commit 8f47dd5779f7f78b5c11f307a74128892ec1d26c
author Garret Rieger <grieger@google.com> Wed Nov 04 11:05:22 2020 -0800
committer Behdad Esfahbod <behdad@behdad.org> Tue Feb 09 20:34:52 2021 -0500
tree 182e5f3f58d71ccc35d0ec689639b7793fbf2c28
parent feeff5928b7764934cec376d047a5c808e9412a6

[subset] don't set lookup visited in closure_lookups_context_t::recurse.
- Lookup::closure_lookups also checks if the lookups visited and sets the lookup to visited. If we set visited in 'recurse' then Lookup::closure_lookups will fail to recurse into the children of the lookup.
- Also when copying ChainRule's skip LookupRecord's that point to lookups which aren't retained. This matches FontTool's behaviour.

src/hb-ot-layout-gsubgpos.hh

diff --git a/src/hb-ot-layout-gsubgpos.hh b/src/hb-ot-layout-gsubgpos.hh
index cb95e6d..389d7af 100644
--- a/src/hb-ot-layout-gsubgpos.hh
+++ b/src/hb-ot-layout-gsubgpos.hh
@@ -146,7 +146,6 @@
     if (is_lookup_visited (lookup_index))
       return;
 
-    set_lookup_visited (lookup_index);
     nesting_level_left--;
     recurse_func (this, lookup_index);
     nesting_level_left++;
@@ -2328,12 +2327,19 @@
 				       | hb_map (mapping));
 
     const ArrayOf<LookupRecord> &lookupRecord = StructAfter<ArrayOf<LookupRecord>> (lookahead);
-    HBUINT16 lookupCount;
-    lookupCount = lookupRecord.len;
-    if (!c->copy (lookupCount)) return_trace (nullptr);
 
-    for (unsigned i = 0; i < (unsigned) lookupCount; i++)
+    HBUINT16* lookupCount = c->embed (&(lookupRecord.len));
+    if (!lookupCount) return_trace (nullptr);
+
+    for (unsigned i = 0; i < lookupRecord.len; i++)
+    {
+      if (!lookup_map->has (lookupRecord[i].lookupListIndex))
+      {
+        (*lookupCount)--;
+        continue;
+      }
       if (!c->copy (lookupRecord[i], lookup_map)) return_trace (nullptr);
+    }
 
     return_trace (out);
   }