(diagnostic
  (schema slovo.diagnostic)
  (version 1)
  (severity error)
  (code SingleFileMainSignature)
  (message "single-file `main` must have no parameters and return `i32`")
  (file "<fixture>")
  (span
    (bytes 16 42)
    (range 4 1 5 8)
  )
  (expected "fn main () -> i32")
  (found "fn main () -> i64")
  (hint "return an i32 exit status from main; use helper functions for wider values")
)