syntax_data: {"ast_node_type":"other","tokens":[{"end":72,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:     // shallow result we are looking for -- that is, what specific impl.
context_before:     // Do the initial selection for the obligation. This yields the
context_after:     let (infcx, param_env) = tcx.infer_ctxt().ignoring_regions().build_with_typing_env(typing_env);