bug#12890: read-face-attribute, face-valid-attribute-values do not handle all :underline etc forms

[Glenn Morris]

Package: emacs
Version: 24.2.50

You can't use read-face-attribute to set list values for :box, :stipple,
or :underline:

emacs -Q --eval "(read-face-attribute 'underline :underline)"
Start to enter: (:color "red")
and get stopped with "no match" when you type the space.
If you force it with C-q space, it takes your input and returns it, but
silently does not actually set the :underline attribute to it.

This is because face-valid-attribute-values does not return such values.

This affects eg M-x set-face-underline.