/usr/lib/R/site-library/fastcluster/NAMESPACE is in r-cran-fastcluster 1.1.24-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 | useDynLib(fastcluster, .registration=TRUE)
export('hclust', 'hclust.vector')
|