Drush 7 compatibility for CiviCRM < 4.5.6 - from https://github.com/omega8cc/boa/issues/410#issuecomment-72892940

civicrm-drush7-compatibility.patch

diff -burp a/drupal/drush/civicrm.drush.inc b/drupal/drush/civicrm.drush.inc
--- a/drupal/drush/civicrm.drush.inc	2014-09-18 11:46:17.000000000 +0000
+++ b/drupal/drush/civicrm.drush.inc	2015-02-04 16:13:25.000000000 +0000
@@ -257,6 +257,20 @@ function civicrm_drush_command() {
  * Implementation of drush_hook_COMMAND_validate for command 'civicrm-install'
  */
 function drush_civicrm_install_validate() {
+
+  switch (substr(drush_core_version(), 0, 1)) {
+    case '7':
+      $sql = drush_get_class('Drush\Sql\Sql', array(), array(drush_drupal_major_version()));
+      $db_spec = $sql->get_db_spec();
+      break;
+    case '6':
+    case '5':
+      $db_spec = _drush_sql_get_db_spec();
+      break;
+    default:
+      drush_set_error('DRUSH_UNSUPPORTED_VERSION', dt('Drush !version is not supported'));
+  }
+
   // TODO: Replace these with required options (Drush 5).
   // Get the drupal credentials in case civi specific db info is not passed.
   if (drush_get_option('db-url', FALSE)) {
@@ -445,7 +459,19 @@ function _civicrm_generate_settings_file
   }

   $baseUrl = !$baseUrl ? ($GLOBALS['base_url']) : ($protocol . '://' . $baseUrl);
+
+  switch (substr(drush_core_version(), 0, 1)) {
+    case '7':
+      $sql = drush_get_class('Drush\Sql\Sql', array(), array(drush_drupal_major_version()));
+      $db_spec = $sql->get_db_spec();
+      break;
+    case '6':
+    case '5':
   $db_spec = _drush_sql_get_db_spec();
+      break;
+    default:
+      drush_set_error('DRUSH_UNSUPPORTED_VERSION', dt('Drush !version is not supported'));
+  }

   // Check version: since 4.1, Drupal6 must be used for the UF in D6
   // The file civicrm-version.php appeared around 4.0, so it is safe to assume
@@ -961,7 +987,19 @@ function drush_civicrm_restore() {
   $restore_backup_dir = rtrim($restore_backup_dir, '/');

   // get confirmation from user -
+  switch (substr(drush_core_version(), 0, 1)) {
+    case '7':
+      $sql = drush_get_class('Drush\Sql\Sql', array(), array(drush_drupal_major_version()));
+      $db_spec = $sql->get_db_spec();
+      break;
+    case '6':
+    case '5':
   $db_spec = _drush_sql_get_db_spec();
+      break;
+    default:
+      drush_set_error('DRUSH_UNSUPPORTED_VERSION', dt('Drush !version is not supported'));
+  }
+
   drush_print(dt("\nProcess involves :"));
   drush_print(dt("1. Restoring '\$restore-dir/civicrm' directory to '!toDir'.", array('!toDir' => $civicrm_root_base)));
   drush_print(dt("2. Dropping and creating '!db' database.", array('!db' => $db_spec['database'])));