Merge pull request #66004 from bruvzg/hb52

Update to version 5.2.0, add new Unicode 15 blocks and scripts.

12 files changed, 164 insertions, 52 deletions

diff --git a/thirdparty/harfbuzz/src/OT/Layout/GPOS/Anchor.hh b/thirdparty/harfbuzz/src/OT/Layout/GPOS/Anchor.hh
index bfe6b36afd..49e76e7750 100644
--- a/thirdparty/harfbuzz/src/OT/Layout/GPOS/Anchor.hh
+++ b/thirdparty/harfbuzz/src/OT/Layout/GPOS/Anchor.hh
@@ -58,8 +58,7 @@ struct Anchor
         return_trace (bool (reinterpret_cast<Anchor *> (u.format1.copy (c->serializer))));
       }
       return_trace (bool (reinterpret_cast<Anchor *> (u.format2.copy (c->serializer))));
-    case 3: return_trace (bool (reinterpret_cast<Anchor *> (u.format3.copy (c->serializer,
-                                                                            c->plan->layout_variation_idx_map))));
+    case 3: return_trace (u.format3.subset (c));
     default:return_trace (false);
     }
   }
diff --git a/thirdparty/harfbuzz/src/OT/Layout/GPOS/AnchorFormat3.hh b/thirdparty/harfbuzz/src/OT/Layout/GPOS/AnchorFormat3.hh
index d77b4699be..2e30ab33c3 100644
--- a/thirdparty/harfbuzz/src/OT/Layout/GPOS/AnchorFormat3.hh
+++ b/thirdparty/harfbuzz/src/OT/Layout/GPOS/AnchorFormat3.hh
@@ -41,24 +41,54 @@ struct AnchorFormat3
       *y += (this+yDeviceTable).get_y_delta (font, c->var_store, c->var_store_cache);
   }
 
-  AnchorFormat3* copy (hb_serialize_context_t *c,
-                       const hb_map_t *layout_variation_idx_map) const
+  bool subset (hb_subset_context_t *c) const
   {
-    TRACE_SERIALIZE (this);
-    if (!layout_variation_idx_map) return_trace (nullptr);
+    TRACE_SUBSET (this);
+    auto *out = c->serializer->start_embed (*this);
+    if (unlikely (!out)) return_trace (false);
+    if (unlikely (!c->serializer->embed (format))) return_trace (false);
+    if (unlikely (!c->serializer->embed (xCoordinate))) return_trace (false);
+    if (unlikely (!c->serializer->embed (yCoordinate))) return_trace (false);
 
-    auto *out = c->embed<AnchorFormat3> (this);
-    if (unlikely (!out)) return_trace (nullptr);
+    unsigned x_varidx = xDeviceTable ? (this+xDeviceTable).get_variation_index () : HB_OT_LAYOUT_NO_VARIATIONS_INDEX;
+    if (c->plan->layout_variation_idx_delta_map->has (x_varidx))
+    {
+      int delta = hb_second (c->plan->layout_variation_idx_delta_map->get (x_varidx));
+      if (delta != 0)
+      {
+        if (!c->serializer->check_assign (out->xCoordinate, xCoordinate + delta,
+                                          HB_SERIALIZE_ERROR_INT_OVERFLOW))
+          return_trace (false);
+      }
+    }
 
-    out->xDeviceTable.serialize_copy (c, xDeviceTable, this, 0, hb_serialize_context_t::Head, layout_variation_idx_map);
-    out->yDeviceTable.serialize_copy (c, yDeviceTable, this, 0, hb_serialize_context_t::Head, layout_variation_idx_map);
+    unsigned y_varidx = yDeviceTable ? (this+yDeviceTable).get_variation_index () : HB_OT_LAYOUT_NO_VARIATIONS_INDEX;
+    if (c->plan->layout_variation_idx_delta_map->has (y_varidx))
+    {
+      int delta = hb_second (c->plan->layout_variation_idx_delta_map->get (y_varidx));
+      if (delta != 0)
+      {
+        if (!c->serializer->check_assign (out->yCoordinate, yCoordinate + delta,
+                                          HB_SERIALIZE_ERROR_INT_OVERFLOW))
+          return_trace (false);
+      }
+    }
+
+    if (c->plan->all_axes_pinned)
+      return_trace (c->serializer->check_assign (out->format, 1, HB_SERIALIZE_ERROR_INT_OVERFLOW));
+
+    if (!c->serializer->embed (xDeviceTable)) return_trace (false);
+    if (!c->serializer->embed (yDeviceTable)) return_trace (false);
+
+    out->xDeviceTable.serialize_copy (c->serializer, xDeviceTable, this, 0, hb_serialize_context_t::Head, c->plan->layout_variation_idx_delta_map);
+    out->yDeviceTable.serialize_copy (c->serializer, yDeviceTable, this, 0, hb_serialize_context_t::Head, c->plan->layout_variation_idx_delta_map);
     return_trace (out);
   }
 
