(diagnostic
  (schema slovo.diagnostic)
  (version 1)
  (severity error)
  (code UnsupportedGenericTypeParameter)
  (message "generic type parameter `T` is reserved but not supported in the current beta")
  (file "<fixture>")
  (span
    (bytes 42 44)
    (range 5 8 5 10)
  )
  (expected "concrete supported type")
  (found "T")
  (hint "use a concrete promoted type such as `i32`, `string`, or `(vec i32)`")
)