fix(trino): ensure that nested array types are inferred correctly

ibis/backends/tests/test_array.py

@@ -186,7 +186,7 @@ def test_array_index(con, idx):
 
 @builtin_array
 @pytest.mark.never(
-    ["clickhouse", "duckdb", "pandas", "pyspark", "snowflake", "polars"],
+    ["clickhouse", "duckdb", "pandas", "pyspark", "snowflake", "polars", "trino"],
     reason="backend does not flatten array types",
     raises=AssertionError,
 )
@@ -255,11 +255,6 @@ def test_array_discovery_clickhouse(backend):
     reason="backend does not support nullable nested types",
     raises=AssertionError,
 )
-@pytest.mark.notimpl(
-    ["trino"],
-    reason="trino supports nested arrays, but not with the postgres connector",
-    raises=AssertionError,
-)
 @pytest.mark.never(
     ["bigquery"],
     reason="doesn't support arrays of arrays",

ibis/backends/trino/__init__.py

@@ -12,6 +12,7 @@
 import ibis.expr.datatypes as dt
 from ibis import util
 from ibis.backends.base.sql.alchemy import BaseAlchemyBackend
+from ibis.backends.base.sql.alchemy.datatypes import ArrayType
 from ibis.backends.trino.compiler import TrinoSQLCompiler
 from ibis.backends.trino.datatypes import ROW, parse
 
@@ -85,6 +86,10 @@ def _new_sa_metadata():
         def column_reflect(inspector, table, column_info):
             if isinstance(typ := column_info["type"], _ROW):
                 column_info["type"] = ROW(typ.attr_types)
+            elif isinstance(typ, sa.ARRAY):
+                column_info["type"] = toolz.nth(
+                    typ.dimensions or 1, toolz.iterate(ArrayType, typ.item_type)
+                )
 
         return meta