Function rustc_trait_selection::infer::error_reporting::unexpected_hidden_region_diagnostic

pub fn unexpected_hidden_region_diagnostic(
    tcx: TyCtxt<'tcx>, 
    span: Span, 
    hidden_ty: &'tcx TyS<'tcx>, 
    hidden_region: &'tcx RegionKind
) -> DiagnosticBuilder<'tcx>