Prepare wpiutil for merge into allwpilib.

wpiutil/src/main/native/cpp/llvm/raw_ostream.cpp

@@ -0,0 +1,733 @@
+//===--- raw_ostream.cpp - Implement the raw_ostream classes --------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This implements support for bulk buffered stream output.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/raw_ostream.h"
+#include "llvm/SmallString.h"
+#include "llvm/SmallVector.h"
+#include "llvm/StringExtras.h"
+#include "llvm/Compiler.h"
+#include "llvm/Format.h"
+#include "llvm/MathExtras.h"
+#include "llvm/WindowsError.h"
+#include <cctype>
+#include <cerrno>
+#include <sys/stat.h>
+#include <system_error>
+
+// <fcntl.h> may provide O_BINARY.
+#include <fcntl.h>
+
+#ifndef _WIN32
+#include <unistd.h>
+#include <sys/uio.h>
+#endif
+
+#if defined(__CYGWIN__)
+#include <io.h>
+#endif
+
+#if defined(_MSC_VER)
+#include <io.h>
+#ifndef STDIN_FILENO
+# define STDIN_FILENO 0
+#endif
+#ifndef STDOUT_FILENO
+# define STDOUT_FILENO 1
+#endif
+#ifndef STDERR_FILENO
+# define STDERR_FILENO 2
+#endif
+#endif
+
+#if defined(_WIN32)
+#include "Windows/WindowsSupport.h"
+#endif
+
+using namespace llvm;
+
+raw_ostream::~raw_ostream() {
+  // raw_ostream's subclasses should take care to flush the buffer
+  // in their destructors.
+  assert(OutBufCur == OutBufStart &&
+         "raw_ostream destructor called with non-empty buffer!");
+
+  if (BufferMode == InternalBuffer)
+    delete [] OutBufStart;
+}
+
+// An out of line virtual method to provide a home for the class vtable.
+void raw_ostream::handle() {}
+
+size_t raw_ostream::preferred_buffer_size() const {
+  // BUFSIZ is intended to be a reasonable default.
+  return BUFSIZ;
+}
+
+void raw_ostream::SetBuffered() {
+  // Ask the subclass to determine an appropriate buffer size.
+  if (size_t Size = preferred_buffer_size())
+    SetBufferSize(Size);
+  else
+    // It may return 0, meaning this stream should be unbuffered.
+    SetUnbuffered();
+}
+
+void raw_ostream::SetBufferAndMode(char *BufferStart, size_t Size,
+                                   BufferKind Mode) {
+  assert(((Mode == Unbuffered && !BufferStart && Size == 0) ||
+          (Mode != Unbuffered && BufferStart && Size != 0)) &&
+         "stream must be unbuffered or have at least one byte");
+  // Make sure the current buffer is free of content (we can't flush here; the
+  // child buffer management logic will be in write_impl).
+  assert(GetNumBytesInBuffer() == 0 && "Current buffer is non-empty!");
+
+  if (BufferMode == InternalBuffer)
+    delete [] OutBufStart;
+  OutBufStart = BufferStart;
+  OutBufEnd = OutBufStart+Size;
+  OutBufCur = OutBufStart;
+  BufferMode = Mode;
+
+  assert(OutBufStart <= OutBufEnd && "Invalid size!");
+}
+
+raw_ostream &raw_ostream::operator<<(unsigned long N) {
+  // Zero is a special case.
+  if (N == 0)
+    return *this << '0';
+
+  char NumberBuffer[20];
+  char *EndPtr = NumberBuffer+sizeof(NumberBuffer);
+  char *CurPtr = EndPtr;
+
+  while (N) {
+    *--CurPtr = '0' + char(N % 10);
+    N /= 10;
+  }
+  return write(CurPtr, EndPtr-CurPtr);
+}
+
+raw_ostream &raw_ostream::operator<<(long N) {
+  if (N <  0) {
+    *this << '-';
+    // Avoid undefined behavior on LONG_MIN with a cast.
+    N = -(unsigned long)N;
+  }
+
+  return this->operator<<(static_cast<unsigned long>(N));
+}
+
+raw_ostream &raw_ostream::operator<<(unsigned long long N) {
+  // Output using 32-bit div/mod when possible.
