Function unsafe_path_diagnostic 

pub(crate) fn unsafe_path_diagnostic(
    message: String,
    path: &str,
    span: &SourceSpan,
    value_span: &SourceSpan,
) -> Diagnostic

Build the MOS0049 unsafe-path diagnostic for a #image / #figure / #bibliography string argument, attaching a fix that rewrites the literal’s contents to the /-only spelling when portable_path_fix can produce one.