1 //===--- TokenConcatenation.cpp - Token Concatenation Avoidance -----------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // This file implements the TokenConcatenation class. 10 // 11 //===----------------------------------------------------------------------===// 12 13 #include "clang/Lex/TokenConcatenation.h" 14 #include "clang/Basic/CharInfo.h" 15 #include "clang/Lex/Preprocessor.h" 16 #include "llvm/Support/ErrorHandling.h" 17 using namespace clang; 18 19 20 /// IsStringPrefix - Return true if Str is a string prefix. 21 /// 'L', 'u', 'U', or 'u8'. Including raw versions. IsStringPrefix(StringRef Str,bool CPlusPlus11)22 static bool IsStringPrefix(StringRef Str, bool CPlusPlus11) { 23 24 if (Str[0] == 'L' || 25 (CPlusPlus11 && (Str[0] == 'u' || Str[0] == 'U' || Str[0] == 'R'))) { 26 27 if (Str.size() == 1) 28 return true; // "L", "u", "U", and "R" 29 30 // Check for raw flavors. Need to make sure the first character wasn't 31 // already R. Need CPlusPlus11 check for "LR". 32 if (Str[1] == 'R' && Str[0] != 'R' && Str.size() == 2 && CPlusPlus11) 33 return true; // "LR", "uR", "UR" 34 35 // Check for "u8" and "u8R" 36 if (Str[0] == 'u' && Str[1] == '8') { 37 if (Str.size() == 2) return true; // "u8" 38 if (Str.size() == 3 && Str[2] == 'R') return true; // "u8R" 39 } 40 } 41 42 return false; 43 } 44 45 /// IsIdentifierStringPrefix - Return true if the spelling of the token 46 /// is literally 'L', 'u', 'U', or 'u8'. Including raw versions. IsIdentifierStringPrefix(const Token & Tok) const47 bool TokenConcatenation::IsIdentifierStringPrefix(const Token &Tok) const { 48 const LangOptions &LangOpts = PP.getLangOpts(); 49 50 if (!Tok.needsCleaning()) { 51 if (Tok.getLength() < 1 || Tok.getLength() > 3) 52 return false; 53 SourceManager &SM = PP.getSourceManager(); 54 const char *Ptr = SM.getCharacterData(SM.getSpellingLoc(Tok.getLocation())); 55 return IsStringPrefix(StringRef(Ptr, Tok.getLength()), 56 LangOpts.CPlusPlus11); 57 } 58 59 if (Tok.getLength() < 256) { 60 char Buffer[256]; 61 const char *TokPtr = Buffer; 62 unsigned length = PP.getSpelling(Tok, TokPtr); 63 return IsStringPrefix(StringRef(TokPtr, length), LangOpts.CPlusPlus11); 64 } 65 66 return IsStringPrefix(StringRef(PP.getSpelling(Tok)), LangOpts.CPlusPlus11); 67 } 68 TokenConcatenation(const Preprocessor & pp)69 TokenConcatenation::TokenConcatenation(const Preprocessor &pp) : PP(pp) { 70 memset(TokenInfo, 0, sizeof(TokenInfo)); 71 72 // These tokens have custom code in AvoidConcat. 73 TokenInfo[tok::identifier ] |= aci_custom; 74 TokenInfo[tok::numeric_constant] |= aci_custom_firstchar; 75 TokenInfo[tok::period ] |= aci_custom_firstchar; 76 TokenInfo[tok::amp ] |= aci_custom_firstchar; 77 TokenInfo[tok::plus ] |= aci_custom_firstchar; 78 TokenInfo[tok::minus ] |= aci_custom_firstchar; 79 TokenInfo[tok::slash ] |= aci_custom_firstchar; 80 TokenInfo[tok::less ] |= aci_custom_firstchar; 81 TokenInfo[tok::greater ] |= aci_custom_firstchar; 82 TokenInfo[tok::pipe ] |= aci_custom_firstchar; 83 TokenInfo[tok::percent ] |= aci_custom_firstchar; 84 TokenInfo[tok::colon ] |= aci_custom_firstchar; 85 TokenInfo[tok::hash ] |= aci_custom_firstchar; 86 TokenInfo[tok::arrow ] |= aci_custom_firstchar; 87 88 // These tokens have custom code in C++11 mode. 89 if (PP.getLangOpts().CPlusPlus11) { 90 TokenInfo[tok::string_literal ] |= aci_custom; 91 TokenInfo[tok::wide_string_literal ] |= aci_custom; 92 TokenInfo[tok::utf8_string_literal ] |= aci_custom; 93 TokenInfo[tok::utf16_string_literal] |= aci_custom; 94 TokenInfo[tok::utf32_string_literal] |= aci_custom; 95 TokenInfo[tok::char_constant ] |= aci_custom; 96 TokenInfo[tok::wide_char_constant ] |= aci_custom; 97 TokenInfo[tok::utf16_char_constant ] |= aci_custom; 98 TokenInfo[tok::utf32_char_constant ] |= aci_custom; 99 } 100 101 // These tokens have custom code in C++17 mode. 102 if (PP.getLangOpts().CPlusPlus17) 103 TokenInfo[tok::utf8_char_constant] |= aci_custom; 104 105 // These tokens have custom code in C++2a mode. 106 if (PP.getLangOpts().CPlusPlus20) 107 TokenInfo[tok::lessequal ] |= aci_custom_firstchar; 108 109 // These tokens change behavior if followed by an '='. 