   void collect_variation_indices (hb_collect_variation_indices_context_t *c) const
   {
-    (this+xDeviceTable).collect_variation_indices (c->layout_variation_indices);
-    (this+yDeviceTable).collect_variation_indices (c->layout_variation_indices);
+    (this+xDeviceTable).collect_variation_indices (c);
+    (this+yDeviceTable).collect_variation_indices (c);
   }
 };
 
diff --git a/thirdparty/harfbuzz/src/OT/Layout/GPOS/Common.hh b/thirdparty/harfbuzz/src/OT/Layout/GPOS/Common.hh
index e16c06729d..408197454f 100644
--- a/thirdparty/harfbuzz/src/OT/Layout/GPOS/Common.hh
+++ b/thirdparty/harfbuzz/src/OT/Layout/GPOS/Common.hh
@@ -22,7 +22,8 @@ template<typename Iterator, typename SrcLookup>
 static void SinglePos_serialize (hb_serialize_context_t *c,
                                  const SrcLookup *src,
                                  Iterator it,
-                                 const hb_map_t *layout_variation_idx_map);
+                                 const hb_hashmap_t<unsigned, hb_pair_t<unsigned, int>> *layout_variation_idx_delta_map,
+                                 bool all_axes_pinned);
 
 
 }
diff --git a/thirdparty/harfbuzz/src/OT/Layout/GPOS/MarkRecord.hh b/thirdparty/harfbuzz/src/OT/Layout/GPOS/MarkRecord.hh
index 7a514453ae..a7d489d2a5 100644
--- a/thirdparty/harfbuzz/src/OT/Layout/GPOS/MarkRecord.hh
+++ b/thirdparty/harfbuzz/src/OT/Layout/GPOS/MarkRecord.hh
@@ -9,7 +9,7 @@ struct MarkRecord
 {
   friend struct MarkArray;
 
-  protected:
+  public:
   HBUINT16      klass;                  /* Class defined for this mark */
   Offset16To<Anchor>
                 markAnchor;             /* Offset to Anchor table--from
diff --git a/thirdparty/harfbuzz/src/OT/Layout/GPOS/PairPosFormat1.hh b/thirdparty/harfbuzz/src/OT/Layout/GPOS/PairPosFormat1.hh
index 3cb207281d..ddf7313f94 100644
--- a/thirdparty/harfbuzz/src/OT/Layout/GPOS/PairPosFormat1.hh
+++ b/thirdparty/harfbuzz/src/OT/Layout/GPOS/PairPosFormat1.hh
@@ -127,6 +127,12 @@ struct PairPosFormat1_3
       out->valueFormat[1] = newFormats.second;
     }
 
+    if (c->plan->all_axes_pinned)
+    {
+      out->valueFormat[0] = out->valueFormat[0].drop_device_table_flags ();
+      out->valueFormat[1] = out->valueFormat[1].drop_device_table_flags ();
+    }
+
     hb_sorted_vector_t<hb_codepoint_t> new_coverage;
 
     + hb_zip (this+coverage, pairSet)
diff --git a/thirdparty/harfbuzz/src/OT/Layout/GPOS/PairPosFormat2.hh b/thirdparty/harfbuzz/src/OT/Layout/GPOS/PairPosFormat2.hh
index a80fe0c226..83b093b988 100644
--- a/thirdparty/harfbuzz/src/OT/Layout/GPOS/PairPosFormat2.hh
+++ b/thirdparty/harfbuzz/src/OT/Layout/GPOS/PairPosFormat2.hh
@@ -274,13 +274,19 @@ struct PairPosFormat2_4
     out->valueFormat1 = newFormats.first;
     out->valueFormat2 = newFormats.second;
 
