Multiple errors with static types

[xwu (Xiaodi Wu)]

@Lua

This must be from before Embedded Swift since "one should use any Error" completely disregards the fact that existentials don't exist in this mode :(

It is not the intention of the language to restrict the use of untyped errors in Embedded Swift. If it's not possible to do so today, it is a shortcoming and not by design:

@Joe_Groff

Typed throws might be a good feature in and of itself, but requiring its use in embedded Swift could be a pretty severe dialectization wedge. Our guidance for long-term stable APIs will likely still be to recommend untyped errors to allow for library evolution, and we'd want libraries that intend to target both desktop and embedded Swift to follow that guidance without having to diverge their APIs.