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1 //===--- LiteralSupport.cpp - Code to parse and process literals ----------===//
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 implements the NumericLiteralParser, CharLiteralParser, and
11 // StringLiteralParser interfaces.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #include "clang/Lex/LiteralSupport.h"
16 #include "clang/Basic/CharInfo.h"
17 #include "clang/Basic/TargetInfo.h"
18 #include "clang/Lex/LexDiagnostic.h"
19 #include "clang/Lex/Preprocessor.h"
20 #include "llvm/ADT/StringExtras.h"
21 #include "llvm/Support/ConvertUTF.h"
22 #include "llvm/Support/ErrorHandling.h"
23 
24 using namespace clang;
25 
getCharWidth(tok::TokenKind kind,const TargetInfo & Target)26 static unsigned getCharWidth(tok::TokenKind kind, const TargetInfo &Target) {
27   switch (kind) {
28   default: llvm_unreachable("Unknown token type!");
29   case tok::char_constant:
30   case tok::string_literal:
31   case tok::utf8_char_constant:
32   case tok::utf8_string_literal:
33     return Target.getCharWidth();
34   case tok::wide_char_constant:
35   case tok::wide_string_literal:
36     return Target.getWCharWidth();
37   case tok::utf16_char_constant:
38   case tok::utf16_string_literal:
39     return Target.getChar16Width();
40   case tok::utf32_char_constant:
41   case tok::utf32_string_literal:
42     return Target.getChar32Width();
43   }
44 }
45 
MakeCharSourceRange(const LangOptions & Features,FullSourceLoc TokLoc,const char * TokBegin,const char * TokRangeBegin,const char * TokRangeEnd)46 static CharSourceRange MakeCharSourceRange(const LangOptions &Features,
47                                            FullSourceLoc TokLoc,
48                                            const char *TokBegin,
49                                            const char *TokRangeBegin,
50                                            const char *TokRangeEnd) {
51   SourceLocation Begin =
52     Lexer::AdvanceToTokenCharacter(TokLoc, TokRangeBegin - TokBegin,
53                                    TokLoc.getManager(), Features);
54   SourceLocation End =
55     Lexer::AdvanceToTokenCharacter(Begin, TokRangeEnd - TokRangeBegin,
56                                    TokLoc.getManager(), Features);
57   return CharSourceRange::getCharRange(Begin, End);
58 }
59 
60 /// \brief Produce a diagnostic highlighting some portion of a literal.
61 ///
62 /// Emits the diagnostic \p DiagID, highlighting the range of characters from
63 /// \p TokRangeBegin (inclusive) to \p TokRangeEnd (exclusive), which must be
64 /// a substring of a spelling buffer for the token beginning at \p TokBegin.
Diag(DiagnosticsEngine * Diags,const LangOptions & Features,FullSourceLoc TokLoc,const char * TokBegin,const char * TokRangeBegin,const char * TokRangeEnd,unsigned DiagID)65 static DiagnosticBuilder Diag(DiagnosticsEngine *Diags,
66                               const LangOptions &Features, FullSourceLoc TokLoc,
67                               const char *TokBegin, const char *TokRangeBegin,
68                               const char *TokRangeEnd, unsigned DiagID) {
69   SourceLocation Begin =
70     Lexer::AdvanceToTokenCharacter(TokLoc, TokRangeBegin - TokBegin,
71                                    TokLoc.getManager(), Features);
72   return Diags->Report(Begin, DiagID) <<
73     MakeCharSourceRange(Features, TokLoc, TokBegin, TokRangeBegin, TokRangeEnd);
74 }
75 
76 /// ProcessCharEscape - Parse a standard C escape sequence, which can occur in
77 /// either a character or a string literal.
ProcessCharEscape(const char * ThisTokBegin,const char * & ThisTokBuf,const char * ThisTokEnd,bool & HadError,FullSourceLoc Loc,unsigned CharWidth,DiagnosticsEngine * Diags,const LangOptions & Features)78 static unsigned ProcessCharEscape(const char *ThisTokBegin,
79                                   const char *&ThisTokBuf,
80                                   const char *ThisTokEnd, bool &HadError,
81                                   FullSourceLoc Loc, unsigned CharWidth,
82                                   DiagnosticsEngine *Diags,
83                                   const LangOptions &Features) {
84   const char *EscapeBegin = ThisTokBuf;
85 
86   // Skip the '\' char.
87   ++ThisTokBuf;
88 
89   // We know that this character can't be off the end of the buffer, because
90   // that would have been \", which would not have been the end of string.
91   unsigned ResultChar = *ThisTokBuf++;
92   switch (ResultChar) {
93   // These map to themselves.
94   case '\\': case '\'': case '"': case '?': break;
95 
96     // These have fixed mappings.
97   case 'a':
98     // TODO: K&R: the meaning of '\\a' is different in traditional C
99     ResultChar = 7;
100     break;
101   case 'b':
102     ResultChar = 8;
103     break;
104   case 'e':
105     if (Diags)
106       Diag(Diags, Features, Loc, ThisTokBegin, EscapeBegin, ThisTokBuf,
107            diag::ext_nonstandard_escape) << "e";
108     ResultChar = 27;
109     break;
110   case 'E':
111     if (Diags)
112       Diag(Diags, Features, Loc, ThisTokBegin, EscapeBegin, ThisTokBuf,
113            diag::ext_nonstandard_escape) << "E";
114     ResultChar = 27;
115     break;
116   case 'f':
117     ResultChar = 12;
118     break;
119   case 'n':
120     ResultChar = 10;
121     break;
122   case 'r':
123     ResultChar = 13;
124     break;
125   case 't':
126     ResultChar = 9;
127     break;
128   case 'v':
129     ResultChar = 11;
130     break;
131   case 'x': { // Hex escape.
132     ResultChar = 0;
133     if (ThisTokBuf == ThisTokEnd || !isHexDigit(*ThisTokBuf)) {
134       if (Diags)
135         Diag(Diags, Features, Loc, ThisTokBegin, EscapeBegin, ThisTokBuf,
136              diag::err_hex_escape_no_digits) << "x";
137       HadError = 1;
138       break;
139     }
140 
141     // Hex escapes are a maximal series of hex digits.
142     bool Overflow = false;
143     for (; ThisTokBuf != ThisTokEnd; ++ThisTokBuf) {
144       int CharVal = llvm::hexDigitValue(ThisTokBuf[0]);
145       if (CharVal == -1) break;
146       // About to shift out a digit?
147       if (ResultChar & 0xF0000000)
148         Overflow = true;
149       ResultChar <<= 4;
150       ResultChar |= CharVal;
151     }
152 
153     // See if any bits will be truncated when evaluated as a character.
154     if (CharWidth != 32 && (ResultChar >> CharWidth) != 0) {
155       Overflow = true;
156       ResultChar &= ~0U >> (32-CharWidth);
157     }
158 
159     // Check for overflow.
160     if (Overflow && Diags)   // Too many digits to fit in
161       Diag(Diags, Features, Loc, ThisTokBegin, EscapeBegin, ThisTokBuf,
162            diag::err_escape_too_large) << 0;
163     break;
164   }
165   case '0': case '1': case '2': case '3':
166   case '4': case '5': case '6': case '7': {
167     // Octal escapes.
168     --ThisTokBuf;
169     ResultChar = 0;
170 
171     // Octal escapes are a series of octal digits with maximum length 3.
172     // "\0123" is a two digit sequence equal to "\012" "3".
173     unsigned NumDigits = 0;
174     do {
175       ResultChar <<= 3;
176       ResultChar |= *ThisTokBuf++ - '0';
177       ++NumDigits;
178     } while (ThisTokBuf != ThisTokEnd && NumDigits < 3 &&
179              ThisTokBuf[0] >= '0' && ThisTokBuf[0] <= '7');
180 
181     // Check for overflow.  Reject '\777', but not L'\777'.
182     if (CharWidth != 32 && (ResultChar >> CharWidth) != 0) {
183       if (Diags)
184         Diag(Diags, Features, Loc, ThisTokBegin, EscapeBegin, ThisTokBuf,
185              diag::err_escape_too_large) << 1;
186       ResultChar &= ~0U >> (32-CharWidth);
187     }
188     break;
189   }
190 
191     // Otherwise, these are not valid escapes.
192   case '(': case '{': case '[': case '%':
193     // GCC accepts these as extensions.  We warn about them as such though.
