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comparison tools/clang/lib/Parse/ParseInit.cpp @ 0:95c75e76d11b LLVM3.4

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LLVM 3.4
author Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
date Thu, 12 Dec 2013 13:56:28 +0900
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children e4204d083e25
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-1:000000000000 0:95c75e76d11b
1 //===--- ParseInit.cpp - Initializer Parsing ------------------------------===//
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 initializer parsing as specified by C99 6.7.8.
11 //
12 //===----------------------------------------------------------------------===//
13
14 #include "clang/Parse/Parser.h"
15 #include "RAIIObjectsForParser.h"
16 #include "clang/Parse/ParseDiagnostic.h"
17 #include "clang/Sema/Designator.h"
18 #include "clang/Sema/Scope.h"
19 #include "llvm/ADT/SmallString.h"
20 #include "llvm/Support/raw_ostream.h"
21 using namespace clang;
22
23
24 /// MayBeDesignationStart - Return true if the current token might be the start
25 /// of a designator. If we can tell it is impossible that it is a designator,
26 /// return false.
27 bool Parser::MayBeDesignationStart() {
28 switch (Tok.getKind()) {
29 default:
30 return false;
31
32 case tok::period: // designator: '.' identifier
33 return true;
34
35 case tok::l_square: { // designator: array-designator
36 if (!PP.getLangOpts().CPlusPlus11)
37 return true;
38
39 // C++11 lambda expressions and C99 designators can be ambiguous all the
40 // way through the closing ']' and to the next character. Handle the easy
41 // cases here, and fall back to tentative parsing if those fail.
42 switch (PP.LookAhead(0).getKind()) {
43 case tok::equal:
44 case tok::r_square:
45 // Definitely starts a lambda expression.
46 return false;
47
48 case tok::amp:
49 case tok::kw_this:
50 case tok::identifier:
51 // We have to do additional analysis, because these could be the
52 // start of a constant expression or a lambda capture list.
53 break;
54
55 default:
56 // Anything not mentioned above cannot occur following a '[' in a
57 // lambda expression.
58 return true;
59 }
60
61 // Handle the complicated case below.
62 break;
63 }
64 case tok::identifier: // designation: identifier ':'
65 return PP.LookAhead(0).is(tok::colon);
66 }
67
68 // Parse up to (at most) the token after the closing ']' to determine
69 // whether this is a C99 designator or a lambda.
70 TentativeParsingAction Tentative(*this);
71 ConsumeBracket();
72 while (true) {
73 switch (Tok.getKind()) {
74 case tok::equal:
75 case tok::amp:
76 case tok::identifier:
77 case tok::kw_this:
78 // These tokens can occur in a capture list or a constant-expression.
79 // Keep looking.
80 ConsumeToken();
81 continue;
82
83 case tok::comma:
84 // Since a comma cannot occur in a constant-expression, this must
85 // be a lambda.
86 Tentative.Revert();
87 return false;
88
89 case tok::r_square: {
90 // Once we hit the closing square bracket, we look at the next
91 // token. If it's an '=', this is a designator. Otherwise, it's a
92 // lambda expression. This decision favors lambdas over the older
93 // GNU designator syntax, which allows one to omit the '=', but is
94 // consistent with GCC.
95 ConsumeBracket();
96 tok::TokenKind Kind = Tok.getKind();
97 Tentative.Revert();
98 return Kind == tok::equal;
99 }
100
101 default:
102 // Anything else cannot occur in a lambda capture list, so it
103 // must be a designator.
104 Tentative.Revert();
105 return true;
106 }
107 }
108
109 return true;
110 }
111
112 static void CheckArrayDesignatorSyntax(Parser &P, SourceLocation Loc,
113 Designation &Desig) {
114 // If we have exactly one array designator, this used the GNU
115 // 'designation: array-designator' extension, otherwise there should be no
116 // designators at all!
117 if (Desig.getNumDesignators() == 1 &&
118 (Desig.getDesignator(0).isArrayDesignator() ||
119 Desig.getDesignator(0).isArrayRangeDesignator()))
120 P.Diag(Loc, diag::ext_gnu_missing_equal_designator);
121 else if (Desig.getNumDesignators() > 0)
122 P.Diag(Loc, diag::err_expected_equal_designator);
123 }
124
125 /// ParseInitializerWithPotentialDesignator - Parse the 'initializer' production
126 /// checking to see if the token stream starts with a designator.
