[debug] Print lookup index in debug-apply output

src/hb-ot-layout-gpos-table.hh

@@ -1568,8 +1568,11 @@ template <typename context_t>
   const GPOS &gpos = *(hb_ot_layout_from_face (c->face)->gpos);
   const PosLookup &l = gpos.get_lookup (lookup_index);
   unsigned int saved_lookup_props = c->lookup_props;
-  c->set_lookup (l);
+  unsigned int saved_lookup_index = c->lookup_index;
+  c->set_lookup_index (lookup_index);
+  c->set_lookup_props (l.get_props ());
   bool ret = l.dispatch (c);
+  c->set_lookup_index (saved_lookup_index);
   c->set_lookup_props (saved_lookup_props);
   return ret;
 }

src/hb-ot-layout-gsub-table.hh

@@ -1311,8 +1311,11 @@ template <typename context_t>
   const GSUB &gsub = *(hb_ot_layout_from_face (c->face)->gsub);
   const SubstLookup &l = gsub.get_lookup (lookup_index);
   unsigned int saved_lookup_props = c->lookup_props;
-  c->set_lookup (l);
+  unsigned int saved_lookup_index = c->lookup_index;
+  c->set_lookup_index (lookup_index);
+  c->set_lookup_props (l.get_props ());
   bool ret = l.dispatch (c);
+  c->set_lookup_index (saved_lookup_index);
   c->set_lookup_props (saved_lookup_props);
   return ret;
 }

src/hb-ot-layout-gsubgpos-private.hh

@@ -266,7 +266,8 @@ struct hb_add_coverage_context_t
 #define TRACE_APPLY(this) \
 	hb_auto_trace_t<HB_DEBUG_APPLY, bool> trace \
 	(&c->debug_depth, c->get_name (), this, HB_FUNC, \
-	 "idx %d codepoint %u", c->buffer->idx, c->buffer->cur().codepoint);
+	 "idx %d gid %u lookup %d", \
+	 c->buffer->idx, c->buffer->cur().codepoint, (int) c->lookup_index);
 
 struct hb_apply_context_t
 {
@@ -481,6 +482,7 @@ struct hb_apply_context_t
   const GDEF &gdef;
   bool has_glyph_classes;
   skipping_iterator_t iter_input, iter_context;
+  unsigned int lookup_index;
   unsigned int debug_depth;
 
 
@@ -499,12 +501,13 @@ struct hb_apply_context_t
 			has_glyph_classes (gdef.has_glyph_classes ()),
 			iter_input (),
 			iter_context (),
+			lookup_index ((unsigned int) -1),
 			debug_depth (0) {}
 
   inline void set_lookup_mask (hb_mask_t mask) { lookup_mask = mask; }
   inline void set_auto_zwj (bool auto_zwj_) { auto_zwj = auto_zwj_; }
   inline void set_recurse_func (recurse_func_t func) { recurse_func = func; }
-  inline void set_lookup (const Lookup &l) { set_lookup_props (l.get_props ()); }
+  inline void set_lookup_index (unsigned int lookup_index_) { lookup_index = lookup_index_; }
   inline void set_lookup_props (unsigned int lookup_props_)
   {
     lookup_props = lookup_props_;

src/hb-ot-layout.cc

@@ -959,7 +959,7 @@ apply_string (OT::hb_apply_context_t *c,
   if (unlikely (!buffer->len || !c->lookup_mask))
     return;
 
-  c->set_lookup (lookup);
+  c->set_lookup_props (lookup.get_props ());
 
   if (likely (!lookup.is_reverse ()))
   {
@@ -1011,6 +1011,7 @@ inline void hb_ot_map_t::apply (const Proxy &proxy,
     for (; i < stage->last_lookup; i++)
     {
       unsigned int lookup_index = lookups[table_index][i].index;
+      c.set_lookup_index (lookup_index);
       c.set_lookup_mask (lookups[table_index][i].mask);
       c.set_auto_zwj (lookups[table_index][i].auto_zwj);
       apply_string<Proxy> (&c,