+    if (c->plan->all_axes_pinned)
+    {
+      out->valueFormat1 = out->valueFormat1.drop_device_table_flags ();
+      out->valueFormat2 = out->valueFormat2.drop_device_table_flags ();
+    }
+
     for (unsigned class1_idx : + hb_range ((unsigned) class1Count) | hb_filter (klass1_map))
     {
       for (unsigned class2_idx : + hb_range ((unsigned) class2Count) | hb_filter (klass2_map))
       {
         unsigned idx = (class1_idx * (unsigned) class2Count + class2_idx) * (len1 + len2);
-        valueFormat1.copy_values (c->serializer, newFormats.first, this, &values[idx], c->plan->layout_variation_idx_map);
-        valueFormat2.copy_values (c->serializer, newFormats.second, this, &values[idx + len1], c->plan->layout_variation_idx_map);
+        valueFormat1.copy_values (c->serializer, out->valueFormat1, this, &values[idx], c->plan->layout_variation_idx_delta_map);
+        valueFormat2.copy_values (c->serializer, out->valueFormat2, this, &values[idx + len1], c->plan->layout_variation_idx_delta_map);
       }
     }
 
diff --git a/thirdparty/harfbuzz/src/OT/Layout/GPOS/PairSet.hh b/thirdparty/harfbuzz/src/OT/Layout/GPOS/PairSet.hh
index 4578fbd1d6..aa48d933c3 100644
--- a/thirdparty/harfbuzz/src/OT/Layout/GPOS/PairSet.hh
+++ b/thirdparty/harfbuzz/src/OT/Layout/GPOS/PairSet.hh
@@ -163,7 +163,7 @@ struct PairSet
       newFormats,
       len1,
       &glyph_map,
-      c->plan->layout_variation_idx_map
+      c->plan->layout_variation_idx_delta_map
     };
 
     const PairValueRecord *record = &firstPairValueRecord;
diff --git a/thirdparty/harfbuzz/src/OT/Layout/GPOS/PairValueRecord.hh b/thirdparty/harfbuzz/src/OT/Layout/GPOS/PairValueRecord.hh
index bd95abde16..3222477764 100644
--- a/thirdparty/harfbuzz/src/OT/Layout/GPOS/PairValueRecord.hh
+++ b/thirdparty/harfbuzz/src/OT/Layout/GPOS/PairValueRecord.hh
@@ -34,7 +34,7 @@ struct PairValueRecord
     const ValueFormat   *newFormats;
     unsigned            len1; /* valueFormats[0].get_len() */
     const hb_map_t      *glyph_map;
-    const hb_map_t      *layout_variation_idx_map;
+    const hb_hashmap_t<unsigned, hb_pair_t<unsigned, int>> *layout_variation_idx_delta_map;
   };
 
   bool subset (hb_subset_context_t *c,
@@ -50,12 +50,12 @@ struct PairValueRecord
     closure->valueFormats[0].copy_values (s,
                                           closure->newFormats[0],
                                           closure->base, &values[0],
-                                          closure->layout_variation_idx_map);
+                                          closure->layout_variation_idx_delta_map);
     closure->valueFormats[1].copy_values (s,
                                           closure->newFormats[1],
                                           closure->base,
                                           &values[closure->len1],
-                                          closure->layout_variation_idx_map);
+                                          closure->layout_variation_idx_delta_map);
 
     return_trace (true);
   }
diff --git a/thirdparty/harfbuzz/src/OT/Layout/GPOS/SinglePos.hh b/thirdparty/harfbuzz/src/OT/Layout/GPOS/SinglePos.hh
index 702f578b3c..6dce3e6343 100644
--- a/thirdparty/harfbuzz/src/OT/Layout/GPOS/SinglePos.hh
+++ b/thirdparty/harfbuzz/src/OT/Layout/GPOS/SinglePos.hh
@@ -38,12 +38,16 @@ struct SinglePos
   void serialize (hb_serialize_context_t *c,
                   const SrcLookup* src,
                   Iterator glyph_val_iter_pairs,
-                  const hb_map_t *layout_variation_idx_map)
+                  const hb_hashmap_t<unsigned, hb_pair_t<unsigned, int>> *layout_variation_idx_delta_map,
+                  bool all_axes_pinned)
   {
     if (unlikely (!c->extend_min (u.format))) return;
     unsigned format = 2;
     ValueFormat new_format = src->get_value_format ();
 
