// Copyright (C) 2020-2022 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/>.

#ifndef RUST_AST_RESOLVE_ITEM_H
#define RUST_AST_RESOLVE_ITEM_H

#include "rust-ast-full-decls.h"
#include "rust-ast-resolve-base.h"
#include "rust-ast-full.h"
#include "rust-ast-resolve-toplevel.h"
#include "rust-ast-resolve-type.h"
#include "rust-ast-resolve-pattern.h"
#include "rust-ast-resolve-stmt.h"

namespace Rust {
namespace Resolver {

class ResolveTraitItems : public ResolverBase
{
  using Rust::Resolver::ResolverBase::visit;

public:
  static void go (AST::TraitItem *item, const CanonicalPath &prefix,
		  const CanonicalPath &canonical_prefix)
  {
    if (item->is_marked_for_strip ())
      return;

    ResolveTraitItems resolver (prefix, canonical_prefix);
    item->accept_vis (resolver);
  };

  void visit (AST::MacroInvocationSemi &invoc) override
  {
    AST::ASTFragment &fragment = invoc.get_fragment ();
    for (auto &node : fragment.get_nodes ())
      node.accept_vis (*this);
  }

  void visit (AST::TraitItemType &type) override
  {
    auto decl = ResolveTraitItemTypeToCanonicalPath::resolve (type);
    auto path = prefix.append (decl);
    auto cpath = canonical_prefix.append (decl);
    mappings->insert_canonical_path (mappings->get_current_crate (),
				     type.get_node_id (), cpath);

    for (auto &bound : type.get_type_param_bounds ())
      ResolveTypeBound::go (bound.get (), type.get_node_id ());
  }

  void visit (AST::TraitItemFunc &func) override
  {
    auto decl = ResolveTraitItemFunctionToCanonicalPath::resolve (func);
    auto path = prefix.append (decl);
    auto cpath = canonical_prefix.append (decl);
    mappings->insert_canonical_path (mappings->get_current_crate (),
				     func.get_node_id (), cpath);

    NodeId scope_node_id = func.get_node_id ();
    resolver->get_name_scope ().push (scope_node_id);
    resolver->get_type_scope ().push (scope_node_id);
    resolver->get_label_scope ().push (scope_node_id);
    resolver->push_new_name_rib (resolver->get_name_scope ().peek ());
    resolver->push_new_type_rib (resolver->get_type_scope ().peek ());
    resolver->push_new_label_rib (resolver->get_type_scope ().peek ());

    AST::TraitFunctionDecl &function = func.get_trait_function_decl ();
    if (function.has_generics ())
      {
	for (auto &generic : function.get_generic_params ())
	  ResolveGenericParam::go (generic.get (), func.get_node_id ());
      }

    if (function.has_return_type ())
      ResolveType::go (function.get_return_type ().get (), func.get_node_id ());

    // we make a new scope so the names of parameters are resolved and shadowed
    // correctly
    for (auto &param : function.get_function_params ())
      {
	ResolveType::go (param.get_type ().get (), param.get_node_id ());
	PatternDeclaration::go (param.get_pattern ().get (),
				param.get_node_id ());

	// the mutability checker needs to verify for immutable decls the number
	// of assignments are <1. This marks an implicit assignment
	resolver->mark_assignment_to_decl (
	  param.get_pattern ()->get_pattern_node_id (), param.get_node_id ());
      }

    if (function.has_where_clause ())
      ResolveWhereClause::Resolve (function.get_where_clause ());

    // trait items have an optional body
    if (func.has_definition ())
      ResolveExpr::go (func.get_definition ().get (), func.get_node_id (), path,
		       cpath);

    resolver->get_name_scope ().pop ();
    resolver->get_type_scope ().pop ();
    resolver->get_label_scope ().pop ();
  }

  void visit (AST::TraitItemMethod &func) override
  {
    auto decl = ResolveTraitItemMethodToCanonicalPath::resolve (func);
    auto path = prefix.append (decl);
    auto cpath = canonical_prefix.append (decl);
    mappings->insert_canonical_path (mappings->get_current_crate (),
				     func.get_node_id (), cpath);

    NodeId scope_node_id = func.get_node_id ();
    resolver->get_name_scope ().push (scope_node_id);
    resolver->get_type_scope ().push (scope_node_id);
    resolver->get_label_scope ().push (scope_node_id);
    resolver->push_new_name_rib (resolver->get_name_scope ().peek ());
    resolver->push_new_type_rib (resolver->get_type_scope ().peek ());
    resolver->push_new_label_rib (resolver->get_type_scope ().peek ());

