Function rustc_typeck::check::dropck::check_drop_obligations

pub(crate) fn check_drop_obligations<'a, 'tcx>(
    rcx: &mut RegionCtxt<'a, 'tcx>, 
    ty: Ty<'tcx>, 
    span: Span, 
    body_id: HirId
) -> Result<(), ErrorReported>

This function is not only checking that the dropck obligations are met for the given type, but it's also currently preventing non-regular recursion in types from causing stack overflows (dropck_no_diverge_on_nonregular_*.rs).