Avoid assertions in find-composition

* src/font.c (font_range): If called with STRING non-nil and FACE
a NULL pointer, compute face by calling face_at_string_position.
(Bug#29506)

* lisp/composite.el (find-composition): Doc fix.

1 files changed, 3 insertions, 2 deletions

diff --git a/lisp/composite.el b/lisp/composite.el
index 72b0ffc8f48..f7e0c4a0912 100644
--- a/lisp/composite.el
+++ b/lisp/composite.el
@@ -337,8 +337,9 @@ When Automatic Composition mode is on, this function also finds a
 chunk of text that is automatically composed.  If such a chunk is
 found closer to POS than the position that has `composition'
 property, the value is a list of FROM, TO, and a glyph-string
-that specifies how the chunk is to be composed.  See the function
-`composition-get-gstring' for the format of the glyph-string."
+that specifies how the chunk is to be composed; DETAIL-P is
+inored this case.  See the function `composition-get-gstring'
+for the format of the glyph-string."
   (let ((result (find-composition-internal pos limit string detail-p)))
     (if (and detail-p (> (length result) 3) (nth 2 result) (not (nth 3 result)))
         ;; This is a valid rule-base composition.