Library fails to parse function

[LucaCappelletti94]

Attempting to parse a function such as the following, which in PostgreSQL works fine, currently fails with ParserError("Expected: ), found: INT")

CREATE OR REPLACE FUNCTION check_values_different(int1 INT, int2 INT) RETURNS BOOLEAN AS $$
BEGIN
    IF int1 <> int2 THEN
        RETURN TRUE;
    ELSE
        RETURN FALSE;
    END IF;
END;
$$ LANGUAGE plpgsql;

Surprisingly enough, the following instead works:

CREATE OR REPLACE FUNCTION check_strings_different(str1 VARCHAR, str2 VARCHAR) RETURNS BOOLEAN AS $$
BEGIN
    IF str1 <> str2 THEN
        RETURN TRUE;
    ELSE
        RETURN FALSE;
    END IF;
END;
$$ LANGUAGE plpgsql;

And even more weird, the following works, so it must be something regarding the name of the attribute int1 and int2 colliding with a type:

CREATE OR REPLACE FUNCTION check_values_different(a INT, b INT) RETURNS BOOLEAN AS $$
BEGIN
    IF a <> b THEN
        RETURN TRUE;
    ELSE
        RETURN FALSE;
    END IF;
END;
$$ LANGUAGE plpgsql;

I will try to fix this error in a PR soon.