Bug Summary

File:tools/clang/lib/Sema/SemaTemplateVariadic.cpp
Warning:line 575, column 11
Called C++ object pointer is null

Annotated Source Code

1//===------- SemaTemplateVariadic.cpp - C++ Variadic Templates ------------===/
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// This file implements semantic analysis for C++0x variadic templates.
10//===----------------------------------------------------------------------===/
11
12#include "clang/Sema/Sema.h"
13#include "TypeLocBuilder.h"
14#include "clang/AST/Expr.h"
15#include "clang/AST/RecursiveASTVisitor.h"
16#include "clang/AST/TypeLoc.h"
17#include "clang/Sema/Lookup.h"
18#include "clang/Sema/ParsedTemplate.h"
19#include "clang/Sema/ScopeInfo.h"
20#include "clang/Sema/SemaInternal.h"
21#include "clang/Sema/Template.h"
22
23using namespace clang;
24
25//----------------------------------------------------------------------------
26// Visitor that collects unexpanded parameter packs
27//----------------------------------------------------------------------------
28
29namespace {
30 /// \brief A class that collects unexpanded parameter packs.
31 class CollectUnexpandedParameterPacksVisitor :
32 public RecursiveASTVisitor<CollectUnexpandedParameterPacksVisitor>
33 {
34 typedef RecursiveASTVisitor<CollectUnexpandedParameterPacksVisitor>
35 inherited;
36
37 SmallVectorImpl<UnexpandedParameterPack> &Unexpanded;
38
39 bool InLambda;
40
41 public:
42 explicit CollectUnexpandedParameterPacksVisitor(
43 SmallVectorImpl<UnexpandedParameterPack> &Unexpanded)
44 : Unexpanded(Unexpanded), InLambda(false) { }
45
46 bool shouldWalkTypesOfTypeLocs() const { return false; }
47
48 //------------------------------------------------------------------------
49 // Recording occurrences of (unexpanded) parameter packs.
50 //------------------------------------------------------------------------
51
52 /// \brief Record occurrences of template type parameter packs.
53 bool VisitTemplateTypeParmTypeLoc(TemplateTypeParmTypeLoc TL) {
54 if (TL.getTypePtr()->isParameterPack())
55 Unexpanded.push_back(std::make_pair(TL.getTypePtr(), TL.getNameLoc()));
56 return true;
57 }
58
59 /// \brief Record occurrences of template type parameter packs
60 /// when we don't have proper source-location information for
61 /// them.
62 ///
63 /// Ideally, this routine would never be used.
64 bool VisitTemplateTypeParmType(TemplateTypeParmType *T) {
65 if (T->isParameterPack())
66 Unexpanded.push_back(std::make_pair(T, SourceLocation()));
67
68 return true;
69 }
70
71 /// \brief Record occurrences of function and non-type template
72 /// parameter packs in an expression.
73 bool VisitDeclRefExpr(DeclRefExpr *E) {
74 if (E->getDecl()->isParameterPack())
75 Unexpanded.push_back(std::make_pair(E->getDecl(), E->getLocation()));
76
77 return true;
78 }
79
80 /// \brief Record occurrences of template template parameter packs.
81 bool TraverseTemplateName(TemplateName Template) {
82 if (TemplateTemplateParmDecl *TTP
83 = dyn_cast_or_null<TemplateTemplateParmDecl>(
84 Template.getAsTemplateDecl()))
85 if (TTP->isParameterPack())
86 Unexpanded.push_back(std::make_pair(TTP, SourceLocation()));
87
88 return inherited::TraverseTemplateName(Template);
89 }
90
91 /// \brief Suppress traversal into Objective-C container literal
92 /// elements that are pack expansions.
93 bool TraverseObjCDictionaryLiteral(ObjCDictionaryLiteral *E) {
94 if (!E->containsUnexpandedParameterPack())
95 return true;
96
97 for (unsigned I = 0, N = E->getNumElements(); I != N; ++I) {
98 ObjCDictionaryElement Element = E->getKeyValueElement(I);
99 if (Element.isPackExpansion())
100 continue;
101
102 TraverseStmt(Element.Key);
103 TraverseStmt(Element.Value);
104 }
105 return true;
106 }
107 //------------------------------------------------------------------------
108 // Pruning the search for unexpanded parameter packs.
109 //------------------------------------------------------------------------
110
111 /// \brief Suppress traversal into statements and expressions that
112 /// do not contain unexpanded parameter packs.
113 bool TraverseStmt(Stmt *S) {
114 Expr *E = dyn_cast_or_null<Expr>(S);
115 if ((E && E->containsUnexpandedParameterPack()) || InLambda)
116 return inherited::TraverseStmt(S);
117
118 return true;
119 }
120
121 /// \brief Suppress traversal into types that do not contain
122 /// unexpanded parameter packs.
123 bool TraverseType(QualType T) {
124 if ((!T.isNull() && T->containsUnexpandedParameterPack()) || InLambda)
125 return inherited::TraverseType(T);
126
127 return true;
128 }
129
130 /// \brief Suppress traversel into types with location information
131 /// that do not contain unexpanded parameter packs.
132 bool TraverseTypeLoc(TypeLoc TL) {
133 if ((!TL.getType().isNull() &&
134 TL.getType()->containsUnexpandedParameterPack()) ||
135 InLambda)
136 return inherited::TraverseTypeLoc(TL);
137
138 return true;
139 }
140
141 /// \brief Suppress traversal of non-parameter declarations, since
142 /// they cannot contain unexpanded parameter packs.
143 bool TraverseDecl(Decl *D) {
144 if ((D && isa<ParmVarDecl>(D)) || InLambda)
145 return inherited::TraverseDecl(D);
146
147 return true;
148 }
149
150 /// \brief Suppress traversal of template argument pack expansions.
151 bool TraverseTemplateArgument(const TemplateArgument &Arg) {
152 if (Arg.isPackExpansion())
153 return true;
154
155 return inherited::TraverseTemplateArgument(Arg);
156 }
157
158 /// \brief Suppress traversal of template argument pack expansions.
159 bool TraverseTemplateArgumentLoc(const TemplateArgumentLoc &ArgLoc) {
160 if (ArgLoc.getArgument().isPackExpansion())
161 return true;
162
163 return inherited::TraverseTemplateArgumentLoc(ArgLoc);
164 }
165
166 /// \brief Note whether we're traversing a lambda containing an unexpanded
167 /// parameter pack. In this case, the unexpanded pack can occur anywhere,
168 /// including all the places where we normally wouldn't look. Within a
169 /// lambda, we don't propagate the 'contains unexpanded parameter pack' bit
170 /// outside an expression.
