[Clang] Remove #pragma clang __debug handle_crash

[aganea]

Summary

As discussed in D70568, remove this because it isn't used anywhere, and I think it's better to go through real crashes for testing (#pragma clang __debug crash).
Also remove the support function CrashRecoveryContext::HandleCrash() which was added at the same time by @ddunbar.

[hans]

clang/lib/Lex/Pragma.cpp

42

I think this can be removed now.

[hans]

Cherry-picked to 10.x in 793d643f6d69e6908a6ece4aacb07b6573e33e18

clang/lib/Lex/Pragma.cpp

 #include "clang/Lex/TokenLexer.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringSwitch.h"
 #include "llvm/ADT/StringRef.h"
-#include "llvm/Support/CrashRecoveryContext.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/ErrorHandling.h"
 #include <algorithm>
 #include <cassert>
 #include <cstddef>
 #include <cstdint>
 #include <limits>
 #include <string>
if (II->isStr("assert")) {
           PP.Diag(IIAndLoc.second, diag::warn_pragma_debug_unknown_module)
               << IIAndLoc.first;
           return;
         }
       }
       M->dump();
     } else if (II->isStr("overflow_stack")) {
       DebugOverflowStack();
-    } else if (II->isStr("handle_crash")) {
-      llvm::CrashRecoveryContext *CRC =llvm::CrashRecoveryContext::GetCurrent();
-      if (CRC)
-        CRC->HandleCrash();
     } else if (II->isStr("captured")) {
       HandleCaptured(PP);
     } else {
       PP.Diag(Tok, diag::warn_pragma_debug_unexpected_command)
         << II->getName();
     }
 
     PPCallbacks *Callbacks = PP.getPPCallbacks();

llvm/include/llvm/Support/CrashRecoveryContext.h

public:
   /// On Darwin, if PRIO_DARWIN_BG is set on the calling thread, it will be
   /// propagated to the new thread as well.
   bool RunSafelyOnThread(function_ref<void()>, unsigned RequestedStackSize = 0);
   bool RunSafelyOnThread(void (*Fn)(void*), void *UserData,
                          unsigned RequestedStackSize = 0) {
     return RunSafelyOnThread([&]() { Fn(UserData); }, RequestedStackSize);
   }
 
-  /// Explicitly trigger a crash recovery in the current process, and
-  /// return failure from RunSafely(). This function does not return.
-  void HandleCrash();
-
   /// In case of a crash, this is the crash identifier.
   int RetCode = 0;
 
   /// Selects whether handling of failures should be done in the same way as
   /// for regular crashes. When this is active, a crash would print the
   /// callstack, clean-up any temporary files and create a coredump/minidump.
   bool DumpStackAndCleanupOnFailure = false;
 };

llvm/lib/Support/CrashRecoveryContext.cpp

bool CrashRecoveryContext::RunSafely(function_ref<void()> Fn) {
   }
 
   Fn();
   return true;
 }
 
 #endif // !_MSC_VER
 
-void CrashRecoveryContext::HandleCrash() {
-  CrashRecoveryContextImpl *CRCI = (CrashRecoveryContextImpl *) Impl;
-  assert(CRCI && "Crash recovery context never initialized!");
-  // As per convention, -2 indicates a crash or timeout as opposed to failure to
-  // execute (see llvm/include/llvm/Support/Program.h)
-  CRCI->HandleCrash(-2, 0);
-}
-
 // FIXME: Portability.
 static void setThreadBackgroundPriority() {
 #ifdef __APPLE__
   setpriority(PRIO_DARWIN_THREAD, 0, PRIO_DARWIN_BG);
 #endif
 }
 
 static bool hasThreadBackgroundPriority() {