lib/Support/raw_ostream.cpp

   1 //===--- raw_ostream.cpp - Implement the raw_ostream classes --------------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This implements support for bulk buffered stream output.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "llvm/Support/raw_ostream.h"
  15 #include "llvm/Support/Format.h"
  16 #include "llvm/System/Program.h"
  17 #include "llvm/System/Process.h"
  18 #include "llvm/ADT/SmallVector.h"
  19 #include "llvm/Config/config.h"
  20 #include "llvm/Support/Compiler.h"
  21 #include "llvm/Support/ErrorHandling.h"
  22 #include "llvm/ADT/STLExtras.h"
  23 #include <cctype>
  24 #include <cerrno>
  25 #include <sys/stat.h>
  26 #include <sys/types.h>
  27
  28 #if defined(HAVE_UNISTD_H)
  29 # include <unistd.h>
  30 #endif
  31 #if defined(HAVE_FCNTL_H)
  32 # include <fcntl.h>
  33 #endif
  34
  35 #if defined(__CYGWIN__)
  36 #include <io.h>
  37 #endif
  38
  39 #if defined(_MSC_VER)
  40 #include <io.h>
  41 #include <fcntl.h>
  42 #ifndef STDIN_FILENO
  43 # define STDIN_FILENO 0
  44 #endif
  45 #ifndef STDOUT_FILENO
  46 # define STDOUT_FILENO 1
  47 #endif
  48 #ifndef STDERR_FILENO
  49 # define STDERR_FILENO 2
  50 #endif
  51 #endif
  52
  53 using namespace llvm;
  54
  55 raw_ostream::~raw_ostream() {
  56   // raw_ostream's subclasses should take care to flush the buffer
  57   // in their destructors.
  58   assert(OutBufCur == OutBufStart &&
  59          "raw_ostream destructor called with non-empty buffer!");
  60
  61   if (BufferMode == InternalBuffer)
  62     delete [] OutBufStart;
  63 }
  64
  65 // An out of line virtual method to provide a home for the class vtable.
  66 void raw_ostream::handle() {}
  67
  68 size_t raw_ostream::preferred_buffer_size() const {
  69   // BUFSIZ is intended to be a reasonable default.
  70   return BUFSIZ;
  71 }
  72
  73 void raw_ostream::SetBuffered() {
  74   // Ask the subclass to determine an appropriate buffer size.
  75   if (size_t Size = preferred_buffer_size())
  76     SetBufferSize(Size);
  77   else
  78     // It may return 0, meaning this stream should be unbuffered.
  79     SetUnbuffered();
  80 }
  81
  82 void raw_ostream::SetBufferAndMode(char *BufferStart, size_t Size,
  83                                     BufferKind Mode) {
  84   assert(((Mode == Unbuffered && BufferStart == 0 && Size == 0) ||
  85           (Mode != Unbuffered && BufferStart && Size)) &&
  86          "stream must be unbuffered or have at least one byte");
  87   // Make sure the current buffer is free of content (we can't flush here; the
  88   // child buffer management logic will be in write_impl).
  89   assert(GetNumBytesInBuffer() == 0 && "Current buffer is non-empty!");
  90
  91   if (BufferMode == InternalBuffer)
  92     delete [] OutBufStart;
  93   OutBufStart = BufferStart;
  94   OutBufEnd = OutBufStart+Size;
  95   OutBufCur = OutBufStart;
  96   BufferMode = Mode;
  97
  98   assert(OutBufStart <= OutBufEnd && "Invalid size!");
  99 }
 100
 101 raw_ostream &raw_ostream::operator<<(unsigned long N) {
 102   // Zero is a special case.
 103   if (N == 0)
 104     return *this << '0';
 105
 106   char NumberBuffer[20];
 107   char *EndPtr = NumberBuffer+sizeof(NumberBuffer);
 108   char *CurPtr = EndPtr;
 109
 110   while (N) {
 111     *--CurPtr = '0' + char(N % 10);
 112     N /= 10;
 113   }
 114   return write(CurPtr, EndPtr-CurPtr);
 115 }
 116
 117 raw_ostream &raw_ostream::operator<<(long N) {
 118   if (N <  0) {
 119     *this << '-';
 120     N = -N;
 121   }
 122
 123   return this->operator<<(static_cast<unsigned long>(N));
 124 }
 125
 126 raw_ostream &raw_ostream::operator<<(unsigned long long N) {
 127   // Output using 32-bit div/mod when possible.
