You have file 'syn/man/syn.Rd' with \docType{package}, likely
intended as a package overview help file, but without the appropriate
PKGNAME-package \alias as per "Documenting packages" in R-exts.
This seems to be the consequence of the breaking change
Using @docType package no longer automatically adds a -package alias.
Instead document _PACKAGE to get all the defaults for package
documentation.
As explained in the issue, to get the desired PKGNAME-package \alias
back, you should either change to the new approach and document the new
special sentinel
Dear maintainer,
You have file 'syn/man/syn.Rd' with \docType{package}, likely intended as a package overview help file, but without the appropriate PKGNAME-package \alias as per "Documenting packages" in R-exts.
This seems to be the consequence of the breaking change
in roxygen2 7.0.0 (2019-11-12) having gone unnoticed, see https://github.com/r-lib/roxygen2/issues/1491.
As explained in the issue, to get the desired PKGNAME-package \alias back, you should either change to the new approach and document the new special sentinel
or manually add
if remaining with the old approach.