[clang] [llvm] [clang][MBD] set up module build daemon infrastructure (PR #67562)

[Michael Spencer via llvm-commits]

================
@@ -0,0 +1,285 @@
+//===------- cc1modbuildd_main.cpp - Clang CC1 Module Build Daemon --------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/Tooling/ModuleBuildDaemon/SocketSupport.h"
+#include "clang/Tooling/ModuleBuildDaemon/Utils.h"
+#include "llvm/Support/FileSystem.h"
+#include "llvm/Support/Path.h"
+#include "llvm/Support/Signals.h"
+#include "llvm/Support/ThreadPool.h"
+
+#include <csignal>
+#include <cstdbool>
+#include <fstream>
+#include <optional>
+#include <string>
+#include <system_error>
+
+#ifdef _WIN32
+#include <windows.h>
+#else
+#include <unistd.h>
+#endif
+
+using namespace llvm;
+using namespace clang::tooling::cc1modbuildd;
+
+// Create unbuffered STDOUT stream so that any logging done by the module build
+// daemon can be viewed without having to terminate the process
+static raw_fd_ostream &unbuff_outs() {
+  static raw_fd_ostream S(fileno(stdout), false, true);
+  return S;
+}
+
+static bool VerboseLog = false;
+static void verboseLog(const llvm::Twine &message) {
+  if (VerboseLog) {
+    unbuff_outs() << message << '\n';
+  }
+}
+
+static void setupSignals(sighandler_t handler) {
----------------
Bigcheese wrote:

`sighandler_t` isn't portable as the std doesn't define a name for the signal handler type. You should be able to use `decltype(SIG_DFL)` to define your own type.

https://github.com/llvm/llvm-project/pull/67562