171 bool TraverseLambdaExpr(LambdaExpr *Lambda) {
172 // The ContainsUnexpandedParameterPack bit on a lambda is always correct,
173 // even if it's contained within another lambda.
174 if (!Lambda->containsUnexpandedParameterPack())
175 return true;
176
177 bool WasInLambda = InLambda;
178 InLambda = true;
179
180 // If any capture names a function parameter pack, that pack is expanded
181 // when the lambda is expanded.
182 for (LambdaExpr::capture_iterator I = Lambda->capture_begin(),
183 E = Lambda->capture_end();
184 I != E; ++I) {
185 if (I->capturesVariable()) {
186 VarDecl *VD = I->getCapturedVar();
187 if (VD->isParameterPack())
188 Unexpanded.push_back(std::make_pair(VD, I->getLocation()));
189 }
190 }
191
192 inherited::TraverseLambdaExpr(Lambda);
193
194 InLambda = WasInLambda;
195 return true;
196 }
197 };
198}
199
200/// \brief Determine whether it's possible for an unexpanded parameter pack to
201/// be valid in this location. This only happens when we're in a declaration
202/// that is nested within an expression that could be expanded, such as a
203/// lambda-expression within a function call.
204///
205/// This is conservatively correct, but may claim that some unexpanded packs are
206/// permitted when they are not.
207bool Sema::isUnexpandedParameterPackPermitted() {
208 for (auto *SI : FunctionScopes)
209 if (isa<sema::LambdaScopeInfo>(SI))
210 return true;
211 return false;
212}
213
214/// \brief Diagnose all of the unexpanded parameter packs in the given
215/// vector.
216bool
217Sema::DiagnoseUnexpandedParameterPacks(SourceLocation Loc,
218 UnexpandedParameterPackContext UPPC,
219 ArrayRef<UnexpandedParameterPack> Unexpanded) {
220 if (Unexpanded.empty())
221 return false;
222
223 // If we are within a lambda expression, that lambda contains an unexpanded
224 // parameter pack, and we are done.
225 // FIXME: Store 'Unexpanded' on the lambda so we don't need to recompute it
226 // later.
227 for (unsigned N = FunctionScopes.size(); N; --N) {
228 if (sema::LambdaScopeInfo *LSI =
229 dyn_cast<sema::LambdaScopeInfo>(FunctionScopes[N-1])) {
230 LSI->ContainsUnexpandedParameterPack = true;
231 return false;
232 }
233 }
234
235 SmallVector<SourceLocation, 4> Locations;
236 SmallVector<IdentifierInfo *, 4> Names;
237 llvm::SmallPtrSet<IdentifierInfo *, 4> NamesKnown;
238
239 for (unsigned I = 0, N = Unexpanded.size(); I != N; ++I) {
240 IdentifierInfo *Name = nullptr;
241 if (const TemplateTypeParmType *TTP
242 = Unexpanded[I].first.dyn_cast<const TemplateTypeParmType *>())
243 Name = TTP->getIdentifier();
244 else
245 Name = Unexpanded[I].first.get<NamedDecl *>()->getIdentifier();
246
247 if (Name && NamesKnown.insert(Name).second)
248 Names.push_back(Name);
249
250 if (Unexpanded[I].second.isValid())
251 Locations.push_back(Unexpanded[I].second);
252 }
253
254 DiagnosticBuilder DB = Diag(Loc, diag::err_unexpanded_parameter_pack)
255 << (int)UPPC << (int)Names.size();
256 for (size_t I = 0, E = std::min(Names.size(), (size_t)2); I != E; ++I)
257 DB << Names[I];
258
259 for (unsigned I = 0, N = Locations.size(); I != N; ++I)
260 DB << SourceRange(Locations[I]);
261 return true;
262}
263
264bool Sema::DiagnoseUnexpandedParameterPack(SourceLocation Loc,
265 TypeSourceInfo *T,
266 UnexpandedParameterPackContext UPPC) {
267 // C++0x [temp.variadic]p5:
268 // An appearance of a name of a parameter pack that is not expanded is
269 // ill-formed.
270 if (!T->getType()->containsUnexpandedParameterPack())
271 return false;
272
273 SmallVector<UnexpandedParameterPack, 2> Unexpanded;
274 CollectUnexpandedParameterPacksVisitor(Unexpanded).TraverseTypeLoc(
275 T->getTypeLoc());
276 assert(!Unexpanded.empty() && "Unable to find unexpanded parameter packs")((!Unexpanded.empty() && "Unable to find unexpanded parameter packs"
) ? static_cast<void> (0) : __assert_fail ("!Unexpanded.empty() && \"Unable to find unexpanded parameter packs\""
, "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn290870/tools/clang/lib/Sema/SemaTemplateVariadic.cpp"
, 276, __PRETTY_FUNCTION__))
;
277 return DiagnoseUnexpandedParameterPacks(Loc, UPPC, Unexpanded);
278}
279
280bool Sema::DiagnoseUnexpandedParameterPack(Expr *E,
281 UnexpandedParameterPackContext UPPC) {
282 // C++0x [temp.variadic]p5:
283 // An appearance of a name of a parameter pack that is not expanded is
284 // ill-formed.
285 if (!E->containsUnexpandedParameterPack())
286 return false;
287
288 SmallVector<UnexpandedParameterPack, 2> Unexpanded;
289 CollectUnexpandedParameterPacksVisitor(Unexpanded).TraverseStmt(E);
290 assert(!Unexpanded.empty() && "Unable to find unexpanded parameter packs")((!Unexpanded.empty() && "Unable to find unexpanded parameter packs"
) ? static_cast<void> (0) : __assert_fail ("!Unexpanded.empty() && \"Unable to find unexpanded parameter packs\""
, "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn290870/tools/clang/lib/Sema/SemaTemplateVariadic.cpp"
, 290, __PRETTY_FUNCTION__))
;
291 return DiagnoseUnexpandedParameterPacks(E->getLocStart(), UPPC, Unexpanded);
292}
293
294bool Sema::DiagnoseUnexpandedParameterPack(const CXXScopeSpec &SS,
295 UnexpandedParameterPackContext UPPC) {
296 // C++0x [temp.variadic]p5:
297 // An appearance of a name of a parameter pack that is not expanded is
298 // ill-formed.
