Pragma.cpp revision 0b9e736308af5397f558ffc8e780c438c2fdb563 
1//===--- Pragma.cpp - Pragma registration and handling --------------------===//
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 PragmaHandler/PragmaTable interfaces and implements
11// pragma related methods of the Preprocessor class.
12//
13//===----------------------------------------------------------------------===//
14
15#include "clang/Lex/Pragma.h"
16#include "clang/Lex/HeaderSearch.h"
17#include "clang/Lex/Preprocessor.h"
18#include "clang/Basic/Diagnostic.h"
19#include "clang/Basic/FileManager.h"
20#include "clang/Basic/SourceManager.h"
21using namespace clang;
22
23// Out-of-line destructor to provide a home for the class.
24PragmaHandler::~PragmaHandler() {
25}
26
27//===----------------------------------------------------------------------===//
28// PragmaNamespace Implementation.
29//===----------------------------------------------------------------------===//
30
31
32PragmaNamespace::~PragmaNamespace() {
33  for (unsigned i = 0, e = Handlers.size(); i != e; ++i)
34    delete Handlers[i];
35}
36
37/// FindHandler - Check to see if there is already a handler for the
38/// specified name.  If not, return the handler for the null identifier if it
39/// exists, otherwise return null.  If IgnoreNull is true (the default) then
40/// the null handler isn't returned on failure to match.
41PragmaHandler *PragmaNamespace::FindHandler(const IdentifierInfo *Name,
42                                            bool IgnoreNull) const {
43  PragmaHandler *NullHandler = 0;
44  for (unsigned i = 0, e = Handlers.size(); i != e; ++i) {
45    if (Handlers[i]->getName() == Name)
46      return Handlers[i];
47
48    if (Handlers[i]->getName() == 0)
49      NullHandler = Handlers[i];
50  }
51  return IgnoreNull ? 0 : NullHandler;
52}
53
54void PragmaNamespace::HandlePragma(Preprocessor &PP, Token &Tok) {
55  // Read the 'namespace' that the directive is in, e.g. STDC.  Do not macro
56  // expand it, the user can have a STDC #define, that should not affect this.
57  PP.LexUnexpandedToken(Tok);
58
59  // Get the handler for this token.  If there is no handler, ignore the pragma.
60  PragmaHandler *Handler = FindHandler(Tok.getIdentifierInfo(), false);
61  if (Handler == 0) return;
62
63  // Otherwise, pass it down.
64  Handler->HandlePragma(PP, Tok);
65}
66
67//===----------------------------------------------------------------------===//
68// Preprocessor Pragma Directive Handling.
69//===----------------------------------------------------------------------===//
70
71/// HandlePragmaDirective - The "#pragma" directive has been parsed.  Lex the
72/// rest of the pragma, passing it to the registered pragma handlers.
73void Preprocessor::HandlePragmaDirective() {
74  ++NumPragma;
75
76  // Invoke the first level of pragma handlers which reads the namespace id.
77  Token Tok;
78  PragmaHandlers->HandlePragma(*this, Tok);
79
80  // If the pragma handler didn't read the rest of the line, consume it now.
81  if (CurLexer->ParsingPreprocessorDirective)
82    DiscardUntilEndOfDirective();
83}
84
85/// Handle_Pragma - Read a _Pragma directive, slice it up, process it, then
86/// return the first token after the directive.  The _Pragma token has just
87/// been read into 'Tok'.
88void Preprocessor::Handle_Pragma(Token &Tok) {
89  // Remember the pragma token location.
90  SourceLocation PragmaLoc = Tok.getLocation();
91
92  // Read the '('.
93  Lex(Tok);
94  if (Tok.isNot(tok::l_paren))
95    return Diag(PragmaLoc, diag::err__Pragma_malformed);
96
97  // Read the '"..."'.
98  Lex(Tok);
99  if (Tok.isNot(tok::string_literal) && Tok.isNot(tok::wide_string_literal))
100    return Diag(PragmaLoc, diag::err__Pragma_malformed);
101
102  // Remember the string.
103  std::string StrVal = getSpelling(Tok);
104  SourceLocation StrLoc = Tok.getLocation();
105
106  // Read the ')'.
