fail early if coincidence can't be resolved

src/pathops/SkAddIntersections.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #include "SkAddIntersections.h"
 #include "SkPathOpsBounds.h"
 
 #if DEBUG_ADD_INTERSECTING_TS
@@ skipping 416 matching lines @@
         SkPoint point = ts.pt(0).asSkPoint();
         int testTAt = wt.addSelfT(point, ts[0][0]);
         int nextTAt = wt.addSelfT(point, ts[1][0]);
         wt.addOtherT(testTAt, ts[1][0], nextTAt);
         wt.addOtherT(nextTAt, ts[0][0], testTAt);
     } while (wt.advance());
 }
 
 // resolve any coincident pairs found while intersecting, and
 // see if coincidence is formed by clipping non-concident segments
-void CoincidenceCheck(SkTArray<SkOpContour*, true>* contourList, int total) {
+bool CoincidenceCheck(SkTArray<SkOpContour*, true>* contourList, int total) {
     int contourCount = (*contourList).count();
     for (int cIndex = 0; cIndex < contourCount; ++cIndex) {
         SkOpContour* contour = (*contourList)[cIndex];
         contour->resolveNearCoincidence();
     }
     for (int cIndex = 0; cIndex < contourCount; ++cIndex) {
         SkOpContour* contour = (*contourList)[cIndex];
         contour->addCoincidentPoints();
     }
     for (int cIndex = 0; cIndex < contourCount; ++cIndex) {
         SkOpContour* contour = (*contourList)[cIndex];
-        contour->calcCoincidentWinding();
+        if (!contour->calcCoincidentWinding()) {
+            return false;
+        }
     }
     for (int cIndex = 0; cIndex < contourCount; ++cIndex) {
         SkOpContour* contour = (*contourList)[cIndex];
         contour->calcPartialCoincidentWinding();
     }
+    return true;
 }