Fix error reporting in the PNaCl bitcode reader.

lib/IRReader/IRReader.cpp

Index: lib/IRReader/IRReader.cpp
diff --git a/lib/IRReader/IRReader.cpp b/lib/IRReader/IRReader.cpp
index d55e1cea656401f2e5fe8e780d66355c089d4eaa..a76d371914e65cbcbd9c1787977640b409510139 100644
--- a/lib/IRReader/IRReader.cpp
+++ b/lib/IRReader/IRReader.cpp
@@ -108,13 +108,13 @@ Module *llvm::NaClParseIR(MemoryBuffer *Buffer,
   if ((Format == PNaClFormat) &&
       isNaClBitcode((const unsigned char *)Buffer->getBufferStart(),
                     (const unsigned char *)Buffer->getBufferEnd())) {
-    std::string ErrMsg;
-    Module *M = NaClParseBitcodeFile(Buffer, Context, &ErrMsg);
-    if (M == 0)
+    ErrorOr<Module *> MOrErr =

[jvoung (off chromium), 2014/12/01 23:23:50]

"ModuleOrError" to be consistent with ParseIR() ?

[JF, 2014/12/02 00:49:04]

Upstream uses MOrErr, so I'd keep that.

[Karl, 2014/12/03 18:32:10]

Since our local version uses ModuleOrError, will make consistent with that.

+        NaClParseBitcodeFile(Buffer, Context, /*VerboseErrors=*/false);

[jvoung (off chromium), 2014/12/01 23:23:50]

how do you decide between setting VerboseErrors to true or false?

[Karl, 2014/12/03 18:32:10]

Good point. Adding as argument so that calling tool can decide.

+    if (std::error_code EC = MOrErr.getError())
       Err = SMDiagnostic(Buffer->getBufferIdentifier(), SourceMgr::DK_Error,
-                         ErrMsg);
+                         EC.message());
     // ParseBitcodeFile does not take ownership of the Buffer.
-    return M;
+    return MOrErr.get();
   } else if (Format == LLVMFormat) {
     if (isBitcode((const unsigned char *)Buffer->getBufferStart(),
                   (const unsigned char *)Buffer->getBufferEnd())) {