110 TokenInfo[tok::amp ] |= aci_avoid_equal; // &= 111 TokenInfo[tok::plus ] |= aci_avoid_equal; // += 112 TokenInfo[tok::minus ] |= aci_avoid_equal; // -= 113 TokenInfo[tok::slash ] |= aci_avoid_equal; // /= 114 TokenInfo[tok::less ] |= aci_avoid_equal; // <= 115 TokenInfo[tok::greater ] |= aci_avoid_equal; // >= 116 TokenInfo[tok::pipe ] |= aci_avoid_equal; // |= 117 TokenInfo[tok::percent ] |= aci_avoid_equal; // %= 118 TokenInfo[tok::star ] |= aci_avoid_equal; // *= 119 TokenInfo[tok::exclaim ] |= aci_avoid_equal; // != 120 TokenInfo[tok::lessless ] |= aci_avoid_equal; // <<= 121 TokenInfo[tok::greatergreater] |= aci_avoid_equal; // >>= 122 TokenInfo[tok::caret ] |= aci_avoid_equal; // ^= 123 TokenInfo[tok::equal ] |= aci_avoid_equal; // == 124 } 125 126 /// GetFirstChar - Get the first character of the token \arg Tok, 127 /// avoiding calls to getSpelling where possible. GetFirstChar(const Preprocessor & PP,const Token & Tok)128 static char GetFirstChar(const Preprocessor &PP, const Token &Tok) { 129 if (IdentifierInfo *II = Tok.getIdentifierInfo()) { 130 // Avoid spelling identifiers, the most common form of token. 131 return II->getNameStart()[0]; 132 } else if (!Tok.needsCleaning()) { 133 if (Tok.isLiteral() && Tok.getLiteralData()) { 134 return *Tok.getLiteralData(); 135 } else { 136 SourceManager &SM = PP.getSourceManager(); 137 return *SM.getCharacterData(SM.getSpellingLoc(Tok.getLocation())); 138 } 139 } else if (Tok.getLength() < 256) { 140 char Buffer[256]; 141 const char *TokPtr = Buffer; 142 PP.getSpelling(Tok, TokPtr); 143 return TokPtr[0]; 144 } else { 145 return PP.getSpelling(Tok)[0]; 146 } 147 } 148 149 /// AvoidConcat - If printing PrevTok immediately followed by Tok would cause 150 /// the two individual tokens to be lexed as a single token, return true 151 /// (which causes a space to be printed between them). This allows the output 152 /// of -E mode to be lexed to the same token stream as lexing the input 153 /// directly would. 154 /// 155 /// This code must conservatively return true if it doesn't want to be 100% 156 /// accurate. This will cause the output to include extra space characters, 157 /// but the resulting output won't have incorrect concatenations going on. 158 /// Examples include "..", which we print with a space between, because we 159 /// don't want to track enough to tell "x.." from "...". AvoidConcat(const Token & PrevPrevTok,const Token & PrevTok,const Token & Tok) const160 bool TokenConcatenation::AvoidConcat(const Token &PrevPrevTok, 161 const Token &PrevTok, 162 const Token &Tok) const { 163 // Conservatively assume that every annotation token that has a printable 164 // form requires whitespace. 165 if (PrevTok.isAnnotation()) 166 return true; 167 168 // First, check to see if the tokens were directly adjacent in the original 169 // source. If they were, it must be okay to stick them together: if there 170 // were an issue, the tokens would have been lexed differently. 171 SourceManager &SM = PP.getSourceManager(); 172 SourceLocation PrevSpellLoc = SM.getSpellingLoc(PrevTok.getLocation()); 173 SourceLocation SpellLoc = SM.getSpellingLoc(Tok.getLocation()); 174 if (PrevSpellLoc.getLocWithOffset(PrevTok.getLength()) == SpellLoc) 175 return false; 176 177 tok::TokenKind PrevKind = PrevTok.getKind(); 178 if (!PrevTok.isAnnotation() && PrevTok.getIdentifierInfo()) 179 PrevKind = tok::identifier; // Language keyword or named operator. 180 181 // Look up information on when we should avoid concatenation with prevtok. 182 unsigned ConcatInfo = TokenInfo[PrevKind]; 183 184 // If prevtok never causes a problem for anything after it, return quickly. 185 if (ConcatInfo == 0) return false; 186 187 if (ConcatInfo & aci_avoid_equal) { 188 // If the next token is '=' or '==', avoid concatenation. 