    AST::TraitMethodDecl &function = func.get_trait_method_decl ();
    if (function.has_generics ())
      {
	for (auto &generic : function.get_generic_params ())
	  ResolveGenericParam::go (generic.get (), func.get_node_id ());
      }

    if (function.has_return_type ())
      ResolveType::go (function.get_return_type ().get (), func.get_node_id ());

    // self turns into (self: Self) as a function param
    AST::SelfParam &self_param = function.get_self_param ();
    AST::IdentifierPattern self_pattern (
      self_param.get_node_id (), "self", self_param.get_locus (),
      self_param.get_has_ref (), self_param.get_is_mut (),
      std::unique_ptr<AST::Pattern> (nullptr));

    std::vector<std::unique_ptr<AST::TypePathSegment> > segments;
    segments.push_back (std::unique_ptr<AST::TypePathSegment> (
      new AST::TypePathSegment ("Self", false, self_param.get_locus ())));

    AST::TypePath self_type_path (std::move (segments),
				  self_param.get_locus ());

    ResolveType::go (&self_type_path, self_param.get_node_id ());
    PatternDeclaration::go (&self_pattern, self_param.get_node_id ());

    resolver->mark_assignment_to_decl (self_pattern.get_node_id (),
				       self_pattern.get_node_id ());

    // we make a new scope so the names of parameters are resolved and shadowed
    // correctly
    for (auto &param : function.get_function_params ())
      {
	ResolveType::go (param.get_type ().get (), param.get_node_id ());
	PatternDeclaration::go (param.get_pattern ().get (),
				param.get_node_id ());

	// the mutability checker needs to verify for immutable decls the number
	// of assignments are <1. This marks an implicit assignment
	resolver->mark_assignment_to_decl (
	  param.get_pattern ()->get_pattern_node_id (), param.get_node_id ());
      }

    if (function.has_where_clause ())
      ResolveWhereClause::Resolve (function.get_where_clause ());

    // trait items have an optional body
    if (func.has_definition ())
      ResolveExpr::go (func.get_definition ().get (), func.get_node_id (), path,
		       cpath);

    resolver->get_name_scope ().pop ();
    resolver->get_type_scope ().pop ();
    resolver->get_label_scope ().pop ();
  }

  void visit (AST::TraitItemConst &constant) override
  {
    auto decl = ResolveTraitItemConstToCanonicalPath::resolve (constant);
    auto path = prefix.append (decl);
    auto cpath = canonical_prefix.append (decl);
    mappings->insert_canonical_path (mappings->get_current_crate (),
				     constant.get_node_id (), cpath);

    ResolveType::go (constant.get_type ().get (), constant.get_node_id ());

    if (constant.has_expr ())
      ResolveExpr::go (constant.get_expr ().get (), constant.get_node_id (),
		       path, cpath);

    // the mutability checker needs to verify for immutable decls the number
    // of assignments are <1. This marks an implicit assignment
    resolver->mark_decl_mutability (constant.get_node_id (), false);
    resolver->mark_assignment_to_decl (constant.get_node_id (),
				       constant.get_node_id ());
  }

private:
  ResolveTraitItems (const CanonicalPath &prefix,
		     const CanonicalPath &canonical_prefix)
    : ResolverBase (UNKNOWN_NODEID), prefix (prefix),
      canonical_prefix (canonical_prefix)
  {}

  const CanonicalPath &prefix;
  const CanonicalPath &canonical_prefix;
};

class ResolveItem : public ResolverBase
{
public:
  using Rust::Resolver::ResolverBase::visit;

  static void go (AST::Item *item, const CanonicalPath &prefix,
		  const CanonicalPath &canonical_prefix)
  {
    ResolveItem resolver (prefix, canonical_prefix);
    item->accept_vis (resolver);
  };

  void visit (AST::MacroInvocationSemi &invoc) override
  {
    AST::ASTFragment &fragment = invoc.get_fragment ();
    for (auto &node : fragment.get_nodes ())
      node.accept_vis (*this);
  }

  void visit (AST::TypeAlias &alias) override
  {
    auto talias = CanonicalPath::new_seg (alias.get_node_id (),
					  alias.get_new_type_name ());
    auto path = prefix.append (talias);
    auto cpath = canonical_prefix.append (talias);
    mappings->insert_canonical_path (mappings->get_current_crate (),
				     alias.get_node_id (), cpath);

