syntax_data: {"ast_node_type":"import","tokens":[{"end":59,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:                 // Patterns can only use monomorphic types.
context_before:                 let field = FieldIdx::new(idx);
context_after:                 let ty = self.tcx.normalize_erasing_regions(self.typing_env, ty);