LLVM  3.7.0
raw_ostream.h
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1 //===--- raw_ostream.h - Raw output stream ----------------------*- C++ -*-===//
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 file defines the raw_ostream class.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #ifndef LLVM_SUPPORT_RAW_OSTREAM_H
15 #define LLVM_SUPPORT_RAW_OSTREAM_H
16 
17 #include "llvm/ADT/SmallVector.h"
18 #include "llvm/ADT/StringRef.h"
19 #include "llvm/Support/DataTypes.h"
20 #include <system_error>
21 
22 namespace llvm {
23 class format_object_base;
24 class FormattedString;
25 class FormattedNumber;
26 template <typename T> class SmallVectorImpl;
27 
28 namespace sys {
29 namespace fs {
30 enum OpenFlags : unsigned;
31 }
32 }
33 
34 /// This class implements an extremely fast bulk output stream that can *only*
35 /// output to a stream. It does not support seeking, reopening, rewinding, line
36 /// buffered disciplines etc. It is a simple buffer that outputs
37 /// a chunk at a time.
38 class raw_ostream {
39 private:
40  void operator=(const raw_ostream &) = delete;
41  raw_ostream(const raw_ostream &) = delete;
42 
43  /// The buffer is handled in such a way that the buffer is
44  /// uninitialized, unbuffered, or out of space when OutBufCur >=
45  /// OutBufEnd. Thus a single comparison suffices to determine if we
46  /// need to take the slow path to write a single character.
47  ///
48  /// The buffer is in one of three states:
49  /// 1. Unbuffered (BufferMode == Unbuffered)
50  /// 1. Uninitialized (BufferMode != Unbuffered && OutBufStart == 0).
51  /// 2. Buffered (BufferMode != Unbuffered && OutBufStart != 0 &&
52  /// OutBufEnd - OutBufStart >= 1).
53  ///
54  /// If buffered, then the raw_ostream owns the buffer if (BufferMode ==
55  /// InternalBuffer); otherwise the buffer has been set via SetBuffer and is
56  /// managed by the subclass.
57  ///
58  /// If a subclass installs an external buffer using SetBuffer then it can wait
59  /// for a \see write_impl() call to handle the data which has been put into
60  /// this buffer.
61  char *OutBufStart, *OutBufEnd, *OutBufCur;
62 
63  enum BufferKind {
64  Unbuffered = 0,
65  InternalBuffer,
66  ExternalBuffer
67  } BufferMode;
68 
69 public:
70  // color order matches ANSI escape sequence, don't change
71  enum Colors {
72  BLACK=0,
73  RED,
81  };
82 
83  explicit raw_ostream(bool unbuffered = false)
84  : BufferMode(unbuffered ? Unbuffered : InternalBuffer) {
85  // Start out ready to flush.
86  OutBufStart = OutBufEnd = OutBufCur = nullptr;
87  }
88 
89  virtual ~raw_ostream();
90 
91  /// tell - Return the current offset with the file.
92  uint64_t tell() const { return current_pos() + GetNumBytesInBuffer(); }
93 
94  //===--------------------------------------------------------------------===//
95  // Configuration Interface
96  //===--------------------------------------------------------------------===//
97 
98  /// Set the stream to be buffered, with an automatically determined buffer
99  /// size.
100  void SetBuffered();
101 
102  /// Set the stream to be buffered, using the specified buffer size.
103  void SetBufferSize(size_t Size) {
104  flush();
105  SetBufferAndMode(new char[Size], Size, InternalBuffer);
106  }
107 
108  size_t GetBufferSize() const {
109  // If we're supposed to be buffered but haven't actually gotten around
110  // to allocating the buffer yet, return the value that would be used.
111  if (BufferMode != Unbuffered && OutBufStart == nullptr)
112  return preferred_buffer_size();
113 
114  // Otherwise just return the size of the allocated buffer.
115  return OutBufEnd - OutBufStart;
116  }
117 
118  /// Set the stream to be unbuffered. When unbuffered, the stream will flush
119  /// after every write. This routine will also flush the buffer immediately
120  /// when the stream is being set to unbuffered.
