[Rd] Unnecessary note when import only used in arg definition

[Duncan Murdoch]

On 06/02/2023 1:59 p.m., Duncan Murdoch wrote:
> I think the usual rule is that a qualified use of a package is
> sufficient to suppress the warning without any entry in the NAMESPACE
> file.  So if there isn't something else going on, Antoine's example
> illustrates a bug (or at least an inconsistency) in the check code.

Here's where the problem arises:

https://github.com/r-devel/r-svn/blob/7a2207dad15b8eed8c3d1c5cc49f29d431c289bd/src/library/tools/R/QC.R#L2105

with code

   if(is.call(e) || is.expression(e)) {

While examining a function definition, the arguments are stored in a 
pairlist.  The test is looking for a call or an expression, and a 
pairlist isn't any of those, so it skips over it.  I think it would work 
properly if that line was changed to

   if(is.call(e) || is.expression(e) || is.pairlist(e)) {

because then it would iterate over the arguments, and would find the use 
of a package in a default value.

Duncan Murdoch

> 
> Here's a version of your example that doesn't import anything from rlang
> using the NAMESPACE, but uses it in code:
> 
>     https://github.com/dmurdoch/imports.example/tree/explicituse
> 
> And here's one like Antoine's, where the only use is in a default value:
> 
>     https://github.com/dmurdoch/imports.example/tree/defaultvalue
> 
> The first one tests clean, the second one gives the note he was talking
> about:
> 
>    ❯ checking dependencies in R code ... NOTE
>      Namespace in Imports field not imported from: ‘rlang’
>        All declared Imports should be used.
> 
> Duncan
> 
> On 06/02/2023 1:03 p.m., Kevin Ushey wrote:
>> Hi Antoine,
>>
>> Maybe I'm misunderstanding, but I think the warning is saying that
>> you've declared the package dependency in the DESCRIPTION file, but
>> you haven't actually imported the package (or any functions) in your
>> package NAMESPACE file?
>>
>> I put together an example package that I think satisfies the point
>> you're describing, and I don't see any R CMD check warnings (using R
>> 4.2.2).
>>
>> https://github.com/kevinushey/imports.example
>>
>> As I understand it, if you declare a package dependency in the
>> DESCRIPTION file, you need to clarify how you're using the package in
>> the NAMESPACE file -- e.g. what symbols you want to import, and so on.
>>
>> Best,
>> Kevin
>>
>> On Mon, Feb 6, 2023 at 6:43 AM Antoine Fabri <antoine.fabri using gmail.com> wrote:
>>>
>>> Dear r-devel,
>>>
>>> When a package is only used in an argument definition, e.g :
>>>
>>>
>>> f <- function(test = testthat::is_testing()) {
>>>
>>>     if (test) 1 else 2
>>>
>>> }
>>>
>>>
>>> R CMD CHECK gives us a note: "Namespace in Imports field not imported from:
>>> 'testthat'"
>>>
>>>
>>> This incites me to remove the package from the Imports field but that'll
>>> make my package brittle.
>>>
>>>
>>> I noted I'm not the first one having the issue (
>>> https://github.com/r-lib/devtools/issues/2456 ) and I've seen some
>>> workarounds too, in particular Hadley Wickham suggests in 'R packages' to
>>> use the following construct :
>>>
>>>
>>> ignore_unused_imports <- *function*() {
>>>
>>>     aaapkg::aaa_fun
>>>
>>> }
>>>
>>>
>>> That's far from obvious though, and not very satisfying.
>>>
>>> Are there any downside to removing this note in this scenario? it makes
>>> little sense to me and incites wrong behaviour AFAIU.
>>>
>>>
>>> Thanks,
>>>
>>>
>>> Antoine
>>>
>>>           [[alternative HTML version deleted]]
>>>
>>> ______________________________________________
>>> R-devel using r-project.org mailing list
>>> https://stat.ethz.ch/mailman/listinfo/r-devel
>>
>> ______________________________________________
>> R-devel using r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-devel
>