syntax_data: {"ast_node_type":"other","tokens":[{"end":24,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:                 // case.
context_before:                 // The type is uninhabited yet there is a witness: we must be in the `MaybeInvalid`
context_after:                 err.note(format!("`{ty}` is uninhabited but is not being matched by value, so a wildcard `_` is required"));