107  Lex(Tok);
108  if (Tok.isNot(tok::r_paren))
109    return Diag(PragmaLoc, diag::err__Pragma_malformed);
110
111  // The _Pragma is lexically sound.  Destringize according to C99 6.10.9.1.
112  if (StrVal[0] == 'L')  // Remove L prefix.
113    StrVal.erase(StrVal.begin());
114  assert(StrVal[0] == '"' && StrVal[StrVal.size()-1] == '"' &&
115         "Invalid string token!");
116
117  // Remove the front quote, replacing it with a space, so that the pragma
118  // contents appear to have a space before them.
119  StrVal[0] = ' ';
120
121  // Replace the terminating quote with a \n\0.
122  StrVal[StrVal.size()-1] = '\n';
123  StrVal += '\0';
124
125  // Remove escaped quotes and escapes.
126  for (unsigned i = 0, e = StrVal.size(); i != e-1; ++i) {
127    if (StrVal[i] == '\\' &&
128        (StrVal[i+1] == '\\' || StrVal[i+1] == '"')) {
129      // \\ -> '\' and \" -> '"'.
130      StrVal.erase(StrVal.begin()+i);
131      --e;
132    }
133  }
134
135  // Plop the string (including the newline and trailing null) into a buffer
136  // where we can lex it.
137  SourceLocation TokLoc = CreateString(&StrVal[0], StrVal.size(), StrLoc);
138  const char *StrData = SourceMgr.getCharacterData(TokLoc);
139
140  // Make and enter a lexer object so that we lex and expand the tokens just
141  // like any others.
142  Lexer *TL = new Lexer(TokLoc, *this,
143                        StrData, StrData+StrVal.size()-1 /* no null */);
144
145  // Ensure that the lexer thinks it is inside a directive, so that end \n will
146  // return an EOM token.
147  TL->ParsingPreprocessorDirective = true;
148
149  // This lexer really is for _Pragma.
150  TL->Is_PragmaLexer = true;
151
152  EnterSourceFileWithLexer(TL, 0);
153
154  // With everything set up, lex this as a #pragma directive.
155  HandlePragmaDirective();
156
157  // Finally, return whatever came after the pragma directive.
158  return Lex(Tok);
159}
160
161
162
163/// HandlePragmaOnce - Handle #pragma once.  OnceTok is the 'once'.
164///
165void Preprocessor::HandlePragmaOnce(Token &OnceTok) {
166  if (isInPrimaryFile()) {
167    Diag(OnceTok, diag::pp_pragma_once_in_main_file);
168    return;
169  }
170
171  // Get the current file lexer we're looking at.  Ignore _Pragma 'files' etc.
172  SourceLocation FileLoc = getCurrentFileLexer()->getFileLoc();
173
174  // Mark the file as a once-only file now.
175  HeaderInfo.MarkFileIncludeOnce(SourceMgr.getFileEntryForLoc(FileLoc));
176}
177
178void Preprocessor::HandlePragmaMark() {
179  assert(CurLexer && "No current lexer?");
180  CurLexer->ReadToEndOfLine();
181}
182
183
184/// HandlePragmaPoison - Handle #pragma GCC poison.  PoisonTok is the 'poison'.
185///
186void Preprocessor::HandlePragmaPoison(Token &PoisonTok) {
187  Token Tok;
188
189  while (1) {
190    // Read the next token to poison.  While doing this, pretend that we are
191    // skipping while reading the identifier to poison.
192    // This avoids errors on code like:
193    //   #pragma GCC poison X
194    //   #pragma GCC poison X
195    if (CurLexer) CurLexer->LexingRawMode = true;
196    LexUnexpandedToken(Tok);
197    if (CurLexer) CurLexer->LexingRawMode = false;
198
199    // If we reached the end of line, we're done.
200    if (Tok.is(tok::eom)) return;
201
202    // Can only poison identifiers.
203    if (Tok.isNot(tok::identifier)) {
204      Diag(Tok, diag::err_pp_invalid_poison);
205      return;
206    }
207
208    // Look up the identifier info for the token.  We disabled identifier lookup
209    // by saying we're skipping contents, so we need to do this manually.
