Initialze #alias_tracker with base table name

Instead of initializing an empty connection use the base table name
instead. Split up and refactor `#create` to be 2 methods `#create` and
`#create_with_joins`. Removes the need to update the count by 1 on
initialzing a JoinDependency.

activerecord/lib/active_record/associations/alias_tracker.rb

@@ -7,18 +7,21 @@ module Associations
     class AliasTracker # :nodoc:
       attr_reader :aliases
 
-      def self.empty(connection)
-        new connection, Hash.new(0)
+      def self.create(connection, initial_table)
+        aliases = Hash.new(0)
+        aliases[initial_table] = 1
+        new connection, aliases
       end
 
-      def self.create(connection, table_joins)
-        if table_joins.empty?
-          empty connection
+      def self.create_with_joins(connection, initial_table, joins, type_caster)
+        if joins.empty?
+          create(connection, initial_table, type_caster)
         else
-          aliases = Hash.new { |h,k|
-            h[k] = initial_count_for(connection, k, table_joins)
+          aliases = Hash.new { |h, k|
+            h[k] = initial_count_for(connection, k, joins)
           }
-          new connection, aliases
+          aliases[initial_table] = 1
+          new connection, aliases, type_caster
         end
       end
 

activerecord/lib/active_record/associations/association_scope.rb

@@ -126,7 +126,6 @@ def initialize(reflection, alias_name)
       def get_chain(refl, association, tracker)
         name = refl.name
         runtime_reflection = ActiveRecord::Reflection::RuntimeReflection.new(refl, association)
-        alias_name = tracker.aliased_table_for(runtime_reflection.table_name, runtime_reflection.alias_candidate(name))
         prev = runtime_reflection
         refl.chain.drop(1).each { |reflection|
           alias_name = tracker.aliased_table_for(reflection.table_name, reflection.alias_candidate(name))

activerecord/lib/active_record/associations/join_dependency.rb

@@ -93,8 +93,7 @@ def self.walk_tree(associations, hash)
       #    joins # =>  []
       #
       def initialize(base, associations, joins)
-        @alias_tracker = AliasTracker.create(base.connection, joins)
-        @alias_tracker.aliased_table_for(base.table_name, base.table_name, type_caster: base.type_caster) # Updates the count for base.table_name to 1
+        @alias_tracker = AliasTracker.create_with_joins(base.connection, base.table_name, joins)
         tree = self.class.make_tree associations
         @join_root = JoinBase.new base, build(tree, base)
         @join_root.children.each { |child| construct_tables! @join_root, child }