From: Eli Zaretskii <eliz@gnu.org>
Date: Thu, 12 Dec 2019 11:16:46 +0000 (+0200)
Subject: Fix face extension of overlay strings on buffer text with faces
X-Git-Tag: emacs-27.0.90~371
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=6ee3675dad6f2404d4177aa1ec8eada7286994f4;p=emacs.git

Fix face extension of overlay strings on buffer text with faces

* src/xdisp.c (face_at_pos): Reject the face returned by
'underlying_face_id' when we are filtering by face attribute,
and that attribute's value fails the filter test.  (Bug#38563)
---

diff --git a/src/xdisp.c b/src/xdisp.c
index 08c6927052c..bfc48e36a99 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -4243,11 +4243,25 @@ face_at_pos (const struct it *it, enum lface_attribute_index attr_filter)
 	     the display string do.  This sounds like a design bug,
 	     but Emacs always did that since v21.1, so changing that
 	     might be a big deal.  */
-	  base_face_id = it->string_from_prefix_prop_p
-	    ? (!NILP (Vface_remapping_alist)
-	       ? lookup_basic_face (it->w, it->f, DEFAULT_FACE_ID)
-	       : DEFAULT_FACE_ID)
-	    : underlying_face_id (it);
+	  bool use_default = (it->string_from_prefix_prop_p != 0);
+	  if (!use_default)
+	    {
+	      base_face_id = underlying_face_id (it);
+	      /* Reject the underlying face, if that face is different
+		 from the iterator face, and we filter by attr_filter,
+		 and that face's value of the filter attribute is nil
+		 or unspecified; use the default face instead.  */
+	      struct face *bf = FACE_FROM_ID_OR_NULL (it->f, base_face_id);
+	      if (base_face_id != it->base_face_id
+		  && attr_filter > 0
+		  && (NILP (bf->lface[attr_filter])
+		      || EQ (bf->lface[attr_filter], Qunspecified)))
+		use_default = true;
+	    }
+	  if (use_default)
+	    base_face_id = (!NILP (Vface_remapping_alist)
+			    ? lookup_basic_face (it->w, it->f, DEFAULT_FACE_ID)
+			    : DEFAULT_FACE_ID);
 	}
 
       return face_at_string_position (it->w,