1//===--- MacroArgs.cpp - Formal argument info for Macros ------------------===//
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 MacroArgs interface.
10//
11//===----------------------------------------------------------------------===//
12
13#include "clang/Lex/MacroArgs.h"
14#include "clang/Lex/LexDiagnostic.h"
15#include "clang/Lex/MacroInfo.h"
16#include "clang/Lex/Preprocessor.h"
17#include "llvm/ADT/SmallString.h"
18#include "llvm/Support/SaveAndRestore.h"
19#include <algorithm>
20
21using namespace clang;
22
23/// MacroArgs ctor function - This destroys the vector passed in.
24MacroArgs *MacroArgs::create(const MacroInfo *MI,
25                             ArrayRef<Token> UnexpArgTokens,
26                             bool VarargsElided, Preprocessor &PP) {
27  assert(MI->isFunctionLike() &&
28         "Can't have args for an object-like macro!");
29  MacroArgs **ResultEnt = nullptr;
30  unsigned ClosestMatch = ~0U;
31
32  // See if we have an entry with a big enough argument list to reuse on the
33  // free list.  If so, reuse it.
34  for (MacroArgs **Entry = &PP.MacroArgCache; *Entry;
35       Entry = &(*Entry)->ArgCache) {
36    if ((*Entry)->NumUnexpArgTokens >= UnexpArgTokens.size() &&
37        (*Entry)->NumUnexpArgTokens < ClosestMatch) {
38      ResultEnt = Entry;
39
40      // If we have an exact match, use it.
41      if ((*Entry)->NumUnexpArgTokens == UnexpArgTokens.size())
42        break;
43      // Otherwise, use the best fit.
44      ClosestMatch = (*Entry)->NumUnexpArgTokens;
45    }
46  }
47  MacroArgs *Result;
48  if (!ResultEnt) {
49    // Allocate memory for a MacroArgs object with the lexer tokens at the end,
50    // and construct the MacroArgs object.
51    Result = new (
52        llvm::safe_malloc(totalSizeToAlloc<Token>(UnexpArgTokens.size())))
53        MacroArgs(UnexpArgTokens.size(), VarargsElided, MI->getNumParams());
54  } else {
55    Result = *ResultEnt;
56    // Unlink this node from the preprocessors singly linked list.
57    *ResultEnt = Result->ArgCache;
58    Result->NumUnexpArgTokens = UnexpArgTokens.size();
59    Result->VarargsElided = VarargsElided;
60    Result->NumMacroArgs = MI->getNumParams();
61  }
62
63  // Copy the actual unexpanded tokens to immediately after the result ptr.
64  if (!UnexpArgTokens.empty()) {
65    static_assert(std::is_trivial_v<Token>,
66                  "assume trivial copyability if copying into the "
67                  "uninitialized array (as opposed to reusing a cached "
68                  "MacroArgs)");
69    std::copy(UnexpArgTokens.begin(), UnexpArgTokens.end(),
70              Result->getTrailingObjects<Token>());
71  }
72
73  return Result;
74}
75
76/// destroy - Destroy and deallocate the memory for this object.
77///
78void MacroArgs::destroy(Preprocessor &PP) {
79  // Don't clear PreExpArgTokens, just clear the entries.  Clearing the entries
80  // would deallocate the element vectors.
81  for (unsigned i = 0, e = PreExpArgTokens.size(); i != e; ++i)
82    PreExpArgTokens[i].clear();
83
84  // Add this to the preprocessor's free list.
85  ArgCache = PP.MacroArgCache;
86  PP.MacroArgCache = this;
87}
88
89/// deallocate - This should only be called by the Preprocessor when managing
90/// its freelist.
91MacroArgs *MacroArgs::deallocate() {
92  MacroArgs *Next = ArgCache;
93
94  // Run the dtor to deallocate the vectors.
95  this->~MacroArgs();
96  // Release the memory for the object.
97  static_assert(std::is_trivially_destructible_v<Token>,
98                "assume trivially destructible and forego destructors");
99  free(this);
100
101  return Next;
102}
103
104
105/// getArgLength - Given a pointer to an expanded or unexpanded argument,
106/// return the number of tokens, not counting the EOF, that make up the
107/// argument.
