Bug#28753085: REMOVE SELECT_LEX_UNIT::THD

Remove the public THD member from SELECT_LEX_UNIT.
Instead have the SELECT_LEX_UNIT member functions take
THD as argument if needed.

This refactoring reduces the state of SELECT_LEX_UNIT,
makes it easier to later replace THD method-by-method,
and makes THD dependencies more explicit.

Change-Id: I4ff16c5ad15748805674f8d80ccc221cc3628149

Author: jhauglid

sql/dd/info_schema/table_stats.cc

@@ -840,7 +840,7 @@ ulonglong Table_statistics::read_stat_by_open_table(
   }
 
 end:
-  lex->unit->cleanup(true);
+  lex->unit->cleanup(thd, true);
 
   /* Restore original LEX value, statement's arena and THD arena values. */
   lex_end(thd->lex);

sql/dd_sql_view.cc

@@ -103,7 +103,7 @@ class View_metadata_updater_context {
     m_thd->set_open_tables_state(&m_open_tables_state_backup);
 
     // Restore lex.
-    m_thd->lex->unit->cleanup(true);
+    m_thd->lex->unit->cleanup(m_thd, true);
     lex_end(m_thd->lex);
     delete static_cast<st_lex_local *>(m_thd->lex);
     m_thd->lex = m_saved_lex;
@@ -494,7 +494,7 @@ static bool open_views_and_update_metadata(
         order->used_alias = false;  /// @see Item::print_for_order()
     }
     Sql_mode_parse_guard parse_guard(thd);
-    thd->lex->unit->print(&view_query, QT_TO_ARGUMENT_CHARSET);
+    thd->lex->unit->print(thd, &view_query, QT_TO_ARGUMENT_CHARSET);
     if (lex_string_strmake(thd->mem_root, &view->select_stmt, view_query.ptr(),
                            view_query.length()))
       DBUG_RETURN(true);
@@ -518,15 +518,15 @@ static bool open_views_and_update_metadata(
         res = trans_commit_stmt(thd) || trans_commit(thd);
     }
     if (res) {
-      view_lex->unit->cleanup(true);
+      view_lex->unit->cleanup(thd, true);
       lex_end(view_lex);
       thd->lex = org_lex;
       DBUG_RETURN(true);
     }
     tdc_remove_table(thd, TDC_RT_REMOVE_ALL, view->get_db_name(),
                      view->get_table_name(), false);
 
-    view_lex->unit->cleanup(true);
+    view_lex->unit->cleanup(thd, true);
     lex_end(view_lex);
     thd->lex = org_lex;
   }

sql/event_data_objects.cc

@@ -1179,7 +1179,7 @@ bool Event_job_data::execute(THD *thd, bool drop) {
     }
   }
   if (save_sctx) event_sctx.restore_security_context(thd, save_sctx);
-  thd->lex->unit->cleanup(true);
+  thd->lex->unit->cleanup(thd, true);
   thd->end_statement();
   thd->cleanup_after_query();
   /* Avoid races with SHOW PROCESSLIST */

sql/item_buff.cc

@@ -1,4 +1,4 @@
-/* Copyright (c) 2000, 2017, Oracle and/or its affiliates. All rights reserved.
+/* Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved.
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License, version 2.0,
@@ -56,16 +56,16 @@ Cached_item *new_Cached_item(THD *thd, Item *item) {
   switch (item->result_type()) {
     case STRING_RESULT:
       if (item->is_temporal())
-        return new (*THR_MALLOC) Cached_item_temporal(item);
+        return new (thd->mem_root) Cached_item_temporal(item);
       if (item->data_type() == MYSQL_TYPE_JSON)
-        return new (*THR_MALLOC) Cached_item_json(item);
-      return new (*THR_MALLOC) Cached_item_str(thd, item);
+        return new (thd->mem_root) Cached_item_json(item);
+      return new (thd->mem_root) Cached_item_str(thd, item);
     case INT_RESULT:
-      return new (*THR_MALLOC) Cached_item_int(item);
+      return new (thd->mem_root) Cached_item_int(item);
     case REAL_RESULT:
-      return new (*THR_MALLOC) Cached_item_real(item);
+      return new (thd->mem_root) Cached_item_real(item);
     case DECIMAL_RESULT:
-      return new (*THR_MALLOC) Cached_item_decimal(item);
+      return new (thd->mem_root) Cached_item_decimal(item);
     case ROW_RESULT:
     default:
       DBUG_ASSERT(0);

sql/item_cmpfunc.cc

@@ -405,7 +405,7 @@ bool Item_func_not_all::empty_underlying_subquery() {
   */
   if (subselect && subselect->substype() != Item_subselect::ANY_SUBS &&
       !subselect->unit->item->is_evaluated())
-    subselect->unit->item->exec();
+    subselect->unit->item->exec(current_thd);
   return ((test_sum_item && !test_sum_item->any_value()) ||
           (test_sub_item && !test_sub_item->any_value()));
 }