[instancer] always check and update default wght/width/slnt if necessary

Sometimes default values in original file are incorrect, and if default value for an axis is not changed, then these values won't be updated

src/hb-ot-os2-table.hh

@@ -246,24 +246,19 @@ struct OS2
     }
 #endif
 
-    if (c->plan->user_axes_location.has (HB_TAG ('w','g','h','t')) &&
-        !c->plan->pinned_at_default)
+    Triple *axis_range;
+    if (c->plan->user_axes_location.has (HB_TAG ('w','g','h','t'), &axis_range))
     {
-      float weight_class = c->plan->user_axes_location.get (HB_TAG ('w','g','h','t')).middle;
-      if (!c->serializer->check_assign (os2_prime->usWeightClass,
-                                        roundf (hb_clamp (weight_class, 1.0f, 1000.0f)),
-                                        HB_SERIALIZE_ERROR_INT_OVERFLOW))
-        return_trace (false);
+      unsigned weight_class = static_cast<unsigned> (roundf (hb_clamp (axis_range->middle, 1.0f, 1000.0f)));
+      if (os2_prime->usWeightClass != weight_class)
+        os2_prime->usWeightClass = weight_class;
     }
 
-    if (c->plan->user_axes_location.has (HB_TAG ('w','d','t','h')) &&
-        !c->plan->pinned_at_default)
+    if (c->plan->user_axes_location.has (HB_TAG ('w','d','t','h'), &axis_range))
     {
-      float width = c->plan->user_axes_location.get (HB_TAG ('w','d','t','h')).middle;
-      if (!c->serializer->check_assign (os2_prime->usWidthClass,
-                                        roundf (map_wdth_to_widthclass (width)),
-                                        HB_SERIALIZE_ERROR_INT_OVERFLOW))
-        return_trace (false);
+      unsigned width_class = static_cast<unsigned> (roundf (map_wdth_to_widthclass (axis_range->middle)));
+      if (os2_prime->usWidthClass != width_class)
+        os2_prime->usWidthClass = width_class;
     }
 
     if (c->plan->flags & HB_SUBSET_FLAGS_NO_PRUNE_UNICODE_RANGES)

src/hb-ot-post-table.hh

@@ -113,12 +113,12 @@ struct post
     }
 #endif
 
-    if (c->plan->user_axes_location.has (HB_TAG ('s','l','n','t')) &&
-        !c->plan->pinned_at_default)
+    Triple *axis_range;
+    if (c->plan->user_axes_location.has (HB_TAG ('s','l','n','t'), &axis_range))
     {
-      float italic_angle = c->plan->user_axes_location.get (HB_TAG ('s','l','n','t')).middle;
-      italic_angle = hb_max (-90.f, hb_min (italic_angle, 90.f));
-      post_prime->italicAngle.set_float (italic_angle);
+      float italic_angle = hb_max (-90.f, hb_min (axis_range->middle, 90.f));
+      if (post_prime->italicAngle.to_float () != italic_angle)
+        post_prime->italicAngle.set_float (italic_angle);
     }
 
     if (glyph_names && version.major == 2)

test/subset/data/tests/update_def_wght.tests

@@ -0,0 +1,12 @@
+FONTS:
+SourceSerifVariable-Roman.ttf
+
+PROFILES:
+no-tables-with-item-variations.txt
+
+SUBSETS:
+*
+
+INSTANCES:
+wght=300:600
+wght=500:800

test/subset/meson.build

@@ -68,7 +68,11 @@ tests = [
 ]
 
 if get_option('experimental_api')
-  tests += ['glyf_partial_instancing', 'mvar_partial_instance']
+  tests += [
+    'glyf_partial_instancing',
+    'mvar_partial_instance',
+    'update_def_wght',
+    ]
 endif
 
 repack_tests = [