299 if (!SS.getScopeRep() ||
300 !SS.getScopeRep()->containsUnexpandedParameterPack())
301 return false;
302
303 SmallVector<UnexpandedParameterPack, 2> Unexpanded;
304 CollectUnexpandedParameterPacksVisitor(Unexpanded)
305 .TraverseNestedNameSpecifier(SS.getScopeRep());
306 assert(!Unexpanded.empty() && "Unable to find unexpanded parameter packs")((!Unexpanded.empty() && "Unable to find unexpanded parameter packs"
) ? static_cast<void> (0) : __assert_fail ("!Unexpanded.empty() && \"Unable to find unexpanded parameter packs\""
, "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn290870/tools/clang/lib/Sema/SemaTemplateVariadic.cpp"
, 306, __PRETTY_FUNCTION__))
;
307 return DiagnoseUnexpandedParameterPacks(SS.getRange().getBegin(),
308 UPPC, Unexpanded);
309}
310
311bool Sema::DiagnoseUnexpandedParameterPack(const DeclarationNameInfo &NameInfo,
312 UnexpandedParameterPackContext UPPC) {
313 // C++0x [temp.variadic]p5:
314 // An appearance of a name of a parameter pack that is not expanded is
315 // ill-formed.
316 switch (NameInfo.getName().getNameKind()) {
317 case DeclarationName::Identifier:
318 case DeclarationName::ObjCZeroArgSelector:
319 case DeclarationName::ObjCOneArgSelector:
320 case DeclarationName::ObjCMultiArgSelector:
321 case DeclarationName::CXXOperatorName:
322 case DeclarationName::CXXLiteralOperatorName:
323 case DeclarationName::CXXUsingDirective:
324 return false;
325
326 case DeclarationName::CXXConstructorName:
327 case DeclarationName::CXXDestructorName:
328 case DeclarationName::CXXConversionFunctionName:
329 // FIXME: We shouldn't need this null check!
330 if (TypeSourceInfo *TSInfo = NameInfo.getNamedTypeInfo())
331 return DiagnoseUnexpandedParameterPack(NameInfo.getLoc(), TSInfo, UPPC);
332
333 if (!NameInfo.getName().getCXXNameType()->containsUnexpandedParameterPack())
334 return false;
335
336 break;
337 }
338
339 SmallVector<UnexpandedParameterPack, 2> Unexpanded;
340 CollectUnexpandedParameterPacksVisitor(Unexpanded)
341 .TraverseType(NameInfo.getName().getCXXNameType());
342 assert(!Unexpanded.empty() && "Unable to find unexpanded parameter packs")((!Unexpanded.empty() && "Unable to find unexpanded parameter packs"
) ? static_cast<void> (0) : __assert_fail ("!Unexpanded.empty() && \"Unable to find unexpanded parameter packs\""
, "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn290870/tools/clang/lib/Sema/SemaTemplateVariadic.cpp"
, 342, __PRETTY_FUNCTION__))
;
343 return DiagnoseUnexpandedParameterPacks(NameInfo.getLoc(), UPPC, Unexpanded);
344}
345
346bool Sema::DiagnoseUnexpandedParameterPack(SourceLocation Loc,
347 TemplateName Template,
348 UnexpandedParameterPackContext UPPC) {
349
350 if (Template.isNull() || !Template.containsUnexpandedParameterPack())
351 return false;
352
353 SmallVector<UnexpandedParameterPack, 2> Unexpanded;
354 CollectUnexpandedParameterPacksVisitor(Unexpanded)
355 .TraverseTemplateName(Template);
356 assert(!Unexpanded.empty() && "Unable to find unexpanded parameter packs")((!Unexpanded.empty() && "Unable to find unexpanded parameter packs"
) ? static_cast<void> (0) : __assert_fail ("!Unexpanded.empty() && \"Unable to find unexpanded parameter packs\""
, "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn290870/tools/clang/lib/Sema/SemaTemplateVariadic.cpp"
, 356, __PRETTY_FUNCTION__))
;
357 return DiagnoseUnexpandedParameterPacks(Loc, UPPC, Unexpanded);
358}
359
360bool Sema::DiagnoseUnexpandedParameterPack(TemplateArgumentLoc Arg,
361 UnexpandedParameterPackContext UPPC) {
362 if (Arg.getArgument().isNull() ||
363 !Arg.getArgument().containsUnexpandedParameterPack())
364 return false;
365
366 SmallVector<UnexpandedParameterPack, 2> Unexpanded;
367 CollectUnexpandedParameterPacksVisitor(Unexpanded)
368 .TraverseTemplateArgumentLoc(Arg);
369 assert(!Unexpanded.empty() && "Unable to find unexpanded parameter packs")((!Unexpanded.empty() && "Unable to find unexpanded parameter packs"
) ? static_cast<void> (0) : __assert_fail ("!Unexpanded.empty() && \"Unable to find unexpanded parameter packs\""
, "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn290870/tools/clang/lib/Sema/SemaTemplateVariadic.cpp"
, 369, __PRETTY_FUNCTION__))
;
370 return DiagnoseUnexpandedParameterPacks(Arg.getLocation(), UPPC, Unexpanded);
371}
372
373void Sema::collectUnexpandedParameterPacks(TemplateArgument Arg,
374 SmallVectorImpl<UnexpandedParameterPack> &Unexpanded) {
375 CollectUnexpandedParameterPacksVisitor(Unexpanded)
376 .TraverseTemplateArgument(Arg);
377}
378
379void Sema::collectUnexpandedParameterPacks(TemplateArgumentLoc Arg,
380 SmallVectorImpl<UnexpandedParameterPack> &Unexpanded) {
381 CollectUnexpandedParameterPacksVisitor(Unexpanded)
382 .TraverseTemplateArgumentLoc(Arg);
383}
384
385void Sema::collectUnexpandedParameterPacks(QualType T,
386 SmallVectorImpl<UnexpandedParameterPack> &Unexpanded) {
