[Rd] Development version of R fails tests and is not installed

[Martin Maechler]

>>>>> Martin Maechler 
>>>>>     on Tue, 5 Mar 2019 12:45:36 +0100 writes:

>>>>> Berwin A Turlach 
>>>>>     on Tue, 5 Mar 2019 16:54:09 +0800 writes:

    >> G'day all,
    >> I have daily scripts running to install the patched version of the
    >> current R version and the development version of R on my linux box
    >> (Ubuntu 18.04.2 LTS).

    >> The last development version that was successfully compiled and
    >> installed was "R Under development (unstable) (2019-02-25 r76159)" on
    >> 26 February.  Since then the script always fails as a regression test
    >> seems to fail.  Specifically, in the tests/ subdirectory of my build
    >> directory I have a file reg-tests-1d.Rout.fail which ends with:

    >>> ## checking ar.yw.default() multivariate case
    >>> estd <- ar(unclass(y) , aic = FALSE, order.max = 2) ## Estimate VAR(2)
    >>> es.d <- ar(unclass(y.), aic = FALSE, order.max = 2, na.action=na.pass)
    >>> stopifnot(exprs = {
    >> +     all.equal(est$ar[1,,], diag(0.8, 2), tol = 0.08)# seen 0.0038
    >> +     all.equal(est[1:6], es.[1:6], tol = 5e-3)
    >> +     all.equal(estd$x.mean, es.d$x.mean, tol = 0.01) # seen 0.0023
    >> +     all.equal(estd[c(1:3,5:6)],
    >> +               es.d[c(1:3,5:6)], tol = 1e-3)## seen {1,3,8}e-4
    >> +     all.equal(lapply(estd[1:6],unname),
    >> +               lapply(est [1:6],unname), tol = 2e-12)# almost identical
    >> +     all.equal(lapply(es.d[1:6],unname),
    >> +               lapply(es. [1:6],unname), tol = 2e-12)
    >> + })
    >> Error: lapply(es.d[1:6], unname) and lapply(es.[1:6], unname) are not equal:
    >> Component "aic": Mean relative difference: 3.297178e-12
    >> Execution halted

    >> Would it be possible to make this tolerance more lenient?  In case it
    >> matters, I am configuring R to be compiled using Openblas and this test
    >> fails for the 64 bit installation, the 32 bit installation seems to
    >> pass all tests.

    > Interesting. But we had another report (on this mailing list!) by
    > Er. Ho., also using OpenBLAS, but then in combination with Cygwin.
    > After Cygwin related problems were solved, on March 1 he said

    >> I have an error at reg-1d.  It stops the process.  However, the mean difference
    >> (as per the file) is 2.0e-12. 

    > and when I asked him to be more precise.. he wasn't but did
    > "solve" the problem by changing the test file.
    > Now we know from you Berwin (thank you for providing the details!)
    > what it has been.

    > ==> I could investigate and -- lo and behold! --  the solution
    > is probably the fact that the RNGkind(sample.kind = *) was
    > introduced *and* the default was to differ from previous
    > versions of R.

    >> Happy to provide any more information/context that might be needed.

    > Can you please try adding

    > suppressWarnings(RNGversion("3.5.0"))

    > e.g. at the very beginning of the   tests/reg-tests-1d.R
    > file or just a few lines above the code you show above,
    > replace in line 1470

    > set.seed(42)
    > by
    > set.seed(42); suppressWarnings(RNGversion("3.5.0"))

oops!  That was a thinko (enticed by my "esthetics"):   Of
course you must *first* set the RNG version and *then* the seed,
so *only* this is correct

   suppressWarnings(RNGversion("3.5.0")); set.seed(42)

where I really would go for

   suppressWarnings(RNGversion("3.5.0")) # back compatibility for now
   set.seed(42)

Note that Brian's advice with an environment variable currently
works "more thoroughly", but it has been labeled "temporary" as it
is not functional / language-explicit [i.e. not visible from
your own R code] ...
and you really should only use it when checking R, *not* otherwise.

Martin