Check that file.path() is used to construct safe and portable paths.
See also
- linters for a complete list of linters available in lintr. 
Examples
# will produce lints
lint(
  text = "'abcdefg/hijklmnop/qrst/uv/wxyz'",
  linters = nonportable_path_linter()
)
#> <text>:1:2: warning: [nonportable_path_linter] Use file.path() to construct portable file paths.
#> 'abcdefg/hijklmnop/qrst/uv/wxyz'
#>  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# okay
lint(
  text = "file.path('abcdefg', 'hijklmnop', 'qrst', 'uv', 'wxyz')",
  linters = nonportable_path_linter()
)
#> ℹ No lints found.