108unsigned MacroArgs::getArgLength(const Token *ArgPtr) {
109  unsigned NumArgTokens = 0;
110  for (; ArgPtr->isNot(tok::eof); ++ArgPtr)
111    ++NumArgTokens;
112  return NumArgTokens;
113}
114
115
116/// getUnexpArgument - Return the unexpanded tokens for the specified formal.
117///
118const Token *MacroArgs::getUnexpArgument(unsigned Arg) const {
119
120  assert(Arg < getNumMacroArguments() && "Invalid arg #");
121  // The unexpanded argument tokens start immediately after the MacroArgs object
122  // in memory.
123  const Token *Start = getTrailingObjects<Token>();
124  const Token *Result = Start;
125
126  // Scan to find Arg.
127  for (; Arg; ++Result) {
128    assert(Result < Start+NumUnexpArgTokens && "Invalid arg #");
129    if (Result->is(tok::eof))
130      --Arg;
131  }
132  assert(Result < Start+NumUnexpArgTokens && "Invalid arg #");
133  return Result;
134}
135
136bool MacroArgs::invokedWithVariadicArgument(const MacroInfo *const MI,
137                                            Preprocessor &PP) {
138  if (!MI->isVariadic())
139    return false;
140  const int VariadicArgIndex = getNumMacroArguments() - 1;
141  return getPreExpArgument(VariadicArgIndex, PP).front().isNot(tok::eof);
142}
143
144/// ArgNeedsPreexpansion - If we can prove that the argument won't be affected
145/// by pre-expansion, return false.  Otherwise, conservatively return true.
146bool MacroArgs::ArgNeedsPreexpansion(const Token *ArgTok,
147                                     Preprocessor &PP) const {
148  // If there are no identifiers in the argument list, or if the identifiers are
149  // known to not be macros, pre-expansion won't modify it.
150  for (; ArgTok->isNot(tok::eof); ++ArgTok)
151    if (IdentifierInfo *II = ArgTok->getIdentifierInfo())
152      if (II->hasMacroDefinition())
153        // Return true even though the macro could be a function-like macro
154        // without a following '(' token, or could be disabled, or not visible.
155        return true;
156  return false;
157}
158
159/// getPreExpArgument - Return the pre-expanded form of the specified
160/// argument.
161const std::vector<Token> &MacroArgs::getPreExpArgument(unsigned Arg,
162                                                       Preprocessor &PP) {
163  assert(Arg < getNumMacroArguments() && "Invalid argument number!");
164
165  // If we have already computed this, return it.
166  if (PreExpArgTokens.size() < getNumMacroArguments())
167    PreExpArgTokens.resize(getNumMacroArguments());
168
169  std::vector<Token> &Result = PreExpArgTokens[Arg];
170  if (!Result.empty()) return Result;
171
172  SaveAndRestore PreExpandingMacroArgs(PP.InMacroArgPreExpansion, true);
173
174  const Token *AT = getUnexpArgument(Arg);
175  unsigned NumToks = getArgLength(AT)+1;  // Include the EOF.
176
177  // Otherwise, we have to pre-expand this argument, populating Result.  To do
178  // this, we set up a fake TokenLexer to lex from the unexpanded argument
179  // list.  With this installed, we lex expanded tokens until we hit the EOF
180  // token at the end of the unexp list.
181  PP.EnterTokenStream(AT, NumToks, false /*disable expand*/,
182                      false /*owns tokens*/, false /*is reinject*/);
183
184  // Lex all of the macro-expanded tokens into Result.
185  do {
186    Result.push_back(Token());
187    Token &Tok = Result.back();
188    PP.Lex(Tok);
189  } while (Result.back().isNot(tok::eof));
190
191  // Pop the token stream off the top of the stack.  We know that the internal
192  // pointer inside of it is to the "end" of the token stream, but the stack
193  // will not otherwise be popped until the next token is lexed.  The problem is
194  // that the token may be lexed sometime after the vector of tokens itself is
195  // destroyed, which would be badness.
196  if (PP.InCachingLexMode())
197    PP.ExitCachingLexMode();
198  PP.RemoveTopOfLexerStack();
199  return Result;
200}
201
202
203/// StringifyArgument - Implement C99 6.10.3.2p2, converting a sequence of
204/// tokens into the literal string token that should be produced by the C #
205/// preprocessor operator.  If Charify is true, then it should be turned into
206/// a character literal for the Microsoft charize (#@) extension.
