[Rd] R-devel internal errors during check produce?

[Jan Gorecki]

Hi R developers,

On R-devel (2020-06-24 r78746) I am getting those two new exceptions
during R check. I found a change which eventually may be related
https://github.com/wch/r-source/commit/69de92b9fb1b7f2a7c8d1394b8d56050881a5465
I think this may be a regression. I grep'ed package manuals and R code
for unique.default but don't see any. Usage section of the unique
method looks fine as well. Errors look a little bit like internal
errors.

* checking Rd \usage sections ... NOTE
 Error in unique.default(env_list) :
   LENGTH or similar applied to environment object
 Calls: <Anonymous> ... .get_S3_generics_as_seen_from_package ->
unique -> unique.default
 Execution halted
 The \usage entries for S3 methods should use the \method markup and not
 their full name.
 * checking S3 generic/method consistency ... WARNING
 Error in unique.default(env_list) :
   LENGTH or similar applied to environment object
 Calls: <Anonymous> ... .get_S3_generics_as_seen_from_package ->
unique -> unique.default

I don't think if it is related but I build R-devel with extra args:
--with-recommended-packages --enable-strict-barrier --disable-long-double
I check with:
--as-cran --no-manual
To reproduce download current data.table from CRAN (1.12.8) and run R check

Best regards,
Jan Gorecki