syntax_data: {"ast_node_type":"other","tokens":[{"end":91,"kind":"keyword","start":0,"text":"LetSource::IfLet"}]}
source_snippet:         LetSource::IfLet | LetSource::ElseIfLet => emit_diag!(IrrefutableLetPatternsIfLet),
context_before:         LetSource::None | LetSource::PlainLet | LetSource::Else => bug!(),
context_after:         LetSource::IfLetGuard => emit_diag!(IrrefutableLetPatternsIfLetGuard),