+    if (all_axes_pinned)
+      new_format = new_format.drop_device_table_flags ();
+
     if (glyph_val_iter_pairs)
       format = get_format (glyph_val_iter_pairs);
 
@@ -53,13 +57,13 @@ struct SinglePos
                                  src,
                                  glyph_val_iter_pairs,
                                  new_format,
-                                 layout_variation_idx_map);
+                                 layout_variation_idx_delta_map);
       return;
     case 2: u.format2.serialize (c,
                                  src,
                                  glyph_val_iter_pairs,
                                  new_format,
-                                 layout_variation_idx_map);
+                                 layout_variation_idx_delta_map);
       return;
     default:return;
     }
@@ -84,8 +88,9 @@ static void
 SinglePos_serialize (hb_serialize_context_t *c,
                      const SrcLookup *src,
                      Iterator it,
-                     const hb_map_t *layout_variation_idx_map)
-{ c->start_embed<SinglePos> ()->serialize (c, src, it, layout_variation_idx_map); }
+                     const hb_hashmap_t<unsigned, hb_pair_t<unsigned, int>> *layout_variation_idx_delta_map,
+                     bool all_axes_pinned)
+{ c->start_embed<SinglePos> ()->serialize (c, src, it, layout_variation_idx_delta_map, all_axes_pinned); }
 
 
 }
diff --git a/thirdparty/harfbuzz/src/OT/Layout/GPOS/SinglePosFormat1.hh b/thirdparty/harfbuzz/src/OT/Layout/GPOS/SinglePosFormat1.hh
index 7cbdf6dc6c..5a9dd58a63 100644
--- a/thirdparty/harfbuzz/src/OT/Layout/GPOS/SinglePosFormat1.hh
+++ b/thirdparty/harfbuzz/src/OT/Layout/GPOS/SinglePosFormat1.hh
@@ -87,7 +87,7 @@ struct SinglePosFormat1
                   const SrcLookup *src,
                   Iterator it,
                   ValueFormat newFormat,
-                  const hb_map_t *layout_variation_idx_map)
+                  const hb_hashmap_t<unsigned, hb_pair_t<unsigned, int>> *layout_variation_idx_delta_map)
   {
     if (unlikely (!c->extend_min (this))) return;
     if (unlikely (!c->check_assign (valueFormat,
@@ -96,7 +96,7 @@ struct SinglePosFormat1
 
     for (const hb_array_t<const Value>& _ : + it | hb_map (hb_second))
     {
-      src->get_value_format ().copy_values (c, newFormat, src,  &_, layout_variation_idx_map);
+      src->get_value_format ().copy_values (c, newFormat, src,  &_, layout_variation_idx_delta_map);
       // Only serialize the first entry in the iterator, the rest are assumed to
       // be the same.
       break;
@@ -126,7 +126,7 @@ struct SinglePosFormat1
     ;
 
     bool ret = bool (it);
-    SinglePos_serialize (c->serializer, this, it, c->plan->layout_variation_idx_map);
+    SinglePos_serialize (c->serializer, this, it, c->plan->layout_variation_idx_delta_map, c->plan->all_axes_pinned);
     return_trace (ret);
   }
 };
diff --git a/thirdparty/harfbuzz/src/OT/Layout/GPOS/SinglePosFormat2.hh b/thirdparty/harfbuzz/src/OT/Layout/GPOS/SinglePosFormat2.hh
index 518fa9dcb0..8a6e8a42a6 100644
--- a/thirdparty/harfbuzz/src/OT/Layout/GPOS/SinglePosFormat2.hh
+++ b/thirdparty/harfbuzz/src/OT/Layout/GPOS/SinglePosFormat2.hh
@@ -99,7 +99,7 @@ struct SinglePosFormat2
                   const SrcLookup *src,
                   Iterator it,
                   ValueFormat newFormat,
-                  const hb_map_t *layout_variation_idx_map)
+                  const hb_hashmap_t<unsigned, hb_pair_t<unsigned, int>> *layout_variation_idx_delta_map)
   {
     auto out = c->extend_min (this);
     if (unlikely (!out)) return;
@@ -109,7 +109,7 @@ struct SinglePosFormat2
     + it
     | hb_map (hb_second)
     | hb_apply ([&] (hb_array_t<const Value> _)
-    { src->get_value_format ().copy_values (c, newFormat, src, &_, layout_variation_idx_map); })
+    { src->get_value_format ().copy_values (c, newFormat, src, &_, layout_variation_idx_delta_map); })
     ;
 
