fn parse_match_arg_attrs(attrs: &[Attribute]) -> Result<MatchArgAttrs>Expand description
Parse #[match_arg(...)] attributes from a list of syn::Attribute.
Extracts rename and rename_all keys. Validates that rename_all uses
one of the supported modes: snake_case, kebab-case, lower, upper.
Returns Err for unknown attribute keys or unsupported rename_all values.