syntax_data: {"ast_node_type":"other","tokens":[{"end":32,"kind":"keyword","start":0,"text":"Mutability::Mut"}]}
source_snippet:             Mutability::Mut => {
context_before:         match mut_outer {
context_after:                 sess.dcx().emit_err(AlreadyMutBorrowed { span: pat.span, occurrences });