+  if (N == static_cast<unsigned long>(N))
+    return this->operator<<(static_cast<unsigned long>(N));
+
+  char NumberBuffer[20];
+  char *EndPtr = std::end(NumberBuffer);
+  char *CurPtr = EndPtr;
+
+  while (N) {
+    *--CurPtr = '0' + char(N % 10);
+    N /= 10;
+  }
+  return write(CurPtr, EndPtr-CurPtr);
+}
+
+raw_ostream &raw_ostream::operator<<(long long N) {
+  if (N < 0) {
+    *this << '-';
+    // Avoid undefined behavior on INT64_MIN with a cast.
+    N = -(unsigned long long)N;
+  }
+
+  return this->operator<<(static_cast<unsigned long long>(N));
+}
+
+raw_ostream &raw_ostream::write_hex(unsigned long long N) {
+  // Zero is a special case.
+  if (N == 0)
+    return *this << '0';
+
+  char NumberBuffer[16];
+  char *EndPtr = std::end(NumberBuffer);
+  char *CurPtr = EndPtr;
+
+  while (N) {
+    unsigned char x = static_cast<unsigned char>(N) % 16;
+    *--CurPtr = hexdigit(x, /*LowerCase*/true);
+    N /= 16;
+  }
+
+  return write(CurPtr, EndPtr-CurPtr);
+}
+
+raw_ostream &raw_ostream::write_escaped(StringRef Str,
+                                        bool UseHexEscapes) {
+  for (unsigned char c : Str) {
+    switch (c) {
+    case '\\':
+      *this << '\\' << '\\';
+      break;
+    case '\t':
+      *this << '\\' << 't';
+      break;
+    case '\n':
+      *this << '\\' << 'n';
+      break;
+    case '"':
+      *this << '\\' << '"';
+      break;
+    default:
+      if (std::isprint(c)) {
+        *this << c;
+        break;
+      }
+
+      // Write out the escaped representation.
+      if (UseHexEscapes) {
+        *this << '\\' << 'x';
+        *this << hexdigit((c >> 4 & 0xF));
+        *this << hexdigit((c >> 0) & 0xF);
+      } else {
+        // Always use a full 3-character octal escape.
+        *this << '\\';
+        *this << char('0' + ((c >> 6) & 7));
+        *this << char('0' + ((c >> 3) & 7));
+        *this << char('0' + ((c >> 0) & 7));
+      }
+    }
+  }
+
+  return *this;
+}
+
+raw_ostream &raw_ostream::operator<<(const void *P) {
+  *this << '0' << 'x';
+
+  return write_hex((uintptr_t) P);
+}
+
+raw_ostream &raw_ostream::operator<<(double N) {
+#ifdef _WIN32
+  // On MSVCRT and compatible, output of %e is incompatible to Posix
+  // by default. Number of exponent digits should be at least 2. "%+03d"
+  // FIXME: Implement our formatter to here or Support/Format.h!
+#if defined(__MINGW32__)
+  // FIXME: It should be generic to C++11.
+  if (N == 0.0 && std::signbit(N))
+    return *this << "-0.000000e+00";
+#else
+  int fpcl = _fpclass(N);
+
+  // negative zero
+  if (fpcl == _FPCLASS_NZ)
+    return *this << "-0.000000e+00";
+#endif
+
+  char buf[16];
+  unsigned len;
+  len = format("%e", N).snprint(buf, sizeof(buf));
+  if (len <= sizeof(buf) - 2) {
+    if (len >= 5 && buf[len - 5] == 'e' && buf[len - 3] == '0') {
+      int cs = buf[len - 4];
+      if (cs == '+' || cs == '-') {
+        int c1 = buf[len - 2];
+        int c0 = buf[len - 1];
+        if (isdigit(static_cast<unsigned char>(c1)) &&
+            isdigit(static_cast<unsigned char>(c0))) {
+          // Trim leading '0': "...e+012" -> "...e+12\0"
+          buf[len - 3] = c1;
+          buf[len - 2] = c0;
+          buf[--len] = 0;
+        }
+      }
+    }
+    return this->operator<<(buf);
+  }
+#endif
+  return this->operator<<(format("%e", N));
+}
+
+
+
+void raw_ostream::flush_nonempty() {
+  assert(OutBufCur > OutBufStart && "Invalid call to flush_nonempty.");
+  size_t Length = OutBufCur - OutBufStart;
+  OutBufCur = OutBufStart;
+  write_impl(OutBufStart, Length);
+}
+
+raw_ostream &raw_ostream::write(unsigned char C) {
+  // Group exceptional cases into a single branch.
