  bool ok = ctx->get_tyctx ()->lookup_type (
    expr.get_method_name ().get_mappings ().get_hirid (), &lookup_fntype);
  rust_assert (ok);
  rust_assert (lookup_fntype->get_kind () == TyTy::TypeKind::FNDEF);
  TyTy::FnType *fntype = static_cast<TyTy::FnType *> (lookup_fntype);

  TyTy::BaseType *receiver = nullptr;
  ok = ctx->get_tyctx ()->lookup_receiver (expr.get_mappings ().get_hirid (),
					   &receiver);
  rust_assert (ok);

  bool is_dyn_dispatch
    = receiver->get_root ()->get_kind () == TyTy::TypeKind::DYNAMIC;
  bool is_generic_receiver = receiver->get_kind () == TyTy::TypeKind::PARAM;
  if (is_generic_receiver)
    {
      TyTy::ParamType *p = static_cast<TyTy::ParamType *> (receiver);
      receiver = p->resolve ();
    }

  if (is_dyn_dispatch)
    {
      const TyTy::DynamicObjectType *dyn
	= static_cast<const TyTy::DynamicObjectType *> (receiver->get_root ());

      std::vector<HIR::Expr *> arguments;
      for (auto &arg : expr.get_arguments ())
	arguments.push_back (arg.get ());

      translated = compile_dyn_dispatch_call (dyn, receiver, fntype, self,
					      arguments, expr.get_locus ());
      return;
    }

  // lookup compiled functions since it may have already been compiled
  HIR::PathExprSegment method_name = expr.get_method_name ();
  HIR::PathIdentSegment segment_name = method_name.get_segment ();
  tree fn_expr
    = resolve_method_address (fntype, ref, receiver, segment_name,
			      expr.get_mappings (), expr.get_locus ());

  // lookup the autoderef mappings
  std::vector<Resolver::Adjustment> *adjustments = nullptr;
  ok = ctx->get_tyctx ()->lookup_autoderef_mappings (
    expr.get_mappings ().get_hirid (), &adjustments);
  rust_assert (ok);

  for (auto &adjustment : *adjustments)
    {
      switch (adjustment.get_type ())
	{
	case Resolver::Adjustment::AdjustmentType::IMM_REF:
	case Resolver::Adjustment::AdjustmentType::MUT_REF:
	  self = ctx->get_backend ()->address_expression (
	    self, expr.get_receiver ()->get_locus ());
	  break;

	case Resolver::Adjustment::AdjustmentType::DEREF_REF:
	  tree expected_type
	    = TyTyResolveCompile::compile (ctx, adjustment.get_expected ());
	  self = ctx->get_backend ()->indirect_expression (
	    expected_type, self, true, /* known_valid*/
	    expr.get_receiver ()->get_locus ());
	  break;
	}
    }

  std::vector<tree> args;
  args.push_back (self); // adjusted self

  // normal args
  for (size_t i = 0; i < expr.get_arguments ().size (); i++)
    {
      auto &argument = expr.get_arguments ().at (i);
      auto rvalue = CompileExpr::Compile (argument.get (), ctx);

      // assignments are coercion sites so lets convert the rvalue if
      // necessary, offset from the already adjusted implicit self
      bool ok;
      TyTy::BaseType *expected = fntype->param_at (i + 1).second;

      TyTy::BaseType *actual = nullptr;
      ok = ctx->get_tyctx ()->lookup_type (
	argument->get_mappings ().get_hirid (), &actual);
      rust_assert (ok);

      // coerce it if required
      rvalue = coercion_site (rvalue, actual, expected, expr.get_locus ());

      // add it to the list
      args.push_back (rvalue);
    }

  auto fncontext = ctx->peek_fn ();
  translated
    = ctx->get_backend ()->call_expression (fncontext.fndecl, fn_expr, args,
					    nullptr, expr.get_locus ());
}

tree
CompileExpr::compile_dyn_dispatch_call (const TyTy::DynamicObjectType *dyn,
					TyTy::BaseType *receiver,
					TyTy::FnType *fntype, tree receiver_ref,
					std::vector<HIR::Expr *> &arguments,
					Location expr_locus)
{
  size_t offs = 0;
  const Resolver::TraitItemReference *ref = nullptr;
  for (auto &bound : dyn->get_object_items ())
    {
      const Resolver::TraitItemReference *item = bound.first;
      auto t = item->get_tyty ();
      rust_assert (t->get_kind () == TyTy::TypeKind::FNDEF);
      auto ft = static_cast<TyTy::FnType *> (t);

      if (ft->get_id () == fntype->get_id ())
	{
	  ref = item;
	  break;
	}
      offs++;
    }

  if (ref == nullptr)
    return ctx->get_backend ()->error_expression ();

