I'm writing a homebrew formula for a project (https://www.cryfs.org). Since it is a file system, it depends on osxfuse, which is unfortunately only available as a cask. That is, the formula should have the cask as a dependency.
I tried the following
depends_on :cask => "osxfuse"
but I got the error message
Unsupported special dependency :cask
What is the syntax for adding casks as dependencies to a formula?