PostgreSQL: COMMENT ON FUNCTION/PROCEDURE/AGGREGATE accepts argmode/argname/VARIADIC (#28)

Postgres permits argmode (IN/OUT/INOUT/VARIADIC) and argname tokens
ahead of each argument type in COMMENT ON FUNCTION / PROCEDURE /
AGGREGATE; they are ignored for identity resolution but appear in
real-world dumps and consumer schema files. The previous parser used
bare parse_data_type for the argument list, which hard-failed on those
shapes.

Switch the function-like arms of parse_comment to parse_function_arg
and project to data_type, since Statement::Comment.arguments stores a
plain Vec<DataType> and the modes/names are intentionally discarded
for identity matching.

Add tests covering argname, IN/OUT/INOUT, VARIADIC, and AGGREGATE.

Author: fmguerreiro

src/parser/mod.rs

@@ -970,9 +970,10 @@ impl<'a> Parser<'a> {
         let arguments = match object_type {
             CommentObject::Function | CommentObject::Procedure | CommentObject::Aggregate => {
                 if self.consume_token(&Token::LParen) {
-                    let list = self.parse_comma_separated0(Self::parse_data_type, Token::RParen)?;
+                    let args =
+                        self.parse_comma_separated0(Self::parse_function_arg, Token::RParen)?;
                     self.expect_token(&Token::RParen)?;
-                    Some(list)
+                    Some(args.into_iter().map(|a| a.data_type).collect())
                 } else {
                     None
                 }

tests/sqlparser_postgres.rs

@@ -10677,6 +10677,46 @@ fn parse_comment_on_function_with_arg_types() {
     }
 }
 
+#[test]
+fn parse_comment_on_function_with_argname() {
+    pg_and_generic().one_statement_parses_to(
+        "COMMENT ON FUNCTION add(a INTEGER, b INTEGER) IS 'adds'",
+        "COMMENT ON FUNCTION add(INTEGER, INTEGER) IS 'adds'",
+    );
+}
+
+#[test]
+fn parse_comment_on_function_with_argmode() {
+    pg_and_generic().one_statement_parses_to(
+        "COMMENT ON FUNCTION upsert(IN id INTEGER, OUT result TEXT) IS 'upserts'",
+        "COMMENT ON FUNCTION upsert(INTEGER, TEXT) IS 'upserts'",
+    );
+    pg_and_generic().one_statement_parses_to(
+        "COMMENT ON FUNCTION swap(INOUT a INTEGER, INOUT b INTEGER) IS 'swap'",
+        "COMMENT ON FUNCTION swap(INTEGER, INTEGER) IS 'swap'",
+    );
+}
+
+#[test]
+fn parse_comment_on_function_with_variadic() {
+    pg_and_generic().one_statement_parses_to(
+        "COMMENT ON FUNCTION concat_all(VARIADIC arr TEXT[]) IS 'joins'",
+        "COMMENT ON FUNCTION concat_all(TEXT[]) IS 'joins'",
+    );
+}
+
+#[test]
+fn parse_comment_on_aggregate_with_argname_and_variadic() {
+    pg_and_generic().one_statement_parses_to(
+        "COMMENT ON AGGREGATE my_sum(val INTEGER) IS 'sums'",
+        "COMMENT ON AGGREGATE my_sum(INTEGER) IS 'sums'",
+    );
+    pg_and_generic().one_statement_parses_to(
+        "COMMENT ON AGGREGATE concat_agg(VARIADIC arr TEXT[]) IS 'agg'",
+        "COMMENT ON AGGREGATE concat_agg(TEXT[]) IS 'agg'",
+    );
+}
+
 #[test]
 fn parse_alter_type_add_attribute() {
     let sql = "ALTER TYPE public.my_type ADD ATTRIBUTE new_attr INTEGER";