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

[Duncan Murdoch]

On 06/02/2023 2:31 p.m., Duncan Murdoch wrote:
> 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

Whoops, I think that's the wrong location.  I think this is the right one:

 
https://github.com/r-devel/r-svn/blob/7a2207dad15b8eed8c3d1c5cc49f29d431c289bd/src/library/tools/R/QC.R#L5754

There are two similar functions in that big source file.

Duncan Murdoch

> 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]]
>>>>
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>>>
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>>
>