121  void SetUnbuffered() {
122  flush();
123  SetBufferAndMode(nullptr, 0, Unbuffered);
124  }
125 
126  size_t GetNumBytesInBuffer() const {
127  return OutBufCur - OutBufStart;
128  }
129 
130  //===--------------------------------------------------------------------===//
131  // Data Output Interface
132  //===--------------------------------------------------------------------===//
133 
134  void flush() {
135  if (OutBufCur != OutBufStart)
136  flush_nonempty();
137  }
138 
140  if (OutBufCur >= OutBufEnd)
141  return write(C);
142  *OutBufCur++ = C;
143  return *this;
144  }
145 
146  raw_ostream &operator<<(unsigned char C) {
147  if (OutBufCur >= OutBufEnd)
148  return write(C);
149  *OutBufCur++ = C;
150  return *this;
151  }
152 
153  raw_ostream &operator<<(signed char C) {
154  if (OutBufCur >= OutBufEnd)
155  return write(C);
156  *OutBufCur++ = C;
157  return *this;
158  }
159 
161  // Inline fast path, particularly for strings with a known length.
162  size_t Size = Str.size();
163 
164  // Make sure we can use the fast path.
165  if (Size > (size_t)(OutBufEnd - OutBufCur))
166  return write(Str.data(), Size);
167 
168  if (Size) {
169  memcpy(OutBufCur, Str.data(), Size);
170  OutBufCur += Size;
171  }
172  return *this;
173  }
174 
175  raw_ostream &operator<<(const char *Str) {
176  // Inline fast path, particularly for constant strings where a sufficiently
177  // smart compiler will simplify strlen.
178 
179  return this->operator<<(StringRef(Str));
180  }
181 
182  raw_ostream &operator<<(const std::string &Str) {
183  // Avoid the fast path, it would only increase code size for a marginal win.
184  return write(Str.data(), Str.length());
185  }
186 
187  raw_ostream &operator<<(const llvm::SmallVectorImpl<char> &Str) {
188  return write(Str.data(), Str.size());
189  }
190 
191  raw_ostream &operator<<(unsigned long N);
192  raw_ostream &operator<<(long N);
193  raw_ostream &operator<<(unsigned long long N);
194  raw_ostream &operator<<(long long N);
195  raw_ostream &operator<<(const void *P);
196  raw_ostream &operator<<(unsigned int N) {
197  return this->operator<<(static_cast<unsigned long>(N));
198  }
199 
201  return this->operator<<(static_cast<long>(N));
202  }
203 
204  raw_ostream &operator<<(double N);
205 
206  /// Output \p N in hexadecimal, without any prefix or padding.
207  raw_ostream &write_hex(unsigned long long N);
208 
209  /// Output \p Str, turning '\\', '\t', '\n', '"', and anything that doesn't
210  /// satisfy std::isprint into an escape sequence.
211  raw_ostream &write_escaped(StringRef Str, bool UseHexEscapes = false);
212 
213  raw_ostream &write(unsigned char C);
214  raw_ostream &write(const char *Ptr, size_t Size);
215 
216  // Formatted output, see the format() function in Support/Format.h.
218 
219  // Formatted output, see the leftJustify() function in Support/Format.h.
221 
222  // Formatted output, see the formatHex() function in Support/Format.h.
224 
225  /// indent - Insert 'NumSpaces' spaces.
226  raw_ostream &indent(unsigned NumSpaces);
227 
228 
229  /// Changes the foreground color of text that will be output from this point
230  /// forward.
231  /// @param Color ANSI color to use, the special SAVEDCOLOR can be used to
232  /// change only the bold attribute, and keep colors untouched
233  /// @param Bold bold/brighter text, default false
234  /// @param BG if true change the background, default: change foreground
235  /// @returns itself so it can be used within << invocations
237  bool Bold = false,
238  bool BG = false) {
239  (void)Color;
240  (void)Bold;
241  (void)BG;
242  return *this;
243  }
244 
245  /// Resets the colors to terminal defaults. Call this when you are done
246  /// outputting colored text, or before program exit.
247  virtual raw_ostream &resetColor() { return *this; }
248 
249  /// Reverses the forground and background colors.
250  virtual raw_ostream &reverseColor() { return *this; }
251 
252  /// This function determines if this stream is connected to a "tty" or
253  /// "console" window. That is, the output would be displayed to the user
254  /// rather than being put on a pipe or stored in a file.