127 ///
128 /// designation:
129 /// designator-list '='
130 /// [GNU] array-designator
131 /// [GNU] identifier ':'
132 ///
133 /// designator-list:
134 /// designator
135 /// designator-list designator
136 ///
137 /// designator:
138 /// array-designator
139 /// '.' identifier
140 ///
141 /// array-designator:
142 /// '[' constant-expression ']'
143 /// [GNU] '[' constant-expression '...' constant-expression ']'
144 ///
145 /// NOTE: [OBC] allows '[ objc-receiver objc-message-args ]' as an
146 /// initializer (because it is an expression). We need to consider this case
147 /// when parsing array designators.
148 ///
149 ExprResult Parser::ParseInitializerWithPotentialDesignator() {
150
151 // If this is the old-style GNU extension:
152 // designation ::= identifier ':'
153 // Handle it as a field designator. Otherwise, this must be the start of a
154 // normal expression.
155 if (Tok.is(tok::identifier)) {
156 const IdentifierInfo *FieldName = Tok.getIdentifierInfo();
157
158 SmallString<256> NewSyntax;
159 llvm::raw_svector_ostream(NewSyntax) << '.' << FieldName->getName()
160 << " = ";
161
162 SourceLocation NameLoc = ConsumeToken(); // Eat the identifier.
163
164 assert(Tok.is(tok::colon) && "MayBeDesignationStart not working properly!");
165 SourceLocation ColonLoc = ConsumeToken();
166
167 Diag(NameLoc, diag::ext_gnu_old_style_field_designator)
168 << FixItHint::CreateReplacement(SourceRange(NameLoc, ColonLoc),
169 NewSyntax.str());
170
171 Designation D;
172 D.AddDesignator(Designator::getField(FieldName, SourceLocation(), NameLoc));
173 return Actions.ActOnDesignatedInitializer(D, ColonLoc, true,
174 ParseInitializer());
175 }
176
177 // Desig - This is initialized when we see our first designator. We may have
178 // an objc message send with no designator, so we don't want to create this
179 // eagerly.
180 Designation Desig;
181
182 // Parse each designator in the designator list until we find an initializer.
183 while (Tok.is(tok::period) || Tok.is(tok::l_square)) {
184 if (Tok.is(tok::period)) {
185 // designator: '.' identifier
186 SourceLocation DotLoc = ConsumeToken();
187
188 if (Tok.isNot(tok::identifier)) {
189 Diag(Tok.getLocation(), diag::err_expected_field_designator);
190 return ExprError();
191 }
192
193 Desig.AddDesignator(Designator::getField(Tok.getIdentifierInfo(), DotLoc,
194 Tok.getLocation()));
195 ConsumeToken(); // Eat the identifier.
196 continue;
197 }
198
199 // We must have either an array designator now or an objc message send.
200 assert(Tok.is(tok::l_square) && "Unexpected token!");
201
202 // Handle the two forms of array designator:
203 // array-designator: '[' constant-expression ']'
204 // array-designator: '[' constant-expression '...' constant-expression ']'
205 //
206 // Also, we have to handle the case where the expression after the
207 // designator an an objc message send: '[' objc-message-expr ']'.
208 // Interesting cases are:
209 // [foo bar] -> objc message send
210 // [foo] -> array designator
211 // [foo ... bar] -> array designator
212 // [4][foo bar] -> obsolete GNU designation with objc message send.
213 //
214 // We do not need to check for an expression starting with [[ here. If it
215 // contains an Objective-C message send, then it is not an ill-formed
216 // attribute. If it is a lambda-expression within an array-designator, then
217 // it will be rejected because a constant-expression cannot begin with a
218 // lambda-expression.
219 InMessageExpressionRAIIObject InMessage(*this, true);
220
221 BalancedDelimiterTracker T(*this, tok::l_square);
222 T.consumeOpen();
223 SourceLocation StartLoc = T.getOpenLocation();
224
225 ExprResult Idx;
226
227 // If Objective-C is enabled and this is a typename (class message
228 // send) or send to 'super', parse this as a message send
229 // expression. We handle C++ and C separately, since C++ requires
230 // much more complicated parsing.
