that contain zero-sized payloads, which should resolve a number of issues with
RemoteMirror incorrectly reflecting enum cases and/or measuring the layout of
structures containing enums.
Background: Enum cases that have zero-sized payloads are handled
differently from other payload-bearing cases.
1. For layout purposes, they're treated as
non-payload cases. This can cause an MPE to
actually get represented in memory as a single-payload
or non-payload enum.
2. However, zero-sized payloads are still considered for
extra inhabitant calculations. Since they have no
extra inhabitants, this tends to cause such enums to
also not expose extra inhabitants to containing enums.
This commit makes several change to how RemoteMirror determines
enum layout:
* The various "*EnumTypeInfo" classes now represent
layout mechanisms -- as described in (1) above,
this can differ from the source code concept.
* An Enum "kind" is separately computed to reflect the
source code concept; this ensures that the dumped
type information reflects the source code.
* For single-payload and no-payload _layouts_,
the extra inhabitant calculation has been adjusted
to ensure that zero-sized payloads are correctly
considered.
Resolves: rdar://92945673