194     if (Diags)
195       Diag(Diags, Features, Loc, ThisTokBegin, EscapeBegin, ThisTokBuf,
196            diag::ext_nonstandard_escape)
197         << std::string(1, ResultChar);
198     break;
199   default:
200     if (!Diags)
201       break;
202 
203     if (isPrintable(ResultChar))
204       Diag(Diags, Features, Loc, ThisTokBegin, EscapeBegin, ThisTokBuf,
205            diag::ext_unknown_escape)
206         << std::string(1, ResultChar);
207     else
208       Diag(Diags, Features, Loc, ThisTokBegin, EscapeBegin, ThisTokBuf,
209            diag::ext_unknown_escape)
210         << "x" + llvm::utohexstr(ResultChar);
211     break;
212   }
213 
214   return ResultChar;
215 }
216 
appendCodePoint(unsigned Codepoint,llvm::SmallVectorImpl<char> & Str)217 static void appendCodePoint(unsigned Codepoint,
218                             llvm::SmallVectorImpl<char> &Str) {
219   char ResultBuf[4];
220   char *ResultPtr = ResultBuf;
221   bool Res = llvm::ConvertCodePointToUTF8(Codepoint, ResultPtr);
222   (void)Res;
223   assert(Res && "Unexpected conversion failure");
224   Str.append(ResultBuf, ResultPtr);
225 }
226 
expandUCNs(SmallVectorImpl<char> & Buf,StringRef Input)227 void clang::expandUCNs(SmallVectorImpl<char> &Buf, StringRef Input) {
228   for (StringRef::iterator I = Input.begin(), E = Input.end(); I != E; ++I) {
229     if (*I != '\\') {
230       Buf.push_back(*I);
231       continue;
232     }
233 
234     ++I;
235     assert(*I == 'u' || *I == 'U');
236 
237     unsigned NumHexDigits;
238     if (*I == 'u')
239       NumHexDigits = 4;
240     else
241       NumHexDigits = 8;
242 
243     assert(I + NumHexDigits <= E);
244 
245     uint32_t CodePoint = 0;
246     for (++I; NumHexDigits != 0; ++I, --NumHexDigits) {
247       unsigned Value = llvm::hexDigitValue(*I);
248       assert(Value != -1U);
249 
250       CodePoint <<= 4;
251       CodePoint += Value;
252     }
253 
254     appendCodePoint(CodePoint, Buf);
255     --I;
256   }
257 }
258 
259 /// ProcessUCNEscape - Read the Universal Character Name, check constraints and
260 /// return the UTF32.
ProcessUCNEscape(const char * ThisTokBegin,const char * & ThisTokBuf,const char * ThisTokEnd,uint32_t & UcnVal,unsigned short & UcnLen,FullSourceLoc Loc,DiagnosticsEngine * Diags,const LangOptions & Features,bool in_char_string_literal=false)261 static bool ProcessUCNEscape(const char *ThisTokBegin, const char *&ThisTokBuf,
262                              const char *ThisTokEnd,
263                              uint32_t &UcnVal, unsigned short &UcnLen,
264                              FullSourceLoc Loc, DiagnosticsEngine *Diags,
265                              const LangOptions &Features,
266                              bool in_char_string_literal = false) {
267   const char *UcnBegin = ThisTokBuf;
268 
269   // Skip the '\u' char's.
270   ThisTokBuf += 2;
271 
272   if (ThisTokBuf == ThisTokEnd || !isHexDigit(*ThisTokBuf)) {
273     if (Diags)
274       Diag(Diags, Features, Loc, ThisTokBegin, UcnBegin, ThisTokBuf,
275            diag::err_hex_escape_no_digits) << StringRef(&ThisTokBuf[-1], 1);
276     return false;
277   }
278   UcnLen = (ThisTokBuf[-1] == 'u' ? 4 : 8);
279   unsigned short UcnLenSave = UcnLen;
280   for (; ThisTokBuf != ThisTokEnd && UcnLenSave; ++ThisTokBuf, UcnLenSave--) {
281     int CharVal = llvm::hexDigitValue(ThisTokBuf[0]);
282     if (CharVal == -1) break;
283     UcnVal <<= 4;
284     UcnVal |= CharVal;
285   }
286   // If we didn't consume the proper number of digits, there is a problem.
287   if (UcnLenSave) {
288     if (Diags)
289       Diag(Diags, Features, Loc, ThisTokBegin, UcnBegin, ThisTokBuf,
290            diag::err_ucn_escape_incomplete);
291     return false;
292   }
293 
294   // Check UCN constraints (C99 6.4.3p2) [C++11 lex.charset p2]
295   if ((0xD800 <= UcnVal && UcnVal <= 0xDFFF) || // surrogate codepoints
296       UcnVal > 0x10FFFF) {                      // maximum legal UTF32 value
297     if (Diags)
298       Diag(Diags, Features, Loc, ThisTokBegin, UcnBegin, ThisTokBuf,
299            diag::err_ucn_escape_invalid);
300     return false;
301   }
302 
303   // C++11 allows UCNs that refer to control characters and basic source
304   // characters inside character and string literals
305   if (UcnVal < 0xa0 &&
306       (UcnVal != 0x24 && UcnVal != 0x40 && UcnVal != 0x60)) {  // $, @, `
307     bool IsError = (!Features.CPlusPlus11 || !in_char_string_literal);
308     if (Diags) {
309       char BasicSCSChar = UcnVal;
310       if (UcnVal >= 0x20 && UcnVal < 0x7f)
311         Diag(Diags, Features, Loc, ThisTokBegin, UcnBegin, ThisTokBuf,
312              IsError ? diag::err_ucn_escape_basic_scs :
313                        diag::warn_cxx98_compat_literal_ucn_escape_basic_scs)
314             << StringRef(&BasicSCSChar, 1);
315       else
316         Diag(Diags, Features, Loc, ThisTokBegin, UcnBegin, ThisTokBuf,
317              IsError ? diag::err_ucn_control_character :
318                        diag::warn_cxx98_compat_literal_ucn_control_character);
319     }
320     if (IsError)
321       return false;
322   }
323 
324   if (!Features.CPlusPlus && !Features.C99 && Diags)
325     Diag(Diags, Features, Loc, ThisTokBegin, UcnBegin, ThisTokBuf,
326          diag::warn_ucn_not_valid_in_c89_literal);
327 
328   return true;
329 }
330 
331 /// MeasureUCNEscape - Determine the number of bytes within the resulting string
332 /// which this UCN will occupy.
MeasureUCNEscape(const char * ThisTokBegin,const char * & ThisTokBuf,const char * ThisTokEnd,unsigned CharByteWidth,const LangOptions & Features,bool & HadError)333 static int MeasureUCNEscape(const char *ThisTokBegin, const char *&ThisTokBuf,
334                             const char *ThisTokEnd, unsigned CharByteWidth,
335                             const LangOptions &Features, bool &HadError) {
336   // UTF-32: 4 bytes per escape.
337   if (CharByteWidth == 4)
338     return 4;
339 
340   uint32_t UcnVal = 0;
341   unsigned short UcnLen = 0;
342   FullSourceLoc Loc;
343 
344   if (!ProcessUCNEscape(ThisTokBegin, ThisTokBuf, ThisTokEnd, UcnVal,
345                         UcnLen, Loc, nullptr, Features, true)) {
346     HadError = true;
347     return 0;
348   }
349 
350   // UTF-16: 2 bytes for BMP, 4 bytes otherwise.
351   if (CharByteWidth == 2)
352     return UcnVal <= 0xFFFF ? 2 : 4;
353 
354   // UTF-8.
355   if (UcnVal < 0x80)
356     return 1;
357   if (UcnVal < 0x800)
358     return 2;
359   if (UcnVal < 0x10000)
360     return 3;
361   return 4;
362 }
363 
364 /// EncodeUCNEscape - Read the Universal Character Name, check constraints and
365 /// convert the UTF32 to UTF8 or UTF16. This is a subroutine of
366 /// StringLiteralParser. When we decide to implement UCN's for identifiers,
367 /// we will likely rework our support for UCN's.
EncodeUCNEscape(const char * ThisTokBegin,const char * & ThisTokBuf,const char * ThisTokEnd,char * & ResultBuf,bool & HadError,FullSourceLoc Loc,unsigned CharByteWidth,DiagnosticsEngine * Diags,const LangOptions & Features)368 static void EncodeUCNEscape(const char *ThisTokBegin, const char *&ThisTokBuf,
369                             const char *ThisTokEnd,
370                             char *&ResultBuf, bool &HadError,
371                             FullSourceLoc Loc, unsigned CharByteWidth,
372                             DiagnosticsEngine *Diags,
373                             const LangOptions &Features) {
374   typedef uint32_t UTF32;
375   UTF32 UcnVal = 0;
376   unsigned short UcnLen = 0;
377   if (!ProcessUCNEscape(ThisTokBegin, ThisTokBuf, ThisTokEnd, UcnVal, UcnLen,
378                         Loc, Diags, Features, true)) {
379     HadError = true;
380     return;
381   }
382 
383   assert((CharByteWidth == 1 || CharByteWidth == 2 || CharByteWidth == 4) &&
384          "only character widths of 1, 2, or 4 bytes supported");
385 
386   (void)UcnLen;
387   assert((UcnLen== 4 || UcnLen== 8) && "only ucn length of 4 or 8 supported");
388 
389   if (CharByteWidth == 4) {
390     // FIXME: Make the type of the result buffer correct instead of
391     // using reinterpret_cast.
392     UTF32 *ResultPtr = reinterpret_cast<UTF32*>(ResultBuf);
393     *ResultPtr = UcnVal;
394     ResultBuf += 4;
395     return;
396   }
397 
398   if (CharByteWidth == 2) {
399     // FIXME: Make the type of the result buffer correct instead of
400     // using reinterpret_cast.
401     UTF16 *ResultPtr = reinterpret_cast<UTF16*>(ResultBuf);
402 
403     if (UcnVal <= (UTF32)0xFFFF) {
404       *ResultPtr = UcnVal;
405       ResultBuf += 2;
406       return;
407     }
408 
409     // Convert to UTF16.
410     UcnVal -= 0x10000;
411     *ResultPtr     = 0xD800 + (UcnVal >> 10);
412     *(ResultPtr+1) = 0xDC00 + (UcnVal & 0x3FF);
413     ResultBuf += 4;
414     return;
415   }
416 
417   assert(CharByteWidth == 1 && "UTF-8 encoding is only for 1 byte characters");
418 
419   // Now that we've parsed/checked the UCN, we convert from UTF32->UTF8.
