syntax_data: {"ast_node_type":"variable","tokens":[{"end":22,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:         let mut diag =
context_before:     fn into_diag(self, dcx: DiagCtxtHandle<'a>, level: Level) -> Diag<'a, G> {
context_after:             Diag::new(dcx, level, fluent::mir_build_non_exhaustive_patterns_type_not_empty);