    NodeId scope_node_id = alias.get_node_id ();
    resolver->get_type_scope ().push (scope_node_id);

    if (alias.has_generics ())
      {
	for (auto &generic : alias.get_generic_params ())
	  ResolveGenericParam::go (generic.get (), alias.get_node_id ());
      }

    if (alias.has_where_clause ())
      ResolveWhereClause::Resolve (alias.get_where_clause ());

    ResolveType::go (alias.get_type_aliased ().get (), alias.get_node_id ());

    resolver->get_type_scope ().pop ();
  }

  void visit (AST::Module &module) override
  {
    auto mod
      = CanonicalPath::new_seg (module.get_node_id (), module.get_name ());
    auto path = prefix.append (mod);
    auto cpath = canonical_prefix.append (mod);
    mappings->insert_canonical_path (mappings->get_current_crate (),
				     module.get_node_id (), cpath);

    NodeId scope_node_id = module.get_node_id ();
    resolver->get_name_scope ().push (scope_node_id);
    resolver->get_type_scope ().push (scope_node_id);
    resolver->get_label_scope ().push (scope_node_id);
    resolver->push_new_name_rib (resolver->get_name_scope ().peek ());
    resolver->push_new_type_rib (resolver->get_type_scope ().peek ());
    resolver->push_new_label_rib (resolver->get_type_scope ().peek ());

    for (auto &item : module.get_items ())
      ResolveTopLevel::go (item.get (), CanonicalPath::create_empty (), cpath);

    for (auto &item : module.get_items ())
      ResolveItem::go (item.get (), path, cpath);

    resolver->get_name_scope ().pop ();
    resolver->get_type_scope ().pop ();
    resolver->get_label_scope ().pop ();
  }

  void visit (AST::TupleStruct &struct_decl) override
  {
    auto decl = CanonicalPath::new_seg (struct_decl.get_node_id (),
					struct_decl.get_identifier ());
    auto path = prefix.append (decl);
    auto cpath = canonical_prefix.append (decl);
    mappings->insert_canonical_path (mappings->get_current_crate (),
				     struct_decl.get_node_id (), cpath);

    NodeId scope_node_id = struct_decl.get_node_id ();
    resolver->get_type_scope ().push (scope_node_id);

    if (struct_decl.has_generics ())
      {
	for (auto &generic : struct_decl.get_generic_params ())
	  {
	    ResolveGenericParam::go (generic.get (),
				     struct_decl.get_node_id ());
	  }
      }

    if (struct_decl.has_where_clause ())
      ResolveWhereClause::Resolve (struct_decl.get_where_clause ());

    for (AST::TupleField &field : struct_decl.get_fields ())
      {
	if (field.get_field_type ()->is_marked_for_strip ())
	  continue;

	ResolveType::go (field.get_field_type ().get (),
			 struct_decl.get_node_id ());
      }

    resolver->get_type_scope ().pop ();
  }

  void visit (AST::Enum &enum_decl) override
  {
    auto decl = CanonicalPath::new_seg (enum_decl.get_node_id (),
					enum_decl.get_identifier ());
    auto path = prefix.append (decl);
    auto cpath = canonical_prefix.append (decl);
    mappings->insert_canonical_path (mappings->get_current_crate (),
				     enum_decl.get_node_id (), cpath);

    NodeId scope_node_id = enum_decl.get_node_id ();
    resolver->get_type_scope ().push (scope_node_id);

    if (enum_decl.has_generics ())
      {
	for (auto &generic : enum_decl.get_generic_params ())
	  {
	    ResolveGenericParam::go (generic.get (), enum_decl.get_node_id ());
	  }
      }

    if (enum_decl.has_where_clause ())
      ResolveWhereClause::Resolve (enum_decl.get_where_clause ());

    /* The actual fields are inside the variants.  */
    for (auto &variant : enum_decl.get_variants ())
      ResolveItem::go (variant.get (), path, cpath);

    resolver->get_type_scope ().pop ();
  }

  /* EnumItem doesn't need to be handled, no fields.  */
  void visit (AST::EnumItem &item) override
  {
    auto decl
      = CanonicalPath::new_seg (item.get_node_id (), item.get_identifier ());
    auto path = prefix.append (decl);
    auto cpath = canonical_prefix.append (decl);
    mappings->insert_canonical_path (mappings->get_current_crate (),
				     item.get_node_id (), cpath);
  }

  void visit (AST::EnumItemTuple &item) override
  {
    auto decl
      = CanonicalPath::new_seg (item.get_node_id (), item.get_identifier ());
    auto path = prefix.append (decl);
    auto cpath = canonical_prefix.append (decl);
    mappings->insert_canonical_path (mappings->get_current_crate (),
				     item.get_node_id (), cpath);

    for (auto &field : item.get_tuple_fields ())
      {
	if (field.get_field_type ()->is_marked_for_strip ())
	  continue;

