[var] Apply variations on empty glyphs

It was ignoring empty glyphs for no good reason, this fixes it.

Fixes #2618

src/hb-ot-glyf-table.hh

@@ -716,7 +716,6 @@ struct glyf
 	if (unlikely (!SimpleGlyph (*header, bytes).get_contour_points (points, phantom_only)))
 	  return false;
 	break;
-      default: return false; /* empty glyph */
       }
 
       hb_face_t *face = font->face;
@@ -787,7 +786,8 @@ struct glyf
 
 	all_points.extend (phantoms);
       } break;
-      default: return false;
+      default:
+	all_points.extend (phantoms);
       }
 
       if (depth == 0) /* Apply at top level */
@@ -860,6 +860,8 @@ struct glyf
     template<typename T>
     bool get_points (hb_font_t *font, hb_codepoint_t gid, T consumer) const
     {
+      if (gid >= num_glyphs) return false;
+
       /* Making this alloc free is not that easy
 	 https://github.com/harfbuzz/harfbuzz/issues/2095
 	 mostly because of gvar handling in VF fonts,

src/hb-ot-var-gvar-table.hh

@@ -540,6 +540,8 @@ struct gvar
       /* num_coords should exactly match gvar's axisCount due to how GlyphVariationData tuples are aligned */
       if (!font->num_coords || font->num_coords != table->axisCount) return true;
 
+      if (unlikely (glyph >= table->glyphCount)) return false;
+
       hb_bytes_t var_data_bytes = table->get_glyph_var_data_bytes (table.get_blob (), glyph);
       if (!var_data_bytes.as<GlyphVariationData> ()->has_data ()) return true;
       hb_vector_t<unsigned int> shared_indices;

test/shaping/data/in-house/Makefile.sources

@@ -57,6 +57,7 @@ TESTS = \
 	tests/use.tests \
 	tests/variations-rounding.tests \
 	tests/variations-rvrn.tests \
+	tests/variations-space.tests \
 	tests/vertical.tests \
 	tests/zero-width-marks.tests \
 	$(NULL)

test/shaping/data/in-house/meson.build

@@ -57,6 +57,7 @@ in_house_tests = [
   'use.tests',
   'variations-rounding.tests',
   'variations-rvrn.tests',
+  'variations-space.tests',
   'vertical.tests',
   'zero-width-marks.tests',
 ]

test/shaping/data/in-house/tests/variations-space.tests

@@ -0,0 +1,2 @@
+../fonts/ab40c89624a6104e5d0a2308e448a989302f515b.ttf:--variations=wdth=60:U+0020:[space=0+266]
+../fonts/ab40c89624a6104e5d0a2308e448a989302f515b.ttf:--variations=wdth=402:U+0020:[space=0+639]