[clang] Use -Wshorten-64-to-32 to enable warnings about 64bit to 32bit truncations.

src/d8.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 
 // Defined when linking against shared lib on Windows.
 #if defined(USING_V8_SHARED) && !defined(V8_SHARED)
 #define V8_SHARED
 #endif
 
@@ skipping 1095 matching lines @@
   return NULL;
 #endif
 }
 
 
 static char* ReadChars(Isolate* isolate, const char* name, int* size_out) {
   FILE* file = FOpen(name, "rb");
   if (file == NULL) return NULL;
 
   fseek(file, 0, SEEK_END);
-  int size = ftell(file);
+  size_t size = ftell(file);
   rewind(file);
 
   char* chars = new char[size + 1];
   chars[size] = '\0';
-  for (int i = 0; i < size;) {
-    int read = static_cast<int>(fread(&chars[i], 1, size - i, file));
-    i += read;
+  for (size_t i = 0; i < size;) {
+    i += fread(&chars[i], 1, size - i, file);
+    if (ferror(file)) {
+      fclose(file);
+      delete[] chars;
+      return nullptr;
+    }
   }
   fclose(file);
-  *size_out = size;
+  *size_out = static_cast<int>(size);
   return chars;
 }
 
 
 struct DataAndPersistent {
   uint8_t* data;
   int byte_length;
   Global<ArrayBuffer> handle;
 };
 
@@ skipping 591 matching lines @@
 }
 
 }  // namespace v8
 
 
 #ifndef GOOGLE3
 int main(int argc, char* argv[]) {
   return v8::Shell::Main(argc, argv);
 }
 #endif