brew cask install fails if Docker or VLC have been installed manually

[maxdanilov]

brew cask install ace-link

==> Downloading https://github.com/blaise-io/acelink/releases/download/1.4.0/Ace.Link.1.4.0.dmg
Already downloaded: /Users/maxim/Library/Caches/Homebrew/downloads/3fb4e10d6014cf040b01334045e8d48e12ac9e5ee9a74bca4ec87ef80c6eb759--Ace.Link.1.4.0.dmg
==> Verifying SHA-256 checksum for Cask 'ace-link'.
==> Installing dependencies: docker
==> Downloading https://download.docker.com/mac/stable/42247/Docker.dmg
Already downloaded: /Users/maxim/Library/Caches/Homebrew/downloads/c8f04506f50dbebfe55fa9e2c36f1e4ab84933b3bfffab22b5b2cb55fb1f2f79--Docker.dmg
==> Verifying SHA-256 checksum for Cask 'docker'.
==> Installing Cask docker
==> Purging files for version 2.2.0.0,42247 of Cask docker
Error: It seems there is already an App at '/Applications/Docker.app'.

[stickperson]

Same if VLC is already installed

[alexreg]

Maybe can be made optional dependencies? Or to recognise if non-cask installations exist?

[blaise-io]

This is a limitation in Homebrew Cask: it does not understand applications that were installed manually and it does not offer an option to skip applications where a manual install exists at the target location.

Workarounds:

1. Skip installing Docker and VLC using brew install ace-link --cask --skip-cask-deps, or
2. Overwrite the existing install of Docker and VLC using brew install ace-link --cask --force

I can't/won't fix this issue but I'll pin it for visibility.

[codery2k]

If anyone has a similar problem while running brew cask upgrade, it should be fixed by running the command with --skip-cask-deps, i.e

brew cask upgrade --skip-cask-deps

[blaise-io]

Reopening to allow discussion on solutions.