231 if (getLangOpts().ObjC1 && getLangOpts().CPlusPlus) {
232 // Send to 'super'.
233 if (Tok.is(tok::identifier) && Tok.getIdentifierInfo() == Ident_super &&
234 NextToken().isNot(tok::period) &&
235 getCurScope()->isInObjcMethodScope()) {
236 CheckArrayDesignatorSyntax(*this, StartLoc, Desig);
237 return ParseAssignmentExprWithObjCMessageExprStart(StartLoc,
238 ConsumeToken(),
239 ParsedType(),
240 0);
241 }
242
243 // Parse the receiver, which is either a type or an expression.
244 bool IsExpr;
245 void *TypeOrExpr;
246 if (ParseObjCXXMessageReceiver(IsExpr, TypeOrExpr)) {
247 SkipUntil(tok::r_square, StopAtSemi);
248 return ExprError();
249 }
250
251 // If the receiver was a type, we have a class message; parse
252 // the rest of it.
253 if (!IsExpr) {
254 CheckArrayDesignatorSyntax(*this, StartLoc, Desig);
255 return ParseAssignmentExprWithObjCMessageExprStart(StartLoc,
256 SourceLocation(),
257 ParsedType::getFromOpaquePtr(TypeOrExpr),
258 0);
259 }
260
261 // If the receiver was an expression, we still don't know
262 // whether we have a message send or an array designator; just
263 // adopt the expression for further analysis below.
264 // FIXME: potentially-potentially evaluated expression above?
265 Idx = ExprResult(static_cast<Expr*>(TypeOrExpr));
266 } else if (getLangOpts().ObjC1 && Tok.is(tok::identifier)) {
267 IdentifierInfo *II = Tok.getIdentifierInfo();
268 SourceLocation IILoc = Tok.getLocation();
269 ParsedType ReceiverType;
270 // Three cases. This is a message send to a type: [type foo]
271 // This is a message send to super: [super foo]
272 // This is a message sent to an expr: [super.bar foo]
273 switch (Sema::ObjCMessageKind Kind
274 = Actions.getObjCMessageKind(getCurScope(), II, IILoc,
275 II == Ident_super,
276 NextToken().is(tok::period),
277 ReceiverType)) {
278 case Sema::ObjCSuperMessage:
279 case Sema::ObjCClassMessage:
280 CheckArrayDesignatorSyntax(*this, StartLoc, Desig);
281 if (Kind == Sema::ObjCSuperMessage)
282 return ParseAssignmentExprWithObjCMessageExprStart(StartLoc,
283 ConsumeToken(),
284 ParsedType(),
285 0);
286 ConsumeToken(); // the identifier
287 if (!ReceiverType) {
288 SkipUntil(tok::r_square, StopAtSemi);
289 return ExprError();
290 }
291
292 return ParseAssignmentExprWithObjCMessageExprStart(StartLoc,
293 SourceLocation(),
294 ReceiverType,
295 0);
296
297 case Sema::ObjCInstanceMessage:
298 // Fall through; we'll just parse the expression and
299 // (possibly) treat this like an Objective-C message send
300 // later.
301 break;
302 }
303 }
304
305 // Parse the index expression, if we haven't already gotten one
306 // above (which can only happen in Objective-C++).
307 // Note that we parse this as an assignment expression, not a constant
308 // expression (allowing *=, =, etc) to handle the objc case. Sema needs
309 // to validate that the expression is a constant.
310 // FIXME: We also need to tell Sema that we're in a
311 // potentially-potentially evaluated context.
312 if (!Idx.get()) {
313 Idx = ParseAssignmentExpression();
314 if (Idx.isInvalid()) {
315 SkipUntil(tok::r_square, StopAtSemi);
316 return Idx;
317 }
318 }
319
320 // Given an expression, we could either have a designator (if the next
321 // tokens are '...' or ']' or an objc message send. If this is an objc
322 // message send, handle it now. An objc-message send is the start of
323 // an assignment-expression production.
