First attempt to capture parser/translation errors in browser.

src/IceBrowserCompileServer.h

 //===- subzero/src/IceBrowserCompileServer.h - Browser server ---*- C++ -*-===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file declares the browser-specific compile server.
@@ skipping 21 matching lines @@
 // The browser variant of the compile server.
 // Compared to the commandline version, this version gets compile
 // requests over IPC. Each compile request will have a slimmed down
 // version of argc, argv while other flags are set to defaults that
 // make sense in the browser case. The output file is specified via
 // a posix FD, and input bytes are pushed to the server.
 class BrowserCompileServer : public CompileServer {
   BrowserCompileServer() = delete;
   BrowserCompileServer(const BrowserCompileServer &) = delete;
   BrowserCompileServer &operator=(const BrowserCompileServer &) = delete;
+  class StringStream;
 
 public:
   explicit BrowserCompileServer(Compiler &Comp)
       : CompileServer(Comp), InputStream(nullptr) {}
 
   ~BrowserCompileServer() final;
 
   void run() final;
 
   // Parse and set up the flags for compile jobs.
@@ skipping 15 matching lines @@
     CompileThread.join();
     LastError.assign(Ctx->getErrorStatus()->value());
     // Reset some state. The InputStream is deleted by the compiler
     // so only reset this to nullptr. Free and flush the rest
     // of the streams.
     InputStream = nullptr;
     EmitStream.reset(nullptr);
     ELFStream.reset(nullptr);
   }
 
+  StringStream &getErrorStream() {
+    return *ErrorStream;
+  }
+
 private:
+  class StringStream {
+  public:
+    StringStream() : StrBuf(Buffer) {}
+    const IceString &getContents() { return StrBuf.str(); }
+    Ostream &getStream() { return StrBuf; }
+  private:
+    std::string Buffer;
+    llvm::raw_string_ostream StrBuf;
+  };
   // This currently only handles a single compile request, hence one copy
   // of the state.
   std::unique_ptr<GlobalContext> Ctx;
   // A borrowed reference to the current InputStream. The compiler owns
   // the actual reference so the server must be careful not to access
   // after the compiler is done.
   llvm::QueueStreamer *InputStream;
   std::unique_ptr<Ostream> LogStream;
   std::unique_ptr<llvm::raw_fd_ostream> EmitStream;
+  std::unique_ptr<StringStream> ErrorStream;
   std::unique_ptr<ELFStreamer> ELFStream;
   ClFlags Flags;
   ClFlagsExtra ExtraFlags;
   std::thread CompileThread;
 };
 
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICEBROWSERCOMPILESERVER_H