Unnecessary note when import only used in arg definition

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 at 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

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