Fix error reporting in the PNaCl bitcode reader.

tools/pnacl-thaw/pnacl-thaw.cpp

 /* Copyright 2013 The Native Client Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can
  * be found in the LICENSE file.
  */
 
 //===-- pnacl-thaw.cpp - The low-level NaCl bitcode thawer ----------------===//
 //
 //===----------------------------------------------------------------------===//
 //
 // Converts NaCl wire format back to LLVM bitcode.
@@ skipping 15 matching lines @@
 
 using namespace llvm;
 
 static cl::opt<std::string>
 OutputFilename("o", cl::desc("Specify thawed pexe filename"),
                cl::value_desc("filename"), cl::init("-"));
 
 static cl::opt<std::string>
 InputFilename(cl::Positional, cl::desc("<frozen file>"), cl::init("-"));
 
+static cl::opt<bool>
+VerboseErrors(
+    "verbose-parse-errors",
+    cl::desc("Print out more descriptive PNaCl bitcode parse errors"),
+    cl::init(false));
+
 static void WriteOutputFile(const Module *M) {
 
   std::string ErrorInfo;
   std::unique_ptr<tool_output_file> Out(
       new tool_output_file(OutputFilename.c_str(), ErrorInfo, sys::fs::F_None));
   if (!ErrorInfo.empty()) {
     errs() << ErrorInfo << '\n';
     exit(1);
   }
 
@@ skipping 20 matching lines @@
   // Use the bitcode streaming interface
   DataStreamer *streamer = getDataFileStreamer(InputFilename, &ErrorMessage);
   std::unique_ptr<StreamingMemoryObject> Buffer(
       new StreamingMemoryObjectImpl(streamer));
   if (streamer) {
     std::string DisplayFilename;
     if (InputFilename == "-")
       DisplayFilename = "<stdin>";
     else
       DisplayFilename = InputFilename;
+    raw_ostream *Verbose = VerboseErrors ? &errs() : nullptr;
     M.reset(getNaClStreamedBitcodeModule(DisplayFilename, Buffer.release(),
-                                         Context, &ErrorMessage,
+                                         Context, Verbose,
+                                         &ErrorMessage,
                                          /*AcceptSupportedOnly=*/false));
     if (M.get())
       if (std::error_code EC = M->materializeAllPermanently()) {
         ErrorMessage = EC.message();
         M.reset();
       }
   }
 
   if (!M.get()) {
     errs() << argv[0] << ": ";
     if (ErrorMessage.size())
       errs() << ErrorMessage << "\n";
     else
       errs() << "bitcode didn't read correctly.\n";
     return 1;
   }
 
   WriteOutputFile(M.get());
   return 0;
 }