Query the built field in DESCRIPTION — desc_get

If the file has no Built field then it throws an error.

desc_get_built(file = ".", normalize = FALSE)

Arguments

file: DESCRIPTION file to use. By default the DESCRIPTION file of the current package (i.e. the package the working directory is part of) is used.
normalize: Whether to "normalize" (reorder and reformat) the fields when writing back the result. See desc_normalize().

A list with fields R, Platform, Date, OStype.