WL#2486 - natural and using join according to SQL:2003

- Corrected problem with N-way nested natural joins in PS mode.
- Code cleanup
- More asserts to check consistency of name resolution contexts
- Fixed potential memory leak of name resolution contexts


mysql-test/r/join.result:
  - Corrected problem with N-way nested natural joins in PS mode.
mysql-test/t/join.test:
  - Corrected problem with N-way nested natural joins in PS mode.
sql/item.h:
  - Fixed potential memory leak.
sql/sql_base.cc:
  - the local context of Item_fields that participate in TABLE_LIST::on_cond for
    natural joins is correctly set to the tables where the corresponding fields
    originate from.
  - removed unused variables
  - correct allocation of contexts
sql/sql_parse.cc:
  - correct allocation of contexts for JOIN ON conditions.
sql/table.cc:
  - added asserts to check the consistency of name resolution contexts
sql/table.h:
  - added asserts to check the consistency of name resolution contexts

1 files changed, 38 insertions, 12 deletions

diff --git a/sql/table.cc b/sql/table.cc
index baf44680807..beecd6442e8 100644
--- a/sql/table.cc
+++ b/sql/table.cc
@@ -2296,6 +2296,7 @@ Natural_join_column::Natural_join_column(Field_translator *field_param,
 Natural_join_column::Natural_join_column(Field *field_param,
                                          TABLE_LIST *tab)
 {
+  DBUG_ASSERT(tab->table == field_param->table);
   table_field= field_param;
   view_field= NULL;
   table_ref= tab;
@@ -2514,6 +2515,18 @@ void Field_iterator_natural_join::set(TABLE_LIST *table_ref)
 }
 
 
+void Field_iterator_natural_join::next()
+{
+  cur_column_ref= (*column_ref_it)++;
+  DBUG_ASSERT(cur_column_ref ?
+              (cur_column_ref->table_field ?
+               cur_column_ref->table_ref->table ==
+               cur_column_ref->table_field->table :
+               TRUE) :
+              TRUE);
+}
+
+
 void Field_iterator_table_ref::set_field_iterator()
 {
   DBUG_ENTER("Field_iterator_table_ref::set_field_iterator");
@@ -2660,18 +2673,31 @@ Field_iterator_table_ref::get_or_create_column_ref(THD *thd, bool *is_created)
 
   *is_created= TRUE;
   if (field_it == &table_field_it)
-    return new Natural_join_column(table_field_it.field(), table_ref);
-  if (field_it == &view_field_it)
-    return new Natural_join_column(view_field_it.field_translator(),
-                                   table_ref);
-
-  /*
-    This is NATURAL join, we already have created a column reference,
-    so just return it.
-  */
-  *is_created= FALSE;
-  nj_col= natural_join_it.column_ref();
-  DBUG_ASSERT(nj_col);
+  {
+    /* The field belongs to a stored table. */
+    Field *field= table_field_it.field();
+    nj_col= new Natural_join_column(field, table_ref);
+  }
+  else if (field_it == &view_field_it)
+  {
+    /* The field belongs to a merge view or information schema table. */
+    Field_translator *translated_field= view_field_it.field_translator();
+    nj_col= new Natural_join_column(translated_field, table_ref);
+  }
+  else
+  {
+    /*
+      The field belongs to a NATURAL join, therefore the column reference was
+      already created via one of the two constructor calls above. In this case
+      we just return the already created column reference.
+    */
+    *is_created= FALSE;
+    nj_col= natural_join_it.column_ref();
+    DBUG_ASSERT(nj_col);
+  }
+  DBUG_ASSERT(nj_col->table_field ?
+              nj_col->table_ref->table == nj_col->table_field->table :
+              TRUE);
   return nj_col;
 }