syntax_data: {"ast_node_type":"variable","tokens":[{"end":52,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:                 let span = captured_place_expr.span;
context_before:             ty::UpvarCapture::ByUse => {
context_after:                 let expr_id = self.thir.exprs.push(captured_place_expr);