From 05f95f0f584d1df3439d5fa51c44b93f4313ee9d Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Wed, 25 Jul 2018 11:04:48 -0700
Subject: [PATCH] [otBase] Try ExtensionLookup if other offset-overflow methods
 fail

If offset overflow happens other than between Lookup and SubTable, or
within SubTable, then we don't know how to fix it currently.  Now we
try to put that lookup in an Extension lookup anyway, since that will
isolate it and sharing with other lookups won't happen, hopefully
avoiding the overflow.

This is really a bandaid... What we want is the 99proof branch to
be finished and replace our current packing algorithm.

Fixes https://github.com/fonttools/fonttools/issues/1296
---
 Lib/fontTools/ttLib/tables/otBase.py   | 8 +++++++-
 Lib/fontTools/ttLib/tables/otTables.py | 9 +++++----
 2 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/Lib/fontTools/ttLib/tables/otBase.py b/Lib/fontTools/ttLib/tables/otBase.py
index 7606572f2..04b82fef7 100644
--- a/Lib/fontTools/ttLib/tables/otBase.py
+++ b/Lib/fontTools/ttLib/tables/otBase.py
@@ -87,7 +87,13 @@ class BaseTTXConverter(DefaultTable):
 					from .otTables import fixSubTableOverFlows
 					ok = fixSubTableOverFlows(font, overflowRecord)
 				if not ok:
-					raise
+					# Try upgrading lookup to Extension and hope
+					# that cross-lookup sharing not happening would
+					# fix overflow...
+					from .otTables import fixLookupOverFlows
+					ok = fixLookupOverFlows(font, overflowRecord)
+					if not ok:
+						raise
 
 	def toXML(self, writer, font):
 		self.table.toXML2(writer, font)
diff --git a/Lib/fontTools/ttLib/tables/otTables.py b/Lib/fontTools/ttLib/tables/otTables.py
index 2e7b06ca2..d12f7e65c 100644
--- a/Lib/fontTools/ttLib/tables/otTables.py
+++ b/Lib/fontTools/ttLib/tables/otTables.py
@@ -1370,7 +1370,6 @@ def fixSubTableOverFlows(ttf, overflowRecord):
 	"""
 	An offset has overflowed within a sub-table. We need to divide this subtable into smaller parts.
 	"""
-	ok = 0
 	table = ttf[overflowRecord.tableType].table
 	lookup = table.LookupList.Lookup[overflowRecord.LookupListIndex]
 	subIndex = overflowRecord.SubTableIndex
@@ -1391,7 +1390,7 @@ def fixSubTableOverFlows(ttf, overflowRecord):
 		newExtSubTableClass = lookupTypes[overflowRecord.tableType][extSubTable.__class__.LookupType]
 		newExtSubTable = newExtSubTableClass()
 		newExtSubTable.Format = extSubTable.Format
-		lookup.SubTable.insert(subIndex + 1, newExtSubTable)
+		toInsert = newExtSubTable
 
 		newSubTableClass = lookupTypes[overflowRecord.tableType][subTableType]
 		newSubTable = newSubTableClass()
@@ -1400,7 +1399,7 @@ def fixSubTableOverFlows(ttf, overflowRecord):
 		subTableType = subtable.__class__.LookupType
 		newSubTableClass = lookupTypes[overflowRecord.tableType][subTableType]
 		newSubTable = newSubTableClass()
-		lookup.SubTable.insert(subIndex + 1, newSubTable)
+		toInsert = newSubTable
 
 	if hasattr(lookup, 'SubTableCount'): # may not be defined yet.
 		lookup.SubTableCount = lookup.SubTableCount + 1
@@ -1413,9 +1412,11 @@ def fixSubTableOverFlows(ttf, overflowRecord):
 			overflowRecord.tableType,
 			subTableType,
 		)
-		return ok
+		return False
 
 	ok = splitFunc(subtable, newSubTable, overflowRecord)
+	if ok:
+		lookup.SubTable.insert(subIndex + 1, toInsert)
 	return ok
 
 # End of OverFlow logic