Fixed MDEV-16512, crashing on re-execution of failing SP

MDEV-16512 Server crashes in find_field_in_table_ref on 2nd
execution of SP referring to non-existing field

Problem was in the natural join code that it changed TABLE_LIST and
Item_fields but didn't restore changed things if things goes wrong
and was not able to re-execute after failure.
Some of the problems could have been avoided if we would have run
fix_fields before doing natural join transformations.

Fixed by marking functions complete AFTER they had executed, instead at
start.
I had also to change some tests that checked if Item_fields are usable.

This doesn't fix all known problems, but at least avoids some crashes.
What should be done in the near future is to mark the statement in the SP
as 'not re-executable' and force a reparse of it on next execution.

Reviewer: Sergei Petrunia <psergey@askmonty.org>

2 files changed, 10 insertions, 8 deletions

diff --git a/sql/sql_base.cc b/sql/sql_base.cc
index 71bbb538b5c..8ffb7bc118b 100644
--- a/sql/sql_base.cc
+++ b/sql/sql_base.cc
@@ -7687,6 +7687,7 @@ store_natural_using_join_columns(THD *thd, TABLE_LIST *natural_using_join,
   Query_arena *arena, backup;
   bool result= TRUE;
   List<Natural_join_column> *non_join_columns;
+  List<Natural_join_column> *join_columns;
   DBUG_ENTER("store_natural_using_join_columns");
 
   DBUG_ASSERT(!natural_using_join->join_columns);
@@ -7694,7 +7695,7 @@ store_natural_using_join_columns(THD *thd, TABLE_LIST *natural_using_join,
   arena= thd->activate_stmt_arena_if_needed(&backup);
 
   if (!(non_join_columns= new List<Natural_join_column>) ||
-      !(natural_using_join->join_columns= new List<Natural_join_column>))
+      !(join_columns= new List<Natural_join_column>))
     goto err;
 
   /* Append the columns of the first join operand. */
@@ -7703,7 +7704,7 @@ store_natural_using_join_columns(THD *thd, TABLE_LIST *natural_using_join,
     nj_col_1= it_1.get_natural_column_ref();
     if (nj_col_1->is_common)
     {
-      natural_using_join->join_columns->push_back(nj_col_1);
+      join_columns->push_back(nj_col_1);
       /* Reset the common columns for the next call to mark_common_columns. */
       nj_col_1->is_common= FALSE;
     }
@@ -7724,7 +7725,7 @@ store_natural_using_join_columns(THD *thd, TABLE_LIST *natural_using_join,
     {
       const char *using_field_name_ptr= using_field_name->c_ptr();
       List_iterator_fast<Natural_join_column>
-        it(*(natural_using_join->join_columns));
+        it(*join_columns);
       Natural_join_column *common_field;
 
       for (;;)
@@ -7757,7 +7758,8 @@ store_natural_using_join_columns(THD *thd, TABLE_LIST *natural_using_join,
   }
 
   if (non_join_columns->elements > 0)
-    natural_using_join->join_columns->concat(non_join_columns);
+    join_columns->concat(non_join_columns);
+  natural_using_join->join_columns= join_columns;
   natural_using_join->is_join_columns_complete= TRUE;
 
   result= FALSE;
@@ -7989,7 +7991,6 @@ static bool setup_natural_join_row_types(THD *thd,
     DBUG_PRINT("info", ("using cached setup_natural_join_row_types"));
     DBUG_RETURN(false);
   }
-  context->select_lex->first_natural_join_processing= false;
 
   List_iterator_fast<TABLE_LIST> table_ref_it(*from_clause);
   TABLE_LIST *table_ref; /* Current table reference. */
@@ -8034,6 +8035,7 @@ static bool setup_natural_join_row_types(THD *thd,
     change on re-execution
   */
   context->natural_join_first_table= context->first_name_resolution_table;
+  context->select_lex->first_natural_join_processing= false;
   DBUG_RETURN (false);
 }
 
diff --git a/sql/table.cc b/sql/table.cc
index 87a249defa0..48aa445e1aa 100644
--- a/sql/table.cc
+++ b/sql/table.cc
@@ -5487,7 +5487,7 @@ Field_iterator_table_ref::get_or_create_column_ref(THD *thd, TABLE_LIST *parent_
     nj_col= natural_join_it.column_ref();
     DBUG_ASSERT(nj_col);
   }
-  DBUG_ASSERT(!nj_col->table_field ||
+  DBUG_ASSERT(!nj_col->table_field || !nj_col->table_field->field ||
               nj_col->table_ref->table == nj_col->table_field->field->table);
 
   /*
@@ -5536,7 +5536,7 @@ Field_iterator_table_ref::get_or_create_column_ref(THD *thd, TABLE_LIST *parent_
 
   RETURN
     #     Pointer to a column of a natural join (or its operand)
-    NULL  No memory to allocate the column
+    NULL  We didn't originally have memory to allocate the column
 */
 
 Natural_join_column *
@@ -5552,7 +5552,7 @@ Field_iterator_table_ref::get_natural_column_ref()
   */
   nj_col= natural_join_it.column_ref();
   DBUG_ASSERT(nj_col &&
-              (!nj_col->table_field ||
+              (!nj_col->table_field || !nj_col->table_field->field ||
                nj_col->table_ref->table == nj_col->table_field->field->table));
   return nj_col;
 }