210    IdentifierInfo *II = LookUpIdentifierInfo(Tok);
211
212    // Already poisoned.
213    if (II->isPoisoned()) continue;
214
215    // If this is a macro identifier, emit a warning.
216    if (II->hasMacroDefinition())
217      Diag(Tok, diag::pp_poisoning_existing_macro);
218
219    // Finally, poison it!
220    II->setIsPoisoned();
221  }
222}
223
224/// HandlePragmaSystemHeader - Implement #pragma GCC system_header.  We know
225/// that the whole directive has been parsed.
226void Preprocessor::HandlePragmaSystemHeader(Token &SysHeaderTok) {
227  if (isInPrimaryFile()) {
228    Diag(SysHeaderTok, diag::pp_pragma_sysheader_in_main_file);
229    return;
230  }
231
232  // Get the current file lexer we're looking at.  Ignore _Pragma 'files' etc.
233  Lexer *TheLexer = getCurrentFileLexer();
234
235  // Mark the file as a system header.
236  const FileEntry *File = SourceMgr.getFileEntryForLoc(TheLexer->getFileLoc());
237  HeaderInfo.MarkFileSystemHeader(File);
238
239  // Notify the client, if desired, that we are in a new source file.
240  if (Callbacks)
241    Callbacks->FileChanged(TheLexer->getSourceLocation(TheLexer->BufferPtr),
242                           PPCallbacks::SystemHeaderPragma, SrcMgr::C_System);
243}
244
245/// HandlePragmaDependency - Handle #pragma GCC dependency "foo" blah.
246///
247void Preprocessor::HandlePragmaDependency(Token &DependencyTok) {
248  Token FilenameTok;
249  CurLexer->LexIncludeFilename(FilenameTok);
250
251  // If the token kind is EOM, the error has already been diagnosed.
252  if (FilenameTok.is(tok::eom))
253    return;
254
255  // Reserve a buffer to get the spelling.
256  llvm::SmallVector<char, 128> FilenameBuffer;
257  FilenameBuffer.resize(FilenameTok.getLength());
258
259  const char *FilenameStart = &FilenameBuffer[0];
260  unsigned Len = getSpelling(FilenameTok, FilenameStart);
261  const char *FilenameEnd = FilenameStart+Len;
262  bool isAngled = GetIncludeFilenameSpelling(FilenameTok.getLocation(),
263                                             FilenameStart, FilenameEnd);
264  // If GetIncludeFilenameSpelling set the start ptr to null, there was an
265  // error.
266  if (FilenameStart == 0)
267    return;
268
269  // Search include directories for this file.
270  const DirectoryLookup *CurDir;
271  const FileEntry *File = LookupFile(FilenameStart, FilenameEnd,
272                                     isAngled, 0, CurDir);
273  if (File == 0)
274    return Diag(FilenameTok, diag::err_pp_file_not_found,
275                std::string(FilenameStart, FilenameEnd));
276
277  SourceLocation FileLoc = getCurrentFileLexer()->getFileLoc();
278  const FileEntry *CurFile = SourceMgr.getFileEntryForLoc(FileLoc);
279
280  // If this file is older than the file it depends on, emit a diagnostic.
281  if (CurFile && CurFile->getModificationTime() < File->getModificationTime()) {
282    // Lex tokens at the end of the message and include them in the message.
283    std::string Message;
284    Lex(DependencyTok);
285    while (DependencyTok.isNot(tok::eom)) {
286      Message += getSpelling(DependencyTok) + " ";
287      Lex(DependencyTok);
288    }
289
290    Message.erase(Message.end()-1);
291    Diag(FilenameTok, diag::pp_out_of_date_dependency, Message);
292  }
293}
294
295
296/// AddPragmaHandler - Add the specified pragma handler to the preprocessor.
297/// If 'Namespace' is non-null, then it is a token required to exist on the
298/// pragma line before the pragma string starts, e.g. "STDC" or "GCC".
299void Preprocessor::AddPragmaHandler(const char *Namespace,
300                                    PragmaHandler *Handler) {
301  PragmaNamespace *InsertNS = PragmaHandlers;
302
303  // If this is specified to be in a namespace, step down into it.
