The DoubleColon cast always skips the AT TIME ZONE part, leading to strange behavior.

[dmitrybugakov]

We have discovered that during DoubleColon cast, the parser consistently skips the AT TIME ZONE part. It functions correctly only when nested.

Consider the following select statement:
"SELECT c FROM t WHERE c >= '2019-03-27T22:00:00.000Z'::timestamp AT TIME ZONE 'Europe/Brussels'"

This results in the following AST, where we attempt to cast the condition under the WHERE clause instead of only the right part:

[Statement(Query(Query { with: None, body: Select(Select { distinct: None, top: None, projection: [UnnamedExpr(Identifier(Ident { value: "c", quote_style: None }))], into: None, from: [TableWithJoins { relation: Table { name: ObjectName([Ident { value: "t", quote_style: None }]), alias: None, args: None, with_hints: [], version: None, partitions: [] }, joins: [] }], lateral_views: [], selection: Some(AtTimeZone { timestamp: BinaryOp { left: Identifier(Ident { value: "c", quote_style: None }), op: GtEq, right: Cast { expr: Value(SingleQuotedString("2019-03-27T22:00:00.000Z")), data_type: Timestamp(None, None), format: None } }, time_zone: "Europe/Brussels" }), group_by: Expressions([]), cluster_by: [], distribute_by: [], sort_by: [], having: None, named_window: [], qualify: None, value_table_mode: None }), order_by: [], limit: None, limit_by: [], offset: None, fetch: None, locks: [], for_clause: None }))]