[subset] layout_features filtering fix

we should not use get_size (), which returns length * item_size

src/hb-subset-plan.cc

@@ -100,11 +100,23 @@ static void _collect_layout_indices (hb_face_t		  *face,
   if (!features.alloc (table.get_feature_count () + 1))
     return;
 
+  hb_set_t visited_features;
+  bool retain_all_features = true;
   for (unsigned i = 0; i < table.get_feature_count (); i++)
   {
     hb_tag_t tag = table.get_feature_tag (i);
-    if (tag && layout_features_to_retain->has (tag))
-      features.push (tag);
+    if (!tag) continue;
+    if (!layout_features_to_retain->has (tag))
+    {
+      retain_all_features = false;
+      continue;
+    }
+    
+    if (visited_features.has (tag))
+      continue;
+
+    features.push (tag);
+    visited_features.add (tag);
   }
 
   if (!features)
@@ -113,7 +125,7 @@ static void _collect_layout_indices (hb_face_t		  *face,
   // The collect function needs a null element to signal end of the array.
   features.push (0);
 
-  if (features.get_size () == table.get_feature_count () + 1)
+  if (retain_all_features)
   {
     // Looking for all features, trigger the faster collection method.
     layout_collect_func (face,

test/subset/data/Makefile.am

@@ -38,6 +38,7 @@ EXTRA_DIST += \
 	expected/layout.gdef-attachlist \
 	expected/layout.notonastaliqurdu \
 	expected/layout.tinos \
+	expected/layout.default_features \
 	expected/layout.duplicate_features \
 	expected/layout.unsorted_featurelist \
 	expected/layout.drop_feature \

test/subset/data/Makefile.sources

@@ -36,6 +36,7 @@ TESTS = \
 	tests/layout.notonastaliqurdu.tests \
 	tests/layout.tests \
 	tests/layout.tinos.tests \
+	tests/layout.default_features.tests \
 	tests/layout.duplicate_features.tests \
 	tests/layout.unsorted_featurelist.tests \
 	tests/layout.drop_feature.tests \

test/subset/data/tests/layout.default_features.tests

@@ -0,0 +1,11 @@
+FONTS:
+FranklinGothic-Regular.ttf
+
+PROFILES:
+layout-test.txt
+default.txt
+retain-gids.txt
+
+SUBSETS:
+achi
+*

test/subset/meson.build

@@ -33,6 +33,7 @@ tests = [
   'layout.duplicate_features',
   'layout.unsorted_featurelist',
   'layout.drop_feature',
+  'layout.default_features',
   'cmap',
   'cmap14',
   'sbix',