fix(ir): self reference fields were incorrectly dereferenced to the p…

…arent relation

ibis/backends/tests/sql/snapshots/test_select_sql/test_self_join_subquery_distinct_equal/out.sql

@@ -1,5 +1,5 @@
 SELECT
-  t7.r_name,
+  t2.r_name,
   t7.n_name
 FROM tpch_region AS t2
 INNER JOIN tpch_nation AS t3

ibis/backends/tests/sql/snapshots/test_select_sql/test_subquery_factor_correlated_subquery/out.sql

@@ -70,7 +70,7 @@ WHERE
           ON t7.o_custkey = t6.c_custkey
       ) AS t12
       WHERE
-        t12.region = t12.region
+        t12.region = t11.region
     ) AS t13
   )
 LIMIT 10

ibis/backends/tests/sql/snapshots/test_sql/test_where_correlated_subquery/out.sql

@@ -16,6 +16,6 @@ WHERE
         t1.y
       FROM foo AS t1
       WHERE
-        t1.dept_id = t1.dept_id
+        t0.dept_id = t1.dept_id
     ) AS t2
   )

ibis/expr/operations/relations.py

@@ -205,6 +205,10 @@ def __init__(self, parent, identifier):
             identifier = next(self._uid_counter)
         super().__init__(parent=parent, identifier=identifier)
 
+    @attribute
+    def values(self):
+        return FrozenDict()
+
 
 JoinKind = Literal[
     "inner",

ibis/expr/tests/test_dereference.py

@@ -0,0 +1,25 @@
+from __future__ import annotations
+
+import ibis
+from ibis.expr.types.relations import dereference_mapping
+
+t = ibis.table(
+    [
+        ("int_col", "int32"),
+        ("double_col", "double"),
+        ("string_col", "string"),
+    ],
+    name="t",
+)
+
+
+def dereference_expect(expected):
+    return {k.op(): v.op() for k, v in expected.items()}
+
+
+def test_dereference_mapping_self_reference():
+    v = t.view()
+
+    mapping = dereference_mapping([v.op()])
+    expected = dereference_expect({})
+    assert mapping == expected