feat: support tailing commas on snowflake dialect. (apache#1205)

Author: ya7010

src/parser/mod.rs

@@ -2946,14 +2946,15 @@ impl<'a> Parser<'a> {
 
     /// Parse a comma-separated list of 1+ SelectItem
     pub fn parse_projection(&mut self) -> Result<Vec<SelectItem>, ParserError> {
-        // BigQuery allows trailing commas, but only in project lists
+        // BigQuery and Snowflake allow trailing commas, but only in project lists
         // e.g. `SELECT 1, 2, FROM t`
         // https://cloud.google.com/bigquery/docs/reference/standard-sql/lexical#trailing_commas
+        // https://docs.snowflake.com/en/release-notes/2024/8_11#select-supports-trailing-commas
         //
         // This pattern could be captured better with RAII type semantics, but it's quite a bit of
         // code to add for just one case, so we'll just do it manually here.
         let old_value = self.options.trailing_commas;
-        self.options.trailing_commas |= dialect_of!(self is BigQueryDialect);
+        self.options.trailing_commas |= dialect_of!(self is BigQueryDialect | SnowflakeDialect);
 
         let ret = self.parse_comma_separated(|p| p.parse_select_item());
         self.options.trailing_commas = old_value;

tests/sqlparser_snowflake.rs

@@ -1536,3 +1536,8 @@ fn parse_comma_outer_join() {
         "SELECT t1.c1, t2.c2 FROM t1, t2 WHERE t1.c1 = t2.c2 (+)",
     );
 }
+
+#[test]
+fn test_sf_trailing_commas() {
+    snowflake().verified_only_select_with_canonical("SELECT 1, 2, FROM t", "SELECT 1, 2 FROM t");
+}