From 0d7d370104a61ca831b8b04bba9348aed45ae6c5 Mon Sep 17 00:00:00 2001
From: Rasmus Andersson <rasmus@notion.se>
Date: Tue, 23 Jan 2018 19:05:54 -0800
Subject: [PATCH] booleanOperations library: remove unreachable break and add
 exception instead of assertion, as done in upstream

---
 misc/pylib/booleanOperations/exceptions.py | 4 ++++
 misc/pylib/booleanOperations/flatten.pyx   | 5 +++--
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/misc/pylib/booleanOperations/exceptions.py b/misc/pylib/booleanOperations/exceptions.py
index 23028b207..38b72e0b2 100644
--- a/misc/pylib/booleanOperations/exceptions.py
+++ b/misc/pylib/booleanOperations/exceptions.py
@@ -19,3 +19,7 @@ class InvalidClippingContourError(InvalidContourError):
 
 class ExecutionError(BooleanOperationsError):
     """Raised when clipping execution fails"""
+
+
+class OpenContourError(BooleanOperationsError):
+    """Raised when any input contour is open"""
diff --git a/misc/pylib/booleanOperations/flatten.pyx b/misc/pylib/booleanOperations/flatten.pyx
index 85b54a03d..606b2005a 100644
--- a/misc/pylib/booleanOperations/flatten.pyx
+++ b/misc/pylib/booleanOperations/flatten.pyx
@@ -3,6 +3,7 @@ import math
 from fontTools.misc import bezierTools
 from fontTools.pens.basePen import decomposeQuadraticSegment
 import pyclipper
+from .exceptions import OpenContourError
 
 """
 To Do:
@@ -343,7 +344,8 @@ class ContourPointDataPen:
         pass
 
     def addPoint(self, pt, segmentType=None, smooth=False, name=None, **kwargs):
-        assert segmentType != "move"
+        if segmentType == "move":
+            raise OpenContourError("Unhandled open contour")
         if not self._foundStartingPoint and segmentType is not None:
             kwargs['startingPoint'] = self._foundStartingPoint = True
         data = InputPoint(
@@ -373,7 +375,6 @@ def _prepPointsForSegments(points):
             point = points.pop()
             points.insert(0, point)
             continue
-        break
 
 
 def _copyPoints(points):