420   // The conversion below was inspired by:
421   //   http://www.unicode.org/Public/PROGRAMS/CVTUTF/ConvertUTF.c
422   // First, we determine how many bytes the result will require.
423   typedef uint8_t UTF8;
424 
425   unsigned short bytesToWrite = 0;
426   if (UcnVal < (UTF32)0x80)
427     bytesToWrite = 1;
428   else if (UcnVal < (UTF32)0x800)
429     bytesToWrite = 2;
430   else if (UcnVal < (UTF32)0x10000)
431     bytesToWrite = 3;
432   else
433     bytesToWrite = 4;
434 
435   const unsigned byteMask = 0xBF;
436   const unsigned byteMark = 0x80;
437 
438   // Once the bits are split out into bytes of UTF8, this is a mask OR-ed
439   // into the first byte, depending on how many bytes follow.
440   static const UTF8 firstByteMark[5] = {
441     0x00, 0x00, 0xC0, 0xE0, 0xF0
442   };
443   // Finally, we write the bytes into ResultBuf.
444   ResultBuf += bytesToWrite;
445   switch (bytesToWrite) { // note: everything falls through.
446   case 4: *--ResultBuf = (UTF8)((UcnVal | byteMark) & byteMask); UcnVal >>= 6;
447   case 3: *--ResultBuf = (UTF8)((UcnVal | byteMark) & byteMask); UcnVal >>= 6;
448   case 2: *--ResultBuf = (UTF8)((UcnVal | byteMark) & byteMask); UcnVal >>= 6;
449   case 1: *--ResultBuf = (UTF8) (UcnVal | firstByteMark[bytesToWrite]);
450   }
451   // Update the buffer.
452   ResultBuf += bytesToWrite;
453 }
454 
455 
456 ///       integer-constant: [C99 6.4.4.1]
457 ///         decimal-constant integer-suffix
458 ///         octal-constant integer-suffix
459 ///         hexadecimal-constant integer-suffix
460 ///         binary-literal integer-suffix [GNU, C++1y]
461 ///       user-defined-integer-literal: [C++11 lex.ext]
462 ///         decimal-literal ud-suffix
463 ///         octal-literal ud-suffix
464 ///         hexadecimal-literal ud-suffix
465 ///         binary-literal ud-suffix [GNU, C++1y]
466 ///       decimal-constant:
467 ///         nonzero-digit
468 ///         decimal-constant digit
469 ///       octal-constant:
470 ///         0
471 ///         octal-constant octal-digit
472 ///       hexadecimal-constant:
473 ///         hexadecimal-prefix hexadecimal-digit
474 ///         hexadecimal-constant hexadecimal-digit
475 ///       hexadecimal-prefix: one of
476 ///         0x 0X
477 ///       binary-literal:
478 ///         0b binary-digit
479 ///         0B binary-digit
480 ///         binary-literal binary-digit
481 ///       integer-suffix:
482 ///         unsigned-suffix [long-suffix]
483 ///         unsigned-suffix [long-long-suffix]
484 ///         long-suffix [unsigned-suffix]
485 ///         long-long-suffix [unsigned-sufix]
486 ///       nonzero-digit:
487 ///         1 2 3 4 5 6 7 8 9
488 ///       octal-digit:
489 ///         0 1 2 3 4 5 6 7
490 ///       hexadecimal-digit:
491 ///         0 1 2 3 4 5 6 7 8 9
492 ///         a b c d e f
493 ///         A B C D E F
494 ///       binary-digit:
495 ///         0
496 ///         1
497 ///       unsigned-suffix: one of
498 ///         u U
499 ///       long-suffix: one of
500 ///         l L
501 ///       long-long-suffix: one of
502 ///         ll LL
503 ///
504 ///       floating-constant: [C99 6.4.4.2]
505 ///         TODO: add rules...
506 ///
NumericLiteralParser(StringRef TokSpelling,SourceLocation TokLoc,Preprocessor & PP)507 NumericLiteralParser::NumericLiteralParser(StringRef TokSpelling,
508                                            SourceLocation TokLoc,
509                                            Preprocessor &PP)
510   : PP(PP), ThisTokBegin(TokSpelling.begin()), ThisTokEnd(TokSpelling.end()) {
511 
512   // This routine assumes that the range begin/end matches the regex for integer
513   // and FP constants (specifically, the 'pp-number' regex), and assumes that
514   // the byte at "*end" is both valid and not part of the regex.  Because of
515   // this, it doesn't have to check for 'overscan' in various places.
516   assert(!isPreprocessingNumberBody(*ThisTokEnd) && "didn't maximally munch?");
517 
518   s = DigitsBegin = ThisTokBegin;
519   saw_exponent = false;
520   saw_period = false;
521   saw_ud_suffix = false;
522   isLong = false;
523   isUnsigned = false;
524   isLongLong = false;
525   isHalf = false;
526   isFloat = false;
527   isImaginary = false;
528   isFloat128 = false;
529   MicrosoftInteger = 0;
530   hadError = false;
531 
532   if (*s == '0') { // parse radix
533     ParseNumberStartingWithZero(TokLoc);
534     if (hadError)
535       return;
536   } else { // the first digit is non-zero
537     radix = 10;
538     s = SkipDigits(s);
539     if (s == ThisTokEnd) {
540       // Done.
541     } else {
542       ParseDecimalOrOctalCommon(TokLoc);
543       if (hadError)
544         return;
545     }
546   }
547 
548   SuffixBegin = s;
549   checkSeparator(TokLoc, s, CSK_AfterDigits);
550 
551   // Parse the suffix.  At this point we can classify whether we have an FP or
552   // integer constant.
553   bool isFPConstant = isFloatingLiteral();
554   const char *ImaginarySuffixLoc = nullptr;
555 
556   // Loop over all of the characters of the suffix.  If we see something bad,
557   // we break out of the loop.
558   for (; s != ThisTokEnd; ++s) {
559     switch (*s) {
560     case 'h':      // FP Suffix for "half".
561     case 'H':
562       // OpenCL Extension v1.2 s9.5 - h or H suffix for half type.
563       if (!PP.getLangOpts().Half) break;
564       if (!isFPConstant) break;  // Error for integer constant.
565       if (isHalf || isFloat || isLong) break; // HH, FH, LH invalid.
566       isHalf = true;
567       continue;  // Success.
568     case 'f':      // FP Suffix for "float"
569     case 'F':
570       if (!isFPConstant) break;  // Error for integer constant.
571       if (isHalf || isFloat || isLong || isFloat128)
572         break; // HF, FF, LF, QF invalid.
573       isFloat = true;
574       continue;  // Success.
575     case 'q':    // FP Suffix for "__float128"
576     case 'Q':
577       if (!isFPConstant) break;  // Error for integer constant.
578       if (isHalf || isFloat || isLong || isFloat128)
579         break; // HQ, FQ, LQ, QQ invalid.
580       isFloat128 = true;
581       continue;  // Success.
582     case 'u':
583     case 'U':
584       if (isFPConstant) break;  // Error for floating constant.
585       if (isUnsigned) break;    // Cannot be repeated.
586       isUnsigned = true;
587       continue;  // Success.
588     case 'l':
589     case 'L':
590       if (isLong || isLongLong) break;  // Cannot be repeated.
591       if (isHalf || isFloat || isFloat128) break;     // LH, LF, LQ invalid.
592 
593       // Check for long long.  The L's need to be adjacent and the same case.
594       if (s[1] == s[0]) {
595         assert(s + 1 < ThisTokEnd && "didn't maximally munch?");
596         if (isFPConstant) break;        // long long invalid for floats.
597         isLongLong = true;
598         ++s;  // Eat both of them.
599       } else {
600         isLong = true;
601       }
602       continue;  // Success.
603     case 'i':
604     case 'I':
605       if (PP.getLangOpts().MicrosoftExt) {
606         if (isLong || isLongLong || MicrosoftInteger)
607           break;
608 
609         if (!isFPConstant) {
610           // Allow i8, i16, i32, and i64.
611           switch (s[1]) {
612           case '8':
613             s += 2; // i8 suffix
614             MicrosoftInteger = 8;
615             break;
616           case '1':
617             if (s[2] == '6') {
618               s += 3; // i16 suffix
619               MicrosoftInteger = 16;
620             }
621             break;
622           case '3':
623             if (s[2] == '2') {
624               s += 3; // i32 suffix
625               MicrosoftInteger = 32;
626             }
627             break;
628           case '6':
629             if (s[2] == '4') {
630               s += 3; // i64 suffix
631               MicrosoftInteger = 64;
632             }
633             break;
634           default:
635             break;
636           }
637         }
638         if (MicrosoftInteger) {
639           assert(s <= ThisTokEnd && "didn't maximally munch?");
640           break;
641         }
642       }
643       // "i", "if", and "il" are user-defined suffixes in C++1y.
644       if (*s == 'i' && PP.getLangOpts().CPlusPlus14)
645         break;
646       // fall through.
647     case 'j':
648     case 'J':
649       if (isImaginary) break;   // Cannot be repeated.
650       isImaginary = true;
651       ImaginarySuffixLoc = s;
652       continue;  // Success.
653     }
654     // If we reached here, there was an error or a ud-suffix.
655     break;
656   }
657 
658   if (s != ThisTokEnd) {
659     // FIXME: Don't bother expanding UCNs if !tok.hasUCN().
