fix: unnest join constraint with alias parsing for BigQuery dialect (#732)

* fix: unnest join constraint with alias parsing for BigQuery dialect

* chore: fix failing tests

Author: Ziinc

src/parser.rs

@@ -5291,12 +5291,15 @@ impl<'a> Parser<'a> {
                 Err(_) => false,
             };
 
-            let with_offset_alias =
+            let with_offset_alias = if with_offset {
                 match self.parse_optional_alias(keywords::RESERVED_FOR_COLUMN_ALIAS) {
                     Ok(Some(alias)) => Some(alias),
                     Ok(None) => None,
                     Err(e) => return Err(e),
-                };
+                }
+            } else {
+                None
+            };
 
             Ok(TableFactor::UNNEST {
                 alias,

tests/sqlparser_bigquery.rs

@@ -94,6 +94,34 @@ fn parse_table_identifiers() {
     test_table_ident("abc5.GROUP", vec![Ident::new("abc5"), Ident::new("GROUP")]);
 }
 
+#[test]
+fn parse_join_constraint_unnest_alias() {
+    assert_eq!(
+        only(
+            bigquery()
+                .verified_only_select("SELECT * FROM t1 JOIN UNNEST(t1.a) AS f ON c1 = c2")
+                .from
+        )
+        .joins,
+        vec![Join {
+            relation: TableFactor::UNNEST {
+                alias: table_alias("f"),
+                array_expr: Box::new(Expr::CompoundIdentifier(vec![
+                    Ident::new("t1"),
+                    Ident::new("a")
+                ])),
+                with_offset: false,
+                with_offset_alias: None
+            },
+            join_operator: JoinOperator::Inner(JoinConstraint::On(Expr::BinaryOp {
+                left: Box::new(Expr::Identifier("c1".into())),
+                op: BinaryOperator::Eq,
+                right: Box::new(Expr::Identifier("c2".into())),
+            })),
+        }]
+    );
+}
+
 #[test]
 fn parse_trailing_comma() {
     for (sql, canonical) in [

tests/sqlparser_common.rs

@@ -3683,25 +3683,6 @@ fn parse_unnest() {
             joins: vec![],
         }],
     );
-    // 5. WITH OFFSET and WITH OFFSET Alias
-    chk(
-        true,
-        false,
-        true,
-        &dialects,
-        vec![TableWithJoins {
-            relation: TableFactor::UNNEST {
-                alias: Some(TableAlias {
-                    name: Ident::new("numbers"),
-                    columns: vec![],
-                }),
-                array_expr: Box::new(Expr::Identifier(Ident::new("expr"))),
-                with_offset: false,
-                with_offset_alias: Some(Ident::new("with_offset_alias")),
-            },
-            joins: vec![],
-        }],
-    );
 }
 
 #[test]