	ResolveType::go (field.get_field_type ().get (), item.get_node_id ());
      }
  }

  void visit (AST::EnumItemStruct &item) override
  {
    auto decl
      = CanonicalPath::new_seg (item.get_node_id (), item.get_identifier ());
    auto path = prefix.append (decl);
    auto cpath = canonical_prefix.append (decl);
    mappings->insert_canonical_path (mappings->get_current_crate (),
				     item.get_node_id (), cpath);

    for (auto &field : item.get_struct_fields ())
      {
	if (field.get_field_type ()->is_marked_for_strip ())
	  continue;

	ResolveType::go (field.get_field_type ().get (), item.get_node_id ());
      }
  }

  void visit (AST::EnumItemDiscriminant &item) override
  {
    auto decl
      = CanonicalPath::new_seg (item.get_node_id (), item.get_identifier ());
    auto path = prefix.append (decl);
    auto cpath = canonical_prefix.append (decl);

    mappings->insert_canonical_path (mappings->get_current_crate (),
				     item.get_node_id (), cpath);
  }

  void visit (AST::StructStruct &struct_decl) override
  {
    auto decl = CanonicalPath::new_seg (struct_decl.get_node_id (),
					struct_decl.get_identifier ());
    auto path = prefix.append (decl);
    auto cpath = canonical_prefix.append (decl);
    mappings->insert_canonical_path (mappings->get_current_crate (),
				     struct_decl.get_node_id (), cpath);

    NodeId scope_node_id = struct_decl.get_node_id ();
    resolver->get_type_scope ().push (scope_node_id);

    if (struct_decl.has_generics ())
      {
	for (auto &generic : struct_decl.get_generic_params ())
	  {
	    ResolveGenericParam::go (generic.get (),
				     struct_decl.get_node_id ());
	  }
      }

    if (struct_decl.has_where_clause ())
      ResolveWhereClause::Resolve (struct_decl.get_where_clause ());

    for (AST::StructField &field : struct_decl.get_fields ())
      {
	if (field.get_field_type ()->is_marked_for_strip ())
	  continue;

	ResolveType::go (field.get_field_type ().get (),
			 struct_decl.get_node_id ());
      }

    resolver->get_type_scope ().pop ();
  }

  void visit (AST::Union &union_decl) override
  {
    auto decl = CanonicalPath::new_seg (union_decl.get_node_id (),
					union_decl.get_identifier ());
    auto path = prefix.append (decl);
    auto cpath = canonical_prefix.append (decl);
    mappings->insert_canonical_path (mappings->get_current_crate (),
				     union_decl.get_node_id (), cpath);

    NodeId scope_node_id = union_decl.get_node_id ();
    resolver->get_type_scope ().push (scope_node_id);

    if (union_decl.has_generics ())
      {
	for (auto &generic : union_decl.get_generic_params ())
	  {
	    ResolveGenericParam::go (generic.get (), union_decl.get_node_id ());
	  }
      }

    if (union_decl.has_where_clause ())
      ResolveWhereClause::Resolve (union_decl.get_where_clause ());

    for (AST::StructField &field : union_decl.get_variants ())
      {
	if (field.get_field_type ()->is_marked_for_strip ())
	  continue;

	ResolveType::go (field.get_field_type ().get (),
			 union_decl.get_node_id ());
      }

    resolver->get_type_scope ().pop ();
  }

  void visit (AST::StaticItem &var) override
  {
    auto decl
      = CanonicalPath::new_seg (var.get_node_id (), var.get_identifier ());
    auto path = prefix.append (decl);
    auto cpath = canonical_prefix.append (decl);
    mappings->insert_canonical_path (mappings->get_current_crate (),
				     var.get_node_id (), cpath);

    ResolveType::go (var.get_type ().get (), var.get_node_id ());
    ResolveExpr::go (var.get_expr ().get (), var.get_node_id (), path, cpath);