     auto glyphs =
@@ -141,7 +141,7 @@ struct SinglePosFormat2
     ;
 
     bool ret = bool (it);
-    SinglePos_serialize (c->serializer, this, it, c->plan->layout_variation_idx_map);
+    SinglePos_serialize (c->serializer, this, it, c->plan->layout_variation_idx_delta_map, c->plan->all_axes_pinned);
     return_trace (ret);
   }
 };
diff --git a/thirdparty/harfbuzz/src/OT/Layout/GPOS/ValueFormat.hh b/thirdparty/harfbuzz/src/OT/Layout/GPOS/ValueFormat.hh
index b29f287bce..26a40f01a3 100644
--- a/thirdparty/harfbuzz/src/OT/Layout/GPOS/ValueFormat.hh
+++ b/thirdparty/harfbuzz/src/OT/Layout/GPOS/ValueFormat.hh
@@ -59,6 +59,24 @@ struct ValueFormat : HBUINT16
   unsigned int get_len () const  { return hb_popcount ((unsigned int) *this); }
   unsigned int get_size () const { return get_len () * Value::static_size; }
 
+  hb_vector_t<unsigned> get_device_table_indices () const {
+    unsigned i = 0;
+    hb_vector_t<unsigned> result;
+    unsigned format = *this;
+
+    if (format & xPlacement) i++;
+    if (format & yPlacement) i++;
+    if (format & xAdvance)   i++;
+    if (format & yAdvance)   i++;
+
+    if (format & xPlaDevice) result.push (i++);
+    if (format & yPlaDevice) result.push (i++);
+    if (format & xAdvDevice) result.push (i++);
+    if (format & yAdvDevice) result.push (i++);
+
+    return result;
+  }
+
   bool apply_value (hb_ot_apply_context_t *c,
                     const void            *base,
                     const Value           *values,
@@ -145,30 +163,50 @@ struct ValueFormat : HBUINT16
                     unsigned int new_format,
                     const void *base,
                     const Value *values,
-                    const hb_map_t *layout_variation_idx_map) const
+                    const hb_hashmap_t<unsigned, hb_pair_t<unsigned, int>> *layout_variation_idx_delta_map) const
   {
     unsigned int format = *this;
     if (!format) return;
 
-    if (format & xPlacement) copy_value (c, new_format, xPlacement, *values++);
-    if (format & yPlacement) copy_value (c, new_format, yPlacement, *values++);
-    if (format & xAdvance)   copy_value (c, new_format, xAdvance, *values++);
-    if (format & yAdvance)   copy_value (c, new_format, yAdvance, *values++);
+    HBINT16 *x_placement = nullptr, *y_placement = nullptr, *x_adv = nullptr, *y_adv = nullptr;
+    if (format & xPlacement) x_placement = copy_value (c, new_format, xPlacement, *values++);
+    if (format & yPlacement) y_placement = copy_value (c, new_format, yPlacement, *values++);
+    if (format & xAdvance)   x_adv = copy_value (c, new_format, xAdvance, *values++);
+    if (format & yAdvance)   y_adv = copy_value (c, new_format, yAdvance, *values++);
 
-    if (format & xPlaDevice) copy_device (c, base, values++, layout_variation_idx_map);
-    if (format & yPlaDevice) copy_device (c, base, values++, layout_variation_idx_map);
-    if (format & xAdvDevice) copy_device (c, base, values++, layout_variation_idx_map);
-    if (format & yAdvDevice) copy_device (c, base, values++, layout_variation_idx_map);
+    if (format & xPlaDevice)
+    {
+      add_delta_to_value (x_placement, base, values, layout_variation_idx_delta_map);
+      copy_device (c, base, values++, layout_variation_idx_delta_map, new_format, xPlaDevice);
+    }
+
+    if (format & yPlaDevice)
+    {
+      add_delta_to_value (y_placement, base, values, layout_variation_idx_delta_map);
+      copy_device (c, base, values++, layout_variation_idx_delta_map, new_format, yPlaDevice);
+    }
+
+    if (format & xAdvDevice)
+    {
+      add_delta_to_value (x_adv, base, values, layout_variation_idx_delta_map);
+      copy_device (c, base, values++, layout_variation_idx_delta_map, new_format, xAdvDevice);
+    }
+
+    if (format & yAdvDevice)
+    {
+      add_delta_to_value (y_adv, base, values, layout_variation_idx_delta_map);
+      copy_device (c, base, values++, layout_variation_idx_delta_map, new_format, yAdvDevice);
+    }
   }
 
