Re: Making hide-ifdef-use-define-alist more user friendly

[Richard Stallman]

    (completing-read "Use define list: " (vconcat (mapcar 'car
    hide-ifdef-define-alist)))

    Allows me to complete more things that those found in:

    (vconcat (mapcar 'car hide-ifdef-define-alist))

The reason for that is that a vector is treated as an obarray.
Obarrays are a special mechanism and they use hidden data structures.
A vector of symbols is not a legitimate argument.