Issue in symfony’s sfToolkit::arrayDeepMerge()

I’ve had a bit of an odd issue where JavaScript files from a plugin I’d written weren’t being included for some reason.

Turns out that there’s a bug / feature (?) in the way symfony merges config files.

plugins/myPlugin/config/view.yml

all:
  javascripts:
    - /js/one.js
    - /js/two.js
    - /js/three.js

app/frontend/config/view.yml

all:
  javascripts:
    - /js/four.js
    - /js/five.js

Expected result:

all:
  javascripts:
    - /js/one.js
    - /js/two.js
    - /js/three.js
    - /js/four.js
    - /js/five.js

However, due to the way arrayDeepMerge merges the two arrays, all values from the first array are being overridden, resulting in:

all:
  javascripts:
    - /js/four.js
    - /js/five.js
    - /js/three.js

This will happen in all config files, most notably view.yml, app.yml, settings.yml, etc. (this has been discussed in http://groups.google.com/group/symfony-devs/browse_thread/thread/3a725483db3dec82 but lies vacant ever since 2007).

A workaround would be to specify a unique index for your javascript, e.g.:

plugins/myPlugin/config/view.yml

all:
  javascripts:
    101: /js/one.js
    102: /js/two.js
    103:
      /js/three.js: { position: first }

Hope this helps if you should run into the same issue.