syntax_data: {"ast_node_type":"other","tokens":[{"end":30,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:         // evaluate the const.
context_before:         // try to resolve e.g. associated constants to their definition on an impl, and then
context_after:         let valtree = match self.tcx.const_eval_resolve_for_typeck(typing_env, uv, self.span) {