255  virtual bool is_displayed() const { return false; }
256 
257  /// This function determines if this stream is displayed and supports colors.
258  virtual bool has_colors() const { return is_displayed(); }
259 
260  //===--------------------------------------------------------------------===//
261  // Subclass Interface
262  //===--------------------------------------------------------------------===//
263 
264 private:
265  /// The is the piece of the class that is implemented by subclasses. This
266  /// writes the \p Size bytes starting at
267  /// \p Ptr to the underlying stream.
268  ///
269  /// This function is guaranteed to only be called at a point at which it is
270  /// safe for the subclass to install a new buffer via SetBuffer.
271  ///
272  /// \param Ptr The start of the data to be written. For buffered streams this
273  /// is guaranteed to be the start of the buffer.
274  ///
275  /// \param Size The number of bytes to be written.
276  ///
277  /// \invariant { Size > 0 }
278  virtual void write_impl(const char *Ptr, size_t Size) = 0;
279 
280  // An out of line virtual method to provide a home for the class vtable.
281  virtual void handle();
282 
283  /// Return the current position within the stream, not counting the bytes
284  /// currently in the buffer.
285  virtual uint64_t current_pos() const = 0;
286 
287 protected:
288  /// Use the provided buffer as the raw_ostream buffer. This is intended for
289  /// use only by subclasses which can arrange for the output to go directly
290  /// into the desired output buffer, instead of being copied on each flush.
291  void SetBuffer(char *BufferStart, size_t Size) {
292  SetBufferAndMode(BufferStart, Size, ExternalBuffer);
293  }
294 
295  /// Return an efficient buffer size for the underlying output mechanism.
296  virtual size_t preferred_buffer_size() const;
297 
298  /// Return the beginning of the current stream buffer, or 0 if the stream is
299  /// unbuffered.
300  const char *getBufferStart() const { return OutBufStart; }
301 
302  //===--------------------------------------------------------------------===//
303  // Private Interface
304  //===--------------------------------------------------------------------===//
305 private:
306  /// Install the given buffer and mode.
307  void SetBufferAndMode(char *BufferStart, size_t Size, BufferKind Mode);
308 
309  /// Flush the current buffer, which is known to be non-empty. This outputs the
310  /// currently buffered data and resets the buffer to empty.
311  void flush_nonempty();
312 
313  /// Copy data into the buffer. Size must not be greater than the number of
314  /// unused bytes in the buffer.
315  void copy_to_buffer(const char *Ptr, size_t Size);
316 };
317 
318 /// An abstract base class for streams implementations that also support a
319 /// pwrite operation. This is usefull for code that can mostly stream out data,
320 /// but needs to patch in a header that needs to know the output size.
322  virtual void pwrite_impl(const char *Ptr, size_t Size, uint64_t Offset) = 0;
323 
324 public:
325  explicit raw_pwrite_stream(bool Unbuffered = false)
326  : raw_ostream(Unbuffered) {}
327  void pwrite(const char *Ptr, size_t Size, uint64_t Offset) {
328 #ifndef NDBEBUG
329  uint64_t Pos = tell();
330  // /dev/null always reports a pos of 0, so we cannot perform this check
331  // in that case.
332  if (Pos)
333  assert(Size + Offset <= Pos && "We don't support extending the stream");
334 #endif
335  pwrite_impl(Ptr, Size, Offset);
336  }
337 };
338 
339 //===----------------------------------------------------------------------===//
340 // File Output Streams
341 //===----------------------------------------------------------------------===//
342 
343 /// A raw_ostream that writes to a file descriptor.
344 ///
346  int FD;
347  bool ShouldClose;
348 
349  /// Error This flag is true if an error of any kind has been detected.
350  ///
351  bool Error;
352 
353  /// Controls whether the stream should attempt to use atomic writes, when
354  /// possible.
355  bool UseAtomicWrites;
356 
357  uint64_t pos;
358 
359  bool SupportsSeeking;
360 
361  /// See raw_ostream::write_impl.
362  void write_impl(const char *Ptr, size_t Size) override;
363 
364  void pwrite_impl(const char *Ptr, size_t Size, uint64_t Offset) override;
365 
366  /// Return the current position within the stream, not counting the bytes
367  /// currently in the buffer.
