Fix MSVC warnings about possible value truncation.

src/loca.cc

 // Copyright (c) 2009 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "loca.h"
 
 #include "head.h"
 #include "maxp.h"
 
 // loca - Index to Location
@@ skipping 58 matching lines @@
 bool ots_loca_serialise(OTSStream *out, OpenTypeFile *file) {
   const OpenTypeLOCA *loca = file->loca;
   const OpenTypeHEAD *head = file->head;
 
   if (!head) {
     return OTS_FAILURE();
   }
 
   if (head->index_to_loc_format == 0) {
     for (unsigned i = 0; i < loca->offsets.size(); ++i) {
-      if (!out->WriteU16(loca->offsets[i] >> 1)) {
+      const uint16_t offset = static_cast<uint16_t>(loca->offsets[i] >> 1);
+      if ((offset != (loca->offsets[i] >> 1)) ||
+          !out->WriteU16(offset)) {
         return OTS_FAILURE();
       }
     }
   } else {
     for (unsigned i = 0; i < loca->offsets.size(); ++i) {
       if (!out->WriteU32(loca->offsets[i])) {
         return OTS_FAILURE();
       }
     }
   }
 
   return true;
 }
 
 void ots_loca_free(OpenTypeFile *file) {
   delete file->loca;
 }
 
 }  // namespace ots