syntax_data: {"ast_node_type":"variable","tokens":[{"end":100,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:                     let temp = unpack!(block = this.as_temp(block, scope, source, Mutability::Not));
context_before:                     let discr_ty = adt_def.repr().discr_type().to_ty(this.tcx);
context_after:                     let discr = this.temp(discr_ty, source_expr.span);