+  if (LLVM_UNLIKELY(OutBufCur >= OutBufEnd)) {
+    if (LLVM_UNLIKELY(!OutBufStart)) {
+      if (BufferMode == Unbuffered) {
+        write_impl(reinterpret_cast<char*>(&C), 1);
+        return *this;
+      }
+      // Set up a buffer and start over.
+      SetBuffered();
+      return write(C);
+    }
+
+    flush_nonempty();
+  }
+
+  *OutBufCur++ = C;
+  return *this;
+}
+
+raw_ostream &raw_ostream::write(const char *Ptr, size_t Size) {
+  // Group exceptional cases into a single branch.
+  if (LLVM_UNLIKELY(size_t(OutBufEnd - OutBufCur) < Size)) {
+    if (LLVM_UNLIKELY(!OutBufStart)) {
+      if (BufferMode == Unbuffered) {
+        write_impl(Ptr, Size);
+        return *this;
+      }
+      // Set up a buffer and start over.
+      SetBuffered();
+      return write(Ptr, Size);
+    }
+
+    size_t NumBytes = OutBufEnd - OutBufCur;
+
+    // If the buffer is empty at this point we have a string that is larger
+    // than the buffer. Directly write the chunk that is a multiple of the
+    // preferred buffer size and put the remainder in the buffer.
+    if (LLVM_UNLIKELY(OutBufCur == OutBufStart)) {
+      assert(NumBytes != 0 && "undefined behavior");
+      size_t BytesToWrite = Size - (Size % NumBytes);
+      write_impl(Ptr, BytesToWrite);
+      size_t BytesRemaining = Size - BytesToWrite;
+      if (BytesRemaining > size_t(OutBufEnd - OutBufCur)) {
+        // Too much left over to copy into our buffer.
+        return write(Ptr + BytesToWrite, BytesRemaining);
+      }
+      copy_to_buffer(Ptr + BytesToWrite, BytesRemaining);
+      return *this;
+    }
+
+    // We don't have enough space in the buffer to fit the string in. Insert as
+    // much as possible, flush and start over with the remainder.
+    copy_to_buffer(Ptr, NumBytes);
+    flush_nonempty();
+    return write(Ptr + NumBytes, Size - NumBytes);
+  }
+
+  copy_to_buffer(Ptr, Size);
+
+  return *this;
+}
+
+void raw_ostream::copy_to_buffer(const char *Ptr, size_t Size) {
+  assert(Size <= size_t(OutBufEnd - OutBufCur) && "Buffer overrun!");
+
+  // Handle short strings specially, memcpy isn't very good at very short
+  // strings.
+  switch (Size) {
+  case 4: OutBufCur[3] = Ptr[3]; // FALL THROUGH
+  case 3: OutBufCur[2] = Ptr[2]; // FALL THROUGH
+  case 2: OutBufCur[1] = Ptr[1]; // FALL THROUGH
+  case 1: OutBufCur[0] = Ptr[0]; // FALL THROUGH
+  case 0: break;
+  default:
+    memcpy(OutBufCur, Ptr, Size);
+    break;
+  }
+
+  OutBufCur += Size;
+}
+
+// Formatted output.
+raw_ostream &raw_ostream::operator<<(const format_object_base &Fmt) {
+  // If we have more than a few bytes left in our output buffer, try
+  // formatting directly onto its end.
+  size_t NextBufferSize = 127;
+  size_t BufferBytesLeft = OutBufEnd - OutBufCur;
+  if (BufferBytesLeft > 3) {
+    size_t BytesUsed = Fmt.print(OutBufCur, BufferBytesLeft);
+
+    // Common case is that we have plenty of space.
+    if (BytesUsed <= BufferBytesLeft) {
+      OutBufCur += BytesUsed;
+      return *this;
+    }
+
+    // Otherwise, we overflowed and the return value tells us the size to try
+    // again with.
+    NextBufferSize = BytesUsed;
+  }
+
+  // If we got here, we didn't have enough space in the output buffer for the
+  // string.  Try printing into a SmallVector that is resized to have enough
+  // space.  Iterate until we win.
+  SmallVector<char, 128> V;
+
+  while (1) {
+    V.resize(NextBufferSize);
+
+    // Try formatting into the SmallVector.