324 if (getLangOpts().ObjC1 && Tok.isNot(tok::ellipsis) &&
325 Tok.isNot(tok::r_square)) {
326 CheckArrayDesignatorSyntax(*this, Tok.getLocation(), Desig);
327 return ParseAssignmentExprWithObjCMessageExprStart(StartLoc,
328 SourceLocation(),
329 ParsedType(),
330 Idx.take());
331 }
332
333 // If this is a normal array designator, remember it.
334 if (Tok.isNot(tok::ellipsis)) {
335 Desig.AddDesignator(Designator::getArray(Idx.release(), StartLoc));
336 } else {
337 // Handle the gnu array range extension.
338 Diag(Tok, diag::ext_gnu_array_range);
339 SourceLocation EllipsisLoc = ConsumeToken();
340
341 ExprResult RHS(ParseConstantExpression());
342 if (RHS.isInvalid()) {
343 SkipUntil(tok::r_square, StopAtSemi);
344 return RHS;
345 }
346 Desig.AddDesignator(Designator::getArrayRange(Idx.release(),
347 RHS.release(),
348 StartLoc, EllipsisLoc));
349 }
350
351 T.consumeClose();
352 Desig.getDesignator(Desig.getNumDesignators() - 1).setRBracketLoc(
353 T.getCloseLocation());
354 }
355
356 // Okay, we're done with the designator sequence. We know that there must be
357 // at least one designator, because the only case we can get into this method
358 // without a designator is when we have an objc message send. That case is
359 // handled and returned from above.
360 assert(!Desig.empty() && "Designator is empty?");
361
362 // Handle a normal designator sequence end, which is an equal.
363 if (Tok.is(tok::equal)) {
364 SourceLocation EqualLoc = ConsumeToken();
365 return Actions.ActOnDesignatedInitializer(Desig, EqualLoc, false,
366 ParseInitializer());
367 }
368
369 // We read some number of designators and found something that isn't an = or
370 // an initializer. If we have exactly one array designator, this
371 // is the GNU 'designation: array-designator' extension. Otherwise, it is a
372 // parse error.
373 if (Desig.getNumDesignators() == 1 &&
374 (Desig.getDesignator(0).isArrayDesignator() ||
375 Desig.getDesignator(0).isArrayRangeDesignator())) {
376 Diag(Tok, diag::ext_gnu_missing_equal_designator)
377 << FixItHint::CreateInsertion(Tok.getLocation(), "= ");
378 return Actions.ActOnDesignatedInitializer(Desig, Tok.getLocation(),
379 true, ParseInitializer());
380 }
381
382 Diag(Tok, diag::err_expected_equal_designator);
383 return ExprError();
384 }
385
386
387 /// ParseBraceInitializer - Called when parsing an initializer that has a
388 /// leading open brace.
389 ///
390 /// initializer: [C99 6.7.8]
391 /// '{' initializer-list '}'
392 /// '{' initializer-list ',' '}'
393 /// [GNU] '{' '}'
394 ///
395 /// initializer-list:
396 /// designation[opt] initializer ...[opt]
397 /// initializer-list ',' designation[opt] initializer ...[opt]
398 ///
399 ExprResult Parser::ParseBraceInitializer() {
400 InMessageExpressionRAIIObject InMessage(*this, false);
401
402 BalancedDelimiterTracker T(*this, tok::l_brace);
403 T.consumeOpen();
404 SourceLocation LBraceLoc = T.getOpenLocation();
405
406 /// InitExprs - This is the actual list of expressions contained in the
407 /// initializer.
408 ExprVector InitExprs;
409
410 if (Tok.is(tok::r_brace)) {
411 // Empty initializers are a C++ feature and a GNU extension to C.
412 if (!getLangOpts().CPlusPlus)
413 Diag(LBraceLoc, diag::ext_gnu_empty_initializer);
414 // Match the '}'.
415 return Actions.ActOnInitList(LBraceLoc, None, ConsumeBrace());
416 }
417
418 bool InitExprsOk = true;
419
420 while (1) {
421 // Handle Microsoft __if_exists/if_not_exists if necessary.