  // get any indirection sorted out
  if (receiver->get_kind () == TyTy::TypeKind::REF)
    {
      TyTy::ReferenceType *r = static_cast<TyTy::ReferenceType *> (receiver);
      auto indirect_ty = r->get_base ();
      tree indrect_compiled_tyty
	= TyTyResolveCompile::compile (ctx, indirect_ty);

      tree indirect
	= ctx->get_backend ()->indirect_expression (indrect_compiled_tyty,
						    receiver_ref, true,
						    expr_locus);
      receiver_ref = indirect;
    }

  // access the offs + 1 for the fnptr and offs=0 for the reciever obj
  tree self_argument
    = ctx->get_backend ()->struct_field_expression (receiver_ref, 0,
						    expr_locus);

  // access the vtable for the fn
  tree fn_vtable_access
    = ctx->get_backend ()->struct_field_expression (receiver_ref, offs + 1,
						    expr_locus);

  // cast it to the correct fntype
  tree expected_fntype = TyTyResolveCompile::compile (ctx, fntype, true);
  tree fn_convert_expr
    = ctx->get_backend ()->convert_expression (expected_fntype,
					       fn_vtable_access, expr_locus);

  fncontext fnctx = ctx->peek_fn ();
  tree enclosing_scope = ctx->peek_enclosing_scope ();
  bool is_address_taken = false;
  tree ret_var_stmt = NULL_TREE;
  Bvariable *fn_convert_expr_tmp
    = ctx->get_backend ()->temporary_variable (fnctx.fndecl, enclosing_scope,
					       expected_fntype, fn_convert_expr,
					       is_address_taken, expr_locus,
					       &ret_var_stmt);
  ctx->add_statement (ret_var_stmt);

  std::vector<tree> args;
  args.push_back (self_argument);
  for (auto &argument : arguments)
    {
      tree compiled_expr = CompileExpr::Compile (argument, ctx);
      args.push_back (compiled_expr);
    }

  tree fn_expr
    = ctx->get_backend ()->var_expression (fn_convert_expr_tmp, expr_locus);

  return ctx->get_backend ()->call_expression (fnctx.fndecl, fn_expr, args,
					       nullptr, expr_locus);
}

tree
CompileExpr::resolve_method_address (TyTy::FnType *fntype, HirId ref,
				     TyTy::BaseType *receiver,
				     HIR::PathIdentSegment &segment,
				     Analysis::NodeMapping expr_mappings,
				     Location expr_locus)
{
  // lookup compiled functions since it may have already been compiled
  tree fn = NULL_TREE;
  if (ctx->lookup_function_decl (fntype->get_ty_ref (), &fn))
    {
      return ctx->get_backend ()->function_code_expression (fn, expr_locus);
    }

  // Now we can try and resolve the address since this might be a forward
  // declared function, generic function which has not be compiled yet or
  // its an not yet trait bound function
  HIR::ImplItem *resolved_item
    = ctx->get_mappings ()->lookup_hir_implitem (expr_mappings.get_crate_num (),
						 ref, nullptr);
  if (resolved_item != nullptr)
    {
      if (!fntype->has_subsititions_defined ())
	return CompileInherentImplItem::Compile (receiver, resolved_item, ctx,
						 true);

      return CompileInherentImplItem::Compile (receiver, resolved_item, ctx,
					       true, fntype);
    }

  // it might be resolved to a trait item
  HIR::TraitItem *trait_item = ctx->get_mappings ()->lookup_hir_trait_item (
    expr_mappings.get_crate_num (), ref);
  HIR::Trait *trait = ctx->get_mappings ()->lookup_trait_item_mapping (
    trait_item->get_mappings ().get_hirid ());

  Resolver::TraitReference *trait_ref
    = &Resolver::TraitReference::error_node ();
  bool ok = ctx->get_tyctx ()->lookup_trait_reference (
    trait->get_mappings ().get_defid (), &trait_ref);
  rust_assert (ok);

  // the type resolver can only resolve type bounds to their trait
  // item so its up to us to figure out if this path should resolve
  // to an trait-impl-block-item or if it can be defaulted to the
  // trait-impl-item's definition

  auto root = receiver->get_root ();
  std::vector<Resolver::PathProbeCandidate> candidates
    = Resolver::PathProbeType::Probe (root, segment, true, false, true);

  if (candidates.size () == 0)
    {
      // this means we are defaulting back to the trait_item if
      // possible
      Resolver::TraitItemReference *trait_item_ref = nullptr;
      bool ok = trait_ref->lookup_hir_trait_item (*trait_item, &trait_item_ref);
      rust_assert (ok);				    // found
      rust_assert (trait_item_ref->is_optional ()); // has definition