+    size_t BytesUsed = Fmt.print(V.data(), NextBufferSize);
+
+    // If BytesUsed fit into the vector, we win.
+    if (BytesUsed <= NextBufferSize)
+      return write(V.data(), BytesUsed);
+
+    // Otherwise, try again with a new size.
+    assert(BytesUsed > NextBufferSize && "Didn't grow buffer!?");
+    NextBufferSize = BytesUsed;
+  }
+}
+
+raw_ostream &raw_ostream::operator<<(const FormattedString &FS) {
+  unsigned Len = FS.Str.size(); 
+  int PadAmount = FS.Width - Len;
+  if (FS.RightJustify && (PadAmount > 0))
+    this->indent(PadAmount);
+  this->operator<<(FS.Str);
+  if (!FS.RightJustify && (PadAmount > 0))
+    this->indent(PadAmount);
+  return *this;
+}
+
+raw_ostream &raw_ostream::operator<<(const FormattedNumber &FN) {
+  if (FN.Hex) {
+    unsigned Nibbles = (64 - countLeadingZeros(FN.HexValue)+3)/4;
+    unsigned PrefixChars = FN.HexPrefix ? 2 : 0;
+    unsigned Width = std::max(FN.Width, Nibbles + PrefixChars);
+
+    char NumberBuffer[20] = "0x0000000000000000";
+    if (!FN.HexPrefix)
+      NumberBuffer[1] = '0';
+    char *EndPtr = NumberBuffer+Width;
+    char *CurPtr = EndPtr;
+    unsigned long long N = FN.HexValue;
+    while (N) {
+      unsigned char x = static_cast<unsigned char>(N) % 16;
+      *--CurPtr = hexdigit(x, !FN.Upper);
+      N /= 16;
+    }
+
+    return write(NumberBuffer, Width);
+  } else {
+    // Zero is a special case.
+    if (FN.DecValue == 0) {
+      this->indent(FN.Width-1);
+      return *this << '0';
+    }
+    char NumberBuffer[32];
+    char *EndPtr = NumberBuffer+sizeof(NumberBuffer);
+    char *CurPtr = EndPtr;
+    bool Neg = (FN.DecValue < 0);
+    uint64_t N = Neg ? -static_cast<uint64_t>(FN.DecValue) : FN.DecValue;
+    while (N) {
+      *--CurPtr = '0' + char(N % 10);
+      N /= 10;
+    }
+    int Len = EndPtr - CurPtr;
+    int Pad = FN.Width - Len;
+    if (Neg) 
+      --Pad;
+    if (Pad > 0)
+      this->indent(Pad);
+    if (Neg)
+      *this << '-';
+    return write(CurPtr, Len);
+  }
+}
+
+
+/// indent - Insert 'NumSpaces' spaces.
+raw_ostream &raw_ostream::indent(unsigned NumSpaces) {
+  static const char Spaces[] = "                                "
+                               "                                "
+                               "                ";
+
+  // Usually the indentation is small, handle it with a fastpath.
+  if (NumSpaces < array_lengthof(Spaces))
+    return write(Spaces, NumSpaces);
+
+  while (NumSpaces) {
+    unsigned NumToWrite = std::min(NumSpaces,
+                                   (unsigned)array_lengthof(Spaces)-1);
+    write(Spaces, NumToWrite);
+    NumSpaces -= NumToWrite;
+  }
+  return *this;
+}
+
+
+//===----------------------------------------------------------------------===//
+//  Formatted Output
+//===----------------------------------------------------------------------===//
+
+// Out of line virtual method.
+void format_object_base::home() {
+}
+
+//===----------------------------------------------------------------------===//
+//  raw_fd_ostream
+//===----------------------------------------------------------------------===//
+
+static int getFD(StringRef Filename, std::error_code &EC,
+                 sys::fs::OpenFlags Flags) {
+  // Handle "-" as stdout. Note that when we do this, we consider ourself
+  // the owner of stdout. This means that we can do things like close the
+  // file descriptor when we're done and set the "binary" flag globally.
+  if (Filename == "-") {
+    EC = std::error_code();
+    // If user requested binary then put stdout into binary mode if
+    // possible.
