syntax_data: {"ast_node_type":"other","tokens":[{"end":77,"kind":"keyword","start":0,"text":"#[deprecated"}]}
source_snippet:     #[deprecated = "should only be used in `DiagCtxtInner::emit_diagnostic`"]
context_before:     /// Don't use this outside of `DiagCtxtInner::emit_diagnostic`!
context_after:     pub fn unchecked_error_guaranteed() -> Self {