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

samples/shell.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 220 matching lines @@
       v8::String::NewFromUtf8(args.GetIsolate(), v8::V8::GetVersion()));
 }
 
 
 // Reads a file into a v8 string.
 v8::Handle<v8::String> ReadFile(v8::Isolate* isolate, const char* name) {
   FILE* file = fopen(name, "rb");
   if (file == NULL) return v8::Handle<v8::String>();
 
   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);
+      return v8::Handle<v8::String>();
+    }
   }
   fclose(file);
-  v8::Handle<v8::String> result =
-      v8::String::NewFromUtf8(isolate, chars, v8::String::kNormalString, size);
+  v8::Handle<v8::String> result = v8::String::NewFromUtf8(
+      isolate, chars, v8::String::kNormalString, static_cast<int>(size));
   delete[] chars;
   return result;
 }
 
 
 // Process remaining command line arguments and execute files
 int RunMain(v8::Isolate* isolate, int argc, char* argv[]) {
   for (int i = 1; i < argc; i++) {
     const char* str = argv[i];
     if (strcmp(str, "--shell") == 0) {
@@ skipping 118 matching lines @@
       fprintf(stderr, "^");
     }
     fprintf(stderr, "\n");
     v8::String::Utf8Value stack_trace(try_catch->StackTrace());
     if (stack_trace.length() > 0) {
       const char* stack_trace_string = ToCString(stack_trace);
       fprintf(stderr, "%s\n", stack_trace_string);
     }
   }
 }