387 CollectUnexpandedParameterPacksVisitor(Unexpanded).TraverseType(T);
388}
389
390void Sema::collectUnexpandedParameterPacks(TypeLoc TL,
391 SmallVectorImpl<UnexpandedParameterPack> &Unexpanded) {
392 CollectUnexpandedParameterPacksVisitor(Unexpanded).TraverseTypeLoc(TL);
393}
394
395void Sema::collectUnexpandedParameterPacks(
396 NestedNameSpecifierLoc NNS,
397 SmallVectorImpl<UnexpandedParameterPack> &Unexpanded) {
398 CollectUnexpandedParameterPacksVisitor(Unexpanded)
399 .TraverseNestedNameSpecifierLoc(NNS);
400}
401
402void Sema::collectUnexpandedParameterPacks(
403 const DeclarationNameInfo &NameInfo,
404 SmallVectorImpl<UnexpandedParameterPack> &Unexpanded) {
405 CollectUnexpandedParameterPacksVisitor(Unexpanded)
406 .TraverseDeclarationNameInfo(NameInfo);
407}
408
409
410ParsedTemplateArgument
411Sema::ActOnPackExpansion(const ParsedTemplateArgument &Arg,
412 SourceLocation EllipsisLoc) {
413 if (Arg.isInvalid())
414 return Arg;
415
416 switch (Arg.getKind()) {
417 case ParsedTemplateArgument::Type: {
418 TypeResult Result = ActOnPackExpansion(Arg.getAsType(), EllipsisLoc);
419 if (Result.isInvalid())
420 return ParsedTemplateArgument();
421
422 return ParsedTemplateArgument(Arg.getKind(), Result.get().getAsOpaquePtr(),
423 Arg.getLocation());
424 }
425
426 case ParsedTemplateArgument::NonType: {
427 ExprResult Result = ActOnPackExpansion(Arg.getAsExpr(), EllipsisLoc);
428 if (Result.isInvalid())
429 return ParsedTemplateArgument();
430
431 return ParsedTemplateArgument(Arg.getKind(), Result.get(),
432 Arg.getLocation());
433 }
434
435 case ParsedTemplateArgument::Template:
436 if (!Arg.getAsTemplate().get().containsUnexpandedParameterPack()) {
437 SourceRange R(Arg.getLocation());
438 if (Arg.getScopeSpec().isValid())
439 R.setBegin(Arg.getScopeSpec().getBeginLoc());
440 Diag(EllipsisLoc, diag::err_pack_expansion_without_parameter_packs)
441 << R;
442 return ParsedTemplateArgument();
443 }
444
445 return Arg.getTemplatePackExpansion(EllipsisLoc);
446 }
447 llvm_unreachable("Unhandled template argument kind?")::llvm::llvm_unreachable_internal("Unhandled template argument kind?"
, "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn290870/tools/clang/lib/Sema/SemaTemplateVariadic.cpp"
, 447)
;
448}
449
450TypeResult Sema::ActOnPackExpansion(ParsedType Type,
451 SourceLocation EllipsisLoc) {
452 TypeSourceInfo *TSInfo;
453 GetTypeFromParser(Type, &TSInfo);
454 if (!TSInfo)
455 return true;
456
457 TypeSourceInfo *TSResult = CheckPackExpansion(TSInfo, EllipsisLoc, None);
458 if (!TSResult)
459 return true;
460
461 return CreateParsedType(TSResult->getType(), TSResult);
462}
463
464TypeSourceInfo *
465Sema::CheckPackExpansion(TypeSourceInfo *Pattern, SourceLocation EllipsisLoc,
466 Optional<unsigned> NumExpansions) {
467 // Create the pack expansion type and source-location information.
468 QualType Result = CheckPackExpansion(Pattern->getType(),
469 Pattern->getTypeLoc().getSourceRange(),
470 EllipsisLoc, NumExpansions);
471 if (Result.isNull())
472 return nullptr;
473
474 TypeLocBuilder TLB;
475 TLB.pushFullCopy(Pattern->getTypeLoc());
476 PackExpansionTypeLoc TL = TLB.push<PackExpansionTypeLoc>(Result);
477 TL.setEllipsisLoc(EllipsisLoc);
478
479 return TLB.getTypeSourceInfo(Context, Result);
480}
481
482QualType Sema::CheckPackExpansion(QualType Pattern, SourceRange PatternRange,
483 SourceLocation EllipsisLoc,
484 Optional<unsigned> NumExpansions) {
485 // C++0x [temp.variadic]p5:
486 // The pattern of a pack expansion shall name one or more
487 // parameter packs that are not expanded by a nested pack
488 // expansion.
489 if (!Pattern->containsUnexpandedParameterPack()) {
490 Diag(EllipsisLoc, diag::err_pack_expansion_without_parameter_packs)
491 << PatternRange;
492 return QualType();
493 }
494
495 return Context.getPackExpansionType(Pattern, NumExpansions);
496}
497
498ExprResult Sema::ActOnPackExpansion(Expr *Pattern, SourceLocation EllipsisLoc) {
499 return CheckPackExpansion(Pattern, EllipsisLoc, None);
500}
501
502ExprResult Sema::CheckPackExpansion(Expr *Pattern, SourceLocation EllipsisLoc,
503 Optional<unsigned> NumExpansions) {
504 if (!Pattern)
505 return ExprError();
506
507 // C++0x [temp.variadic]p5:
508 // The pattern of a pack expansion shall name one or more
509 // parameter packs that are not expanded by a nested pack
510 // expansion.
511 if (!Pattern->containsUnexpandedParameterPack()) {
512 Diag(EllipsisLoc, diag::err_pack_expansion_without_parameter_packs)
513 << Pattern->getSourceRange();
514 return ExprError();
515 }
516
517 // Create the pack expansion expression and source-location information.
518 return new (Context)
519 PackExpansionExpr(Context.DependentTy, Pattern, EllipsisLoc, NumExpansions);
520}
521
522/// \brief Retrieve the depth and index of a parameter pack.
