[Rd] Undocumented 'use.names' argument to c()

[Suharto Anggono Suharto Anggono]

By "an argument named 'use.names' is included for concatenation", I meant something like this, that someone might try.

> c(as.Date("2016-01-01"), use.names=FALSE)
                use.names 
"2016-01-01" "1970-01-01" 

See, 'use.names' is in the output. That's precisely because 'c.Date' doesn't have 'use.names', so that 'use.names' is absorbed into '...'.
--------------------------------------------
On Sun, 25/9/16, Martin Maechler <maechler at stat.math.ethz.ch> wrote:

 Subject: Re: [Rd] Undocumented 'use.names' argument to c()

 Cc: "R-devel" <R-devel at r-project.org>
 Date: Sunday, 25 September, 2016, 10:14 PM
 
>>>>> Suharto Anggono Suharto Anggono via R-devel <r-devel at r-project.org>
>>>>>     on Sun, 25 Sep 2016 14:12:10 +0000 writes:

    >> From comments in
    >> http://stackoverflow.com/questions/24815572/why-does-function-c-accept-an-undocumented-argument/24815653
    >> : The code of c() and unlist() was formerly shared but
    >> has been (long time passing) separated. From July 30,
    >> 1998, is where do_c got split into do_c and do_unlist.
    > With the implementation of 'c.Date' in R devel r71350, an
    > argument named 'use.names' is included for
    > concatenation. So, it doesn't follow the documented
    > 'c'. But, 'c.Date' is not explicitly documented in
    > Dates.Rd, that has 'c.Date' as an alias.

I do not see any  c.Date  in R-devel with a 'use.names'; its a
base function, hence not hidden ..

As mentioned before, 'use.names' is used in unlist() in quite a
few places, and such an argument also exists for

    lengths()            and
    all.equal.list()

and now c()