Reordering fails when GDEF table is absent harfbuzz#2140

Preserve glyph class if there's no GDEF and no guess.

Fixes harfbuzz#2140

src/hb-ot-layout-gsubgpos.hh

@@ -645,53 +645,56 @@ struct hb_ot_apply_context_t :
     return true;
   }
 
-  void _set_glyph_props (hb_codepoint_t glyph_index,
-			  unsigned int class_guess = 0,
-			  bool ligature = false,
-			  bool component = false) const
-  {
-    unsigned int add_in = _hb_glyph_info_get_glyph_props (&buffer->cur()) &
-			  HB_OT_LAYOUT_GLYPH_PROPS_PRESERVE;
-    add_in |= HB_OT_LAYOUT_GLYPH_PROPS_SUBSTITUTED;
+  void _set_glyph_class (hb_codepoint_t glyph_index,
+			 unsigned int class_guess = 0,
+			 bool ligature = false,
+			 bool component = false) const
+  {
+    unsigned int props = _hb_glyph_info_get_glyph_props (&buffer->cur());
+
+    props |= HB_OT_LAYOUT_GLYPH_PROPS_SUBSTITUTED;
     if (ligature)
     {
-      add_in |= HB_OT_LAYOUT_GLYPH_PROPS_LIGATED;
+      props |= HB_OT_LAYOUT_GLYPH_PROPS_LIGATED;
       /* In the only place that the MULTIPLIED bit is used, Uniscribe
        * seems to only care about the "last" transformation between
        * Ligature and Multiple substitutions.  Ie. if you ligate, expand,
        * and ligate again, it forgives the multiplication and acts as
        * if only ligation happened.  As such, clear MULTIPLIED bit.
        */
-      add_in &= ~HB_OT_LAYOUT_GLYPH_PROPS_MULTIPLIED;
+      props &= ~HB_OT_LAYOUT_GLYPH_PROPS_MULTIPLIED;
     }
     if (component)
-      add_in |= HB_OT_LAYOUT_GLYPH_PROPS_MULTIPLIED;
+      props |= HB_OT_LAYOUT_GLYPH_PROPS_MULTIPLIED;
+
     if (likely (has_glyph_classes))
-      _hb_glyph_info_set_glyph_props (&buffer->cur(), add_in | gdef.get_glyph_props (glyph_index));
+      props = (props & ~HB_OT_LAYOUT_GLYPH_PROPS_CLASS_MASK) | gdef.get_glyph_props (glyph_index);
     else if (class_guess)
-      _hb_glyph_info_set_glyph_props (&buffer->cur(), add_in | class_guess);
+      props = (props & ~HB_OT_LAYOUT_GLYPH_PROPS_CLASS_MASK) | class_guess;
+
+    _hb_glyph_info_set_glyph_props (&buffer->cur(), props);
   }
 
   void replace_glyph (hb_codepoint_t glyph_index) const
   {
-    _set_glyph_props (glyph_index);
+    _set_glyph_class (glyph_index);
     buffer->replace_glyph (glyph_index);
   }
   void replace_glyph_inplace (hb_codepoint_t glyph_index) const
   {
-    _set_glyph_props (glyph_index);
+    _set_glyph_class (glyph_index);
     buffer->cur().codepoint = glyph_index;
   }
   void replace_glyph_with_ligature (hb_codepoint_t glyph_index,
-					   unsigned int class_guess) const
+				    unsigned int class_guess) const
   {
-    _set_glyph_props (glyph_index, class_guess, true);
+    _set_glyph_class (glyph_index, class_guess, true);
     buffer->replace_glyph (glyph_index);
   }
   void output_glyph_for_component (hb_codepoint_t glyph_index,
-					  unsigned int class_guess) const
+				   unsigned int class_guess) const
   {
-    _set_glyph_props (glyph_index, class_guess, false, true);
+    _set_glyph_class (glyph_index, class_guess, false, true);
     buffer->output_glyph (glyph_index);
   }
 };

src/hb-ot-layout.hh

@@ -80,14 +80,14 @@ enum hb_ot_layout_glyph_props_flags_t
   HB_OT_LAYOUT_GLYPH_PROPS_LIGATURE	= 0x04u,
   HB_OT_LAYOUT_GLYPH_PROPS_MARK		= 0x08u,
 
+  HB_OT_LAYOUT_GLYPH_PROPS_CLASS_MASK   = HB_OT_LAYOUT_GLYPH_PROPS_BASE_GLYPH |
+					  HB_OT_LAYOUT_GLYPH_PROPS_LIGATURE |
+					  HB_OT_LAYOUT_GLYPH_PROPS_MARK,
+
   /* The following are used internally; not derived from GDEF. */
   HB_OT_LAYOUT_GLYPH_PROPS_SUBSTITUTED	= 0x10u,
   HB_OT_LAYOUT_GLYPH_PROPS_LIGATED	= 0x20u,
   HB_OT_LAYOUT_GLYPH_PROPS_MULTIPLIED	= 0x40u,
-
-  HB_OT_LAYOUT_GLYPH_PROPS_PRESERVE     = HB_OT_LAYOUT_GLYPH_PROPS_SUBSTITUTED |
-					  HB_OT_LAYOUT_GLYPH_PROPS_LIGATED |
-					  HB_OT_LAYOUT_GLYPH_PROPS_MULTIPLIED
 };
 HB_MARK_AS_FLAG_T (hb_ot_layout_glyph_props_flags_t);