    // the mutability checker needs to verify for immutable decls the number
    // of assignments are <1. This marks an implicit assignment
    resolver->mark_assignment_to_decl (var.get_node_id (), var.get_node_id ());
  }

  void visit (AST::ConstantItem &constant) override
  {
    auto decl = ResolveConstantItemToCanonicalPath::resolve (constant);
    auto path = prefix.append (decl);
    auto cpath = canonical_prefix.append (decl);
    mappings->insert_canonical_path (mappings->get_current_crate (),
				     constant.get_node_id (), cpath);

    ResolveType::go (constant.get_type ().get (), constant.get_node_id ());
    ResolveExpr::go (constant.get_expr ().get (), constant.get_node_id (), path,
		     cpath);

    // the mutability checker needs to verify for immutable decls the number
    // of assignments are <1. This marks an implicit assignment
    resolver->mark_decl_mutability (constant.get_node_id (), false);
    resolver->mark_assignment_to_decl (constant.get_node_id (),
				       constant.get_node_id ());
  }

  void visit (AST::Function &function) override
  {
    auto decl = ResolveFunctionItemToCanonicalPath::resolve (function);
    auto path = prefix.append (decl);
    auto cpath = canonical_prefix.append (decl);
    mappings->insert_canonical_path (mappings->get_current_crate (),
				     function.get_node_id (), cpath);

    NodeId scope_node_id = function.get_node_id ();
    resolver->get_name_scope ().push (scope_node_id);
    resolver->get_type_scope ().push (scope_node_id);
    resolver->get_label_scope ().push (scope_node_id);
    resolver->push_new_name_rib (resolver->get_name_scope ().peek ());
    resolver->push_new_type_rib (resolver->get_type_scope ().peek ());
    resolver->push_new_label_rib (resolver->get_type_scope ().peek ());

    if (function.has_generics ())
      {
	for (auto &generic : function.get_generic_params ())
	  ResolveGenericParam::go (generic.get (), function.get_node_id ());
      }

    // resolve any where clause items
    if (function.has_where_clause ())
      ResolveWhereClause::Resolve (function.get_where_clause ());

    if (function.has_return_type ())
      ResolveType::go (function.get_return_type ().get (),
		       function.get_node_id ());

    // we make a new scope so the names of parameters are resolved and shadowed
    // correctly
    for (auto &param : function.get_function_params ())
      {
	ResolveType::go (param.get_type ().get (), param.get_node_id ());
	PatternDeclaration::go (param.get_pattern ().get (),
				param.get_node_id ());

	// the mutability checker needs to verify for immutable decls the number
	// of assignments are <1. This marks an implicit assignment
	resolver->mark_assignment_to_decl (
	  param.get_pattern ()->get_pattern_node_id (), param.get_node_id ());
      }

    // resolve the function body
    ResolveExpr::go (function.get_definition ().get (), function.get_node_id (),
		     path, cpath);

    resolver->get_name_scope ().pop ();
    resolver->get_type_scope ().pop ();
    resolver->get_label_scope ().pop ();
  }

  void visit (AST::InherentImpl &impl_block) override
  {
    NodeId scope_node_id = impl_block.get_node_id ();
    resolver->get_name_scope ().push (scope_node_id);
    resolver->get_type_scope ().push (scope_node_id);
    resolver->push_new_name_rib (resolver->get_name_scope ().peek ());
    resolver->push_new_type_rib (resolver->get_type_scope ().peek ());

    if (impl_block.has_generics ())
      {
	for (auto &generic : impl_block.get_generic_params ())
	  {
	    ResolveGenericParam::go (generic.get (), impl_block.get_node_id ());
	  }
      }

    // resolve any where clause items
    if (impl_block.has_where_clause ())
      ResolveWhereClause::Resolve (impl_block.get_where_clause ());

    // FIXME this needs to be protected behind nominal type-checks see:
    // rustc --explain E0118

    CanonicalPath self_cpath = CanonicalPath::create_empty ();
    bool canonicalize_type_with_generics = false;
    NodeId resolved_node
      = ResolveType::go (impl_block.get_type ().get (),
			 impl_block.get_node_id (),
			 canonicalize_type_with_generics, &self_cpath);
    if (resolved_node == UNKNOWN_NODEID)
      {
	resolver->get_type_scope ().pop ();
	resolver->get_name_scope ().pop ();
	return;
      }

    // Setup paths
    bool canonicalize_type_args = !impl_block.has_generics ();
    bool type_resolve_generic_args = false;

