http://compresscafe.i2p/blog/applying_the_diagnostics_pattern_in_practice.html
, sample_fmt } , ) ; z.diag ( .warn, .decoder, {} , "The {s} field was duplicated." , . { "width" } ) ; Caveats: The size of the message is limited. This does not include a stack trace. You can always add one, though. The "error" is always there, even when no error has been specified.