368  uint64_t current_pos() const override { return pos; }
369 
370  /// Determine an efficient buffer size.
371  size_t preferred_buffer_size() const override;
372 
373  /// Set the flag indicating that an output error has been encountered.
374  void error_detected() { Error = true; }
375 
376 public:
377  /// Open the specified file for writing. If an error occurs, information
378  /// about the error is put into EC, and the stream should be immediately
379  /// destroyed;
380  /// \p Flags allows optional flags to control how the file will be opened.
381  ///
382  /// As a special case, if Filename is "-", then the stream will use
383  /// STDOUT_FILENO instead of opening a file. Note that it will still consider
384  /// itself to own the file descriptor. In particular, it will close the
385  /// file descriptor when it is done (this is necessary to detect
386  /// output errors).
387  raw_fd_ostream(StringRef Filename, std::error_code &EC,
389 
390  /// FD is the file descriptor that this writes to. If ShouldClose is true,
391  /// this closes the file when the stream is destroyed.
392  raw_fd_ostream(int fd, bool shouldClose, bool unbuffered=false);
393 
394  ~raw_fd_ostream() override;
395 
396  /// Manually flush the stream and close the file. Note that this does not call
397  /// fsync.
398  void close();
399 
400  bool supportsSeeking() { return SupportsSeeking; }
401 
402  /// Flushes the stream and repositions the underlying file descriptor position
403  /// to the offset specified from the beginning of the file.
404  uint64_t seek(uint64_t off);
405 
406  /// Set the stream to attempt to use atomic writes for individual output
407  /// routines where possible.
408  ///
409  /// Note that because raw_ostream's are typically buffered, this flag is only
410  /// sensible when used on unbuffered streams which will flush their output
411  /// immediately.
413  UseAtomicWrites = Value;
414  }
415 
416  raw_ostream &changeColor(enum Colors colors, bool bold=false,
417  bool bg=false) override;
418  raw_ostream &resetColor() override;
419 
420  raw_ostream &reverseColor() override;
421 
422  bool is_displayed() const override;
423 
424  bool has_colors() const override;
425 
426  /// Return the value of the flag in this raw_fd_ostream indicating whether an
427  /// output error has been encountered.
428  /// This doesn't implicitly flush any pending output. Also, it doesn't
429  /// guarantee to detect all errors unless the stream has been closed.
430  bool has_error() const {
431  return Error;
432  }
433 
434  /// Set the flag read by has_error() to false. If the error flag is set at the
435  /// time when this raw_ostream's destructor is called, report_fatal_error is
436  /// called to report the error. Use clear_error() after handling the error to
437  /// avoid this behavior.
438  ///
439  /// "Errors should never pass silently.
440  /// Unless explicitly silenced."
441  /// - from The Zen of Python, by Tim Peters
442  ///
443  void clear_error() {
444  Error = false;
445  }
446 };
447 
448 /// This returns a reference to a raw_ostream for standard output. Use it like:
449 /// outs() << "foo" << "bar";
450 raw_ostream &outs();
451 
452 /// This returns a reference to a raw_ostream for standard error. Use it like:
453 /// errs() << "foo" << "bar";
454 raw_ostream &errs();
455 
456 /// This returns a reference to a raw_ostream which simply discards output.
457 raw_ostream &nulls();
458 
459 //===----------------------------------------------------------------------===//
460 // Output Stream Adaptors
461 //===----------------------------------------------------------------------===//
462 
463 /// A raw_ostream that writes to an std::string. This is a simple adaptor
464 /// class. This class does not encounter output errors.
466  std::string &OS;
467 
468  /// See raw_ostream::write_impl.
469  void write_impl(const char *Ptr, size_t Size) override;
470 
471  /// Return the current position within the stream, not counting the bytes
472  /// currently in the buffer.
473  uint64_t current_pos() const override { return OS.size(); }
474 public:
475  explicit raw_string_ostream(std::string &O) : OS(O) {}
476  ~raw_string_ostream() override;
477 
478  /// Flushes the stream contents to the target string and returns the string's
479  /// reference.
480  std::string& str() {
481  flush();
482  return OS;
483  }
484 };
485 
486 /// A raw_ostream that writes to an SmallVector or SmallString. This is a
487 /// simple adaptor class. This class does not encounter output errors.