660     expandUCNs(UDSuffixBuf, StringRef(SuffixBegin, ThisTokEnd - SuffixBegin));
661     if (isValidUDSuffix(PP.getLangOpts(), UDSuffixBuf)) {
662       // Any suffix pieces we might have parsed are actually part of the
663       // ud-suffix.
664       isLong = false;
665       isUnsigned = false;
666       isLongLong = false;
667       isFloat = false;
668       isHalf = false;
669       isImaginary = false;
670       MicrosoftInteger = 0;
671 
672       saw_ud_suffix = true;
673       return;
674     }
675 
676     // Report an error if there are any.
677     PP.Diag(PP.AdvanceToTokenCharacter(TokLoc, SuffixBegin - ThisTokBegin),
678             diag::err_invalid_suffix_constant)
679       << StringRef(SuffixBegin, ThisTokEnd-SuffixBegin) << isFPConstant;
680     hadError = true;
681     return;
682   }
683 
684   if (isImaginary) {
685     PP.Diag(PP.AdvanceToTokenCharacter(TokLoc,
686                                        ImaginarySuffixLoc - ThisTokBegin),
687             diag::ext_imaginary_constant);
688   }
689 }
690 
691 /// ParseDecimalOrOctalCommon - This method is called for decimal or octal
692 /// numbers. It issues an error for illegal digits, and handles floating point
693 /// parsing. If it detects a floating point number, the radix is set to 10.
ParseDecimalOrOctalCommon(SourceLocation TokLoc)694 void NumericLiteralParser::ParseDecimalOrOctalCommon(SourceLocation TokLoc){
695   assert((radix == 8 || radix == 10) && "Unexpected radix");
696 
697   // If we have a hex digit other than 'e' (which denotes a FP exponent) then
698   // the code is using an incorrect base.
699   if (isHexDigit(*s) && *s != 'e' && *s != 'E') {
700     PP.Diag(PP.AdvanceToTokenCharacter(TokLoc, s-ThisTokBegin),
701             diag::err_invalid_digit) << StringRef(s, 1) << (radix == 8 ? 1 : 0);
702     hadError = true;
703     return;
704   }
705 
706   if (*s == '.') {
707     checkSeparator(TokLoc, s, CSK_AfterDigits);
708     s++;
709     radix = 10;
710     saw_period = true;
711     checkSeparator(TokLoc, s, CSK_BeforeDigits);
712     s = SkipDigits(s); // Skip suffix.
713   }
714   if (*s == 'e' || *s == 'E') { // exponent
715     checkSeparator(TokLoc, s, CSK_AfterDigits);
716     const char *Exponent = s;
717     s++;
718     radix = 10;
719     saw_exponent = true;
720     if (*s == '+' || *s == '-')  s++; // sign
721     const char *first_non_digit = SkipDigits(s);
722     if (containsDigits(s, first_non_digit)) {
723       checkSeparator(TokLoc, s, CSK_BeforeDigits);
724       s = first_non_digit;
725     } else {
726       PP.Diag(PP.AdvanceToTokenCharacter(TokLoc, Exponent-ThisTokBegin),
727               diag::err_exponent_has_no_digits);
728       hadError = true;
729       return;
730     }
731   }
732 }
733 
734 /// Determine whether a suffix is a valid ud-suffix. We avoid treating reserved
735 /// suffixes as ud-suffixes, because the diagnostic experience is better if we
736 /// treat it as an invalid suffix.
isValidUDSuffix(const LangOptions & LangOpts,StringRef Suffix)737 bool NumericLiteralParser::isValidUDSuffix(const LangOptions &LangOpts,
738                                            StringRef Suffix) {
739   if (!LangOpts.CPlusPlus11 || Suffix.empty())
740     return false;
741 
742   // By C++11 [lex.ext]p10, ud-suffixes starting with an '_' are always valid.
743   if (Suffix[0] == '_')
744     return true;
745 
746   // In C++11, there are no library suffixes.
747   if (!LangOpts.CPlusPlus14)
748     return false;
749 
750   // In C++1y, "s", "h", "min", "ms", "us", and "ns" are used in the library.
751   // Per tweaked N3660, "il", "i", and "if" are also used in the library.
752   return llvm::StringSwitch<bool>(Suffix)
753       .Cases("h", "min", "s", true)
754       .Cases("ms", "us", "ns", true)
755       .Cases("il", "i", "if", true)
756       .Default(false);
757 }
758 
checkSeparator(SourceLocation TokLoc,const char * Pos,CheckSeparatorKind IsAfterDigits)759 void NumericLiteralParser::checkSeparator(SourceLocation TokLoc,
760                                           const char *Pos,
761                                           CheckSeparatorKind IsAfterDigits) {
762   if (IsAfterDigits == CSK_AfterDigits) {
763     if (Pos == ThisTokBegin)
764       return;
765     --Pos;
766   } else if (Pos == ThisTokEnd)
767     return;
768 
769   if (isDigitSeparator(*Pos))
770     PP.Diag(PP.AdvanceToTokenCharacter(TokLoc, Pos - ThisTokBegin),
771             diag::err_digit_separator_not_between_digits)
772       << IsAfterDigits;
773 }
774 
775 /// ParseNumberStartingWithZero - This method is called when the first character
776 /// of the number is found to be a zero.  This means it is either an octal
777 /// number (like '04') or a hex number ('0x123a') a binary number ('0b1010') or
778 /// a floating point number (01239.123e4).  Eat the prefix, determining the
779 /// radix etc.
ParseNumberStartingWithZero(SourceLocation TokLoc)780 void NumericLiteralParser::ParseNumberStartingWithZero(SourceLocation TokLoc) {
781   assert(s[0] == '0' && "Invalid method call");
782   s++;
783 
784   int c1 = s[0];
785 
786   // Handle a hex number like 0x1234.
787   if ((c1 == 'x' || c1 == 'X') && (isHexDigit(s[1]) || s[1] == '.')) {
788     s++;
789     assert(s < ThisTokEnd && "didn't maximally munch?");
790     radix = 16;
791     DigitsBegin = s;
792     s = SkipHexDigits(s);
793     bool HasSignificandDigits = containsDigits(DigitsBegin, s);
794     if (s == ThisTokEnd) {
795       // Done.
796     } else if (*s == '.') {
797       s++;
798       saw_period = true;
799       const char *floatDigitsBegin = s;
800       s = SkipHexDigits(s);
801       if (containsDigits(floatDigitsBegin, s))
802         HasSignificandDigits = true;
803       if (HasSignificandDigits)
804         checkSeparator(TokLoc, floatDigitsBegin, CSK_BeforeDigits);
805     }
806 
807     if (!HasSignificandDigits) {
808       PP.Diag(PP.AdvanceToTokenCharacter(TokLoc, s - ThisTokBegin),
809               diag::err_hex_constant_requires)
810           << PP.getLangOpts().CPlusPlus << 1;
811       hadError = true;
812       return;
813     }
814 
815     // A binary exponent can appear with or with a '.'. If dotted, the
816     // binary exponent is required.
817     if (*s == 'p' || *s == 'P') {
818       checkSeparator(TokLoc, s, CSK_AfterDigits);
819       const char *Exponent = s;
820       s++;
821       saw_exponent = true;
822       if (*s == '+' || *s == '-')  s++; // sign
823       const char *first_non_digit = SkipDigits(s);
824       if (!containsDigits(s, first_non_digit)) {
825         PP.Diag(PP.AdvanceToTokenCharacter(TokLoc, Exponent-ThisTokBegin),
826                 diag::err_exponent_has_no_digits);
827         hadError = true;
828         return;
829       }
830       checkSeparator(TokLoc, s, CSK_BeforeDigits);
831       s = first_non_digit;
832 
833       if (!PP.getLangOpts().HexFloats)
834         PP.Diag(TokLoc, PP.getLangOpts().CPlusPlus
835                             ? diag::ext_hex_literal_invalid
836                             : diag::ext_hex_constant_invalid);
837       else if (PP.getLangOpts().CPlusPlus1z)
838         PP.Diag(TokLoc, diag::warn_cxx1z_hex_literal);
839     } else if (saw_period) {
840       PP.Diag(PP.AdvanceToTokenCharacter(TokLoc, s - ThisTokBegin),
841               diag::err_hex_constant_requires)
842           << PP.getLangOpts().CPlusPlus << 0;
843       hadError = true;
844     }
845     return;
846   }
847 
848   // Handle simple binary numbers 0b01010
849   if ((c1 == 'b' || c1 == 'B') && (s[1] == '0' || s[1] == '1')) {
850     // 0b101010 is a C++1y / GCC extension.
851     PP.Diag(TokLoc,
852             PP.getLangOpts().CPlusPlus14
853               ? diag::warn_cxx11_compat_binary_literal
854               : PP.getLangOpts().CPlusPlus
855                 ? diag::ext_binary_literal_cxx14
856                 : diag::ext_binary_literal);
857     ++s;
858     assert(s < ThisTokEnd && "didn't maximally munch?");
859     radix = 2;
860     DigitsBegin = s;
861     s = SkipBinaryDigits(s);
862     if (s == ThisTokEnd) {
863       // Done.
864     } else if (isHexDigit(*s)) {
865       PP.Diag(PP.AdvanceToTokenCharacter(TokLoc, s-ThisTokBegin),
866               diag::err_invalid_digit) << StringRef(s, 1) << 2;
867       hadError = true;
868     }
869     // Other suffixes will be diagnosed by the caller.
870     return;
871   }
872 
873   // For now, the radix is set to 8. If we discover that we have a
874   // floating point constant, the radix will change to 10. Octal floating
875   // point constants are not permitted (only decimal and hexadecimal).
