Merge pull request rails#8868 from tehgeekmeister/master

Use the index name explicitly provided in a migration when reverting.

Fixes rails#8868

Conflicts:
	activerecord/CHANGELOG.md

Author: rafaelfranca

activerecord/CHANGELOG.md

@@ -1,5 +1,16 @@
 ## Rails 4.0.0 (unreleased) ##
 
+*   When `:name` option is provided to `remove_index`, use it if there is no
+    index by the conventional name.
+
+    For example, previously if an index was removed like so
+    `remove_index :values, column: :value, name: 'a_different_name'`
+    the generated SQL would not contain the specified index name,
+    and hence the migration would fail.
+    Fixes #8858.
+
+    *Ezekiel Smithburg*
+
 *   Created block to by-pass the prepared statement bindings.
     This will allow to compose fragments of large SQL statements to
     avoid multiple round-trips between Ruby and the DB.

activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb

@@ -687,6 +687,12 @@ def index_name_for_remove(table_name, options = {})
           index_name = index_name(table_name, options)
 
           unless index_name_exists?(table_name, index_name, true)
+            if options.has_key? :name
+              options_without_column = options.dup
+              options_without_column.delete :column
+              index_name_without_column = index_name(table_name, options_without_column)
+              return index_name_without_column if index_name_exists?(table_name, index_name_without_column, false)
+            end
             raise ArgumentError, "Index name '#{index_name}' on table '#{table_name}' does not exist"
           end
 

activerecord/test/cases/migration_test.rb

@@ -462,6 +462,22 @@ def test_drop_index_from_table_named_values
   end
 end
 
+class ExplicitlyNamedIndexMigrationTest < ActiveRecord::TestCase
+  def test_drop_index_by_name
+    connection = Person.connection
+    connection.create_table :values, force: true do |t|
+      t.integer :value
+    end
+
+    assert_nothing_raised ArgumentError do
+      connection.add_index :values, :value, name: 'a_different_name'
+      connection.remove_index :values, column: :value, name: 'a_different_name'
+    end
+
+    connection.drop_table :values rescue nil
+  end
+end
+
 if ActiveRecord::Base.connection.supports_bulk_alter?
   class BulkAlterTableMigrationsTest < ActiveRecord::TestCase
     def setup