490 
491  /// See raw_ostream::write_impl.
492  void write_impl(const char *Ptr, size_t Size) override;
493 
494  void pwrite_impl(const char *Ptr, size_t Size, uint64_t Offset) override;
495 
496  /// Return the current position within the stream, not counting the bytes
497  /// currently in the buffer.
498  uint64_t current_pos() const override;
499 
500 protected:
501  // Like the regular constructor, but doesn't call init.
502  explicit raw_svector_ostream(SmallVectorImpl<char> &O, unsigned);
503  void init();
504 
505 public:
506  /// Construct a new raw_svector_ostream.
507  ///
508  /// \param O The vector to write to; this should generally have at least 128
509  /// bytes free to avoid any extraneous memory overhead.
511  ~raw_svector_ostream() override;
512 
513 
514  /// This is called when the SmallVector we're appending to is changed outside
515  /// of the raw_svector_ostream's control. It is only safe to do this if the
516  /// raw_svector_ostream has previously been flushed.
517  void resync();
518 
519  /// Flushes the stream contents to the target vector and return a StringRef
520  /// for the vector contents.
521  StringRef str();
522 };
523 
524 /// A raw_ostream that discards all output.
526  /// See raw_ostream::write_impl.
527  void write_impl(const char *Ptr, size_t size) override;
528  void pwrite_impl(const char *Ptr, size_t Size, uint64_t Offset) override;
529 
530  /// Return the current position within the stream, not counting the bytes
531  /// currently in the buffer.
532  uint64_t current_pos() const override;
533 
534 public:
535  explicit raw_null_ostream() {}
536  ~raw_null_ostream() override;
537 };
538 
540  raw_ostream &OS;
541  SmallVector<char, 0> Buffer;
542 
543 public:
544  buffer_ostream(raw_ostream &OS) : raw_svector_ostream(Buffer, 0), OS(OS) {
545  init();
546  }
547  ~buffer_ostream() { OS << str(); }
548 };
549 
550 } // end llvm namespace
551 
552 #endif
bool has_colors() const override
This function determines if this stream is displayed and supports colors.
bool is_displayed() const override
This function determines if this stream is connected to a "tty" or "console" window.
void SetUseAtomicWrites(bool Value)
Set the stream to attempt to use atomic writes for individual output routines where possible...
Definition: raw_ostream.h:412
raw_ostream & errs()
This returns a reference to a raw_ostream for standard error.
const char * getBufferStart() const
Return the beginning of the current stream buffer, or 0 if the stream is unbuffered.
Definition: raw_ostream.h:300
size_t size() const
size - Get the string size.
Definition: StringRef.h:113
raw_string_ostream(std::string &O)
Definition: raw_ostream.h:475
buffer_ostream(raw_ostream &OS)
Definition: raw_ostream.h:544
A raw_ostream that discards all output.
Definition: raw_ostream.h:525
virtual ~raw_ostream()
Definition: raw_ostream.cpp:62
uint64_t seek(uint64_t off)
Flushes the stream and repositions the underlying file descriptor position to the offset specified fr...
virtual bool has_colors() const
This function determines if this stream is displayed and supports colors.
Definition: raw_ostream.h:258
virtual raw_ostream & changeColor(enum Colors Color, bool Bold=false, bool BG=false)
Changes the foreground color of text that will be output from this point forward. ...
Definition: raw_ostream.h:236
raw_ostream & indent(unsigned NumSpaces)
indent - Insert 'NumSpaces' spaces.
raw_svector_ostream(SmallVectorImpl< char > &O, unsigned)
A raw_ostream that writes to an SmallVector or SmallString.
Definition: raw_ostream.h:488
raw_ostream & operator<<(const std::string &Str)
Definition: raw_ostream.h:182
raw_ostream & operator<<(const char *Str)
Definition: raw_ostream.h:175
This is a helper class used for left_justify() and right_justify().
Definition: Format.h:116
bool has_error() const
Return the value of the flag in this raw_fd_ostream indicating whether an output error has been encou...
Definition: raw_ostream.h:430
raw_ostream & operator<<(int N)
Definition: raw_ostream.h:200
void SetBuffer(char *BufferStart, size_t Size)
Use the provided buffer as the raw_ostream buffer.