    CanonicalPath impl_type
      = ResolveTypeToCanonicalPath::resolve (*impl_block.get_type ().get (),
					     canonicalize_type_args,
					     type_resolve_generic_args);
    CanonicalPath impl_prefix = prefix.append (impl_type);

    // see https://godbolt.org/z/a3vMbsT6W
    CanonicalPath cpath = CanonicalPath::create_empty ();
    if (canonical_prefix.size () <= 1)
      {
	cpath = self_cpath;
      }
    else
      {
	std::string seg_buf = "<impl " + self_cpath.get () + ">";
	CanonicalPath seg
	  = CanonicalPath::new_seg (impl_block.get_node_id (), seg_buf);
	cpath = canonical_prefix.append (seg);
      }
    // done setup paths

    auto Self
      = CanonicalPath::get_big_self (impl_block.get_type ()->get_node_id ());

    resolver->get_type_scope ().insert (Self,
					impl_block.get_type ()->get_node_id (),
					impl_block.get_type ()->get_locus ());

    for (auto &impl_item : impl_block.get_impl_items ())
      {
	resolve_impl_item (impl_item.get (), impl_prefix, cpath);
      }

    resolver->get_type_scope ().peek ()->clear_name (
      Self, impl_block.get_type ()->get_node_id ());

    resolver->get_type_scope ().pop ();
    resolver->get_name_scope ().pop ();
  }

  void visit (AST::Method &method) override
  {
    auto decl = ResolveMethodItemToCanonicalPath::resolve (method);
    auto path = prefix.append (decl);
    auto cpath = canonical_prefix.append (decl);
    mappings->insert_canonical_path (mappings->get_current_crate (),
				     method.get_node_id (), cpath);

    NodeId scope_node_id = method.get_node_id ();
    resolver->get_name_scope ().push (scope_node_id);
    resolver->get_type_scope ().push (scope_node_id);
    resolver->get_label_scope ().push (scope_node_id);
    resolver->push_new_name_rib (resolver->get_name_scope ().peek ());
    resolver->push_new_type_rib (resolver->get_type_scope ().peek ());
    resolver->push_new_label_rib (resolver->get_type_scope ().peek ());

    if (method.has_generics ())
      {
	for (auto &generic : method.get_generic_params ())
	  ResolveGenericParam::go (generic.get (), method.get_node_id ());
      }

    // resolve any where clause items
    if (method.has_where_clause ())
      ResolveWhereClause::Resolve (method.get_where_clause ());

    if (method.has_return_type ())
      ResolveType::go (method.get_return_type ().get (), method.get_node_id ());

    // self turns into (self: Self) as a function param
    AST::SelfParam &self_param = method.get_self_param ();
    AST::IdentifierPattern self_pattern (
      self_param.get_node_id (), "self", self_param.get_locus (),
      self_param.get_has_ref (), self_param.get_is_mut (),
      std::unique_ptr<AST::Pattern> (nullptr));

    std::vector<std::unique_ptr<AST::TypePathSegment> > segments;
    segments.push_back (std::unique_ptr<AST::TypePathSegment> (
      new AST::TypePathSegment ("Self", false, self_param.get_locus ())));

    AST::TypePath self_type_path (std::move (segments),
				  self_param.get_locus ());

    ResolveType::go (&self_type_path, self_param.get_node_id ());
    PatternDeclaration::go (&self_pattern, self_param.get_node_id ());

    resolver->mark_assignment_to_decl (self_pattern.get_node_id (),
				       self_pattern.get_node_id ());

    // we make a new scope so the names of parameters are resolved and shadowed
    // correctly
    for (auto &param : method.get_function_params ())
      {
	ResolveType::go (param.get_type ().get (), param.get_node_id ());
	PatternDeclaration::go (param.get_pattern ().get (),
				param.get_node_id ());

	// the mutability checker needs to verify for immutable decls the number
	// of assignments are <1. This marks an implicit assignment
	resolver->mark_assignment_to_decl (
	  param.get_pattern ()->get_pattern_node_id (), param.get_node_id ());
      }

    // resolve any where clause items
    if (method.has_where_clause ())
      ResolveWhereClause::Resolve (method.get_where_clause ());

