Function detect_variant_from_bytes 

pub fn detect_variant_from_bytes<'a>(
    layout: &'a LayoutData<RustcFieldIdx, RustcEnumVariantIdx>,
    db: &(dyn HirDatabase + 'static),
    target_data_layout: &TargetDataLayout,
    b: &[u8],
    e: EnumId,
) -> Option<(EnumVariantId, &'a LayoutData<RustcFieldIdx, RustcEnumVariantIdx>)>