[subset] fix failing colrv0 subsetting when font has composite glyphs.

Composite glyph collection was happening along side colrv0 glyph collection which meant it was possible to miss grabbing the component glyphs for a glyph added by colrv0.

src/hb-subset-plan.cc

@@ -254,18 +254,26 @@ _populate_gids_to_retain (hb_subset_plan_t* plan,
 #endif
   _remove_invalid_gids (plan->_glyphset_gsub, plan->source->get_num_glyphs ());
 
+  // Collect all glyphs referenced by COLRv0
+  hb_set_t* cur_glyphset = plan->_glyphset_gsub;
+  hb_set_t glyphset_colrv0;
+  if (colr.is_valid ())
+  {
+    glyphset_colrv0.union_ (cur_glyphset);
+    for (hb_codepoint_t gid : cur_glyphset->iter ())
+      colr.closure_glyphs (gid, &glyphset_colrv0);
+    cur_glyphset = &glyphset_colrv0;
+  }
+
   // Populate a full set of glyphs to retain by adding all referenced
   // composite glyphs.
-  hb_codepoint_t gid = HB_SET_VALUE_INVALID;
-  while (plan->_glyphset_gsub->next (&gid))
+  for (hb_codepoint_t gid : cur_glyphset->iter ())
   {
     glyf.add_gid_and_children (gid, plan->_glyphset);
 #ifndef HB_NO_SUBSET_CFF
     if (cff.is_valid ())
       _add_cff_seac_components (cff, gid, plan->_glyphset);
 #endif
-    if (colr.is_valid ())
-      colr.closure_glyphs (gid, plan->_glyphset);
   }
 
   _remove_invalid_gids (plan->_glyphset, plan->source->get_num_glyphs ());

test/subset/data/Makefile.am

@@ -36,6 +36,7 @@ EXTRA_DIST += \
 	expected/cmap14 \
 	expected/sbix \
 	expected/colr \
+	expected/colr_with_components \
 	expected/cbdt \
 	expected/variable \
 	fonts \

test/subset/data/Makefile.sources

@@ -6,6 +6,7 @@ TESTS = \
 	tests/cmap.tests \
 	tests/cmap14.tests \
 	tests/colr.tests \
+	tests/colr_with_components.tests \
 	tests/full-font.tests \
 	tests/japanese.tests \
 	tests/layout.context.tests \

test/subset/data/tests/colr_with_components.tests

@@ -0,0 +1,11 @@
+FONTS:
+colr-table.ttf
+
+PROFILES:
+default.txt
+drop-hints.txt
+drop-hints-retain-gids.txt
+retain-gids.txt
+
+SUBSETS:
+k

test/subset/meson.build

@@ -28,6 +28,7 @@ tests = [
   'cmap14',
   'sbix',
   'colr',
+  'colr_with_components',
   'cbdt',
   'variable',
 ]