    // resolve the function body
    ResolveExpr::go (method.get_definition ().get (), method.get_node_id (),
		     path, cpath);

    resolver->get_name_scope ().pop ();
    resolver->get_type_scope ().pop ();
    resolver->get_label_scope ().pop ();
  }

  void visit (AST::TraitImpl &impl_block) override
  {
    NodeId scope_node_id = impl_block.get_node_id ();
    resolver->get_name_scope ().push (scope_node_id);
    resolver->get_type_scope ().push (scope_node_id);
    resolver->push_new_name_rib (resolver->get_name_scope ().peek ());
    resolver->push_new_type_rib (resolver->get_type_scope ().peek ());

    if (impl_block.has_generics ())
      {
	for (auto &generic : impl_block.get_generic_params ())
	  {
	    ResolveGenericParam::go (generic.get (), impl_block.get_node_id ());
	  }
      }

    // resolve any where clause items
    if (impl_block.has_where_clause ())
      ResolveWhereClause::Resolve (impl_block.get_where_clause ());

    CanonicalPath canonical_trait_type = CanonicalPath::create_empty ();
    bool canonicalize_type_with_generics = false;
    NodeId trait_resolved_node
      = ResolveType::go (&impl_block.get_trait_path (),
			 impl_block.get_node_id (),
			 canonicalize_type_with_generics,
			 &canonical_trait_type);
    if (trait_resolved_node == UNKNOWN_NODEID)
      {
	resolver->get_type_scope ().pop ();
	resolver->get_name_scope ().pop ();
	return;
      }

    CanonicalPath canonical_impl_type = CanonicalPath::create_empty ();
    NodeId type_resolved_node
      = ResolveType::go (impl_block.get_type ().get (),
			 impl_block.get_node_id (),
			 canonicalize_type_with_generics, &canonical_impl_type);
    if (type_resolved_node == UNKNOWN_NODEID)
      {
	resolver->get_type_scope ().pop ();
	resolver->get_name_scope ().pop ();
	return;
      }

    // setup paths
    bool canonicalize_type_args = !impl_block.has_generics ();
    bool type_resolve_generic_args = false;

    CanonicalPath impl_type_seg
      = ResolveTypeToCanonicalPath::resolve (*impl_block.get_type ().get (),
					     canonicalize_type_args,
					     type_resolve_generic_args);
    CanonicalPath trait_type_seg
      = ResolveTypeToCanonicalPath::resolve (impl_block.get_trait_path (),
					     canonicalize_type_args,
					     type_resolve_generic_args);

    CanonicalPath projection
      = TraitImplProjection::resolve (impl_block.get_node_id (), trait_type_seg,
				      impl_type_seg);
    CanonicalPath impl_prefix = prefix.append (projection);

    // setup canonical-path
    CanonicalPath canonical_projection
      = TraitImplProjection::resolve (impl_block.get_node_id (),
				      canonical_trait_type,
				      canonical_impl_type);
    CanonicalPath cpath = CanonicalPath::create_empty ();
    if (canonical_prefix.size () <= 1)
      {
	cpath = canonical_projection;
      }
    else
      {
	std::string projection_str = canonical_projection.get ();
	std::string seg_buf
	  = "<impl " + projection_str.substr (1, projection_str.size () - 2)
	    + ">";
	CanonicalPath seg
	  = CanonicalPath::new_seg (impl_block.get_node_id (), seg_buf);
	cpath = canonical_prefix.append (seg);
      }

    // DONE setup canonical-path

    auto Self
      = CanonicalPath::get_big_self (impl_block.get_type ()->get_node_id ());

    resolver->get_type_scope ().insert (Self,
					impl_block.get_type ()->get_node_id (),
					impl_block.get_type ()->get_locus ());

    for (auto &impl_item : impl_block.get_impl_items ())
      {
	resolve_impl_item (impl_item.get (), impl_prefix, cpath);
      }

    resolver->get_type_scope ().peek ()->clear_name (
      Self, impl_block.get_type ()->get_node_id ());
    resolver->get_type_scope ().pop ();
  }

  void visit (AST::Trait &trait) override
  {
    NodeId scope_node_id = trait.get_node_id ();
    resolver->get_name_scope ().push (scope_node_id);
    resolver->get_type_scope ().push (scope_node_id);
    resolver->push_new_name_rib (resolver->get_name_scope ().peek ());
    resolver->push_new_type_rib (resolver->get_type_scope ().peek ());

