ggplot2::waiver throws a warning on r-devel

[bgoodri]

The recent R commit r71841 deprecates what ggplot2::waiver does. In the development version of R,

ggplot2::waiver()

yields

Warning message:
In structure(NULL, class = "waiver") :
Calling 'structure(NULL, *)' is deprecated, as NULL cannot have attributes.
Consider 'structure(list(), *)' instead.

This is leading to some largely spurious test failures in other packages that use testthat::expect_silent() but end up calling something in ggplot2 that calls waiver internally.

[bbolker]

just to follow up:

• occurs here
• being discussed on r-pkg-devel here