pub const fn unpack_boundaries(value: u32) -> Option<(Boundaries, Needs)>Expand description
Read what tocat_boundaries returned.
None for any bit outside the two masks, which is a guest built against a
later ABI than this host speaks. Refusing it is the point: reading an
unknown value as Boundaries::Fuse would run a stage whose requirement
the host cannot see, and the symptom would be a corrupt stream rather than
an error.
Zero is a fixed point: it is what a guest that does not export the function
at all is taken to have answered, so Boundaries::Fuse and
Needs::Nothing have to stay at 0. Both are the reading that claims
nothing and asks for nothing, which is the only safe thing to assume of a
stage that did not say.