523static std::pair<unsigned, unsigned>
524getDepthAndIndex(NamedDecl *ND) {
525 if (TemplateTypeParmDecl *TTP = dyn_cast<TemplateTypeParmDecl>(ND))
526 return std::make_pair(TTP->getDepth(), TTP->getIndex());
527
528 if (NonTypeTemplateParmDecl *NTTP = dyn_cast<NonTypeTemplateParmDecl>(ND))
529 return std::make_pair(NTTP->getDepth(), NTTP->getIndex());
530
531 TemplateTemplateParmDecl *TTP = cast<TemplateTemplateParmDecl>(ND);
532 return std::make_pair(TTP->getDepth(), TTP->getIndex());
533}
534
535bool Sema::CheckParameterPacksForExpansion(
536 SourceLocation EllipsisLoc, SourceRange PatternRange,
537 ArrayRef<UnexpandedParameterPack> Unexpanded,
538 const MultiLevelTemplateArgumentList &TemplateArgs, bool &ShouldExpand,
539 bool &RetainExpansion, Optional<unsigned> &NumExpansions) {
540 ShouldExpand = true;
541 RetainExpansion = false;
542 std::pair<IdentifierInfo *, SourceLocation> FirstPack;
543 bool HaveFirstPack = false;
544
545 for (ArrayRef<UnexpandedParameterPack>::iterator i = Unexpanded.begin(),
2
Loop condition is true. Entering loop body
13
Loop condition is true. Entering loop body
21
Loop condition is true. Entering loop body
546 end = Unexpanded.end();
547 i != end; ++i) {
1
Assuming 'i' is not equal to 'end'
548 // Compute the depth and index for this parameter pack.
549 unsigned Depth = 0, Index = 0;
550 IdentifierInfo *Name;
551 bool IsFunctionParameterPack = false;
552
553 if (const TemplateTypeParmType *TTP
3
Taking false branch
14
Taking false branch
22
Taking false branch
554 = i->first.dyn_cast<const TemplateTypeParmType *>()) {
555 Depth = TTP->getDepth();
556 Index = TTP->getIndex();
557 Name = TTP->getIdentifier();
558 } else {
559 NamedDecl *ND = i->first.get<NamedDecl *>();
560 if (isa<ParmVarDecl>(ND))
4
Taking false branch
15
Taking false branch
23
Taking true branch
561 IsFunctionParameterPack = true;
562 else
563 std::tie(Depth, Index) = getDepthAndIndex(ND);
564
565 Name = ND->getIdentifier();
566 }
567
568 // Determine the size of this argument pack.
569 unsigned NewPackSize;
570 if (IsFunctionParameterPack) {
5
Taking false branch
16
Taking false branch
24
Taking true branch
571 // Figure out whether we're instantiating to an argument pack or not.
572 typedef LocalInstantiationScope::DeclArgumentPack DeclArgumentPack;
573
574 llvm::PointerUnion<Decl *, DeclArgumentPack *> *Instantiation
575 = CurrentInstantiationScope->findInstantiationOf(
25
Called C++ object pointer is null
576 i->first.get<NamedDecl *>());
577 if (Instantiation->is<DeclArgumentPack *>()) {
578 // We could expand this function parameter pack.
579 NewPackSize = Instantiation->get<DeclArgumentPack *>()->size();
580 } else {
581 // We can't expand this function parameter pack, so we can't expand
582 // the pack expansion.
583 ShouldExpand = false;
584 continue;
585 }
586 } else {
587 // If we don't have a template argument at this depth/index, then we
588 // cannot expand the pack expansion. Make a note of this, but we still
589 // want to check any parameter packs we *do* have arguments for.
590 if (Depth >= TemplateArgs.getNumLevels() ||
6
Taking false branch
17
Taking false branch
591 !TemplateArgs.hasTemplateArgument(Depth, Index)) {
592 ShouldExpand = false;
593 continue;
594 }
595
596 // Determine the size of the argument pack.
597 NewPackSize = TemplateArgs(Depth, Index).pack_size();
598 }
599
600 // C++0x [temp.arg.explicit]p9:
601 // Template argument deduction can extend the sequence of template
602 // arguments corresponding to a template parameter pack, even when the
603 // sequence contains explicitly specified template arguments.
604 if (!IsFunctionParameterPack && CurrentInstantiationScope) {
7
Assuming the condition is false
8
Assuming pointer value is null
9
Taking false branch
18
Taking false branch
605 if (NamedDecl *PartialPack
606 = CurrentInstantiationScope->getPartiallySubstitutedPack()){
607 unsigned PartialDepth, PartialIndex;
608 std::tie(PartialDepth, PartialIndex) = getDepthAndIndex(PartialPack);
609 if (PartialDepth == Depth && PartialIndex == Index)
610 RetainExpansion = true;
611 }
612 }
613
614 if (!NumExpansions) {
10
Assuming the condition is false
11
Taking false branch
19
Taking false branch
615 // The is the first pack we've seen for which we have an argument.
616 // Record it.
617 NumExpansions = NewPackSize;
618 FirstPack.first = Name;
619 FirstPack.second = i->second;
620 HaveFirstPack = true;
621 continue;
622 }
623
624 if (NewPackSize != *NumExpansions) {
12
Taking false branch
20
Taking false branch
625 // C++0x [temp.variadic]p5:
626 // All of the parameter packs expanded by a pack expansion shall have
627 // the same number of arguments specified.
628 if (HaveFirstPack)
629 Diag(EllipsisLoc, diag::err_pack_expansion_length_conflict)
630 << FirstPack.first << Name << *NumExpansions << NewPackSize
631 << SourceRange(FirstPack.second) << SourceRange(i->second);
632 else
633 Diag(EllipsisLoc, diag::err_pack_expansion_length_conflict_multilevel)
634 << Name << *NumExpansions << NewPackSize
635 << SourceRange(i->second);
636 return true;
637 }
638 }
639
640 return false;
641}
642
643Optional<unsigned> Sema::getNumArgumentsInExpansion(QualType T,
644 const MultiLevelTemplateArgumentList &TemplateArgs) {
645 QualType Pattern = cast<PackExpansionType>(T)->getPattern();
646 SmallVector<UnexpandedParameterPack, 2> Unexpanded;
647 CollectUnexpandedParameterPacksVisitor(Unexpanded).TraverseType(Pattern);
648
649 Optional<unsigned> Result;
650 for (unsigned I = 0, N = Unexpanded.size(); I != N; ++I) {
651 // Compute the depth and index for this parameter pack.
652 unsigned Depth;
653 unsigned Index;
654
655 if (const TemplateTypeParmType *TTP
656 = Unexpanded[I].first.dyn_cast<const TemplateTypeParmType *>()) {
657 Depth = TTP->getDepth();
658 Index = TTP->getIndex();
659 } else {
660 NamedDecl *ND = Unexpanded[I].first.get<NamedDecl *>();
661 if (isa<ParmVarDecl>(ND)) {
662 // Function parameter pack.