876   radix = 8;
877   DigitsBegin = s;
878   s = SkipOctalDigits(s);
879   if (s == ThisTokEnd)
880     return; // Done, simple octal number like 01234
881 
882   // If we have some other non-octal digit that *is* a decimal digit, see if
883   // this is part of a floating point number like 094.123 or 09e1.
884   if (isDigit(*s)) {
885     const char *EndDecimal = SkipDigits(s);
886     if (EndDecimal[0] == '.' || EndDecimal[0] == 'e' || EndDecimal[0] == 'E') {
887       s = EndDecimal;
888       radix = 10;
889     }
890   }
891 
892   ParseDecimalOrOctalCommon(TokLoc);
893 }
894 
alwaysFitsInto64Bits(unsigned Radix,unsigned NumDigits)895 static bool alwaysFitsInto64Bits(unsigned Radix, unsigned NumDigits) {
896   switch (Radix) {
897   case 2:
898     return NumDigits <= 64;
899   case 8:
900     return NumDigits <= 64 / 3; // Digits are groups of 3 bits.
901   case 10:
902     return NumDigits <= 19; // floor(log10(2^64))
903   case 16:
904     return NumDigits <= 64 / 4; // Digits are groups of 4 bits.
905   default:
906     llvm_unreachable("impossible Radix");
907   }
908 }
909 
910 /// GetIntegerValue - Convert this numeric literal value to an APInt that
911 /// matches Val's input width.  If there is an overflow, set Val to the low bits
912 /// of the result and return true.  Otherwise, return false.
GetIntegerValue(llvm::APInt & Val)913 bool NumericLiteralParser::GetIntegerValue(llvm::APInt &Val) {
914   // Fast path: Compute a conservative bound on the maximum number of
915   // bits per digit in this radix. If we can't possibly overflow a
916   // uint64 based on that bound then do the simple conversion to
917   // integer. This avoids the expensive overflow checking below, and
918   // handles the common cases that matter (small decimal integers and
919   // hex/octal values which don't overflow).
920   const unsigned NumDigits = SuffixBegin - DigitsBegin;
921   if (alwaysFitsInto64Bits(radix, NumDigits)) {
922     uint64_t N = 0;
923     for (const char *Ptr = DigitsBegin; Ptr != SuffixBegin; ++Ptr)
924       if (!isDigitSeparator(*Ptr))
925         N = N * radix + llvm::hexDigitValue(*Ptr);
926 
927     // This will truncate the value to Val's input width. Simply check
928     // for overflow by comparing.
929     Val = N;
930     return Val.getZExtValue() != N;
931   }
932 
933   Val = 0;
934   const char *Ptr = DigitsBegin;
935 
936   llvm::APInt RadixVal(Val.getBitWidth(), radix);
937   llvm::APInt CharVal(Val.getBitWidth(), 0);
938   llvm::APInt OldVal = Val;
939 
940   bool OverflowOccurred = false;
941   while (Ptr < SuffixBegin) {
942     if (isDigitSeparator(*Ptr)) {
943       ++Ptr;
944       continue;
945     }
946 
947     unsigned C = llvm::hexDigitValue(*Ptr++);
948 
949     // If this letter is out of bound for this radix, reject it.
950     assert(C < radix && "NumericLiteralParser ctor should have rejected this");
951 
952     CharVal = C;
953 
954     // Add the digit to the value in the appropriate radix.  If adding in digits
955     // made the value smaller, then this overflowed.
956     OldVal = Val;
957 
958     // Multiply by radix, did overflow occur on the multiply?
959     Val *= RadixVal;
960     OverflowOccurred |= Val.udiv(RadixVal) != OldVal;
961 
962     // Add value, did overflow occur on the value?
963     //   (a + b) ult b  <=> overflow
964     Val += CharVal;
965     OverflowOccurred |= Val.ult(CharVal);
966   }
967   return OverflowOccurred;
968 }
969 
970 llvm::APFloat::opStatus
GetFloatValue(llvm::APFloat & Result)971 NumericLiteralParser::GetFloatValue(llvm::APFloat &Result) {
972   using llvm::APFloat;
973 
974   unsigned n = std::min(SuffixBegin - ThisTokBegin, ThisTokEnd - ThisTokBegin);
975 
976   llvm::SmallString<16> Buffer;
977   StringRef Str(ThisTokBegin, n);
978   if (Str.find('\'') != StringRef::npos) {
979     Buffer.reserve(n);
980     std::remove_copy_if(Str.begin(), Str.end(), std::back_inserter(Buffer),
981                         &isDigitSeparator);
982     Str = Buffer;
983   }
984 
985   return Result.convertFromString(Str, APFloat::rmNearestTiesToEven);
986 }
987 
988 
989 /// \verbatim
990 ///       user-defined-character-literal: [C++11 lex.ext]
991 ///         character-literal ud-suffix
992 ///       ud-suffix:
993 ///         identifier
994 ///       character-literal: [C++11 lex.ccon]
995 ///         ' c-char-sequence '
996 ///         u' c-char-sequence '
997 ///         U' c-char-sequence '
998 ///         L' c-char-sequence '
999 ///         u8' c-char-sequence ' [C++1z lex.ccon]
1000 ///       c-char-sequence:
1001 ///         c-char
1002 ///         c-char-sequence c-char
1003 ///       c-char:
1004 ///         any member of the source character set except the single-quote ',
1005 ///           backslash \, or new-line character
1006 ///         escape-sequence
1007 ///         universal-character-name
1008 ///       escape-sequence:
1009 ///         simple-escape-sequence
1010 ///         octal-escape-sequence
1011 ///         hexadecimal-escape-sequence
1012 ///       simple-escape-sequence:
1013 ///         one of \' \" \? \\ \a \b \f \n \r \t \v
1014 ///       octal-escape-sequence:
1015 ///         \ octal-digit
1016 ///         \ octal-digit octal-digit
1017 ///         \ octal-digit octal-digit octal-digit
1018 ///       hexadecimal-escape-sequence:
1019 ///         \x hexadecimal-digit
1020 ///         hexadecimal-escape-sequence hexadecimal-digit
1021 ///       universal-character-name: [C++11 lex.charset]
1022 ///         \u hex-quad
1023 ///         \U hex-quad hex-quad
1024 ///       hex-quad:
1025 ///         hex-digit hex-digit hex-digit hex-digit
1026 /// \endverbatim
1027 ///
CharLiteralParser(const char * begin,const char * end,SourceLocation Loc,Preprocessor & PP,tok::TokenKind kind)1028 CharLiteralParser::CharLiteralParser(const char *begin, const char *end,
1029                                      SourceLocation Loc, Preprocessor &PP,
1030                                      tok::TokenKind kind) {
1031   // At this point we know that the character matches the regex "(L|u|U)?'.*'".
1032   HadError = false;
1033 
1034   Kind = kind;
1035 
1036   const char *TokBegin = begin;
1037 
1038   // Skip over wide character determinant.
1039   if (Kind != tok::char_constant)
1040     ++begin;
1041   if (Kind == tok::utf8_char_constant)
1042     ++begin;
1043 
1044   // Skip over the entry quote.
1045   assert(begin[0] == '\'' && "Invalid token lexed");
1046   ++begin;
1047 
1048   // Remove an optional ud-suffix.
1049   if (end[-1] != '\'') {
1050     const char *UDSuffixEnd = end;
1051     do {
1052       --end;
1053     } while (end[-1] != '\'');
1054     // FIXME: Don't bother with this if !tok.hasUCN().
1055     expandUCNs(UDSuffixBuf, StringRef(end, UDSuffixEnd - end));
1056     UDSuffixOffset = end - TokBegin;
1057   }
1058 
1059   // Trim the ending quote.
1060   assert(end != begin && "Invalid token lexed");
1061   --end;
1062 
1063   // FIXME: The "Value" is an uint64_t so we can handle char literals of
1064   // up to 64-bits.
1065   // FIXME: This extensively assumes that 'char' is 8-bits.
1066   assert(PP.getTargetInfo().getCharWidth() == 8 &&
1067          "Assumes char is 8 bits");
1068   assert(PP.getTargetInfo().getIntWidth() <= 64 &&
1069          (PP.getTargetInfo().getIntWidth() & 7) == 0 &&
1070          "Assumes sizeof(int) on target is <= 64 and a multiple of char");
1071   assert(PP.getTargetInfo().getWCharWidth() <= 64 &&
1072          "Assumes sizeof(wchar) on target is <= 64");
1073 
1074   SmallVector<uint32_t, 4> codepoint_buffer;
1075   codepoint_buffer.resize(end - begin);
1076   uint32_t *buffer_begin = &codepoint_buffer.front();
1077   uint32_t *buffer_end = buffer_begin + codepoint_buffer.size();
1078 
1079   // Unicode escapes representing characters that cannot be correctly
1080   // represented in a single code unit are disallowed in character literals
1081   // by this implementation.
1082   uint32_t largest_character_for_kind;
1083   if (tok::wide_char_constant == Kind) {
1084     largest_character_for_kind =
1085         0xFFFFFFFFu >> (32-PP.getTargetInfo().getWCharWidth());
1086   } else if (tok::utf8_char_constant == Kind) {
1087     largest_character_for_kind = 0x7F;
1088   } else if (tok::utf16_char_constant == Kind) {
1089     largest_character_for_kind = 0xFFFF;
1090   } else if (tok::utf32_char_constant == Kind) {
1091     largest_character_for_kind = 0x10FFFF;
1092   } else {
1093     largest_character_for_kind = 0x7Fu;
1094   }
1095 
1096   while (begin != end) {
1097     // Is this a span of non-escape characters?
