[PATCH] error_code for dynamically generated error messages

[kledzik at apple.com]

================
Comment at: lib/Core/Error.cpp:189
@@ +188,3 @@
+private:
+  std::vector<std::string> _messages;
+  llvm::sys::SmartMutex<true> _mutex;
----------------
Shankar Easwaran wrote:
> How do we use the vector of messages ? Are these for predefined messages ? If so should it be a vector of StringRef ?
Each time make_dynamic_error_code() is called it copies the string to the vector which dynamically creates a new error code value.  So rather that fixed error values and messages, we get dynamic error values and messages.  Of course, this only makes sense if the clients never look at the value (other than testing against zero).

http://reviews.llvm.org/D3881