+    if (!(Flags & sys::fs::F_Text)) {
+#if defined(_WIN32)
+      _setmode(_fileno(stdout), _O_BINARY);
+#endif
+    }
+    return STDOUT_FILENO;
+  }
+
+  int FD;
+
+  EC = sys::fs::openFileForWrite(Filename, FD, Flags);
+  if (EC)
+    return -1;
+
+  EC = std::error_code();
+  return FD;
+}
+
+raw_fd_ostream::raw_fd_ostream(StringRef Filename, std::error_code &EC,
+                               sys::fs::OpenFlags Flags)
+    : raw_fd_ostream(getFD(Filename, EC, Flags), true) {}
+
+/// FD is the file descriptor that this writes to.  If ShouldClose is true, this
+/// closes the file when the stream is destroyed.
+raw_fd_ostream::raw_fd_ostream(int fd, bool shouldClose, bool unbuffered)
+    : raw_pwrite_stream(unbuffered), FD(fd), ShouldClose(shouldClose),
+      Error(false) {
+  if (FD < 0 ) {
+    ShouldClose = false;
+    return;
+  }
+
+  // Get the starting position.
+  off_t loc = ::lseek(FD, 0, SEEK_CUR);
+#ifdef _WIN32
+  // MSVCRT's _lseek(SEEK_CUR) doesn't return -1 for pipes.
+  SupportsSeeking = loc != (off_t)-1 && ::GetFileType(reinterpret_cast<HANDLE>(::_get_osfhandle(FD))) != FILE_TYPE_PIPE;
+#else
+  SupportsSeeking = loc != (off_t)-1;
+#endif
+  if (!SupportsSeeking)
+    pos = 0;
+  else
+    pos = static_cast<uint64_t>(loc);
+}
+
+raw_fd_ostream::~raw_fd_ostream() {
+  if (FD >= 0) {
+    flush();
+    if (ShouldClose && ::close(FD) < 0)
+      error_detected();
+  }
+
+#ifdef __MINGW32__
+  // On mingw, global dtors should not call exit().
+  // report_fatal_error() invokes exit(). We know report_fatal_error()
+  // might not write messages to stderr when any errors were detected
+  // on FD == 2.
+  if (FD == 2) return;
+#endif
+}
+
+
+void raw_fd_ostream::write_impl(const char *Ptr, size_t Size) {
+  assert(FD >= 0 && "File already closed.");
+  pos += Size;
+
+#ifndef _WIN32
+  bool ShouldWriteInChunks = false;
+#else
+  // Writing a large size of output to Windows console returns ENOMEM. It seems
+  // that, prior to Windows 8, WriteFile() is redirecting to WriteConsole(), and
+  // the latter has a size limit (66000 bytes or less, depending on heap usage).
+  bool ShouldWriteInChunks = !!::_isatty(FD) && !RunningWindows8OrGreater();
+#endif
+
+  do {
+    size_t ChunkSize = Size;
+    if (ChunkSize > 32767 && ShouldWriteInChunks)
+        ChunkSize = 32767;
+
+#ifdef _WIN32
+    int ret = ::_write(FD, Ptr, ChunkSize);
+#else
+    ssize_t ret = ::write(FD, Ptr, ChunkSize);
+#endif
+
+    if (ret < 0) {
+      // If it's a recoverable error, swallow it and retry the write.
+      //
+      // Ideally we wouldn't ever see EAGAIN or EWOULDBLOCK here, since
+      // raw_ostream isn't designed to do non-blocking I/O. However, some
+      // programs, such as old versions of bjam, have mistakenly used
+      // O_NONBLOCK. For compatibility, emulate blocking semantics by
+      // spinning until the write succeeds. If you don't want spinning,
+      // don't use O_NONBLOCK file descriptors with raw_ostream.
+      if (errno == EINTR || errno == EAGAIN
+#ifdef EWOULDBLOCK
+          || errno == EWOULDBLOCK
+#endif
+          )
+        continue;
+
+      // Otherwise it's a non-recoverable error. Note it and quit.
+      error_detected();
+      break;
+    }
+
+    // The write may have written some or all of the data. Update the
+    // size and buffer pointer to reflect the remainder that needs
+    // to be written. If there are no bytes left, we're done.