1098     if (begin[0] != '\\') {
1099       char const *start = begin;
1100       do {
1101         ++begin;
1102       } while (begin != end && *begin != '\\');
1103 
1104       char const *tmp_in_start = start;
1105       uint32_t *tmp_out_start = buffer_begin;
1106       ConversionResult res =
1107           ConvertUTF8toUTF32(reinterpret_cast<UTF8 const **>(&start),
1108                              reinterpret_cast<UTF8 const *>(begin),
1109                              &buffer_begin, buffer_end, strictConversion);
1110       if (res != conversionOK) {
1111         // If we see bad encoding for unprefixed character literals, warn and
1112         // simply copy the byte values, for compatibility with gcc and
1113         // older versions of clang.
1114         bool NoErrorOnBadEncoding = isAscii();
1115         unsigned Msg = diag::err_bad_character_encoding;
1116         if (NoErrorOnBadEncoding)
1117           Msg = diag::warn_bad_character_encoding;
1118         PP.Diag(Loc, Msg);
1119         if (NoErrorOnBadEncoding) {
1120           start = tmp_in_start;
1121           buffer_begin = tmp_out_start;
1122           for (; start != begin; ++start, ++buffer_begin)
1123             *buffer_begin = static_cast<uint8_t>(*start);
1124         } else {
1125           HadError = true;
1126         }
1127       } else {
1128         for (; tmp_out_start < buffer_begin; ++tmp_out_start) {
1129           if (*tmp_out_start > largest_character_for_kind) {
1130             HadError = true;
1131             PP.Diag(Loc, diag::err_character_too_large);
1132           }
1133         }
1134       }
1135 
1136       continue;
1137     }
1138     // Is this a Universal Character Name escape?
1139     if (begin[1] == 'u' || begin[1] == 'U') {
1140       unsigned short UcnLen = 0;
1141       if (!ProcessUCNEscape(TokBegin, begin, end, *buffer_begin, UcnLen,
1142                             FullSourceLoc(Loc, PP.getSourceManager()),
1143                             &PP.getDiagnostics(), PP.getLangOpts(), true)) {
1144         HadError = true;
1145       } else if (*buffer_begin > largest_character_for_kind) {
1146         HadError = true;
1147         PP.Diag(Loc, diag::err_character_too_large);
1148       }
1149 
1150       ++buffer_begin;
1151       continue;
1152     }
1153     unsigned CharWidth = getCharWidth(Kind, PP.getTargetInfo());
1154     uint64_t result =
1155       ProcessCharEscape(TokBegin, begin, end, HadError,
1156                         FullSourceLoc(Loc,PP.getSourceManager()),
1157                         CharWidth, &PP.getDiagnostics(), PP.getLangOpts());
1158     *buffer_begin++ = result;
1159   }
1160 
1161   unsigned NumCharsSoFar = buffer_begin - &codepoint_buffer.front();
1162 
1163   if (NumCharsSoFar > 1) {
1164     if (isWide())
1165       PP.Diag(Loc, diag::warn_extraneous_char_constant);
1166     else if (isAscii() && NumCharsSoFar == 4)
1167       PP.Diag(Loc, diag::ext_four_char_character_literal);
1168     else if (isAscii())
1169       PP.Diag(Loc, diag::ext_multichar_character_literal);
1170     else
1171       PP.Diag(Loc, diag::err_multichar_utf_character_literal);
1172     IsMultiChar = true;
1173   } else {
1174     IsMultiChar = false;
1175   }
1176 
1177   llvm::APInt LitVal(PP.getTargetInfo().getIntWidth(), 0);
1178 
1179   // Narrow character literals act as though their value is concatenated
1180   // in this implementation, but warn on overflow.
1181   bool multi_char_too_long = false;
1182   if (isAscii() && isMultiChar()) {
1183     LitVal = 0;
1184     for (size_t i = 0; i < NumCharsSoFar; ++i) {
1185       // check for enough leading zeros to shift into
1186       multi_char_too_long |= (LitVal.countLeadingZeros() < 8);
1187       LitVal <<= 8;
1188       LitVal = LitVal + (codepoint_buffer[i] & 0xFF);
1189     }
1190   } else if (NumCharsSoFar > 0) {
1191     // otherwise just take the last character
1192     LitVal = buffer_begin[-1];
1193   }
1194 
1195   if (!HadError && multi_char_too_long) {
1196     PP.Diag(Loc, diag::warn_char_constant_too_large);
1197   }
1198 
1199   // Transfer the value from APInt to uint64_t
1200   Value = LitVal.getZExtValue();
1201 
1202   // If this is a single narrow character, sign extend it (e.g. '\xFF' is "-1")
1203   // if 'char' is signed for this target (C99 6.4.4.4p10).  Note that multiple
1204   // character constants are not sign extended in the this implementation:
1205   // '\xFF\xFF' = 65536 and '\x0\xFF' = 255, which matches GCC.
1206   if (isAscii() && NumCharsSoFar == 1 && (Value & 128) &&
1207       PP.getLangOpts().CharIsSigned)
1208     Value = (signed char)Value;
1209 }
1210 
1211 /// \verbatim
1212 ///       string-literal: [C++0x lex.string]
1213 ///         encoding-prefix " [s-char-sequence] "
1214 ///         encoding-prefix R raw-string
1215 ///       encoding-prefix:
1216 ///         u8
1217 ///         u
1218 ///         U
1219 ///         L
1220 ///       s-char-sequence:
1221 ///         s-char
1222 ///         s-char-sequence s-char
1223 ///       s-char:
1224 ///         any member of the source character set except the double-quote ",
1225 ///           backslash \, or new-line character
1226 ///         escape-sequence
1227 ///         universal-character-name
1228 ///       raw-string:
1229 ///         " d-char-sequence ( r-char-sequence ) d-char-sequence "
1230 ///       r-char-sequence:
1231 ///         r-char
1232 ///         r-char-sequence r-char
1233 ///       r-char:
1234 ///         any member of the source character set, except a right parenthesis )
1235 ///           followed by the initial d-char-sequence (which may be empty)
1236 ///           followed by a double quote ".
1237 ///       d-char-sequence:
1238 ///         d-char
1239 ///         d-char-sequence d-char
1240 ///       d-char:
1241 ///         any member of the basic source character set except:
1242 ///           space, the left parenthesis (, the right parenthesis ),
1243 ///           the backslash \, and the control characters representing horizontal
1244 ///           tab, vertical tab, form feed, and newline.
1245 ///       escape-sequence: [C++0x lex.ccon]
1246 ///         simple-escape-sequence
1247 ///         octal-escape-sequence
1248 ///         hexadecimal-escape-sequence
1249 ///       simple-escape-sequence:
1250 ///         one of \' \" \? \\ \a \b \f \n \r \t \v
1251 ///       octal-escape-sequence:
1252 ///         \ octal-digit
1253 ///         \ octal-digit octal-digit
1254 ///         \ octal-digit octal-digit octal-digit
1255 ///       hexadecimal-escape-sequence:
1256 ///         \x hexadecimal-digit
1257 ///         hexadecimal-escape-sequence hexadecimal-digit
1258 ///       universal-character-name:
1259 ///         \u hex-quad
1260 ///         \U hex-quad hex-quad
1261 ///       hex-quad:
1262 ///         hex-digit hex-digit hex-digit hex-digit
1263 /// \endverbatim
1264 ///
1265 StringLiteralParser::
StringLiteralParser(ArrayRef<Token> StringToks,Preprocessor & PP,bool Complain)1266 StringLiteralParser(ArrayRef<Token> StringToks,
1267                     Preprocessor &PP, bool Complain)
1268   : SM(PP.getSourceManager()), Features(PP.getLangOpts()),
1269     Target(PP.getTargetInfo()), Diags(Complain ? &PP.getDiagnostics() :nullptr),
1270     MaxTokenLength(0), SizeBound(0), CharByteWidth(0), Kind(tok::unknown),
1271     ResultPtr(ResultBuf.data()), hadError(false), Pascal(false) {
1272   init(StringToks);
1273 }
1274 
init(ArrayRef<Token> StringToks)1275 void StringLiteralParser::init(ArrayRef<Token> StringToks){
1276   // The literal token may have come from an invalid source location (e.g. due
1277   // to a PCH error), in which case the token length will be 0.
1278   if (StringToks.empty() || StringToks[0].getLength() < 2)
1279     return DiagnoseLexingError(SourceLocation());
1280 
1281   // Scan all of the string portions, remember the max individual token length,
1282   // computing a bound on the concatenated string length, and see whether any
1283   // piece is a wide-string.  If any of the string portions is a wide-string
1284   // literal, the result is a wide-string literal [C99 6.4.5p4].
1285   assert(!StringToks.empty() && "expected at least one token");
1286   MaxTokenLength = StringToks[0].getLength();
1287   assert(StringToks[0].getLength() >= 2 && "literal token is invalid!");
1288   SizeBound = StringToks[0].getLength()-2;  // -2 for "".
1289   Kind = StringToks[0].getKind();
1290 
1291   hadError = false;
1292 
1293   // Implement Translation Phase #6: concatenation of string literals
1294   /// (C99 5.1.1.2p1).  The common case is only one string fragment.
