Extern in .cpp files is a code smell.

fpdfsdk/src/javascript/global.cpp

 // Copyright 2014 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
 #include "../../include/javascript/IJavaScript.h"
 #include "../../include/javascript/JS_Context.h"
 #include "../../include/javascript/JS_Define.h"
 #include "../../include/javascript/JS_EventHandler.h"
@@ skipping 20 matching lines @@
 template <unsigned ACC, wchar_t N>
 struct CHash<ACC, N> {
   static const unsigned value = (ACC * 1313LLU + N) & 0xFFFFFFFF;
 };
 
 template <unsigned ACC, wchar_t N, wchar_t... Ns>
 struct CHash<ACC, N, Ns...> {
   static const unsigned value = CHash<CHash<ACC, N>::value, Ns...>::value;
 };
 
-extern const unsigned int JSCONST_nStringHash =
+const unsigned int JSCONST_nStringHash =
     CHash<'s', 't', 'r', 'i', 'n', 'g'>::value;
-extern const unsigned int JSCONST_nNumberHash =
+const unsigned int JSCONST_nNumberHash =
     CHash<'n', 'u', 'm', 'b', 'e', 'r'>::value;
-extern const unsigned int JSCONST_nBoolHash =
+const unsigned int JSCONST_nBoolHash =
     CHash<'b', 'o', 'o', 'l', 'e', 'a', 'n'>::value;
-extern const unsigned int JSCONST_nDateHash = CHash<'d', 'a', 't', 'e'>::value;
-extern const unsigned int JSCONST_nObjectHash =
+const unsigned int JSCONST_nDateHash = CHash<'d', 'a', 't', 'e'>::value;
+const unsigned int JSCONST_nObjectHash =
     CHash<'o', 'b', 'j', 'e', 'c', 't'>::value;
-extern const unsigned int JSCONST_nFXobjHash =
-    CHash<'f', 'x', 'o', 'b', 'j'>::value;
-extern const unsigned int JSCONST_nNullHash = CHash<'n', 'u', 'l', 'l'>::value;
-extern const unsigned int JSCONST_nUndefHash =
+const unsigned int JSCONST_nFXobjHash = CHash<'f', 'x', 'o', 'b', 'j'>::value;
+const unsigned int JSCONST_nNullHash = CHash<'n', 'u', 'l', 'l'>::value;
+const unsigned int JSCONST_nUndefHash =
     CHash<'u', 'n', 'd', 'e', 'f', 'i', 'n', 'e', 'd'>::value;
 
 #ifdef _DEBUG
 class HashVerify {
  public:
   HashVerify();
 } g_hashVerify;
 
 HashVerify::HashVerify() {
   ASSERT(JSCONST_nStringHash ==
@@ skipping 469 matching lines @@
     return VT_boolean;
   if (nHash == JSCONST_nDateHash)
     return VT_date;
   if (nHash == JSCONST_nObjectHash)
     return VT_object;
   if (nHash == JSCONST_nFXobjHash)
     return VT_fxobject;
 
   return VT_unknown;
 }