 128   if (N == static_cast<unsigned long>(N))
 129     return this->operator<<(static_cast<unsigned long>(N));
 130
 131   char NumberBuffer[20];
 132   char *EndPtr = NumberBuffer+sizeof(NumberBuffer);
 133   char *CurPtr = EndPtr;
 134
 135   while (N) {
 136     *--CurPtr = '0' + char(N % 10);
 137     N /= 10;
 138   }
 139   return write(CurPtr, EndPtr-CurPtr);
 140 }
 141
 142 raw_ostream &raw_ostream::operator<<(long long N) {
 143   if (N < 0) {
 144     *this << '-';
 145     // Avoid undefined behavior on INT64_MIN with a cast.
 146     N = -(unsigned long long)N;
 147   }
 148
 149   return this->operator<<(static_cast<unsigned long long>(N));
 150 }
 151
 152 raw_ostream &raw_ostream::write_hex(unsigned long long N) {
 153   // Zero is a special case.
 154   if (N == 0)
 155     return *this << '0';
 156
 157   char NumberBuffer[20];
 158   char *EndPtr = NumberBuffer+sizeof(NumberBuffer);
 159   char *CurPtr = EndPtr;
 160
 161   while (N) {
 162     uintptr_t x = N % 16;
 163     *--CurPtr = (x < 10 ? '0' + x : 'a' + x - 10);
 164     N /= 16;
 165   }
 166
 167   return write(CurPtr, EndPtr-CurPtr);
 168 }
 169
 170 raw_ostream &raw_ostream::write_escaped(StringRef Str) {
 171   for (unsigned i = 0, e = Str.size(); i != e; ++i) {
 172     unsigned char c = Str[i];
 173
 174     switch (c) {
 175     case '\\':
 176       *this << '\\' << '\\';
 177       break;
 178     case '\t':
 179       *this << '\\' << 't';
 180       break;
 181     case '\n':
 182       *this << '\\' << 'n';
 183       break;
 184     case '"':
 185       *this << '\\' << '"';
 186       break;
 187     default:
 188       if (std::isprint(c)) {
 189         *this << c;
 190         break;
 191       }
 192
 193       // Always expand to a 3-character octal escape.
 194       *this << '\\';
 195       *this << char('0' + ((c >> 6) & 7));
 196       *this << char('0' + ((c >> 3) & 7));
 197       *this << char('0' + ((c >> 0) & 7));
 198     }
 199   }
 200
 201   return *this;
 202 }
 203
 204 raw_ostream &raw_ostream::operator<<(const void *P) {
 205   *this << '0' << 'x';
 206
 207   return write_hex((uintptr_t) P);
 208 }
 209
 210 raw_ostream &raw_ostream::operator<<(double N) {
 211   return this->operator<<(format("%e", N));
 212 }
 213
 214
 215
 216 void raw_ostream::flush_nonempty() {
 217   assert(OutBufCur > OutBufStart && "Invalid call to flush_nonempty.");
 218   size_t Length = OutBufCur - OutBufStart;
 219   OutBufCur = OutBufStart;
 220   write_impl(OutBufStart, Length);
 221 }
 222
 223 raw_ostream &raw_ostream::write(unsigned char C) {
 224   // Group exceptional cases into a single branch.
 225   if (BUILTIN_EXPECT(OutBufCur >= OutBufEnd, false)) {
 226     if (BUILTIN_EXPECT(!OutBufStart, false)) {
 227       if (BufferMode == Unbuffered) {
 228         write_impl(reinterpret_cast<char*>(&C), 1);
 229         return *this;
 230       }
 231       // Set up a buffer and start over.
 232       SetBuffered();
 233       return write(C);
 234     }
 235
 236     flush_nonempty();
 237   }
 238
 239   *OutBufCur++ = C;
 240   return *this;
 241 }
 242
 243 raw_ostream &raw_ostream::write(const char *Ptr, size_t Size) {
 244   // Group exceptional cases into a single branch.
 245   if (BUILTIN_EXPECT(OutBufCur+Size > OutBufEnd, false)) {
 246     if (BUILTIN_EXPECT(!OutBufStart, false)) {
 247       if (BufferMode == Unbuffered) {
 248         write_impl(Ptr, Size);
 249         return *this;
 250       }
 251       // Set up a buffer and start over.
