(diagnostic
  (schema slovo.diagnostic)
  (version 1)
  (severity error)
  (code UnsupportedFloatLiteral)
  (message "f64 literals must be finite in exp-20")
  (file "<fixture>")
  (span
    (bytes 52 55)
    (range 5 18 5 21)
  )
  (expected "finite f64 literal")
  (found "NaN")
  (hint "NaN and infinity semantics remain deferred")
)