1295   for (unsigned i = 1; i != StringToks.size(); ++i) {
1296     if (StringToks[i].getLength() < 2)
1297       return DiagnoseLexingError(StringToks[i].getLocation());
1298 
1299     // The string could be shorter than this if it needs cleaning, but this is a
1300     // reasonable bound, which is all we need.
1301     assert(StringToks[i].getLength() >= 2 && "literal token is invalid!");
1302     SizeBound += StringToks[i].getLength()-2;  // -2 for "".
1303 
1304     // Remember maximum string piece length.
1305     if (StringToks[i].getLength() > MaxTokenLength)
1306       MaxTokenLength = StringToks[i].getLength();
1307 
1308     // Remember if we see any wide or utf-8/16/32 strings.
1309     // Also check for illegal concatenations.
1310     if (StringToks[i].isNot(Kind) && StringToks[i].isNot(tok::string_literal)) {
1311       if (isAscii()) {
1312         Kind = StringToks[i].getKind();
1313       } else {
1314         if (Diags)
1315           Diags->Report(StringToks[i].getLocation(),
1316                         diag::err_unsupported_string_concat);
1317         hadError = true;
1318       }
1319     }
1320   }
1321 
1322   // Include space for the null terminator.
1323   ++SizeBound;
1324 
1325   // TODO: K&R warning: "traditional C rejects string constant concatenation"
1326 
1327   // Get the width in bytes of char/wchar_t/char16_t/char32_t
1328   CharByteWidth = getCharWidth(Kind, Target);
1329   assert((CharByteWidth & 7) == 0 && "Assumes character size is byte multiple");
1330   CharByteWidth /= 8;
1331 
1332   // The output buffer size needs to be large enough to hold wide characters.
1333   // This is a worst-case assumption which basically corresponds to L"" "long".
1334   SizeBound *= CharByteWidth;
1335 
1336   // Size the temporary buffer to hold the result string data.
1337   ResultBuf.resize(SizeBound);
1338 
1339   // Likewise, but for each string piece.
1340   SmallString<512> TokenBuf;
1341   TokenBuf.resize(MaxTokenLength);
1342 
1343   // Loop over all the strings, getting their spelling, and expanding them to
1344   // wide strings as appropriate.
1345   ResultPtr = &ResultBuf[0];   // Next byte to fill in.
1346 
1347   Pascal = false;
1348 
1349   SourceLocation UDSuffixTokLoc;
1350 
1351   for (unsigned i = 0, e = StringToks.size(); i != e; ++i) {
1352     const char *ThisTokBuf = &TokenBuf[0];
1353     // Get the spelling of the token, which eliminates trigraphs, etc.  We know
1354     // that ThisTokBuf points to a buffer that is big enough for the whole token
1355     // and 'spelled' tokens can only shrink.
1356     bool StringInvalid = false;
1357     unsigned ThisTokLen =
1358       Lexer::getSpelling(StringToks[i], ThisTokBuf, SM, Features,
1359                          &StringInvalid);
1360     if (StringInvalid)
1361       return DiagnoseLexingError(StringToks[i].getLocation());
1362 
1363     const char *ThisTokBegin = ThisTokBuf;
1364     const char *ThisTokEnd = ThisTokBuf+ThisTokLen;
1365 
1366     // Remove an optional ud-suffix.
1367     if (ThisTokEnd[-1] != '"') {
1368       const char *UDSuffixEnd = ThisTokEnd;
1369       do {
1370         --ThisTokEnd;
1371       } while (ThisTokEnd[-1] != '"');
1372 
1373       StringRef UDSuffix(ThisTokEnd, UDSuffixEnd - ThisTokEnd);
1374 
1375       if (UDSuffixBuf.empty()) {
1376         if (StringToks[i].hasUCN())
1377           expandUCNs(UDSuffixBuf, UDSuffix);
1378         else
1379           UDSuffixBuf.assign(UDSuffix);
1380         UDSuffixToken = i;
1381         UDSuffixOffset = ThisTokEnd - ThisTokBuf;
1382         UDSuffixTokLoc = StringToks[i].getLocation();
1383       } else {
1384         SmallString<32> ExpandedUDSuffix;
1385         if (StringToks[i].hasUCN()) {
1386           expandUCNs(ExpandedUDSuffix, UDSuffix);
1387           UDSuffix = ExpandedUDSuffix;
1388         }
1389 
1390         // C++11 [lex.ext]p8: At the end of phase 6, if a string literal is the
1391         // result of a concatenation involving at least one user-defined-string-
1392         // literal, all the participating user-defined-string-literals shall
1393         // have the same ud-suffix.
1394         if (UDSuffixBuf != UDSuffix) {
1395           if (Diags) {
1396             SourceLocation TokLoc = StringToks[i].getLocation();
1397             Diags->Report(TokLoc, diag::err_string_concat_mixed_suffix)
1398               << UDSuffixBuf << UDSuffix
1399               << SourceRange(UDSuffixTokLoc, UDSuffixTokLoc)
1400               << SourceRange(TokLoc, TokLoc);
1401           }
1402           hadError = true;
1403         }
1404       }
1405     }
1406 
1407     // Strip the end quote.
1408     --ThisTokEnd;
1409 
1410     // TODO: Input character set mapping support.
1411 
1412     // Skip marker for wide or unicode strings.
1413     if (ThisTokBuf[0] == 'L' || ThisTokBuf[0] == 'u' || ThisTokBuf[0] == 'U') {
1414       ++ThisTokBuf;
1415       // Skip 8 of u8 marker for utf8 strings.
1416       if (ThisTokBuf[0] == '8')
1417         ++ThisTokBuf;
1418     }
1419 
1420     // Check for raw string
1421     if (ThisTokBuf[0] == 'R') {
1422       ThisTokBuf += 2; // skip R"
1423 
1424       const char *Prefix = ThisTokBuf;
1425       while (ThisTokBuf[0] != '(')
1426         ++ThisTokBuf;
1427       ++ThisTokBuf; // skip '('
1428 
1429       // Remove same number of characters from the end
1430       ThisTokEnd -= ThisTokBuf - Prefix;
1431       assert(ThisTokEnd >= ThisTokBuf && "malformed raw string literal");
1432 
1433       // C++14 [lex.string]p4: A source-file new-line in a raw string literal
1434       // results in a new-line in the resulting execution string-literal.
1435       StringRef RemainingTokenSpan(ThisTokBuf, ThisTokEnd - ThisTokBuf);
1436       while (!RemainingTokenSpan.empty()) {
1437         // Split the string literal on \r\n boundaries.
1438         size_t CRLFPos = RemainingTokenSpan.find("\r\n");
1439         StringRef BeforeCRLF = RemainingTokenSpan.substr(0, CRLFPos);
1440         StringRef AfterCRLF = RemainingTokenSpan.substr(CRLFPos);
1441 
1442         // Copy everything before the \r\n sequence into the string literal.
1443         if (CopyStringFragment(StringToks[i], ThisTokBegin, BeforeCRLF))
1444           hadError = true;
1445 
1446         // Point into the \n inside the \r\n sequence and operate on the
1447         // remaining portion of the literal.
1448         RemainingTokenSpan = AfterCRLF.substr(1);
1449       }
1450     } else {
1451       if (ThisTokBuf[0] != '"') {
1452         // The file may have come from PCH and then changed after loading the
1453         // PCH; Fail gracefully.
1454         return DiagnoseLexingError(StringToks[i].getLocation());
1455       }
1456       ++ThisTokBuf; // skip "
1457 
1458       // Check if this is a pascal string
1459       if (Features.PascalStrings && ThisTokBuf + 1 != ThisTokEnd &&
1460           ThisTokBuf[0] == '\\' && ThisTokBuf[1] == 'p') {
1461 
1462         // If the \p sequence is found in the first token, we have a pascal string
1463         // Otherwise, if we already have a pascal string, ignore the first \p
1464         if (i == 0) {
1465           ++ThisTokBuf;
1466           Pascal = true;
1467         } else if (Pascal)
1468           ThisTokBuf += 2;
1469       }
1470 
1471       while (ThisTokBuf != ThisTokEnd) {
1472         // Is this a span of non-escape characters?
1473         if (ThisTokBuf[0] != '\\') {
1474           const char *InStart = ThisTokBuf;
1475           do {
1476             ++ThisTokBuf;
1477           } while (ThisTokBuf != ThisTokEnd && ThisTokBuf[0] != '\\');
1478 
1479           // Copy the character span over.
1480           if (CopyStringFragment(StringToks[i], ThisTokBegin,
1481                                  StringRef(InStart, ThisTokBuf - InStart)))
1482             hadError = true;
1483           continue;
1484         }
1485         // Is this a Universal Character Name escape?
1486         if (ThisTokBuf[1] == 'u' || ThisTokBuf[1] == 'U') {
1487           EncodeUCNEscape(ThisTokBegin, ThisTokBuf, ThisTokEnd,
1488                           ResultPtr, hadError,
1489                           FullSourceLoc(StringToks[i].getLocation(), SM),
1490                           CharByteWidth, Diags, Features);
1491           continue;
1492         }
1493         // Otherwise, this is a non-UCN escape character.  Process it.
1494         unsigned ResultChar =
1495           ProcessCharEscape(ThisTokBegin, ThisTokBuf, ThisTokEnd, hadError,
1496                             FullSourceLoc(StringToks[i].getLocation(), SM),
1497                             CharByteWidth*8, Diags, Features);
1498 
1499         if (CharByteWidth == 4) {
1500           // FIXME: Make the type of the result buffer correct instead of
1501           // using reinterpret_cast.