 252       SetBuffered();
 253       return write(Ptr, Size);
 254     }
 255
 256     // Write out the data in buffer-sized blocks until the remainder
 257     // fits within the buffer.
 258     do {
 259       size_t NumBytes = OutBufEnd - OutBufCur;
 260       copy_to_buffer(Ptr, NumBytes);
 261       flush_nonempty();
 262       Ptr += NumBytes;
 263       Size -= NumBytes;
 264     } while (OutBufCur+Size > OutBufEnd);
 265   }
 266
 267   copy_to_buffer(Ptr, Size);
 268
 269   return *this;
 270 }
 271
 272 void raw_ostream::copy_to_buffer(const char *Ptr, size_t Size) {
 273   assert(Size <= size_t(OutBufEnd - OutBufCur) && "Buffer overrun!");
 274
 275   // Handle short strings specially, memcpy isn't very good at very short
 276   // strings.
 277   switch (Size) {
 278   case 4: OutBufCur[3] = Ptr[3]; // FALL THROUGH
 279   case 3: OutBufCur[2] = Ptr[2]; // FALL THROUGH
 280   case 2: OutBufCur[1] = Ptr[1]; // FALL THROUGH
 281   case 1: OutBufCur[0] = Ptr[0]; // FALL THROUGH
 282   case 0: break;
 283   default:
 284     memcpy(OutBufCur, Ptr, Size);
 285     break;
 286   }
 287
 288   OutBufCur += Size;
 289 }
 290
 291 // Formatted output.
 292 raw_ostream &raw_ostream::operator<<(const format_object_base &Fmt) {
 293   // If we have more than a few bytes left in our output buffer, try
 294   // formatting directly onto its end.
 295   size_t NextBufferSize = 127;
 296   size_t BufferBytesLeft = OutBufEnd - OutBufCur;
 297   if (BufferBytesLeft > 3) {
 298     size_t BytesUsed = Fmt.print(OutBufCur, BufferBytesLeft);
 299
 300     // Common case is that we have plenty of space.
 301     if (BytesUsed <= BufferBytesLeft) {
 302       OutBufCur += BytesUsed;
 303       return *this;
 304     }
 305
 306     // Otherwise, we overflowed and the return value tells us the size to try
 307     // again with.
 308     NextBufferSize = BytesUsed;
 309   }
 310
 311   // If we got here, we didn't have enough space in the output buffer for the
 312   // string.  Try printing into a SmallVector that is resized to have enough
 313   // space.  Iterate until we win.
 314   SmallVector<char, 128> V;
 315
 316   while (1) {
 317     V.resize(NextBufferSize);
 318
 319     // Try formatting into the SmallVector.
 320     size_t BytesUsed = Fmt.print(V.data(), NextBufferSize);
 321
 322     // If BytesUsed fit into the vector, we win.
 323     if (BytesUsed <= NextBufferSize)
 324       return write(V.data(), BytesUsed);
 325
 326     // Otherwise, try again with a new size.
 327     assert(BytesUsed > NextBufferSize && "Didn't grow buffer!?");
 328     NextBufferSize = BytesUsed;
 329   }
 330 }
 331
 332 /// indent - Insert 'NumSpaces' spaces.
 333 raw_ostream &raw_ostream::indent(unsigned NumSpaces) {
 334   static const char Spaces[] = "                                "
 335                                "                                "
 336                                "                ";
 337
 338   // Usually the indentation is small, handle it with a fastpath.
 339   if (NumSpaces < array_lengthof(Spaces))
 340     return write(Spaces, NumSpaces);
 341
 342   while (NumSpaces) {
 343     unsigned NumToWrite = std::min(NumSpaces,
 344                                    (unsigned)array_lengthof(Spaces)-1);
 345     write(Spaces, NumToWrite);
 346     NumSpaces -= NumToWrite;
 347   }
 348   return *this;
 349 }
 350
 351
 352 //===----------------------------------------------------------------------===//
 353 //  Formatted Output
 354 //===----------------------------------------------------------------------===//
 355
 356 // Out of line virtual method.
