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diff --git a/externals/demangle/Utility.h b/externals/demangle/Utility.h
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+//===--- Utility.h ----------------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-FileCopyrightText: Part of the LLVM Project
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// Provide some utility classes for use in the demangler(s).
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef DEMANGLE_UTILITY_H
+#define DEMANGLE_UTILITY_H
+
+#include "StringView.h"
+#include <cstdint>
+#include <cstdlib>
+#include <cstring>
+#include <iterator>
+#include <limits>
+
+DEMANGLE_NAMESPACE_BEGIN
+
+// Stream that AST nodes write their string representation into after the AST
+// has been parsed.
+class OutputStream {
+  char *Buffer;
+  size_t CurrentPosition;
+  size_t BufferCapacity;
+
+  // Ensure there is at least n more positions in buffer.
+  void grow(size_t N) {
+    if (N + CurrentPosition >= BufferCapacity) {
+      BufferCapacity *= 2;
+      if (BufferCapacity < N + CurrentPosition)
+        BufferCapacity = N + CurrentPosition;
+      Buffer = static_cast<char *>(std::realloc(Buffer, BufferCapacity));
+      if (Buffer == nullptr)
+        std::terminate();
+    }
+  }
+
+  void writeUnsigned(uint64_t N, bool isNeg = false) {
+    // Handle special case...
+    if (N == 0) {
+      *this << '0';
+      return;
+    }
+
+    char Temp[21];
+    char *TempPtr = std::end(Temp);
+
+    while (N) {
+      *--TempPtr = '0' + char(N % 10);
+      N /= 10;
+    }
+
+    // Add negative sign...
+    if (isNeg)
+      *--TempPtr = '-';
+    this->operator<<(StringView(TempPtr, std::end(Temp)));
+  }
+
+public:
+  OutputStream(char *StartBuf, size_t Size)
+      : Buffer(StartBuf), CurrentPosition(0), BufferCapacity(Size) {}
+  OutputStream() = default;
+  void reset(char *Buffer_, size_t BufferCapacity_) {
+    CurrentPosition = 0;
+    Buffer = Buffer_;
+    BufferCapacity = BufferCapacity_;
+  }
+
+  /// If a ParameterPackExpansion (or similar type) is encountered, the offset
+  /// into the pack that we're currently printing.
+  unsigned CurrentPackIndex = std::numeric_limits<unsigned>::max();
+  unsigned CurrentPackMax = std::numeric_limits<unsigned>::max();
+
+  OutputStream &operator+=(StringView R) {
+    size_t Size = R.size();
+    if (Size == 0)
+      return *this;
+    grow(Size);
+    std::memmove(Buffer + CurrentPosition, R.begin(), Size);
+    CurrentPosition += Size;
+    return *this;
+  }
+
+  OutputStream &operator+=(char C) {
+    grow(1);
+    Buffer[CurrentPosition++] = C;
+    return *this;
+  }
+
+  OutputStream &operator<<(StringView R) { return (*this += R); }
+
+  OutputStream &operator<<(char C) { return (*this += C); }
+
+  OutputStream &operator<<(long long N) {
+    if (N < 0)
+      writeUnsigned(static_cast<unsigned long long>(-N), true);
+    else
+      writeUnsigned(static_cast<unsigned long long>(N));
+    return *this;
+  }
+
+  OutputStream &operator<<(unsigned long long N) {
+    writeUnsigned(N, false);
+    return *this;
+  }
+
+  OutputStream &operator<<(long N) {
+    return this->operator<<(static_cast<long long>(N));
+  }
+
+  OutputStream &operator<<(unsigned long N) {
+    return this->operator<<(static_cast<unsigned long long>(N));
+  }
+
+  OutputStream &operator<<(int N) {
+    return this->operator<<(static_cast<long long>(N));
+  }
+
+  OutputStream &operator<<(unsigned int N) {
+    return this->operator<<(static_cast<unsigned long long>(N));
+  }
+
+  size_t getCurrentPosition() const { return CurrentPosition; }
+  void setCurrentPosition(size_t NewPos) { CurrentPosition = NewPos; }
+
+  char back() const {
+    return CurrentPosition ? Buffer[CurrentPosition - 1] : '\0';
+  }
+
+  bool empty() const { return CurrentPosition == 0; }
+
+  char *getBuffer() { return Buffer; }
+  char *getBufferEnd() { return Buffer + CurrentPosition - 1; }
+  size_t getBufferCapacity() { return BufferCapacity; }
+};
+
+template <class T> class SwapAndRestore {
+  T &Restore;
+  T OriginalValue;
+  bool ShouldRestore = true;
+
+public:
+  SwapAndRestore(T &Restore_) : SwapAndRestore(Restore_, Restore_) {}
+
+  SwapAndRestore(T &Restore_, T NewVal)
+      : Restore(Restore_), OriginalValue(Restore) {
+    Restore = std::move(NewVal);
+  }
+  ~SwapAndRestore() {
+    if (ShouldRestore)
+      Restore = std::move(OriginalValue);
+  }
+
+  void shouldRestore(bool ShouldRestore_) { ShouldRestore = ShouldRestore_; }
+
+  void restoreNow(bool Force) {
+    if (!Force && !ShouldRestore)
+      return;
+
+    Restore = std::move(OriginalValue);
+    ShouldRestore = false;
+  }
+
+  SwapAndRestore(const SwapAndRestore &) = delete;
+  SwapAndRestore &operator=(const SwapAndRestore &) = delete;
+};
+
+inline bool initializeOutputStream(char *Buf, size_t *N, OutputStream &S,
+                                   size_t InitSize) {
+  size_t BufferSize;
+  if (Buf == nullptr) {
+    Buf = static_cast<char *>(std::malloc(InitSize));
+    if (Buf == nullptr)
+      return false;
+    BufferSize = InitSize;
+  } else
+    BufferSize = *N;
+
+  S.reset(Buf, BufferSize);
+  return true;
+}
+
+DEMANGLE_NAMESPACE_END
+
+#endif