Avoid assertion violations with variable-weight fonts

* src/font.c (font_score, font_delete_unmatched): Don't assume
weight, slant, and width properties of the font must be fixnums:
some variable-weight fonts violate that assumption.  Reported
by Sean Whitton <spwhitton@spwhitton.name>.  This is for builds
with Fontconfig < v2.11.91, for which the fix in
'ftfont_pattern_entity' cannot work.  (Bug#52888)

1 files changed, 25 insertions, 18 deletions

diff --git a/src/font.c b/src/font.c
index 266e5bc75c6..7e0219181c9 100644
--- a/src/font.c
+++ b/src/font.c
@@ -2183,7 +2183,9 @@ font_score (Lisp_Object entity, Lisp_Object *spec_prop)
 
   /* Score three style numeric fields.  Maximum difference is 127. */
   for (i = FONT_WEIGHT_INDEX; i <= FONT_WIDTH_INDEX; i++)
-    if (! NILP (spec_prop[i]) && ! EQ (AREF (entity, i), spec_prop[i]))
+    if (! NILP (spec_prop[i])
+        && ! EQ (AREF (entity, i), spec_prop[i])
+        && FIXNUMP (AREF (entity, i)))
       {
         EMACS_INT diff = ((XFIXNUM (AREF (entity, i)) >> 8)
                           - (XFIXNUM (spec_prop[i]) >> 8));
@@ -2764,26 +2766,31 @@ font_delete_unmatched (Lisp_Object vec, Lisp_Object spec, int size)
         {
           if (FIXNUMP (AREF (spec, prop)))
             {
-              int required = XFIXNUM (AREF (spec, prop)) >> 8;
-              int candidate = XFIXNUM (AREF (entity, prop)) >> 8;
+              if (!FIXNUMP (AREF (entity, prop)))
+                prop = FONT_SPEC_MAX;
+              else
+                {
+                  int required = XFIXNUM (AREF (spec, prop)) >> 8;
+                  int candidate = XFIXNUM (AREF (entity, prop)) >> 8;
 
-              if (candidate != required
+                  if (candidate != required
 #ifdef HAVE_NTGUI
-                  /* A kludge for w32 font search, where listing a
-                     family returns only 4 standard weights: regular,
-                     italic, bold, bold-italic.  For other values one
-                     must specify the font, not just the family in the
-                     :family attribute of the face.  But specifying
-                     :family in the face attributes looks for regular
-                     weight, so if we require exact match, the
-                     non-regular font will be rejected.  So we relax
-                     the accuracy of the match here, and let
-                     font_sort_entities find the best match.  */
-                  && (prop != FONT_WEIGHT_INDEX
-                      || eabs (candidate - required) > 100)
+                      /* A kludge for w32 font search, where listing a
+                         family returns only 4 standard weights: regular,
+                         italic, bold, bold-italic.  For other values one
+                         must specify the font, not just the family in the
+                         :family attribute of the face.  But specifying
+                         :family in the face attributes looks for regular
+                         weight, so if we require exact match, the
+                         non-regular font will be rejected.  So we relax
+                         the accuracy of the match here, and let
+                         font_sort_entities find the best match.  */
+                      && (prop != FONT_WEIGHT_INDEX
+                          || eabs (candidate - required) > 100)
 #endif
-                  )
-                prop = FONT_SPEC_MAX;
+                      )
+                    prop = FONT_SPEC_MAX;
+                }
             }
         }
       if (prop < FONT_SPEC_MAX