 357 void format_object_base::home() {
 358 }
 359
 360 //===----------------------------------------------------------------------===//
 361 //  raw_fd_ostream
 362 //===----------------------------------------------------------------------===//
 363
 364 /// raw_fd_ostream - Open the specified file for writing. If an error
 365 /// occurs, information about the error is put into ErrorInfo, and the
 366 /// stream should be immediately destroyed; the string will be empty
 367 /// if no error occurred.
 368 raw_fd_ostream::raw_fd_ostream(const char *Filename, std::string &ErrorInfo,
 369                                unsigned Flags) : Error(false), pos(0) {
 370   assert(Filename != 0 && "Filename is null");
 371   // Verify that we don't have both "append" and "excl".
 372   assert((!(Flags & F_Excl) || !(Flags & F_Append)) &&
 373          "Cannot specify both 'excl' and 'append' file creation flags!");
 374
 375   ErrorInfo.clear();
 376
 377   // Handle "-" as stdout. Note that when we do this, we consider ourself
 378   // the owner of stdout. This means that we can do things like close the
 379   // file descriptor when we're done and set the "binary" flag globally.
 380   if (Filename[0] == '-' && Filename[1] == 0) {
 381     FD = STDOUT_FILENO;
 382     // If user requested binary then put stdout into binary mode if
 383     // possible.
 384     if (Flags & F_Binary)
 385       sys::Program::ChangeStdoutToBinary();
 386     // Close stdout when we're done, to detect any output errors.
 387     ShouldClose = true;
 388     return;
 389   }
 390
 391   int OpenFlags = O_WRONLY|O_CREAT;
 392 #ifdef O_BINARY
 393   if (Flags & F_Binary)
 394     OpenFlags |= O_BINARY;
 395 #endif
 396
 397   if (Flags & F_Append)
 398     OpenFlags |= O_APPEND;
 399   else
 400     OpenFlags |= O_TRUNC;
 401   if (Flags & F_Excl)
 402     OpenFlags |= O_EXCL;
 403
 404   while ((FD = open(Filename, OpenFlags, 0664)) < 0) {
 405     if (errno != EINTR) {
 406       ErrorInfo = "Error opening output file '" + std::string(Filename) + "'";
 407       ShouldClose = false;
 408       return;
 409     }
 410   }
 411
 412   // Ok, we successfully opened the file, so it'll need to be closed.
 413   ShouldClose = true;
 414 }
 415
 416 /// raw_fd_ostream ctor - FD is the file descriptor that this writes to.  If
 417 /// ShouldClose is true, this closes the file when the stream is destroyed.
 418 raw_fd_ostream::raw_fd_ostream(int fd, bool shouldClose, bool unbuffered)
 419   : raw_ostream(unbuffered), FD(fd),
 420     ShouldClose(shouldClose), Error(false) {
 421 #ifdef O_BINARY
 422   // Setting STDOUT and STDERR to binary mode is necessary in Win32
 423   // to avoid undesirable linefeed conversion.
 424   if (fd == STDOUT_FILENO || fd == STDERR_FILENO)
 425     setmode(fd, O_BINARY);
 426 #endif
 427 }
 428
 429 raw_fd_ostream::~raw_fd_ostream() {
 430   if (FD >= 0) {
 431     flush();
 432     if (ShouldClose)
 433       while (::close(FD) != 0)
 434         if (errno != EINTR) {
 435           error_detected();
 436           break;
 437         }
 438   }
 439
 440   // If there are any pending errors, report them now. Clients wishing
 441   // to avoid report_fatal_error calls should check for errors with
 442   // has_error() and clear the error flag with clear_error() before
 443   // destructing raw_ostream objects which may have errors.
 444   if (has_error())
 445     report_fatal_error("IO failure on output stream.");
 446 }
 447
 448
 449 void raw_fd_ostream::write_impl(const char *Ptr, size_t Size) {
 450   assert(FD >= 0 && "File already closed.");
 451   pos += Size;
 452
 453   do {
 454     ssize_t ret = ::write(FD, Ptr, Size);
 455
 456     if (ret < 0) {
 457       // If it's a recoverable error, swallow it and retry the write.
 458       //
 459       // Ideally we wouldn't ever see EAGAIN or EWOULDBLOCK here, since
 460       // raw_ostream isn't designed to do non-blocking I/O. However, some
 461       // programs, such as old versions of bjam, have mistakenly used
 462       // O_NONBLOCK. For compatibility, emulate blocking semantics by
 463       // spinning until the write succeeds. If you don't want spinning,
 464       // don't use O_NONBLOCK file descriptors with raw_ostream.