663 typedef LocalInstantiationScope::DeclArgumentPack DeclArgumentPack;
664
665 llvm::PointerUnion<Decl *, DeclArgumentPack *> *Instantiation
666 = CurrentInstantiationScope->findInstantiationOf(
667 Unexpanded[I].first.get<NamedDecl *>());
668 if (Instantiation->is<Decl*>())
669 // The pattern refers to an unexpanded pack. We're not ready to expand
670 // this pack yet.
671 return None;
672
673 unsigned Size = Instantiation->get<DeclArgumentPack *>()->size();
674 assert((!Result || *Result == Size) && "inconsistent pack sizes")(((!Result || *Result == Size) && "inconsistent pack sizes"
) ? static_cast<void> (0) : __assert_fail ("(!Result || *Result == Size) && \"inconsistent pack sizes\""
, "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn290870/tools/clang/lib/Sema/SemaTemplateVariadic.cpp"
, 674, __PRETTY_FUNCTION__))
;
675 Result = Size;
676 continue;
677 }
678
679 std::tie(Depth, Index) = getDepthAndIndex(ND);
680 }
681 if (Depth >= TemplateArgs.getNumLevels() ||
682 !TemplateArgs.hasTemplateArgument(Depth, Index))
683 // The pattern refers to an unknown template argument. We're not ready to
684 // expand this pack yet.
685 return None;
686
687 // Determine the size of the argument pack.
688 unsigned Size = TemplateArgs(Depth, Index).pack_size();
689 assert((!Result || *Result == Size) && "inconsistent pack sizes")(((!Result || *Result == Size) && "inconsistent pack sizes"
) ? static_cast<void> (0) : __assert_fail ("(!Result || *Result == Size) && \"inconsistent pack sizes\""
, "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn290870/tools/clang/lib/Sema/SemaTemplateVariadic.cpp"
, 689, __PRETTY_FUNCTION__))
;
690 Result = Size;
691 }
692
693 return Result;
694}
695
696bool Sema::containsUnexpandedParameterPacks(Declarator &D) {
697 const DeclSpec &DS = D.getDeclSpec();
698 switch (DS.getTypeSpecType()) {
699 case TST_typename:
700 case TST_typeofType:
701 case TST_underlyingType:
702 case TST_atomic: {
703 QualType T = DS.getRepAsType().get();
704 if (!T.isNull() && T->containsUnexpandedParameterPack())
705 return true;
706 break;
707 }
708
709 case TST_typeofExpr:
710 case TST_decltype:
711 if (DS.getRepAsExpr() &&
712 DS.getRepAsExpr()->containsUnexpandedParameterPack())
713 return true;
714 break;
715
716 case TST_unspecified:
717 case TST_void:
718 case TST_char:
719 case TST_wchar:
720 case TST_char16:
721 case TST_char32:
722 case TST_int:
723 case TST_int128:
724 case TST_half:
725 case TST_float:
726 case TST_double:
727 case TST_float128:
728 case TST_bool:
729 case TST_decimal32:
730 case TST_decimal64:
731 case TST_decimal128:
732 case TST_enum:
733 case TST_union:
734 case TST_struct:
735 case TST_interface:
736 case TST_class:
737 case TST_auto:
738 case TST_auto_type:
739 case TST_decltype_auto:
740#define GENERIC_IMAGE_TYPE(ImgType, Id) case TST_##ImgType##_t:
741#include "clang/Basic/OpenCLImageTypes.def"
742 case TST_unknown_anytype:
743 case TST_error:
744 break;
745 }
746
747 for (unsigned I = 0, N = D.getNumTypeObjects(); I != N; ++I) {
748 const DeclaratorChunk &Chunk = D.getTypeObject(I);
749 switch (Chunk.Kind) {
750 case DeclaratorChunk::Pointer:
751 case DeclaratorChunk::Reference:
752 case DeclaratorChunk::Paren:
753 case DeclaratorChunk::Pipe:
754 case DeclaratorChunk::BlockPointer:
755 // These declarator chunks cannot contain any parameter packs.
756 break;
757
758 case DeclaratorChunk::Array:
759 if (Chunk.Arr.NumElts &&
760 Chunk.Arr.NumElts->containsUnexpandedParameterPack())
761 return true;
762 break;
763 case DeclaratorChunk::Function:
764 for (unsigned i = 0, e = Chunk.Fun.NumParams; i != e; ++i) {
765 ParmVarDecl *Param = cast<ParmVarDecl>(Chunk.Fun.Params[i].Param);
766 QualType ParamTy = Param->getType();
767 assert(!ParamTy.isNull() && "Couldn't parse type?")((!ParamTy.isNull() && "Couldn't parse type?") ? static_cast
<void> (0) : __assert_fail ("!ParamTy.isNull() && \"Couldn't parse type?\""
, "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn290870/tools/clang/lib/Sema/SemaTemplateVariadic.cpp"
, 767, __PRETTY_FUNCTION__))
;
768 if (ParamTy->containsUnexpandedParameterPack()) return true;
769 }
770
771 if (Chunk.Fun.getExceptionSpecType() == EST_Dynamic) {
772 for (unsigned i = 0; i != Chunk.Fun.getNumExceptions(); ++i) {
773 if (Chunk.Fun.Exceptions[i]
774 .Ty.get()
775 ->containsUnexpandedParameterPack())
776 return true;
777 }
778 } else if (Chunk.Fun.getExceptionSpecType() == EST_ComputedNoexcept &&
779 Chunk.Fun.NoexceptExpr->containsUnexpandedParameterPack())
780 return true;
781
782 if (Chunk.Fun.hasTrailingReturnType()) {
783 QualType T = Chunk.Fun.getTrailingReturnType().get();
784 if (!T.isNull() && T->containsUnexpandedParameterPack())
785 return true;
786 }
787 break;
788
789 case DeclaratorChunk::MemberPointer:
790 if (Chunk.Mem.Scope().getScopeRep() &&
791 Chunk.Mem.Scope().getScopeRep()->containsUnexpandedParameterPack())
792 return true;
793 break;
794 }
795 }
796
797 return false;
798}
799
800namespace {
801
802// Callback to only accept typo corrections that refer to parameter packs.
803class ParameterPackValidatorCCC : public CorrectionCandidateCallback {
804 public:
805 bool ValidateCandidate(const TypoCorrection &candidate) override {
806 NamedDecl *ND = candidate.getCorrectionDecl();
807 return ND && ND->isParameterPack();
808 }
809};
810
811}
812
813/// \brief Called when an expression computing the size of a parameter pack
814/// is parsed.
