Install notion of diagnostic handler into PNaCl bitcode readers.

unittests/Bitcode/NaClMungeTest.cpp

+//===- llvm/unittests/Bitcode/NaClMungeTest.cpp - Test munging utils ------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Implements stringify methods for munging tests.
+//
+//===----------------------------------------------------------------------===//
+
+#include "NaClMungeTest.h"
+#include <regex>
+
+using namespace llvm;
+
+namespace naclmungetest {
+
+static bool matchErrorPrefixForLine(const std::string &Line, std::regex &Exp,
+                                    std::string &Suffix) {
+  std::smatch Match;
+  if (std::regex_search(Line, Match, Exp)) {
+    // Note: Element 0 is the original string.
+    Suffix = Match[2];
+    return true;
+  }
+  Suffix.clear();
+  return false;
+}
+
+static std::string stripErrorPrefixForLine(const std::string &Line) {
+  std::string Suffix;
+  std::regex ErrorExp("[Ee]rror: (\\(.*\\) )?(.*)");
+  if (matchErrorPrefixForLine(Line, ErrorExp, Suffix))
+    return Suffix;
+  std::regex WarningExp("[Ww]arning: (\\(.*\\) )?(.*)");
+  if (matchErrorPrefixForLine(Line, WarningExp, Suffix))
+    return Suffix;
+  return Line;
+}
+
+std::string stripErrorPrefix(const std::string &Message) {
+  std::string Result;
+  size_t StartPos = 0;
+  size_t NextEoln = Message.find('\n', StartPos);
+  while (NextEoln != std::string::npos) {
+    std::string Line(Message.c_str() + StartPos, NextEoln - StartPos);
+    Result.append(stripErrorPrefixForLine(Line)).push_back('\n');
+    StartPos = NextEoln + 1;
+    NextEoln = Message.find_first_of("\n", StartPos);
+  }
+  if (StartPos < Message.size()) {
+    std::string Remainder(Message.c_str() + StartPos,
+                          Message.size() - StartPos);
+    Result.append(stripErrorPrefixForLine(Remainder));
+  }
+  return Result;
+}
+
+} // end of naclmungetest namespace