Definition: raw_ostream.h:291
uint64_t tell() const
tell - Return the current offset with the file.
Definition: raw_ostream.h:92
const char * data() const
data - Get a pointer to the start of the string (which may not be null terminated).
Definition: StringRef.h:107
raw_ostream & write_hex(unsigned long long N)
Output N in hexadecimal, without any prefix or padding.
~raw_fd_ostream() override
virtual bool is_displayed() const
This function determines if this stream is connected to a "tty" or "console" window.
Definition: raw_ostream.h:255
This is a helper class used for handling formatted output.
Definition: Format.h:37
raw_ostream & operator<<(char C)
Definition: raw_ostream.h:139
raw_ostream & outs()
This returns a reference to a raw_ostream for standard output.
#define P(N)
raw_ostream & resetColor() override
Resets the colors to terminal defaults.
void resync()
This is called when the SmallVector we're appending to is changed outside of the raw_svector_ostream'...
void SetUnbuffered()
Set the stream to be unbuffered.
Definition: raw_ostream.h:121
raw_ostream & operator<<(unsigned char C)
Definition: raw_ostream.h:146
void pwrite(const char *Ptr, size_t Size, uint64_t Offset)
Definition: raw_ostream.h:327
virtual raw_ostream & reverseColor()
Reverses the forground and background colors.
Definition: raw_ostream.h:250
raw_fd_ostream(StringRef Filename, std::error_code &EC, sys::fs::OpenFlags Flags)
Open the specified file for writing.
raw_ostream(bool unbuffered=false)
Definition: raw_ostream.h:83
void SetBufferSize(size_t Size)
Set the stream to be buffered, using the specified buffer size.
Definition: raw_ostream.h:103
std::string & str()
Flushes the stream contents to the target string and returns the string's reference.
Definition: raw_ostream.h:480
~raw_null_ostream() override
raw_ostream & write(unsigned char C)
size_t GetBufferSize() const
Definition: raw_ostream.h:108
raw_ostream & write_escaped(StringRef Str, bool UseHexEscapes=false)
Output Str, turning '\', '', ' ', '"', and anything that doesn't satisfy std::isprint into an escape...
This is a helper class used for format_hex() and format_decimal().
Definition: Format.h:141
Color
A "color", which is either even or odd.
virtual size_t preferred_buffer_size() const
Return an efficient buffer size for the underlying output mechanism.
Definition: raw_ostream.cpp:75
raw_ostream & operator<<(unsigned int N)
Definition: raw_ostream.h:196
void SetBuffered()
Set the stream to be buffered, with an automatically determined buffer size.
Definition: raw_ostream.cpp:80
StringRef str()
Flushes the stream contents to the target vector and return a StringRef for the vector contents...
raw_pwrite_stream(bool Unbuffered=false)
Definition: raw_ostream.h:325
A raw_ostream that writes to a file descriptor.
Definition: raw_ostream.h:345
#define N
void size_t size
raw_ostream & operator<<(StringRef Str)
Definition: raw_ostream.h:160
void close()
Manually flush the stream and close the file.
An abstract base class for streams implementations that also support a pwrite operation.
Definition: raw_ostream.h:321
A raw_ostream that writes to an std::string.
Definition: raw_ostream.h:465
virtual raw_ostream & resetColor()
Resets the colors to terminal defaults.
Definition: raw_ostream.h:247
LLVM Value Representation.
Definition: Value.h:69
raw_ostream & nulls()
This returns a reference to a raw_ostream which simply discards output.
raw_ostream & changeColor(enum Colors colors, bool bold=false, bool bg=false) override
Changes the foreground color of text that will be output from this point forward. ...
This class implements an extremely fast bulk output stream that can only output to a stream...
Definition: raw_ostream.h:38
StringRef - Represent a constant reference to a string, i.e.
Definition: StringRef.h:40
raw_ostream & operator<<(signed char C)
Definition: raw_ostream.h:153
raw_ostream & reverseColor() override
Reverses the forground and background colors.
size_t GetNumBytesInBuffer() const
Definition: raw_ostream.h:126
void clear_error()
Set the flag read by has_error() to false.
Definition: raw_ostream.h:443