+    Ptr += ret;
+    Size -= ret;
+  } while (Size > 0);
+}
+
+void raw_fd_ostream::close() {
+  assert(ShouldClose);
+  ShouldClose = false;
+  flush();
+  if (::close(FD) < 0)
+    error_detected();
+  FD = -1;
+}
+
+uint64_t raw_fd_ostream::seek(uint64_t off) {
+  assert(SupportsSeeking && "Stream does not support seeking!");
+  flush();
+  pos = ::lseek(FD, off, SEEK_SET);
+  if (pos == (uint64_t)-1)
+    error_detected();
+  return pos;
+}
+
+void raw_fd_ostream::pwrite_impl(const char *Ptr, size_t Size,
+                                 uint64_t Offset) {
+  uint64_t Pos = tell();
+  seek(Offset);
+  write(Ptr, Size);
+  seek(Pos);
+}
+
+size_t raw_fd_ostream::preferred_buffer_size() const {
+#if !defined(_MSC_VER) && !defined(__MINGW32__) && !defined(__minix)
+  // Windows and Minix have no st_blksize.
+  assert(FD >= 0 && "File not yet open!");
+  struct stat statbuf;
+  if (fstat(FD, &statbuf) != 0)
+    return 0;
+
+  // If this is a terminal, don't use buffering. Line buffering
+  // would be a more traditional thing to do, but it's not worth
+  // the complexity.
+  if (S_ISCHR(statbuf.st_mode) && isatty(FD))
+    return 0;
+  // Return the preferred block size.
+  return statbuf.st_blksize;
+#else
+  return raw_ostream::preferred_buffer_size();
+#endif
+}
+
+//===----------------------------------------------------------------------===//
+//  outs(), errs(), nulls()
+//===----------------------------------------------------------------------===//
+
+/// outs() - This returns a reference to a raw_ostream for standard output.
+/// Use it like: outs() << "foo" << "bar";
+raw_ostream &llvm::outs() {
+  // Set buffer settings to model stdout behavior.  Delete the file descriptor
+  // when the program exits, forcing error detection.  This means that if you
+  // ever call outs(), you can't open another raw_fd_ostream on stdout, as we'll
+  // close stdout twice and print an error the second time.
+  std::error_code EC;
+  static raw_fd_ostream S("-", EC, sys::fs::F_None);
+  assert(!EC);
+  return S;
+}
+
+/// errs() - This returns a reference to a raw_ostream for standard error.
+/// Use it like: errs() << "foo" << "bar";
+raw_ostream &llvm::errs() {
+  // Set standard error to be unbuffered by default.
+  static raw_fd_ostream S(STDERR_FILENO, false, true);
+  return S;
+}
+
+/// nulls() - This returns a reference to a raw_ostream which discards output.
+raw_ostream &llvm::nulls() {
+  static raw_null_ostream S;
+  return S;
+}
+
+
+//===----------------------------------------------------------------------===//
+//  raw_string_ostream
+//===----------------------------------------------------------------------===//
+
+raw_string_ostream::~raw_string_ostream() {
+  flush();
+}
+
+void raw_string_ostream::write_impl(const char *Ptr, size_t Size) {
+  OS.append(Ptr, Size);
+}
+
+//===----------------------------------------------------------------------===//
+//  raw_svector_ostream
+//===----------------------------------------------------------------------===//
+
+uint64_t raw_svector_ostream::current_pos() const { return OS.size(); }
+
+void raw_svector_ostream::write_impl(const char *Ptr, size_t Size) {
+  OS.append(Ptr, Ptr + Size);
+}
+
+void raw_svector_ostream::pwrite_impl(const char *Ptr, size_t Size,
+                                      uint64_t Offset) {
+  memcpy(OS.data() + Offset, Ptr, Size);
+}
+
+//===----------------------------------------------------------------------===//
+//  raw_null_ostream
+//===----------------------------------------------------------------------===//
+
+raw_null_ostream::~raw_null_ostream() {
+#ifndef NDEBUG
+  // ~raw_ostream asserts that the buffer is empty. This isn't necessary
+  // with raw_null_ostream, but it's better to have raw_null_ostream follow
+  // the rules than to change the rules just for raw_null_ostream.
+  flush();
+#endif
+}
+
+void raw_null_ostream::write_impl(const char * /*Ptr*/, size_t /*Size*/) {}
+
+uint64_t raw_null_ostream::current_pos() const {
+  return 0;
+}
+
+void raw_null_ostream::pwrite_impl(const char * /*Ptr*/, size_t /*Size*/,
+                                   uint64_t /*Offset*/) {}