189 if (Tok.isOneOf(tok::equal, tok::equalequal)) 190 return true; 191 ConcatInfo &= ~aci_avoid_equal; 192 } 193 if (Tok.isAnnotation()) { 194 // Modules annotation can show up when generated automatically for includes. 195 assert(Tok.isOneOf(tok::annot_module_include, tok::annot_module_begin, 196 tok::annot_module_end, tok::annot_embed) && 197 "unexpected annotation in AvoidConcat"); 198 199 ConcatInfo = 0; 200 if (Tok.is(tok::annot_embed)) 201 return true; 202 } 203 204 if (ConcatInfo == 0) 205 return false; 206 207 // Basic algorithm: we look at the first character of the second token, and 208 // determine whether it, if appended to the first token, would form (or 209 // would contribute) to a larger token if concatenated. 210 char FirstChar = 0; 211 if (ConcatInfo & aci_custom) { 212 // If the token does not need to know the first character, don't get it. 213 } else { 214 FirstChar = GetFirstChar(PP, Tok); 215 } 216 217 switch (PrevKind) { 218 default: 219 llvm_unreachable("InitAvoidConcatTokenInfo built wrong"); 220 221 case tok::raw_identifier: 222 llvm_unreachable("tok::raw_identifier in non-raw lexing mode!"); 223 224 case tok::string_literal: 225 case tok::wide_string_literal: 226 case tok::utf8_string_literal: 227 case tok::utf16_string_literal: 228 case tok::utf32_string_literal: 229 case tok::char_constant: 230 case tok::wide_char_constant: 231 case tok::utf8_char_constant: 232 case tok::utf16_char_constant: 233 case tok::utf32_char_constant: 234 if (!PP.getLangOpts().CPlusPlus11) 235 return false; 236 237 // In C++11, a string or character literal followed by an identifier is a 238 // single token. 239 if (Tok.getIdentifierInfo()) 240 return true; 241 242 // A ud-suffix is an identifier. If the previous token ends with one, treat 243 // it as an identifier. 244 if (!PrevTok.hasUDSuffix()) 245 return false; 246 [[fallthrough]]; 247 case tok::identifier: // id+id or id+number or id+L"foo". 248 // id+'.'... will not append. 249 if (Tok.is(tok::numeric_constant)) 250 return GetFirstChar(PP, Tok) != '.'; 251 252 if (Tok.getIdentifierInfo() || 253 Tok.isOneOf(tok::wide_string_literal, tok::utf8_string_literal, 254 tok::utf16_string_literal, tok::utf32_string_literal, 255 tok::wide_char_constant, tok::utf8_char_constant, 256 tok::utf16_char_constant, tok::utf32_char_constant)) 257 return true; 258 259 // If this isn't identifier + string, we're done. 260 if (Tok.isNot(tok::char_constant) && Tok.isNot(tok::string_literal)) 261 return false; 262 263 // Otherwise, this is a narrow character or string. If the *identifier* 264 // is a literal 'L', 'u8', 'u' or 'U', avoid pasting L "foo" -> L"foo". 265 return IsIdentifierStringPrefix(PrevTok); 266 267 case tok::numeric_constant: 268 return isPreprocessingNumberBody(FirstChar) || 269 FirstChar == '+' || FirstChar == '-'; 270 case tok::period: // ..., .*, .1234 271 return (FirstChar == '.' && PrevPrevTok.is(tok::period)) || 272 isDigit(FirstChar) || 273 (PP.getLangOpts().CPlusPlus && FirstChar == '*'); 274 case tok::amp: // && 275 return FirstChar == '&'; 276 case tok::plus: // ++ 277 return FirstChar == '+'; 278 case tok::minus: // --, ->, ->* 279 return FirstChar == '-' || FirstChar == '>'; 280 case tok::slash: //, /*, // 281 return FirstChar == '*' || FirstChar == '/'; 282 case tok::less: // <<, <<=, <:, <% 283 return FirstChar == '<' || FirstChar == ':' || FirstChar == '%'; 284 case tok::greater: // >>, >>= 285 return FirstChar == '>'; 286 case tok::pipe: // || 287 return FirstChar == '|'; 288 case tok::percent: // %>, %: 289 return FirstChar == '>' || FirstChar == ':'; 290 case tok::colon: // ::, :> 291 return FirstChar == '>' || 292 (PP.getLangOpts().CPlusPlus && FirstChar == ':'); 293 case tok::hash: // ##, #@, %:%: 294 return FirstChar == '#' || FirstChar == '@' || FirstChar == '%'; 295 case tok::arrow: // ->* 296 return PP.getLangOpts().CPlusPlus && FirstChar == '*'; 297 case tok::lessequal: // <=> (C++2a) 298 return PP.getLangOpts().CPlusPlus20 && FirstChar == '>'; 299 } 300 } 301