207///
208Token MacroArgs::StringifyArgument(const Token *ArgToks,
209                                   Preprocessor &PP, bool Charify,
210                                   SourceLocation ExpansionLocStart,
211                                   SourceLocation ExpansionLocEnd) {
212  Token Tok;
213  Tok.startToken();
214  Tok.setKind(Charify ? tok::char_constant : tok::string_literal);
215
216  const Token *ArgTokStart = ArgToks;
217
218  // Stringify all the tokens.
219  SmallString<128> Result;
220  Result += "\"";
221
222  bool isFirst = true;
223  for (; ArgToks->isNot(tok::eof); ++ArgToks) {
224    const Token &Tok = *ArgToks;
225    if (!isFirst && (Tok.hasLeadingSpace() || Tok.isAtStartOfLine()))
226      Result += ' ';
227    isFirst = false;
228
229    // If this is a string or character constant, escape the token as specified
230    // by 6.10.3.2p2.
231    if (tok::isStringLiteral(Tok.getKind()) || // "foo", u8R"x(foo)x"_bar, etc.
232        Tok.is(tok::char_constant) ||          // 'x'
233        Tok.is(tok::wide_char_constant) ||     // L'x'.
234        Tok.is(tok::utf8_char_constant) ||     // u8'x'.
235        Tok.is(tok::utf16_char_constant) ||    // u'x'.
236        Tok.is(tok::utf32_char_constant)) {    // U'x'.
237      bool Invalid = false;
238      std::string TokStr = PP.getSpelling(Tok, &Invalid);
239      if (!Invalid) {
240        std::string Str = Lexer::Stringify(TokStr);
241        Result.append(Str.begin(), Str.end());
242      }
243    } else if (Tok.is(tok::code_completion)) {
244      PP.CodeCompleteNaturalLanguage();
245    } else {
246      // Otherwise, just append the token.  Do some gymnastics to get the token
247      // in place and avoid copies where possible.
248      unsigned CurStrLen = Result.size();
249      Result.resize(CurStrLen+Tok.getLength());
250      const char *BufPtr = Result.data() + CurStrLen;
251      bool Invalid = false;
252      unsigned ActualTokLen = PP.getSpelling(Tok, BufPtr, &Invalid);
253
254      if (!Invalid) {
255        // If getSpelling returned a pointer to an already uniqued version of
256        // the string instead of filling in BufPtr, memcpy it onto our string.
257        if (ActualTokLen && BufPtr != &Result[CurStrLen])
258          memcpy(&Result[CurStrLen], BufPtr, ActualTokLen);
259
260        // If the token was dirty, the spelling may be shorter than the token.
261        if (ActualTokLen != Tok.getLength())
262          Result.resize(CurStrLen+ActualTokLen);
263      }
264    }
265  }
266
267  // If the last character of the string is a \, and if it isn't escaped, this
268  // is an invalid string literal, diagnose it as specified in C99.
269  if (Result.back() == '\\') {
270    // Count the number of consecutive \ characters.  If even, then they are
271    // just escaped backslashes, otherwise it's an error.
272    unsigned FirstNonSlash = Result.size()-2;
273    // Guaranteed to find the starting " if nothing else.
274    while (Result[FirstNonSlash] == '\\')
275      --FirstNonSlash;
276    if ((Result.size()-1-FirstNonSlash) & 1) {
277      // Diagnose errors for things like: #define F(X) #X   /   F(\)
278      PP.Diag(ArgToks[-1], diag::pp_invalid_string_literal);
279      Result.pop_back();  // remove one of the \'s.
280    }
281  }
282  Result += '"';
283
284  // If this is the charify operation and the result is not a legal character
285  // constant, diagnose it.
286  if (Charify) {
287    // First step, turn double quotes into single quotes:
288    Result[0] = '\'';
289    Result[Result.size()-1] = '\'';
290
291    // Check for bogus character.
292    bool isBad = false;
293    if (Result.size() == 3)
294      isBad = Result[1] == '\'';   // ''' is not legal. '\' already fixed above.
295    else
296      isBad = (Result.size() != 4 || Result[1] != '\\');  // Not '\x'
297
298    if (isBad) {
299      PP.Diag(ArgTokStart[0], diag::err_invalid_character_to_charify);
300      Result = "' '";  // Use something arbitrary, but legal.
301    }
302  }
303
304  PP.CreateString(Result, Tok,
305                  ExpansionLocStart, ExpansionLocEnd);
306  return Tok;
307}
308