It is dangerous to ignore SkRect::intersect's return value

src/core/SkScan_AntiPath.cpp

 
 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #include "SkScanPriv.h"
@@ skipping 436 matching lines @@
 {
     SkASSERT(CanHandleRect(ir));
     SkASSERT(!isInverse);
 
     fMask.fImage    = (uint8_t*)fStorage;
     fMask.fBounds   = ir;
     fMask.fRowBytes = ir.width();
     fMask.fFormat   = SkMask::kA8_Format;
 
     fClipRect = ir;
-    fClipRect.intersect(clip.getBounds());
+    if (!fClipRect.intersect(clip.getBounds())) {
+        SkASSERT(0);
+        fClipRect.setEmpty();
+    }
 
     // For valgrind, write 1 extra byte at the end so we don't read
     // uninitialized memory. See comment in add_aa_span and fStorage[].
     memset(fStorage, 0, fMask.fBounds.height() * fMask.fRowBytes + 1);
 }
 
 static void add_aa_span(uint8_t* alpha, U8CPU startAlpha) {
     /*  I should be able to just add alpha[x] + startAlpha.
         However, if the trailing edge of the previous span and the leading
         edge of the current span round to the same super-sampled x value,
@@ skipping 295 matching lines @@
         AntiFillPath(path, clip.bwRgn(), blitter);
     } else {
         SkRegion        tmp;
         SkAAClipBlitter aaBlitter;
 
         tmp.setRect(clip.getBounds());
         aaBlitter.init(blitter, &clip.aaRgn());
         SkScan::AntiFillPath(path, tmp, &aaBlitter, true);
     }
 }