Function fixed_values_equal 

pub fn fixed_values_equal(
    a: &str,
    b: &str,
    type_key: Option<TypeKey>,
    schema_set: &SchemaSet,
) -> bool

Value-space equality for fixed/default values (§3.3.4.3 clause 5.2.2.2.2, §3.2.4.4).

Fast-path lexical match; otherwise parses both strings against type_key and compares their typed values. Returns false when type_key is None or when either parse fails.