      // FIXME Optional means it has a definition and an associated
      // block which can be a default implementation, if it does not
      // contain an implementation we should actually return
      // error_mark_node

      return CompileTraitItem::Compile (receiver,
					trait_item_ref->get_hir_trait_item (),
					ctx, fntype, true, expr_locus);
    }
  else
    {
      std::vector<Resolver::Adjustment> adjustments;
      Resolver::PathProbeCandidate *candidate
	= Resolver::MethodResolution::Select (candidates, root, adjustments);

      // FIXME this will be a case to return error_mark_node, there is
      // an error scenario where a Trait Foo has a method Bar, but this
      // receiver does not implement this trait or has an incompatible
      // implementation and we should just return error_mark_node
      rust_assert (candidate != nullptr);
      rust_assert (candidate->is_impl_candidate ());

      HIR::ImplItem *impl_item = candidate->item.impl.impl_item;
      if (!fntype->has_subsititions_defined ())
	return CompileInherentImplItem::Compile (receiver, impl_item, ctx,
						 true);

      return CompileInherentImplItem::Compile (receiver, impl_item, ctx, true,
					       fntype);
    }
}

tree
CompileExpr::resolve_operator_overload (
  Analysis::RustLangItem::ItemType lang_item_type, HIR::OperatorExpr &expr,
  tree lhs, tree rhs, HIR::Expr *lhs_expr, HIR::Expr *rhs_expr)
{
  TyTy::FnType *fntype;
  bool is_op_overload = ctx->get_tyctx ()->lookup_operator_overload (
    expr.get_mappings ().get_hirid (), &fntype);
  rust_assert (is_op_overload);

  // lookup the resolved name
  NodeId resolved_node_id = UNKNOWN_NODEID;
  bool ok = ctx->get_resolver ()->lookup_resolved_name (
    expr.get_mappings ().get_nodeid (), &resolved_node_id);
  rust_assert (ok);

  // reverse lookup
  HirId ref;
  ok = ctx->get_mappings ()->lookup_node_to_hir (
    expr.get_mappings ().get_crate_num (), resolved_node_id, &ref);
  rust_assert (ok);

  TyTy::BaseType *receiver = nullptr;
  ok = ctx->get_tyctx ()->lookup_receiver (expr.get_mappings ().get_hirid (),
					   &receiver);
  rust_assert (ok);

  bool is_dyn_dispatch
    = receiver->get_root ()->get_kind () == TyTy::TypeKind::DYNAMIC;
  bool is_generic_receiver = receiver->get_kind () == TyTy::TypeKind::PARAM;
  if (is_generic_receiver)
    {
      TyTy::ParamType *p = static_cast<TyTy::ParamType *> (receiver);
      receiver = p->resolve ();
    }

  if (is_dyn_dispatch)
    {
      const TyTy::DynamicObjectType *dyn
	= static_cast<const TyTy::DynamicObjectType *> (receiver->get_root ());

      std::vector<HIR::Expr *> arguments;
      if (rhs_expr != nullptr) // can be null for negation_expr (unary ones)
	arguments.push_back (rhs_expr);

      return compile_dyn_dispatch_call (dyn, receiver, fntype, lhs, arguments,
					expr.get_locus ());
    }

  // lookup compiled functions since it may have already been compiled
  HIR::PathIdentSegment segment_name (
    Analysis::RustLangItem::ToString (lang_item_type));
  tree fn_expr
    = resolve_method_address (fntype, ref, receiver, segment_name,
			      expr.get_mappings (), expr.get_locus ());

  // lookup the autoderef mappings
  std::vector<Resolver::Adjustment> *adjustments = nullptr;
  ok = ctx->get_tyctx ()->lookup_autoderef_mappings (
    expr.get_mappings ().get_hirid (), &adjustments);
  rust_assert (ok);

  // FIXME refactor this out
  tree self = lhs;
  for (auto &adjustment : *adjustments)
    {
      switch (adjustment.get_type ())
	{
	case Resolver::Adjustment::AdjustmentType::IMM_REF:
	case Resolver::Adjustment::AdjustmentType::MUT_REF:
	  self
	    = ctx->get_backend ()->address_expression (self,
						       lhs_expr->get_locus ());
	  break;

	case Resolver::Adjustment::AdjustmentType::DEREF_REF:
	  tree expected_type
	    = TyTyResolveCompile::compile (ctx, adjustment.get_expected ());
	  self
	    = ctx->get_backend ()->indirect_expression (expected_type, self,
							true, /* known_valid*/
							lhs_expr->get_locus ());
	  break;
	}
    }

  std::vector<tree> args;
  args.push_back (self); // adjusted self
  if (rhs != nullptr)	 // can be null for negation_expr (unary ones)
    args.push_back (rhs);

  auto fncontext = ctx->peek_fn ();
  return ctx->get_backend ()->call_expression (fncontext.fndecl, fn_expr, args,
					       nullptr, expr.get_locus ());
}

} // namespace Compile
} // namespace Rust