1502           UTF32 *ResultWidePtr = reinterpret_cast<UTF32*>(ResultPtr);
1503           *ResultWidePtr = ResultChar;
1504           ResultPtr += 4;
1505         } else if (CharByteWidth == 2) {
1506           // FIXME: Make the type of the result buffer correct instead of
1507           // using reinterpret_cast.
1508           UTF16 *ResultWidePtr = reinterpret_cast<UTF16*>(ResultPtr);
1509           *ResultWidePtr = ResultChar & 0xFFFF;
1510           ResultPtr += 2;
1511         } else {
1512           assert(CharByteWidth == 1 && "Unexpected char width");
1513           *ResultPtr++ = ResultChar & 0xFF;
1514         }
1515       }
1516     }
1517   }
1518 
1519   if (Pascal) {
1520     if (CharByteWidth == 4) {
1521       // FIXME: Make the type of the result buffer correct instead of
1522       // using reinterpret_cast.
1523       UTF32 *ResultWidePtr = reinterpret_cast<UTF32*>(ResultBuf.data());
1524       ResultWidePtr[0] = GetNumStringChars() - 1;
1525     } else if (CharByteWidth == 2) {
1526       // FIXME: Make the type of the result buffer correct instead of
1527       // using reinterpret_cast.
1528       UTF16 *ResultWidePtr = reinterpret_cast<UTF16*>(ResultBuf.data());
1529       ResultWidePtr[0] = GetNumStringChars() - 1;
1530     } else {
1531       assert(CharByteWidth == 1 && "Unexpected char width");
1532       ResultBuf[0] = GetNumStringChars() - 1;
1533     }
1534 
1535     // Verify that pascal strings aren't too large.
1536     if (GetStringLength() > 256) {
1537       if (Diags)
1538         Diags->Report(StringToks.front().getLocation(),
1539                       diag::err_pascal_string_too_long)
1540           << SourceRange(StringToks.front().getLocation(),
1541                          StringToks.back().getLocation());
1542       hadError = true;
1543       return;
1544     }
1545   } else if (Diags) {
1546     // Complain if this string literal has too many characters.
1547     unsigned MaxChars = Features.CPlusPlus? 65536 : Features.C99 ? 4095 : 509;
1548 
1549     if (GetNumStringChars() > MaxChars)
1550       Diags->Report(StringToks.front().getLocation(),
1551                     diag::ext_string_too_long)
1552         << GetNumStringChars() << MaxChars
1553         << (Features.CPlusPlus ? 2 : Features.C99 ? 1 : 0)
1554         << SourceRange(StringToks.front().getLocation(),
1555                        StringToks.back().getLocation());
1556   }
1557 }
1558 
resyncUTF8(const char * Err,const char * End)1559 static const char *resyncUTF8(const char *Err, const char *End) {
1560   if (Err == End)
1561     return End;
1562   End = Err + std::min<unsigned>(getNumBytesForUTF8(*Err), End-Err);
1563   while (++Err != End && (*Err & 0xC0) == 0x80)
1564     ;
1565   return Err;
1566 }
1567 
1568 /// \brief This function copies from Fragment, which is a sequence of bytes
1569 /// within Tok's contents (which begin at TokBegin) into ResultPtr.
1570 /// Performs widening for multi-byte characters.
CopyStringFragment(const Token & Tok,const char * TokBegin,StringRef Fragment)1571 bool StringLiteralParser::CopyStringFragment(const Token &Tok,
1572                                              const char *TokBegin,
1573                                              StringRef Fragment) {
1574   const UTF8 *ErrorPtrTmp;
1575   if (ConvertUTF8toWide(CharByteWidth, Fragment, ResultPtr, ErrorPtrTmp))
1576     return false;
1577 
1578   // If we see bad encoding for unprefixed string literals, warn and
1579   // simply copy the byte values, for compatibility with gcc and older
1580   // versions of clang.
1581   bool NoErrorOnBadEncoding = isAscii();
1582   if (NoErrorOnBadEncoding) {
1583     memcpy(ResultPtr, Fragment.data(), Fragment.size());
1584     ResultPtr += Fragment.size();
1585   }
1586 
1587   if (Diags) {
1588     const char *ErrorPtr = reinterpret_cast<const char *>(ErrorPtrTmp);
1589 
1590     FullSourceLoc SourceLoc(Tok.getLocation(), SM);
1591     const DiagnosticBuilder &Builder =
1592       Diag(Diags, Features, SourceLoc, TokBegin,
1593            ErrorPtr, resyncUTF8(ErrorPtr, Fragment.end()),
1594            NoErrorOnBadEncoding ? diag::warn_bad_string_encoding
1595                                 : diag::err_bad_string_encoding);
1596 
1597     const char *NextStart = resyncUTF8(ErrorPtr, Fragment.end());
1598     StringRef NextFragment(NextStart, Fragment.end()-NextStart);
1599 
1600     // Decode into a dummy buffer.
1601     SmallString<512> Dummy;
1602     Dummy.reserve(Fragment.size() * CharByteWidth);
1603     char *Ptr = Dummy.data();
1604 
1605     while (!ConvertUTF8toWide(CharByteWidth, NextFragment, Ptr, ErrorPtrTmp)) {
1606       const char *ErrorPtr = reinterpret_cast<const char *>(ErrorPtrTmp);
1607       NextStart = resyncUTF8(ErrorPtr, Fragment.end());
1608       Builder << MakeCharSourceRange(Features, SourceLoc, TokBegin,
1609                                      ErrorPtr, NextStart);
1610       NextFragment = StringRef(NextStart, Fragment.end()-NextStart);
1611     }
1612   }
1613   return !NoErrorOnBadEncoding;
1614 }
1615 
DiagnoseLexingError(SourceLocation Loc)1616 void StringLiteralParser::DiagnoseLexingError(SourceLocation Loc) {
1617   hadError = true;
1618   if (Diags)
1619     Diags->Report(Loc, diag::err_lexing_string);
1620 }
1621 
1622 /// getOffsetOfStringByte - This function returns the offset of the
1623 /// specified byte of the string data represented by Token.  This handles
1624 /// advancing over escape sequences in the string.
getOffsetOfStringByte(const Token & Tok,unsigned ByteNo) const1625 unsigned StringLiteralParser::getOffsetOfStringByte(const Token &Tok,
1626                                                     unsigned ByteNo) const {
1627   // Get the spelling of the token.
1628   SmallString<32> SpellingBuffer;
1629   SpellingBuffer.resize(Tok.getLength());
1630 
1631   bool StringInvalid = false;
1632   const char *SpellingPtr = &SpellingBuffer[0];
1633   unsigned TokLen = Lexer::getSpelling(Tok, SpellingPtr, SM, Features,
1634                                        &StringInvalid);
1635   if (StringInvalid)
1636     return 0;
1637 
1638   const char *SpellingStart = SpellingPtr;
1639   const char *SpellingEnd = SpellingPtr+TokLen;
1640 
1641   // Handle UTF-8 strings just like narrow strings.
1642   if (SpellingPtr[0] == 'u' && SpellingPtr[1] == '8')
1643     SpellingPtr += 2;
1644 
1645   assert(SpellingPtr[0] != 'L' && SpellingPtr[0] != 'u' &&
1646          SpellingPtr[0] != 'U' && "Doesn't handle wide or utf strings yet");
1647 
1648   // For raw string literals, this is easy.
1649   if (SpellingPtr[0] == 'R') {
1650     assert(SpellingPtr[1] == '"' && "Should be a raw string literal!");
1651     // Skip 'R"'.
1652     SpellingPtr += 2;
1653     while (*SpellingPtr != '(') {
1654       ++SpellingPtr;
1655       assert(SpellingPtr < SpellingEnd && "Missing ( for raw string literal");
1656     }
1657     // Skip '('.
1658     ++SpellingPtr;
1659     return SpellingPtr - SpellingStart + ByteNo;
1660   }
1661 
1662   // Skip over the leading quote
1663   assert(SpellingPtr[0] == '"' && "Should be a string literal!");
1664   ++SpellingPtr;
1665 
1666   // Skip over bytes until we find the offset we're looking for.
1667   while (ByteNo) {
1668     assert(SpellingPtr < SpellingEnd && "Didn't find byte offset!");
1669 
1670     // Step over non-escapes simply.
1671     if (*SpellingPtr != '\\') {
1672       ++SpellingPtr;
1673       --ByteNo;
1674       continue;
1675     }
1676 
1677     // Otherwise, this is an escape character.  Advance over it.
1678     bool HadError = false;
1679     if (SpellingPtr[1] == 'u' || SpellingPtr[1] == 'U') {
1680       const char *EscapePtr = SpellingPtr;
1681       unsigned Len = MeasureUCNEscape(SpellingStart, SpellingPtr, SpellingEnd,
1682                                       1, Features, HadError);
1683       if (Len > ByteNo) {
1684         // ByteNo is somewhere within the escape sequence.
1685         SpellingPtr = EscapePtr;
1686         break;
1687       }
1688       ByteNo -= Len;
1689     } else {
1690       ProcessCharEscape(SpellingStart, SpellingPtr, SpellingEnd, HadError,
1691                         FullSourceLoc(Tok.getLocation(), SM),
1692                         CharByteWidth*8, Diags, Features);
1693       --ByteNo;
1694     }
1695     assert(!HadError && "This method isn't valid on erroneous strings");
1696   }
1697 
1698   return SpellingPtr-SpellingStart;
1699 }
1700