syntax_data: {"ast_node_type":"other","tokens":[{"end":68,"kind":"keyword","start":0,"text":"err.subdiagnostic(SuggestUpgradeCompiler::ui_testing());"}]}
source_snippet:             err.subdiagnostic(SuggestUpgradeCompiler::ui_testing());
context_before:         } else if sess.opts.unstable_opts.ui_testing {
context_after:         } else if let Some(suggestion) = SuggestUpgradeCompiler::new() {