syntax_data: {"ast_node_type":"variable","tokens":[{"end":72,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:                 let value = as_constant_inner(expr, |_| None, self.tcx);
context_before:             | ExprKind::ConstBlock { .. } => Ok({
context_after:                 value.const_.eval_bits(self.tcx, self.typing_env)