syntax_data: {"ast_node_type":"other","tokens":[{"end":92,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:             // We could only allow functions that we *can* resolve and *are* `track_caller`,
context_before:             // this point (THIR can be polymorphic, we may have an unresolved trait function).
context_after:             // but that would turn changing `track_caller`-ness into a breaking change,