1 files changed, 27 insertions, 14 deletions

diff --git a/thirdparty/harfbuzz/src/hb-ot-layout-gsubgpos.hh b/thirdparty/harfbuzz/src/hb-ot-layout-gsubgpos.hh
index 65de131f85..3faa1e53d5 100644
--- a/thirdparty/harfbuzz/src/hb-ot-layout-gsubgpos.hh
+++ b/thirdparty/harfbuzz/src/hb-ot-layout-gsubgpos.hh
@@ -408,12 +408,11 @@ struct hb_ot_apply_context_t :
   {
     matcher_t () :
 	     lookup_props (0),
+	     mask (-1),
 	     ignore_zwnj (false),
 	     ignore_zwj (false),
-	     mask (-1),
-#define arg1(arg) (arg) /* Remove the macro to see why it's needed! */
-	     syllable arg1(0),
-#undef arg1
+	     per_syllable (false),
+	     syllable {0},
 	     match_func (nullptr),
 	     match_data (nullptr) {}
 
@@ -423,7 +422,8 @@ struct hb_ot_apply_context_t :
     void set_ignore_zwj (bool ignore_zwj_) { ignore_zwj = ignore_zwj_; }
     void set_lookup_props (unsigned int lookup_props_) { lookup_props = lookup_props_; }
     void set_mask (hb_mask_t mask_) { mask = mask_; }
-    void set_syllable (uint8_t syllable_)  { syllable = syllable_; }
+    void set_per_syllable (bool per_syllable_) { per_syllable = per_syllable_; }
+    void set_syllable (uint8_t syllable_)  { syllable = per_syllable ? syllable_ : 0; }
     void set_match_func (match_func_t match_func_,
 			 const void *match_data_)
     { match_func = match_func_; match_data = match_data_; }
@@ -469,9 +469,10 @@ struct hb_ot_apply_context_t :
 
     protected:
     unsigned int lookup_props;
+    hb_mask_t mask;
     bool ignore_zwnj;
     bool ignore_zwj;
-    hb_mask_t mask;
+    bool per_syllable;
     uint8_t syllable;
     match_func_t match_func;
     const void *match_data;
@@ -490,6 +491,7 @@ struct hb_ot_apply_context_t :
       /* Ignore ZWJ if we are matching context, or asked to. */
       matcher.set_ignore_zwj  (context_match || c->auto_zwj);
       matcher.set_mask (context_match ? -1 : c->lookup_mask);
+      matcher.set_per_syllable (c->per_syllable);
     }
     void set_lookup_props (unsigned int lookup_props)
     {
@@ -636,6 +638,7 @@ struct hb_ot_apply_context_t :
   bool has_glyph_classes;
   bool auto_zwnj;
   bool auto_zwj;
+  bool per_syllable;
   bool random;
 
   uint32_t random_state;
@@ -664,6 +667,7 @@ struct hb_ot_apply_context_t :
 			has_glyph_classes (gdef.has_glyph_classes ()),
 			auto_zwnj (true),
 			auto_zwj (true),
+			per_syllable (false),
 			random (false),
 			random_state (1) { init_iters (); }
 
@@ -676,6 +680,7 @@ struct hb_ot_apply_context_t :
   void set_lookup_mask (hb_mask_t mask) { lookup_mask = mask; init_iters (); }
   void set_auto_zwj (bool auto_zwj_) { auto_zwj = auto_zwj_; init_iters (); }
   void set_auto_zwnj (bool auto_zwnj_) { auto_zwnj = auto_zwnj_; init_iters (); }
+  void set_per_syllable (bool per_syllable_) { per_syllable = per_syllable_; init_iters (); }
   void set_random (bool random_) { random = random_; }
   void set_recurse_func (recurse_func_t func) { recurse_func = func; }
   void set_lookup_index (unsigned int lookup_index_) { lookup_index = lookup_index_; }
@@ -1415,13 +1420,18 @@ static inline void apply_lookup (hb_ot_apply_context_t *c,
     if (unlikely (idx == 0 && lookupRecord[i].lookupListIndex == c->lookup_index))
       continue;
 
+    unsigned int orig_len = buffer->backtrack_len () + buffer->lookahead_len ();
+
+    /* This can happen if earlier recursed lookups deleted many entries. */
+    if (unlikely (match_positions[idx] >= orig_len))
+      continue;
+
     if (unlikely (!buffer->move_to (match_positions[idx])))
       break;
 
     if (unlikely (buffer->max_ops <= 0))
       break;
 
-    unsigned int orig_len = buffer->backtrack_len () + buffer->lookahead_len ();
     if (!c->recurse (lookupRecord[i].lookupListIndex))
       continue;
 
@@ -1457,15 +1467,18 @@ static inline void apply_lookup (hb_ot_apply_context_t *c,
      */
 
     end += delta;
-    if (end <= int (match_positions[idx]))
+    if (end < int (match_positions[idx]))
     {
       /* End might end up being smaller than match_positions[idx] if the recursed
-       * lookup ended up removing many items, more than we have had matched.
-       * Just never rewind end back and get out of here.
-       * https://bugs.chromium.org/p/chromium/issues/detail?id=659496 */
+       * lookup ended up removing many items.
+       * Just never rewind end beyond start of current position, since that is
+       * not possible in the recursed lookup.  Also adjust delta as such.
+       *
+       * https://bugs.chromium.org/p/chromium/issues/detail?id=659496
+       * https://github.com/harfbuzz/harfbuzz/issues/1611
+       */
+      delta += match_positions[idx] - end;
       end = match_positions[idx];
-      /* There can't be any further changes. */
-      break;
     }
 
     unsigned int next = idx + 1; /* next now is the position after the recursed lookup. */
@@ -1477,7 +1490,7 @@ static inline void apply_lookup (hb_ot_apply_context_t *c,
     }
     else
     {
-      /* NOTE: delta is negative. */
+      /* NOTE: delta is non-positive. */
       delta = hb_max (delta, (int) next - (int) count);
       next -= delta;
     }