syntax_data: {"ast_node_type":"variable","tokens":[{"end":81,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:                 let pattern_source_info = self.source_info(irrefutable_pat.span);
context_before:                 // Inject a fake read, see comments on `FakeReadCause::ForLet`.
context_after:                 let cause_let = FakeReadCause::ForLet(None);