Fix error reporting in the PNaCl bitcode reader.

tools/llvm-dis/llvm-dis.cpp

Index: tools/llvm-dis/llvm-dis.cpp
diff --git a/tools/llvm-dis/llvm-dis.cpp b/tools/llvm-dis/llvm-dis.cpp
index bdce91184a377f36175d2469ce0b2109b2d1be0d..0e9f19bf335420e5d4f54a7f8f6b900627515531 100644
--- a/tools/llvm-dis/llvm-dis.cpp
+++ b/tools/llvm-dis/llvm-dis.cpp
@@ -65,6 +65,12 @@ InputFileFormat(
         clEnumValN(PNaClFormat, "pnacl", "PNaCl bitcode file"),
         clEnumValEnd),
     cl::init(LLVMFormat));
+
+static cl::opt<bool>
+VerboseErrors(
+    "verbose-parse-errors",
+    cl::desc("Print out more descriptive PNaCl bitcode parse errors"),
+    cl::init(false));
 // @LOCALMOD-END
 
 namespace {
@@ -160,10 +166,13 @@ int main(int argc, char **argv) {
         M.reset(getStreamedBitcodeModule(
             DisplayFilename, Buffer.release(), Context, &ErrorMessage));
         break;
-      case PNaClFormat:
+      case PNaClFormat: {
+        raw_ostream *Verbose = VerboseErrors ? &errs() : nullptr;

[jvoung (off chromium), 2014/12/03 19:43:46]

I guess I was okay with this unconditionally having VerboseErrors. Thoughts?

[Karl, 2014/12/03 20:53:44]

Since this is an LLVM tool, I guess we should be just as cryptic. Changing to
use nullptr.

         M.reset(getNaClStreamedBitcodeModule(
-            DisplayFilename, Buffer.release(), Context, &ErrorMessage));
+            DisplayFilename, Buffer.release(), Context, Verbose,
+            &ErrorMessage));
         break;
+      }
       default:
         ErrorMessage = "Don't understand specified bitcode format";
         break;