Clarify intent of FACE_FROM_ID and IMAGE_FROM_ID

* src/dispextern.h (FACE_OPT_FROM_ID): Don’t use FACE_FROM_ID,
since it is intended to be used only when it returns a non-null
pointer, and here the pointer might be null.
(IMAGE_OPT_FROM_ID): Don’t use IMAGE_FROM_ID, for similar reasons.

diff --git a/src/dispextern.h b/src/dispextern.h
index d0fc3b24df775d9e28536cb8b9e72ae2166c951b..08dcd89709a9046f84516bdf8c3ea12dccfbcc74 100644 (file)
--- a/src/dispextern.h
+++ b/src/dispextern.h
@@ -1812,7 +1812,7 @@ struct face_cache
   bool_bf menu_face_changed_p : 1;
 };
 
-/* Return a pointer to the cached face with ID on frame F.  */
+/* Return a non-null pointer to the cached face with ID on frame F.  */
 
 #define FACE_FROM_ID(F, ID)                                    \
   (eassert (UNSIGNED_CMP (ID, <, FRAME_FACE_CACHE (F)->used)), \
@@ -1823,7 +1823,7 @@ struct face_cache
 
 #define FACE_OPT_FROM_ID(F, ID)                                \
   (UNSIGNED_CMP (ID, <, FRAME_FACE_CACHE (F)->used)    \
-   ? FACE_FROM_ID (F, ID)                              \
+   ? FRAME_FACE_CACHE (F)->faces_by_id[ID]             \
    : NULL)
 
 /* True if FACE is suitable for displaying ASCII characters.  */
@@ -3093,7 +3093,7 @@ struct image_cache
 };
 
 
-/* A pointer to the image with id ID on frame F.  */
+/* A non-null pointer to the image with id ID on frame F.  */
 
 #define IMAGE_FROM_ID(F, ID)                                   \
   (eassert (UNSIGNED_CMP (ID, <, FRAME_IMAGE_CACHE (F)->used)),        \
@@ -3104,7 +3104,7 @@ struct image_cache
 
 #define IMAGE_OPT_FROM_ID(F, ID)                               \
   (UNSIGNED_CMP (ID, <, FRAME_IMAGE_CACHE (F)->used)           \
-   ? IMAGE_FROM_ID (F, ID)                                     \
+   ? FRAME_IMAGE_CACHE (F)->images[ID]                         \
    : NULL)
 
 /* Size of bucket vector of image caches.  Should be prime.  */