Function rustc_typeck::check::check::check_opaque

pub(in check) fn check_opaque<'tcx>(
    tcx: TyCtxt<'tcx>, 
    def_id: LocalDefId, 
    substs: SubstsRef<'tcx>, 
    span: Span, 
    origin: &OpaqueTyOrigin
)

Checks that an opaque type does not contain cycles and does not use Self or T::Foo projections that would result in "inheriting lifetimes".