syntax_data: {"ast_node_type":"other","tokens":[{"end":96,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:             // typeck (which type_of invokes below), will call back into opaque_types_defined_by
context_before:             // If the type of the item uses `_`, we're gonna error out anyway, but
context_after:             // causing a cycle. So we just bail out in this case.