syntax_data: {"ast_node_type":"other","tokens":[{"end":90,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:             // Only prefer the built-in `Sized` candidate if its nested goals are certain.
context_before:             debug_assert_eq!(sized_candidates.next(), None);
context_after:             // Otherwise, we may encounter failure later on if inference causes this candidate