Fixes related to face underlining

* lisp/faces.el (face-underline-p): Doc fix.  Handle :underline being
things other than `t' (a string, a list).
(face-inverse-video-p): Doc fix.
(set-face-underline): Rename it back from set-face-underline-p.
Doc fix.  Allow interactive input of values other than t.
(read-face-attribute): Apply formatting to :underline,
since like :box and :stipple it can take list values.

* doc/lispref/display.texi (Face Attributes): Fix :underline COLOR description.
(Attribute Functions): Update for set-face-underline rename.
Tweak descriptions of face-underline-p, face-inverse-video-p.

* etc/NEWS: Related edit.

1 files changed, 8 insertions, 0 deletions

diff --git a/src/xfaces.c b/src/xfaces.c
index 221387c4b6d..5eda6dca6da 100644
--- a/src/xfaces.c
+++ b/src/xfaces.c
@@ -2906,6 +2906,12 @@ FRAME 0 means change the face on all frames, and change the default
           Lisp_Object key, val, list;
 
           list = value;
+          /* FIXME?  This errs on the side of acceptance.  Eg it accepts:
+               (defface foo '((t :underline 'foo) "doc")
+             Maybe this is intentional, maybe it isn't.
+             Non-nil symbols other than t are not documented as being valid.
+             Eg compare with inverse-video, which explicitly rejects them.
+          */
           valid_p = 1;
 
           while (!NILP (CAR_SAFE(list)))
@@ -5727,6 +5733,8 @@ realize_x_face (struct face_cache *cache, Lisp_Object attrs[LFACE_VECTOR_SIZE])
       face->underline_defaulted_p = 1;
       face->underline_type = FACE_UNDER_LINE;
 
+      /* FIXME?  This is also not robust about checking the precise form.
+         See comments in Finternal_set_lisp_face_attribute.  */
       while (CONSP (underline))
         {
           Lisp_Object keyword, value;