422 if (getLangOpts().MicrosoftExt && (Tok.is(tok::kw___if_exists) ||
423 Tok.is(tok::kw___if_not_exists))) {
424 if (ParseMicrosoftIfExistsBraceInitializer(InitExprs, InitExprsOk)) {
425 if (Tok.isNot(tok::comma)) break;
426 ConsumeToken();
427 }
428 if (Tok.is(tok::r_brace)) break;
429 continue;
430 }
431
432 // Parse: designation[opt] initializer
433
434 // If we know that this cannot be a designation, just parse the nested
435 // initializer directly.
436 ExprResult SubElt;
437 if (MayBeDesignationStart())
438 SubElt = ParseInitializerWithPotentialDesignator();
439 else
440 SubElt = ParseInitializer();
441
442 if (Tok.is(tok::ellipsis))
443 SubElt = Actions.ActOnPackExpansion(SubElt.get(), ConsumeToken());
444
445 // If we couldn't parse the subelement, bail out.
446 if (!SubElt.isInvalid()) {
447 InitExprs.push_back(SubElt.release());
448 } else {
449 InitExprsOk = false;
450
451 // We have two ways to try to recover from this error: if the code looks
452 // grammatically ok (i.e. we have a comma coming up) try to continue
453 // parsing the rest of the initializer. This allows us to emit
454 // diagnostics for later elements that we find. If we don't see a comma,
455 // assume there is a parse error, and just skip to recover.
456 // FIXME: This comment doesn't sound right. If there is a r_brace
457 // immediately, it can't be an error, since there is no other way of
458 // leaving this loop except through this if.
459 if (Tok.isNot(tok::comma)) {
460 SkipUntil(tok::r_brace, StopBeforeMatch);
461 break;
462 }
463 }
464
465 // If we don't have a comma continued list, we're done.
466 if (Tok.isNot(tok::comma)) break;
467
468 // TODO: save comma locations if some client cares.
469 ConsumeToken();
470
471 // Handle trailing comma.
472 if (Tok.is(tok::r_brace)) break;
473 }
474
475 bool closed = !T.consumeClose();
476
477 if (InitExprsOk && closed)
478 return Actions.ActOnInitList(LBraceLoc, InitExprs,
479 T.getCloseLocation());
480
481 return ExprError(); // an error occurred.
482 }
483
484
485 // Return true if a comma (or closing brace) is necessary after the
486 // __if_exists/if_not_exists statement.
487 bool Parser::ParseMicrosoftIfExistsBraceInitializer(ExprVector &InitExprs,
488 bool &InitExprsOk) {
489 bool trailingComma = false;
490 IfExistsCondition Result;
491 if (ParseMicrosoftIfExistsCondition(Result))
492 return false;
493
494 BalancedDelimiterTracker Braces(*this, tok::l_brace);
495 if (Braces.consumeOpen()) {
496 Diag(Tok, diag::err_expected_lbrace);
497 return false;
498 }
499
500 switch (Result.Behavior) {
501 case IEB_Parse:
502 // Parse the declarations below.
503 break;
504
505 case IEB_Dependent:
506 Diag(Result.KeywordLoc, diag::warn_microsoft_dependent_exists)
507 << Result.IsIfExists;
508 // Fall through to skip.
509
510 case IEB_Skip:
511 Braces.skipToEnd();
512 return false;
513 }
514
515 while (Tok.isNot(tok::eof)) {
516 trailingComma = false;
517 // If we know that this cannot be a designation, just parse the nested
518 // initializer directly.
519 ExprResult SubElt;
520 if (MayBeDesignationStart())
521 SubElt = ParseInitializerWithPotentialDesignator();
522 else
523 SubElt = ParseInitializer();
524
525 if (Tok.is(tok::ellipsis))
526 SubElt = Actions.ActOnPackExpansion(SubElt.get(), ConsumeToken());
527
528 // If we couldn't parse the subelement, bail out.
529 if (!SubElt.isInvalid())
530 InitExprs.push_back(SubElt.release());
531 else
532 InitExprsOk = false;
533
534 if (Tok.is(tok::comma)) {
535 ConsumeToken();
536 trailingComma = true;
537 }
538
539 if (Tok.is(tok::r_brace))
540 break;
541 }
542
543 Braces.consumeClose();
544
545 return !trailingComma;
546 }