[Sqlalchemy-tickets] Issue #4147: Incorrect handling of complex indexes by Table.tometadata (zzzeek/sqlalchemy)

[Paweł S. <iss...@bi...>]

New issue 4147: Incorrect handling of complex indexes by Table.tometadata
https://bitbucket.org/zzzeek/sqlalchemy/issues/4147/incorrect-handling-of-complex-indexes-by

Paweł Stiasny:

Current implementation Table.tometada doesn't correctly support functional and text indexes.

Consider the following test:
```diff
diff --git a/test/sql/test_metadata.py b/test/sql/test_metadata.py
index 45eb594..25ac689 100644
--- a/test/sql/test_metadata.py
+++ b/test/sql/test_metadata.py
@@ -1042,18 +1042,21 @@ class ToMetaDataTest(fixtures.TestBase, ComparesTables):
 
     def test_indexes(self):
         meta = MetaData()
 
         table = Table('mytable', meta,
                       Column('id', Integer, primary_key=True),
                       Column('data1', Integer, index=True),
                       Column('data2', Integer),
+                      Index('text', text('data1 + 1')),
                       )
-        Index('multi', table.c.data1, table.c.data2),
+        Index('multi', table.c.data1, table.c.data2)
+        Index('func', func.abs(table.c.data1))
+        Index('multi-func', table.c.data1, func.abs(table.c.data2))
 
         meta2 = MetaData()
         table_c = table.tometadata(meta2)
 
         def _get_key(i):
             return [i.name, i.unique] + \
                 sorted(i.kwargs.items()) + \
                 list(i.columns.keys())

```

* The `text` expression index is ignored
* `func` is improperly classified as the default index of a column and ignored
* In `multi-func` the second component is incorrect (should be a Function, is a Column)