syntax_data: {"ast_node_type":"other","tokens":[{"end":33,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:     // `thunk-extern` like Clang.
context_before:     // kept as a `match` to force a change if new ones are added, even if we currently only support
context_after:     match sess.opts.unstable_opts.function_return {