Fixed bug in LEFT JOIN ... WHERE not_null_key_column=NULL;

Docs/manual.texi:
  ChangeLog
sql/field.h:
  New virtual function to set a field to null or signal an error
sql/field_conv.cc:
  New function to set a field to null or signal an error
sql/item.cc:
  When setting a field to null internally (for WHERE testing) don't autoconvert NULL -> now() or last_insert_id()
sql/item.h:
  New virtual function to set a field to null or signal an error

1 files changed, 36 insertions, 19 deletions

diff --git a/sql/field_conv.cc b/sql/field_conv.cc
index 606edd84c74..dab96a9b827 100644
--- a/sql/field_conv.cc
+++ b/sql/field_conv.cc
@@ -112,35 +112,52 @@ static void do_outer_field_to_null_str(Copy_field *copy)
 bool
 set_field_to_null(Field *field)
 {
-  if (field->maybe_null())
+  if (field->real_maybe_null())
   {
     field->set_null();
     field->reset();
+    return 0;
   }
-  else
+  return 1;
+}
+
+
+bool
+set_field_to_null_with_conversions(Field *field)
+{
+  if (field->real_maybe_null())
   {
-    if (field->type() == FIELD_TYPE_TIMESTAMP)
-    {
-      ((Field_timestamp*) field)->set_time();
-      return 0;					// Ok to set time to NULL
-    }
+    field->set_null();
     field->reset();
-    if (field == field->table->next_number_field)
-      return 0;					// field is set in handler.cc
-    if (current_thd->count_cuted_fields)
-    {
-      current_thd->cuted_fields++;		// Increment error counter
-      return 0;
-    }
-    if (!current_thd->no_errors)
-      my_printf_error(ER_BAD_NULL_ERROR,ER(ER_BAD_NULL_ERROR),MYF(0),
-		      field->field_name);
-    return 1;
+    return 0;
+  }
+
+  /*
+    Check if this is a special type, which will get a special walue
+    when set to NULL
+  */
+  if (field->type() == FIELD_TYPE_TIMESTAMP)
+  {
+    ((Field_timestamp*) field)->set_time();
+    return 0;					// Ok to set time to NULL
+  }
+  field->reset();
+  if (field == field->table->next_number_field)
+    return 0;					// field is set in handler.cc
+  if (current_thd->count_cuted_fields)
+  {
+    current_thd->cuted_fields++;		// Increment error counter
+    return 0;
   }
-  return 0;
+  if (!current_thd->no_errors)
+    my_printf_error(ER_BAD_NULL_ERROR,ER(ER_BAD_NULL_ERROR),MYF(0),
+		    field->field_name);
+  return 1;
 }
 
 
+
+
 static void do_skip(Copy_field *copy __attribute__((unused)))
 {
 }