Kavon Farvardin f608fc03ef Reparenting: even more feature guarding improvements ...

The only known condfail scenario is inheriting from
a protocol P that inherits from a reparentable one R.

We already guard P if it mentions R in its inheritance clause.
So older compilers will simply report that "P" is missing in the
interface, which is a better error message than virally guarding
everything mentioning P. It's an ABI break anyway to do that
without introducing a `@reparented` extension, which needs a guard.

In theory, older compilers shouldn't have too much go wrong if they
were to ignore `@reparentable`, though the RequirementMachine and
witness tables will look different.

rdar://174263176

2026-04-08 10:48:40 -07:00

2.8 KiB

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