Function generated_params 

fn generated_params<'p, 'd>(
    r_params: &'p str,
    doc_tags: &[String],
    page: &str,
    choice_docs: Option<&'d HashMap<String, String>>,
) -> Vec<(&'p str, Option<&'d str>)>

The formals of r_params that doc_tags leaves undocumented, each with its choice text from choice_docs (the write-time placeholder of a match_arg parameter, the literal line of a choices(...) one), or None for a formal that has none. Skips .mx_self, .ptr and ..., and yields nothing when the tags take the arguments from another topic (roxygen::params_documented_elsewhere against page, #1590). The class page default a builder appends is not in doc_tags, and an author @rdname naming page is the same page, so neither suppresses them.

Splits on top-level commas only: a naive split(", ") shreds a mode = c("fast", "slow") default into a bogus "slow") formal.