When specifying a customizable variable
foo-paths as follows:
(defcustom foo-paths nil "Paths for foo-related things." :group 'foo :options '(foo-1 foo-2) :type '(alist :key-type symbol :value-type (file :must-match t)))
There doesn't seem to be any enforcement of the value type in the Customize interface. I can enter any text I want for the values, not just a file (let alone an existing file).
Am I missing something here? The manual says:
(file :must-match t)
The value must be a file name for an existing file. The widget provides completion.
What completion is the widget providing? I don't see any; all I see is a plain text box.
I'm using Emacs 25.1.1.