304  if (Namespace) {
305    IdentifierInfo *NSID = getIdentifierInfo(Namespace);
306
307    // If there is already a pragma handler with the name of this namespace,
308    // we either have an error (directive with the same name as a namespace) or
309    // we already have the namespace to insert into.
310    if (PragmaHandler *Existing = PragmaHandlers->FindHandler(NSID)) {
311      InsertNS = Existing->getIfNamespace();
312      assert(InsertNS != 0 && "Cannot have a pragma namespace and pragma"
313             " handler with the same name!");
314    } else {
315      // Otherwise, this namespace doesn't exist yet, create and insert the
316      // handler for it.
317      InsertNS = new PragmaNamespace(NSID);
318      PragmaHandlers->AddPragma(InsertNS);
319    }
320  }
321
322  // Check to make sure we don't already have a pragma for this identifier.
323  assert(!InsertNS->FindHandler(Handler->getName()) &&
324         "Pragma handler already exists for this identifier!");
325  InsertNS->AddPragma(Handler);
326}
327
328namespace {
329/// PragmaOnceHandler - "#pragma once" marks the file as atomically included.
330struct PragmaOnceHandler : public PragmaHandler {
331  PragmaOnceHandler(const IdentifierInfo *OnceID) : PragmaHandler(OnceID) {}
332  virtual void HandlePragma(Preprocessor &PP, Token &OnceTok) {
333    PP.CheckEndOfDirective("#pragma once");
334    PP.HandlePragmaOnce(OnceTok);
335  }
336};
337
338/// PragmaMarkHandler - "#pragma mark ..." is ignored by the compiler, and the
339/// rest of the line is not lexed.
340struct PragmaMarkHandler : public PragmaHandler {
341  PragmaMarkHandler(const IdentifierInfo *MarkID) : PragmaHandler(MarkID) {}
342  virtual void HandlePragma(Preprocessor &PP, Token &MarkTok) {
343    PP.HandlePragmaMark();
344  }
345};
346
347/// PragmaPoisonHandler - "#pragma poison x" marks x as not usable.
348struct PragmaPoisonHandler : public PragmaHandler {
349  PragmaPoisonHandler(const IdentifierInfo *ID) : PragmaHandler(ID) {}
350  virtual void HandlePragma(Preprocessor &PP, Token &PoisonTok) {
351    PP.HandlePragmaPoison(PoisonTok);
352  }
353};
354
355/// PragmaSystemHeaderHandler - "#pragma system_header" marks the current file
356/// as a system header, which silences warnings in it.
357struct PragmaSystemHeaderHandler : public PragmaHandler {
358  PragmaSystemHeaderHandler(const IdentifierInfo *ID) : PragmaHandler(ID) {}
359  virtual void HandlePragma(Preprocessor &PP, Token &SHToken) {
360    PP.HandlePragmaSystemHeader(SHToken);
361    PP.CheckEndOfDirective("#pragma");
362  }
363};
364struct PragmaDependencyHandler : public PragmaHandler {
365  PragmaDependencyHandler(const IdentifierInfo *ID) : PragmaHandler(ID) {}
366  virtual void HandlePragma(Preprocessor &PP, Token &DepToken) {
367    PP.HandlePragmaDependency(DepToken);
368  }
369};
370}  // end anonymous namespace
371
372
373/// RegisterBuiltinPragmas - Install the standard preprocessor pragmas:
374/// #pragma GCC poison/system_header/dependency and #pragma once.
375void Preprocessor::RegisterBuiltinPragmas() {
376  AddPragmaHandler(0, new PragmaOnceHandler(getIdentifierInfo("once")));
377  AddPragmaHandler(0, new PragmaMarkHandler(getIdentifierInfo("mark")));
378  AddPragmaHandler("GCC", new PragmaPoisonHandler(getIdentifierInfo("poison")));
379  AddPragmaHandler("GCC", new PragmaSystemHeaderHandler(
380                                          getIdentifierInfo("system_header")));
381  AddPragmaHandler("GCC", new PragmaDependencyHandler(
382                                          getIdentifierInfo("dependency")));
383}
384