From fea3299e309655903aa5c54e5819096fc01ce88e Mon Sep 17 00:00:00 2001
From: Jo <46752250+GeorgeSittas@users.noreply.github.com>
Date: Wed, 14 Jun 2023 20:17:44 +0300
Subject: [PATCH] Fix(parser): don't parse an alias for non-source UNNESTs
 (#1774)

* Fix(parser): don't parse an alias for non-source UNNESTs

* Add test
---
 sqlglot/parser.py               | 7 ++++---
 tests/dialects/test_bigquery.py | 1 +
 tests/test_parser.py            | 5 +++++
 3 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/sqlglot/parser.py b/sqlglot/parser.py
index 651baec0e7..556ce260c2 100644
--- a/sqlglot/parser.py
+++ b/sqlglot/parser.py
@@ -2346,13 +2346,14 @@ def _parse_table(
 
         return this
 
-    def _parse_unnest(self) -> t.Optional[exp.Unnest]:
+    def _parse_unnest(self, with_alias: bool = True) -> t.Optional[exp.Unnest]:
         if not self._match(TokenType.UNNEST):
             return None
 
         expressions = self._parse_wrapped_csv(self._parse_type)
         ordinality = self._match_pair(TokenType.WITH, TokenType.ORDINALITY)
-        alias = self._parse_table_alias()
+
+        alias = self._parse_table_alias() if with_alias else None
 
         if alias and self.UNNEST_COLUMN_ONLY:
             if alias.args.get("columns"):
@@ -2792,7 +2793,7 @@ def _parse_is(self, this: t.Optional[exp.Expression]) -> t.Optional[exp.Expressi
         return self.expression(exp.Not, this=this) if negate else this
 
     def _parse_in(self, this: t.Optional[exp.Expression], alias: bool = False) -> exp.In:
-        unnest = self._parse_unnest()
+        unnest = self._parse_unnest(with_alias=False)
         if unnest:
             this = self.expression(exp.In, this=this, unnest=unnest)
         elif self._match(TokenType.L_PAREN):
diff --git a/tests/dialects/test_bigquery.py b/tests/dialects/test_bigquery.py
index 801b1f7325..26980573e3 100644
--- a/tests/dialects/test_bigquery.py
+++ b/tests/dialects/test_bigquery.py
@@ -6,6 +6,7 @@ class TestBigQuery(Validator):
     dialect = "bigquery"
 
     def test_bigquery(self):
+        self.validate_identity("SELECT foo IN UNNEST(bar) AS bla")
         self.validate_identity("SELECT * FROM x-0.a")
         self.validate_identity("SELECT * FROM pivot CROSS JOIN foo")
         self.validate_identity("SAFE_CAST(x AS STRING)")
diff --git a/tests/test_parser.py b/tests/test_parser.py
index 897357f0cf..96192cdbb3 100644
--- a/tests/test_parser.py
+++ b/tests/test_parser.py
@@ -81,6 +81,11 @@ def test_column(self):
     def test_float(self):
         self.assertEqual(parse_one(".2"), parse_one("0.2"))
 
+    def test_unnest_projection(self):
+        expr = parse_one("SELECT foo IN UNNEST(bla) AS bar")
+        self.assertIsInstance(expr.selects[0], exp.Alias)
+        self.assertEqual(expr.selects[0].output_name, "bar")
+
     def test_unary_plus(self):
         self.assertEqual(parse_one("+15"), exp.Literal.number(15))