-  void copy_value (hb_serialize_context_t *c,
-                   unsigned int new_format,
-                   Flags flag,
-                   Value value) const
+  HBINT16* copy_value (hb_serialize_context_t *c,
+                       unsigned int new_format,
+                       Flags flag,
+                       Value value) const
   {
     // Filter by new format.
-    if (!(new_format & flag)) return;
-    c->copy (value);
+    if (!(new_format & flag)) return nullptr;
+    return reinterpret_cast<HBINT16 *> (c->copy (value));
   }
 
   void collect_variation_indices (hb_collect_variation_indices_context_t *c,
@@ -183,31 +221,40 @@ struct ValueFormat : HBUINT16
     if (format & yAdvance) i++;
     if (format & xPlaDevice)
     {
-      (base + get_device (&(values[i]))).collect_variation_indices (c->layout_variation_indices);
+      (base + get_device (&(values[i]))).collect_variation_indices (c);
       i++;
     }
 
     if (format & ValueFormat::yPlaDevice)
     {
-      (base + get_device (&(values[i]))).collect_variation_indices (c->layout_variation_indices);
+      (base + get_device (&(values[i]))).collect_variation_indices (c);
       i++;
     }
 
     if (format & ValueFormat::xAdvDevice)
     {
 
-      (base + get_device (&(values[i]))).collect_variation_indices (c->layout_variation_indices);
+      (base + get_device (&(values[i]))).collect_variation_indices (c);
       i++;
     }
 
     if (format & ValueFormat::yAdvDevice)
     {
 
-      (base + get_device (&(values[i]))).collect_variation_indices (c->layout_variation_indices);
+      (base + get_device (&(values[i]))).collect_variation_indices (c);
       i++;
     }
   }
 
+  unsigned drop_device_table_flags () const
+  {
+    unsigned format = *this;
+    for (unsigned flag = xPlaDevice; flag <= yAdvDevice; flag = flag << 1)
+      format = format & ~flag;
+
+    return format;
+  }
+
   private:
   bool sanitize_value_devices (hb_sanitize_context_t *c, const void *base, const Value *values) const
   {
@@ -236,9 +283,27 @@ struct ValueFormat : HBUINT16
     return *static_cast<const Offset16To<Device> *> (value);
   }
 
+  void add_delta_to_value (HBINT16 *value,
+                           const void *base,
+                           const Value *src_value,
+                           const hb_hashmap_t<unsigned, hb_pair_t<unsigned, int>> *layout_variation_idx_delta_map) const
+  {
+    if (!value) return;
+    unsigned varidx = (base + get_device (src_value)).get_variation_index ();
+    hb_pair_t<unsigned, int> *varidx_delta;
+    if (!layout_variation_idx_delta_map->has (varidx, &varidx_delta)) return;
+
+    *value += hb_second (*varidx_delta);
+  }
+
   bool copy_device (hb_serialize_context_t *c, const void *base,
-                    const Value *src_value, const hb_map_t *layout_variation_idx_map) const
+                    const Value *src_value,
+                    const hb_hashmap_t<unsigned, hb_pair_t<unsigned, int>> *layout_variation_idx_delta_map,
+                    unsigned int new_format, Flags flag) const
   {
+    // Filter by new format.
+    if (!(new_format & flag)) return true;
+
     Value       *dst_value = c->copy (*src_value);
 
     if (!dst_value) return false;
@@ -246,7 +311,7 @@ struct ValueFormat : HBUINT16
 
     *dst_value = 0;
     c->push ();
-    if ((base + get_device (src_value)).copy (c, layout_variation_idx_map))
+    if ((base + get_device (src_value)).copy (c, layout_variation_idx_delta_map))
     {
       c->add_link (*dst_value, c->pop_pack ());
       return true;