[Rd] Suggestion: Make _R_CHECK_LENGTH_1_LOGIC2_=warn the default for R 3.6.2

[Henrik Bengtsson]

.On Mon, Nov 18, 2019 at 12:35 AM Martin Maechler
<maechler using stat.math.ethz.ch> wrote:
>
> >>>>> Henrik Bengtsson
> >>>>>     on Sun, 17 Nov 2019 20:42:32 -0800 writes:
>
>     > Hi,
>
>     > I'm not sure where we are in getting CRAN packages getting their
>     > _R_CHECK_LENGTH_1_LOGIC2_=true bugs fixed (*), but maybe it'd help to
>     > make _R_CHECK_LENGTH_1_LOGIC2_=warn the new default in the upcoming R
>     > 3.6.2?
>
> Interesting, I had similar thoughts the last few days
> ... but not for R 3.6.x --- I think it's out of the question to
> do that for a "minor" update --- but for R 4.0.0.
>
>     > Warnings of type:
>
>     > $ R --vanilla
>     >> Sys.setenv("_R_CHECK_LENGTH_1_LOGIC2_" = "warn")
>     >> c(TRUE, FALSE) && TRUE
>     > [1] TRUE
>     > Warning message:
>     > In c(TRUE, FALSE) && TRUE : 'length(x) = 2 > 1' in coercion to 'logical(1)'
>
>     > could help encourage more package maintainers to fix these bugs
>     > sooner. Enabling this warning by default is in line with what the
>     > current default behavior for _R_CHECK_LENGTH_1_CONDITION_ bugs:
>
>     >> if (c(TRUE, FALSE)) 42
>     > [1] 42
>     > Warning message:
>     > In if (c(TRUE, FALSE)) 42 :
>     > the condition has length > 1 and only the first element will be used
>
>     > which has been the case for many years.
>
>     > Hopefully in a not too far future, we get to a point where we can have
>     > _R_CHECK_LENGTH_1_LOGIC2_=true and _R_CHECK_LENGTH_1_CONDITION_=true
>     > as the new defaults.
>
> Exactly.  My own thoughts (mentioned above) were actually more about
> the *other* _R_CHECK_LENGTH_1_* variable, i.e., _R_CHECK_LENGTH_1_CONDITION_
> and that ---- as I have only noticed these days, when considering
> the exact impact of the upcoming
>
>     class(<matrix>)  |-->  c("matrix", "array")
>
> change --- has actually *not* been part of the  '--as-cran'
> checks, nor (AFAIK, but I don't really know) of extra CRAN
> incoming checks.
>
> I'm proposing to add   _R_CHECK_LENGTH_1_CONDITION_=true
> to the --as-cran  checks  ASAP (within weeks)

To do that, I think we would need:

_R_CHECK_LENGTH_1_CONDITION_=package:_R_CHECK_PACKAGE_NAME_,abort,verbose

such that the check only applies to the code of the package being R
CMD check:ed and not to code elsewhere. If not, there will be lots of
confusing "false-positives" and extra work for CRAN. Unfortunately,
the (great) "package:_R_CHECK_PACKAGE_NAME_" mechanism is not
implemented for _R_CHECK_LENGTH_1_CONDITION_.

> and indeed, I
> think we should consider to have *both*  _R_CHECK_LENGTH_1_* = true
> become the default in R 4.0.0.

That would be great, but I'm a bit skeptical at the same time - I
think R 4.0.0 might be too optimistic but I won't complain if that
would be goal. I suspect there are still lots of CRAN packages that
would break this way overnight which would cause a major headache for
everything and much work for the CRAN Team.  This is why I wrote "I'm
not sure where we are in getting CRAN packages getting their
_R_CHECK_LENGTH_1_LOGIC2_=true bugs fixed"; I'm not aware of anyone
having checked the CRAN status for this bug.

/Henrik

>
> Martin Maechler
> ETH Zurich  and  R Core
>
>
>     > (*) I understand that CRAN incoming checks with
>     > _R_CHECK_LENGTH_1_LOGIC2_=package:_R_CHECK_PACKAGE_NAME_,abort,verbose,
>     > so all packages submitted to CRAN have to pass this check.  I don't
>     > think Bioconductor checks for these yet, but I could be wrong.
>
>     > /Henrik
>
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