{"ast_node_type":"function","tokens":[{"end":99,"kind":"keyword","start":0,"text":"fn"}]}
    fn check_extern_fn_signature(&self, abi: ExternAbi, ctxt: FnCtxt, ident: &Ident, sig: &FnSig) {
    /// Check that the signature of this function does not violate the constraints of its ABI.
        match AbiMap::from_target(&self.sess.target).canonize_abi(abi, false) {