 465       if (errno == EINTR || errno == EAGAIN
 466 #ifdef EWOULDBLOCK
 467           || errno == EWOULDBLOCK
 468 #endif
 469           )
 470         continue;
 471
 472       // Otherwise it's a non-recoverable error. Note it and quit.
 473       error_detected();
 474       break;
 475     }
 476
 477     // The write may have written some or all of the data. Update the
 478     // size and buffer pointer to reflect the remainder that needs
 479     // to be written. If there are no bytes left, we're done.
 480     Ptr += ret;
 481     Size -= ret;
 482   } while (Size > 0);
 483 }
 484
 485 void raw_fd_ostream::close() {
 486   assert(ShouldClose);
 487   ShouldClose = false;
 488   flush();
 489   while (::close(FD) != 0)
 490     if (errno != EINTR) {
 491       error_detected();
 492       break;
 493     }
 494   FD = -1;
 495 }
 496
 497 uint64_t raw_fd_ostream::seek(uint64_t off) {
 498   flush();
 499   pos = ::lseek(FD, off, SEEK_SET);
 500   if (pos != off)
 501     error_detected();
 502   return pos;
 503 }
 504
 505 size_t raw_fd_ostream::preferred_buffer_size() const {
 506 #if !defined(_MSC_VER) && !defined(__MINGW32__) && !defined(__minix)
 507   // Windows and Minix have no st_blksize.
 508   assert(FD >= 0 && "File not yet open!");
 509   struct stat statbuf;
 510   if (fstat(FD, &statbuf) != 0)
 511     return 0;
 512
 513   // If this is a terminal, don't use buffering. Line buffering
 514   // would be a more traditional thing to do, but it's not worth
 515   // the complexity.
 516   if (S_ISCHR(statbuf.st_mode) && isatty(FD))
 517     return 0;
 518   // Return the preferred block size.
 519   return statbuf.st_blksize;
 520 #else
 521   return raw_ostream::preferred_buffer_size();
 522 #endif
 523 }
 524
 525 raw_ostream &raw_fd_ostream::changeColor(enum Colors colors, bool bold,
 526                                          bool bg) {
 527   if (sys::Process::ColorNeedsFlush())
 528     flush();
 529   const char *colorcode =
 530     (colors == SAVEDCOLOR) ? sys::Process::OutputBold(bg)
 531     : sys::Process::OutputColor(colors, bold, bg);
 532   if (colorcode) {
 533     size_t len = strlen(colorcode);
 534     write(colorcode, len);
 535     // don't account colors towards output characters
 536     pos -= len;
 537   }
 538   return *this;
 539 }
 540
 541 raw_ostream &raw_fd_ostream::resetColor() {
 542   if (sys::Process::ColorNeedsFlush())
 543     flush();
 544   const char *colorcode = sys::Process::ResetColor();
 545   if (colorcode) {
 546     size_t len = strlen(colorcode);
 547     write(colorcode, len);
 548     // don't account colors towards output characters
 549     pos -= len;
 550   }
 551   return *this;
 552 }
 553
 554 bool raw_fd_ostream::is_displayed() const {
 555   return sys::Process::FileDescriptorIsDisplayed(FD);
 556 }
 557
 558 //===----------------------------------------------------------------------===//
 559 //  outs(), errs(), nulls()
 560 //===----------------------------------------------------------------------===//
 561
 562 /// outs() - This returns a reference to a raw_ostream for standard output.
 563 /// Use it like: outs() << "foo" << "bar";
 564 raw_ostream &llvm::outs() {
 565   // Set buffer settings to model stdout behavior.
 566   // Delete the file descriptor when the program exists, forcing error
 567   // detection. If you don't want this behavior, don't use outs().
 568   static raw_fd_ostream S(STDOUT_FILENO, true);
 569   return S;
 570 }
 571
 572 /// errs() - This returns a reference to a raw_ostream for standard error.
 573 /// Use it like: errs() << "foo" << "bar";
 574 raw_ostream &llvm::errs() {
 575   // Set standard error to be unbuffered by default.
 576   static raw_fd_ostream S(STDERR_FILENO, false, true);
 577   return S;
 578 }
 579
 580 /// nulls() - This returns a reference to a raw_ostream which discards output.
