Function is_parquet_field_match_source_schema 

pub fn is_parquet_field_match_source_schema(
    arrow_field: &Field,
    rw_data_type: &DataType,
) -> bool

Field-aware version of is_parquet_schema_match_source_schema: it inspects the field metadata to match an arrow.parquet.variant struct against Variant. A variant extension binds exclusively to Variant at every nesting depth — declaring such a column as anything else (e.g. the raw physical struct) is an illegal type mismatch, so the parser NULL-fills it instead of decoding a diverging type. Other extensions do not affect matching: decode follows the declared side, which simply ignores them. Prefer this whenever a Field is available.