Fix for bug#23113: Different behavior on altering ENUM fields between 5.0 and 5.1

Problem: mysqld doesn't detect that enum data must be reinserted performing
'ALTER TABLE' in some cases.

Fix: reinsert data altering an enum field if enum values are changed.


mysql-test/r/alter_table.result:
  Fix for bug#23113: Different behavior on altering ENUM fields between 5.0 and 5.1
    - test result.
mysql-test/t/alter_table.test:
  Fix for bug#23113: Different behavior on altering ENUM fields between 5.0 and 5.1
    - test case.
sql/field.cc:
  Fix for bug#23113: Different behavior on altering ENUM fields between 5.0 and 5.1
    - Field_enum::is_equal() introduced, which is called to detect that a field
  is changing by 'ALTER TABLE'.
sql/field.h:
  Fix for bug#23113: Different behavior on altering ENUM fields between 5.0 and 5.1
    - Field_enum::is_equal() introduced, which is called to detect that a field
  is changing by 'ALTER TABLE'.

1 files changed, 25 insertions, 10 deletions

diff --git a/sql/field.cc b/sql/field.cc
index 16bf0fdb070..a03beb4e8af 100644
--- a/sql/field.cc
+++ b/sql/field.cc
@@ -8783,28 +8783,43 @@ bool Field::eq_def(Field *field)
   return 1;
 }
 
+
 /**
   @return
   returns 1 if the fields are equally defined
 */
+
 bool Field_enum::eq_def(Field *field)
 {
   if (!Field::eq_def(field))
     return 0;
-  TYPELIB *from_lib=((Field_enum*) field)->typelib;
+  return compare_enum_values(((Field_enum*) field)->typelib);
+}
 
-  if (typelib->count < from_lib->count)
-    return 0;
-  for (uint i=0 ; i < from_lib->count ; i++)
+
+bool Field_enum::compare_enum_values(TYPELIB *values)
+{
+  if (typelib->count != values->count)
+    return FALSE;
+  for (uint i= 0; i < typelib->count; i++)
     if (my_strnncoll(field_charset,
-                     (const uchar*)typelib->type_names[i],
-                     strlen(typelib->type_names[i]),
-                     (const uchar*)from_lib->type_names[i],
-                     strlen(from_lib->type_names[i])))
-      return 0;
-  return 1;
+                     (const uchar*) typelib->type_names[i],
+                     typelib->type_lengths[i],
+                     (const uchar*) values->type_names[i],
+                     values->type_lengths[i]))
+      return FALSE;
+  return TRUE;
+}
+
+
+uint Field_enum::is_equal(Create_field *new_field)
+{
+  if (!Field_str::is_equal(new_field))
+    return 0;
+  return compare_enum_values(new_field->interval);
 }
 
+
 /**
   @return
   returns 1 if the fields are equally defined