 581 raw_ostream &llvm::nulls() {
 582   static raw_null_ostream S;
 583   return S;
 584 }
 585
 586
 587 //===----------------------------------------------------------------------===//
 588 //  raw_string_ostream
 589 //===----------------------------------------------------------------------===//
 590
 591 raw_string_ostream::~raw_string_ostream() {
 592   flush();
 593 }
 594
 595 void raw_string_ostream::write_impl(const char *Ptr, size_t Size) {
 596   OS.append(Ptr, Size);
 597 }
 598
 599 //===----------------------------------------------------------------------===//
 600 //  raw_svector_ostream
 601 //===----------------------------------------------------------------------===//
 602
 603 // The raw_svector_ostream implementation uses the SmallVector itself as the
 604 // buffer for the raw_ostream. We guarantee that the raw_ostream buffer is
 605 // always pointing past the end of the vector, but within the vector
 606 // capacity. This allows raw_ostream to write directly into the correct place,
 607 // and we only need to set the vector size when the data is flushed.
 608
 609 raw_svector_ostream::raw_svector_ostream(SmallVectorImpl<char> &O) : OS(O) {
 610   // Set up the initial external buffer. We make sure that the buffer has at
 611   // least 128 bytes free; raw_ostream itself only requires 64, but we want to
 612   // make sure that we don't grow the buffer unnecessarily on destruction (when
 613   // the data is flushed). See the FIXME below.
 614   OS.reserve(OS.size() + 128);
 615   SetBuffer(OS.end(), OS.capacity() - OS.size());
 616 }
 617
 618 raw_svector_ostream::~raw_svector_ostream() {
 619   // FIXME: Prevent resizing during this flush().
 620   flush();
 621 }
 622
 623 /// resync - This is called when the SmallVector we're appending to is changed
 624 /// outside of the raw_svector_ostream's control.  It is only safe to do this
 625 /// if the raw_svector_ostream has previously been flushed.
 626 void raw_svector_ostream::resync() {
 627   assert(GetNumBytesInBuffer() == 0 && "Didn't flush before mutating vector");
 628
 629   if (OS.capacity() - OS.size() < 64)
 630     OS.reserve(OS.capacity() * 2);
 631   SetBuffer(OS.end(), OS.capacity() - OS.size());
 632 }
 633
 634 void raw_svector_ostream::write_impl(const char *Ptr, size_t Size) {
 635   // If we're writing bytes from the end of the buffer into the smallvector, we
 636   // don't need to copy the bytes, just commit the bytes because they are
 637   // already in the right place.
 638   if (Ptr == OS.end()) {
 639     assert(OS.size() + Size <= OS.capacity() && "Invalid write_impl() call!");
 640     OS.set_size(OS.size() + Size);
 641   } else {
 642     assert(GetNumBytesInBuffer() == 0 &&
 643            "Should be writing from buffer if some bytes in it");
 644     // Otherwise, do copy the bytes.
 645     OS.append(Ptr, Ptr+Size);
 646   }
 647
 648   // Grow the vector if necessary.
 649   if (OS.capacity() - OS.size() < 64)
 650     OS.reserve(OS.capacity() * 2);
 651
 652   // Update the buffer position.
 653   SetBuffer(OS.end(), OS.capacity() - OS.size());
 654 }
 655
 656 uint64_t raw_svector_ostream::current_pos() const {
 657    return OS.size();
 658 }
 659
 660 StringRef raw_svector_ostream::str() {
 661   flush();
 662   return StringRef(OS.begin(), OS.size());
 663 }
 664
 665 //===----------------------------------------------------------------------===//
 666 //  raw_null_ostream
 667 //===----------------------------------------------------------------------===//
 668
 669 raw_null_ostream::~raw_null_ostream() {
 670 #ifndef NDEBUG
 671   // ~raw_ostream asserts that the buffer is empty. This isn't necessary
 672   // with raw_null_ostream, but it's better to have raw_null_ostream follow
 673   // the rules than to change the rules just for raw_null_ostream.
 674   flush();
 675 #endif
 676 }
 677
 678 void raw_null_ostream::write_impl(const char *Ptr, size_t Size) {
 679 }
 680
 681 uint64_t raw_null_ostream::current_pos() const {
 682   return 0;
 683 }