815///
816/// \code
817/// template<typename ...Types> struct count {
818/// static const unsigned value = sizeof...(Types);
819/// };
820/// \endcode
821///
822//
823/// \param OpLoc The location of the "sizeof" keyword.
824/// \param Name The name of the parameter pack whose size will be determined.
825/// \param NameLoc The source location of the name of the parameter pack.
826/// \param RParenLoc The location of the closing parentheses.
827ExprResult Sema::ActOnSizeofParameterPackExpr(Scope *S,
828 SourceLocation OpLoc,
829 IdentifierInfo &Name,
830 SourceLocation NameLoc,
831 SourceLocation RParenLoc) {
832 // C++0x [expr.sizeof]p5:
833 // The identifier in a sizeof... expression shall name a parameter pack.
834 LookupResult R(*this, &Name, NameLoc, LookupOrdinaryName);
835 LookupName(R, S);
836
837 NamedDecl *ParameterPack = nullptr;
838 switch (R.getResultKind()) {
839 case LookupResult::Found:
840 ParameterPack = R.getFoundDecl();
841 break;
842
843 case LookupResult::NotFound:
844 case LookupResult::NotFoundInCurrentInstantiation:
845 if (TypoCorrection Corrected =
846 CorrectTypo(R.getLookupNameInfo(), R.getLookupKind(), S, nullptr,
847 llvm::make_unique<ParameterPackValidatorCCC>(),
848 CTK_ErrorRecovery)) {
849 diagnoseTypo(Corrected,
850 PDiag(diag::err_sizeof_pack_no_pack_name_suggest) << &Name,
851 PDiag(diag::note_parameter_pack_here));
852 ParameterPack = Corrected.getCorrectionDecl();
853 }
854
855 case LookupResult::FoundOverloaded:
856 case LookupResult::FoundUnresolvedValue:
857 break;
858
859 case LookupResult::Ambiguous:
860 DiagnoseAmbiguousLookup(R);
861 return ExprError();
862 }
863
864 if (!ParameterPack || !ParameterPack->isParameterPack()) {
865 Diag(NameLoc, diag::err_sizeof_pack_no_pack_name)
866 << &Name;
867 return ExprError();
868 }
869
870 MarkAnyDeclReferenced(OpLoc, ParameterPack, true);
871
872 return SizeOfPackExpr::Create(Context, OpLoc, ParameterPack, NameLoc,
873 RParenLoc);
874}
875
876TemplateArgumentLoc
877Sema::getTemplateArgumentPackExpansionPattern(
878 TemplateArgumentLoc OrigLoc,
879 SourceLocation &Ellipsis, Optional<unsigned> &NumExpansions) const {
880 const TemplateArgument &Argument = OrigLoc.getArgument();
881 assert(Argument.isPackExpansion())((Argument.isPackExpansion()) ? static_cast<void> (0) :
__assert_fail ("Argument.isPackExpansion()", "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn290870/tools/clang/lib/Sema/SemaTemplateVariadic.cpp"
, 881, __PRETTY_FUNCTION__))
;
882 switch (Argument.getKind()) {
883 case TemplateArgument::Type: {
884 // FIXME: We shouldn't ever have to worry about missing
885 // type-source info!
886 TypeSourceInfo *ExpansionTSInfo = OrigLoc.getTypeSourceInfo();
887 if (!ExpansionTSInfo)
888 ExpansionTSInfo = Context.getTrivialTypeSourceInfo(Argument.getAsType(),
889 Ellipsis);
890 PackExpansionTypeLoc Expansion =
891 ExpansionTSInfo->getTypeLoc().castAs<PackExpansionTypeLoc>();
892 Ellipsis = Expansion.getEllipsisLoc();
893
894 TypeLoc Pattern = Expansion.getPatternLoc();
895 NumExpansions = Expansion.getTypePtr()->getNumExpansions();
896
897 // We need to copy the TypeLoc because TemplateArgumentLocs store a
898 // TypeSourceInfo.
899 // FIXME: Find some way to avoid the copy?
900 TypeLocBuilder TLB;
901 TLB.pushFullCopy(Pattern);
902 TypeSourceInfo *PatternTSInfo =
903 TLB.getTypeSourceInfo(Context, Pattern.getType());
904 return TemplateArgumentLoc(TemplateArgument(Pattern.getType()),
905 PatternTSInfo);
906 }
907
908 case TemplateArgument::Expression: {
909 PackExpansionExpr *Expansion
910 = cast<PackExpansionExpr>(Argument.getAsExpr());
911 Expr *Pattern = Expansion->getPattern();
912 Ellipsis = Expansion->getEllipsisLoc();
913 NumExpansions = Expansion->getNumExpansions();
914 return TemplateArgumentLoc(Pattern, Pattern);
915 }
916
917 case TemplateArgument::TemplateExpansion:
918 Ellipsis = OrigLoc.getTemplateEllipsisLoc();
919 NumExpansions = Argument.getNumTemplateExpansions();
920 return TemplateArgumentLoc(Argument.getPackExpansionPattern(),
921 OrigLoc.getTemplateQualifierLoc(),
922 OrigLoc.getTemplateNameLoc());
923
924 case TemplateArgument::Declaration:
925 case TemplateArgument::NullPtr:
926 case TemplateArgument::Template:
927 case TemplateArgument::Integral:
928 case TemplateArgument::Pack:
929 case TemplateArgument::Null:
930 return TemplateArgumentLoc();
931 }
932
933 llvm_unreachable("Invalid TemplateArgument Kind!")::llvm::llvm_unreachable_internal("Invalid TemplateArgument Kind!"
, "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn290870/tools/clang/lib/Sema/SemaTemplateVariadic.cpp"
, 933)
;
934}
935
936Optional<unsigned> Sema::getFullyPackExpandedSize(TemplateArgument Arg) {
937 assert(Arg.containsUnexpandedParameterPack())((Arg.containsUnexpandedParameterPack()) ? static_cast<void
> (0) : __assert_fail ("Arg.containsUnexpandedParameterPack()"
, "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn290870/tools/clang/lib/Sema/SemaTemplateVariadic.cpp"
, 937, __PRETTY_FUNCTION__))
;
938
939 // If this is a substituted pack, grab that pack. If not, we don't know
940 // the size yet.
