Brew Cask dependency order when both Cask and Formula dependencies used.

[hasinthaindrajee]

Description of feature/enhancement

When a Cask depens_on both Formulas and Casks, the formula dependencies are satisfied first and then casks dependencies are satisfied. According to the source the order of dependency resolution is, first it installs Formula dependencies and then only Cask dependencies are installed.[1] https://github.com/Homebrew/brew/blob/1b18943317ed2f97ec689c1560504ed5f278e9c7/Library/Homebrew/cask/installer.rb#L248-L257

Justification

There are some formulas which depends on software which are not available as formulas. Instead those dependencies are available as casks. If my application cask depends on a formula which has defined a Requirement on a Cask, the installation will fail even if I add the Cask as my applications dependency.

Example use case

I have an application which uses sshfs formula. sshfs uses osxfuse as a d requirement. I am adding below depens_on clauses in my Cask.

depends_on cask: ‘osxfuse’
depends_on formula: ‘sshfs’

This fails due to unsatisfied requirement of asxfuse in sshfs. What I expect is to resolve the dependencies in the order they have defined so that this problem will go away.