Fix `add_index` to normalize column names and options

Currently does not work the following code.

```ruby
  add_index(:people, ["last_name", "first_name"], order: { last_name: :desc, first_name: :asc })
```

Normalize column names and options to fix the issue.

2 files changed, 3 insertions, 1 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb b/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
index 29520ed9c8..6146be436d 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
@@ -1171,6 +1171,7 @@ module ActiveRecord
           if order = options[:order]
             case order
             when Hash
+              order = order.symbolize_keys
               quoted_columns.each { |name, column| column << " #{order[name].upcase}" if order[name].present? }
             when String
               quoted_columns.each { |name, column| column << " #{order.upcase}" if order.present? }
@@ -1192,7 +1193,7 @@ module ActiveRecord
         def quoted_columns_for_index(column_names, **options)
           return [column_names] if column_names.is_a?(String)
 
-          quoted_columns = Hash[column_names.map { |name| [name, quote_column_name(name).dup] }]
+          quoted_columns = Hash[column_names.map { |name| [name.to_sym, quote_column_name(name).dup] }]
           add_options_for_index_columns(quoted_columns, options).values
         end
 
diff --git a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
index be8511f119..fd8cb5d7c3 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
@@ -718,6 +718,7 @@ module ActiveRecord
           if length = options[:length]
             case length
             when Hash
+              length = length.symbolize_keys
               quoted_columns.each { |name, column| column << "(#{length[name]})" if length[name].present? }
             when Integer
               quoted_columns.each { |name, column| column << "(#{length})" }