    // we need to inject an implicit self TypeParam here
    AST::TypeParam *implicit_self
      = new AST::TypeParam ("Self", trait.get_locus ());
    trait.insert_implict_self (
      std::unique_ptr<AST::GenericParam> (implicit_self));
    CanonicalPath Self = CanonicalPath::get_big_self (trait.get_node_id ());

    for (auto &generic : trait.get_generic_params ())
      {
	ResolveGenericParam::go (generic.get (), trait.get_node_id ());
      }

    // Self is an implicit TypeParam so lets mark it as such
    resolver->get_type_scope ().append_reference_for_def (
      Self.get_node_id (), implicit_self->get_node_id ());

    if (trait.has_type_param_bounds ())
      {
	for (auto &bound : trait.get_type_param_bounds ())
	  {
	    ResolveTypeBound::go (bound.get (), trait.get_node_id ());
	  }
      }

    // resolve any where clause items
    if (trait.has_where_clause ())
      ResolveWhereClause::Resolve (trait.get_where_clause ());

    // resolve the paths
    CanonicalPath path = CanonicalPath::create_empty ();
    CanonicalPath cpath = CanonicalPath::create_empty ();
    //

    for (auto &item : trait.get_trait_items ())
      {
	ResolveTraitItems::go (item.get (), path, cpath);
      }

    resolver->get_type_scope ().pop ();
    resolver->get_name_scope ().pop ();
  }

  void visit (AST::ExternBlock &extern_block) override
  {
    for (auto &item : extern_block.get_extern_items ())
      {
	resolve_extern_item (item.get ());
      }
  }

protected:
  void resolve_impl_item (AST::TraitImplItem *item, const CanonicalPath &prefix,
			  const CanonicalPath &canonical_prefix);
  void resolve_impl_item (AST::InherentImplItem *item,
			  const CanonicalPath &prefix,
			  const CanonicalPath &canonical_prefix);
  void resolve_extern_item (AST::ExternalItem *item);

  ResolveItem (const CanonicalPath &prefix,
	       const CanonicalPath &canonical_prefix)
    : ResolverBase (UNKNOWN_NODEID), prefix (prefix),
      canonical_prefix (canonical_prefix)
  {}

  const CanonicalPath &prefix;
  const CanonicalPath &canonical_prefix;
};

class ResolveImplItems : public ResolveItem
{
  using Rust::Resolver::ResolveItem::visit;

public:
  static void go (AST::InherentImplItem *item, const CanonicalPath &prefix,
		  const CanonicalPath &canonical_prefix)
  {
    if (item->is_marked_for_strip ())
      return;

    ResolveImplItems resolver (prefix, canonical_prefix);
    item->accept_vis (resolver);
  };

  static void go (AST::TraitImplItem *item, const CanonicalPath &prefix,
		  const CanonicalPath &canonical_prefix)
  {
    if (item->is_marked_for_strip ())
      return;

    ResolveImplItems resolver (prefix, canonical_prefix);
    item->accept_vis (resolver);
  };

  void visit (AST::TypeAlias &alias) override
  {
    ResolveItem::visit (alias);

    // FIXME this stops the erronious unused decls which will be fixed later on
    resolver->get_type_scope ().append_reference_for_def (alias.get_node_id (),
							  alias.get_node_id ());
  }

private:
  ResolveImplItems (const CanonicalPath &prefix,
		    const CanonicalPath &canonical_prefix)
    : ResolveItem (prefix, canonical_prefix)
  {}
};

class ResolveExternItem : public ResolverBase
{
  using Rust::Resolver::ResolverBase::visit;

public:
  static void go (AST::ExternalItem *item)
  {
    ResolveExternItem resolver;
    item->accept_vis (resolver);
  };

  void visit (AST::ExternalFunctionItem &function) override
  {
    if (function.has_generics ())
      {
	for (auto &generic : function.get_generic_params ())
	  ResolveGenericParam::go (generic.get (), function.get_node_id ());
      }

    if (function.has_return_type ())
      ResolveType::go (function.get_return_type ().get (),
		       function.get_node_id ());

    // we make a new scope so the names of parameters are resolved and shadowed
    // correctly
    for (auto &param : function.get_function_params ())
      {
	ResolveType::go (param.get_type ().get (), param.get_node_id ());
      }
  }

  void visit (AST::ExternalStaticItem &item) override
  {
    ResolveType::go (item.get_type ().get (), item.get_node_id ());
  }

private:
  ResolveExternItem () : ResolverBase (UNKNOWN_NODEID) {}
};

} // namespace Resolver
} // namespace Rust

#endif // RUST_AST_RESOLVE_ITEM_H