From d026cb91e7f59c7eff32f798b4c902e6c50ce122 Mon Sep 17 00:00:00 2001
From: Claudia <claui@users.noreply.github.com>
Date: Tue, 21 Apr 2020 17:45:34 +0200
Subject: [PATCH] Fix cask loading after adding an artifact type

This commit fixes an issue where we added a new global artifact
and then updated a cask to make use of that new artifact.
This caused a number of `brew cask` commands to fail for users
who had the cask installed before the artifact was added.

When loading the definition of an installed cask, we configure it
using a snapshot from install time, e. g. `/usr/local/Caskroom/markdownmdimporter/.metadata/config.json`.

The snapshot looks like this:

```
{
  "default": {
    "appdir": "/Applications",
    "prefpanedir": "/Users/claudia/Library/PreferencePanes",
    "qlplugindir": "/Users/claudia/Library/QuickLook",
    "dictionarydir": "/Users/claudia/Library/Dictionaries",
    "fontdir": "/Users/claudia/Library/Fonts",
    "colorpickerdir": "/Users/claudia/Library/ColorPickers",
    "servicedir": "/Users/claudia/Library/Services",
    "input_methoddir": "/Users/claudia/Library/Input Methods",
    "internet_plugindir": "/Users/claudia/Library/Internet Plug-Ins",
    "audio_unit_plugindir": "/Users/claudia/Library/Audio/Plug-Ins/Components",
    "vst_plugindir": "/Users/claudia/Library/Audio/Plug-Ins/VST",
    "vst3_plugindir": "/Users/claudia/Library/Audio/Plug-Ins/VST3",
    "screen_saverdir": "/Users/claudia/Library/Screen Savers"
  },
  "env": {},
  "explicit": {}
}
```

Note that there is no `mdimporterdir` because the cask was installed
before the artifact was added.

The root cause is that the cask loading code still expects the snapshot
to contain directory configuration for all artifact types.
Since the snapshot never learned about the new artifact type, cask
loading would fail.

The fix applied in this commit is to fall back to the global default
whenever the `default` directory map of a configuration snapshot is
incomplete.

See also:
- https://github.com/Homebrew/brew/pull/7286#issuecomment-613376568
- https://discourse.brew.sh/t/cask-definition-is-invalid-invalid-mdimporter-stanza-key-not-found-mdimporterdir
---
 Library/Homebrew/cask/config.rb | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Library/Homebrew/cask/config.rb b/Library/Homebrew/cask/config.rb
index 12d2c96586..6ddad5430b 100644
--- a/Library/Homebrew/cask/config.rb
+++ b/Library/Homebrew/cask/config.rb
@@ -69,7 +69,7 @@ module Cask
     attr_accessor :explicit
 
     def initialize(default: nil, env: nil, explicit: {})
-      @default = self.class.canonicalize(default) if default
+      @default = DEFAULT_DIRS.merge(self.class.canonicalize(default)) if default
       @env = self.class.canonicalize(env) if env
       @explicit = self.class.canonicalize(explicit)