941 // FIXME: We could find a size in more cases by looking for a substituted
942 // pack anywhere within this argument, but that's not necessary in the common
943 // case for 'sizeof...(A)' handling.
944 TemplateArgument Pack;
945 switch (Arg.getKind()) {
946 case TemplateArgument::Type:
947 if (auto *Subst = Arg.getAsType()->getAs<SubstTemplateTypeParmPackType>())
948 Pack = Subst->getArgumentPack();
949 else
950 return None;
951 break;
952
953 case TemplateArgument::Expression:
954 if (auto *Subst =
955 dyn_cast<SubstNonTypeTemplateParmPackExpr>(Arg.getAsExpr()))
956 Pack = Subst->getArgumentPack();
957 else if (auto *Subst = dyn_cast<FunctionParmPackExpr>(Arg.getAsExpr())) {
958 for (ParmVarDecl *PD : *Subst)
959 if (PD->isParameterPack())
960 return None;
961 return Subst->getNumExpansions();
962 } else
963 return None;
964 break;
965
966 case TemplateArgument::Template:
967 if (SubstTemplateTemplateParmPackStorage *Subst =
968 Arg.getAsTemplate().getAsSubstTemplateTemplateParmPack())
969 Pack = Subst->getArgumentPack();
970 else
971 return None;
972 break;
973
974 case TemplateArgument::Declaration:
975 case TemplateArgument::NullPtr:
976 case TemplateArgument::TemplateExpansion:
977 case TemplateArgument::Integral:
978 case TemplateArgument::Pack:
979 case TemplateArgument::Null:
980 return None;
981 }
982
983 // Check that no argument in the pack is itself a pack expansion.
984 for (TemplateArgument Elem : Pack.pack_elements()) {
985 // There's no point recursing in this case; we would have already
986 // expanded this pack expansion into the enclosing pack if we could.
987 if (Elem.isPackExpansion())
988 return None;
989 }
990 return Pack.pack_size();
991}
992
993static void CheckFoldOperand(Sema &S, Expr *E) {
994 if (!E)
995 return;
996
997 E = E->IgnoreImpCasts();
998 auto *OCE = dyn_cast<CXXOperatorCallExpr>(E);
999 if ((OCE && OCE->isInfixBinaryOp()) || isa<BinaryOperator>(E) ||
1000 isa<AbstractConditionalOperator>(E)) {
1001 S.Diag(E->getExprLoc(), diag::err_fold_expression_bad_operand)
1002 << E->getSourceRange()
1003 << FixItHint::CreateInsertion(E->getLocStart(), "(")
1004 << FixItHint::CreateInsertion(E->getLocEnd(), ")");
1005 }
1006}
1007
1008ExprResult Sema::ActOnCXXFoldExpr(SourceLocation LParenLoc, Expr *LHS,
1009 tok::TokenKind Operator,
1010 SourceLocation EllipsisLoc, Expr *RHS,
1011 SourceLocation RParenLoc) {
1012 // LHS and RHS must be cast-expressions. We allow an arbitrary expression
1013 // in the parser and reduce down to just cast-expressions here.
1014 CheckFoldOperand(*this, LHS);
1015 CheckFoldOperand(*this, RHS);
1016
1017 // [expr.prim.fold]p3:
1018 // In a binary fold, op1 and op2 shall be the same fold-operator, and
1019 // either e1 shall contain an unexpanded parameter pack or e2 shall contain
1020 // an unexpanded parameter pack, but not both.
1021 if (LHS && RHS &&
1022 LHS->containsUnexpandedParameterPack() ==
1023 RHS->containsUnexpandedParameterPack()) {
1024 return Diag(EllipsisLoc,
1025 LHS->containsUnexpandedParameterPack()
1026 ? diag::err_fold_expression_packs_both_sides
1027 : diag::err_pack_expansion_without_parameter_packs)
1028 << LHS->getSourceRange() << RHS->getSourceRange();
1029 }
1030
1031 // [expr.prim.fold]p2:
1032 // In a unary fold, the cast-expression shall contain an unexpanded
1033 // parameter pack.
1034 if (!LHS || !RHS) {
1035 Expr *Pack = LHS ? LHS : RHS;
1036 assert(Pack && "fold expression with neither LHS nor RHS")((Pack && "fold expression with neither LHS nor RHS")
? static_cast<void> (0) : __assert_fail ("Pack && \"fold expression with neither LHS nor RHS\""
, "/tmp/buildd/llvm-toolchain-snapshot-4.0~svn290870/tools/clang/lib/Sema/SemaTemplateVariadic.cpp"
, 1036, __PRETTY_FUNCTION__))
;
1037 if (!Pack->containsUnexpandedParameterPack())
1038 return Diag(EllipsisLoc, diag::err_pack_expansion_without_parameter_packs)
1039 << Pack->getSourceRange();
1040 }
1041
1042 BinaryOperatorKind Opc = ConvertTokenKindToBinaryOpcode(Operator);
1043 return BuildCXXFoldExpr(LParenLoc, LHS, Opc, EllipsisLoc, RHS, RParenLoc);
1044}
1045
1046ExprResult Sema::BuildCXXFoldExpr(SourceLocation LParenLoc, Expr *LHS,
1047 BinaryOperatorKind Operator,
1048 SourceLocation EllipsisLoc, Expr *RHS,
1049 SourceLocation RParenLoc) {
1050 return new (Context) CXXFoldExpr(Context.DependentTy, LParenLoc, LHS,
1051 Operator, EllipsisLoc, RHS, RParenLoc);
1052}
1053
1054ExprResult Sema::BuildEmptyCXXFoldExpr(SourceLocation EllipsisLoc,
1055 BinaryOperatorKind Operator) {
1056 // [temp.variadic]p9:
1057 // If N is zero for a unary fold-expression, the value of the expression is
1058 // && -> true
1059 // || -> false
1060 // , -> void()
1061 // if the operator is not listed [above], the instantiation is ill-formed.
1062 //
1063 // Note that we need to use something like int() here, not merely 0, to
1064 // prevent the result from being a null pointer constant.
1065 QualType ScalarType;
1066 switch (Operator) {
1067 case BO_LOr:
1068 return ActOnCXXBoolLiteral(EllipsisLoc, tok::kw_false);
1069 case BO_LAnd:
1070 return ActOnCXXBoolLiteral(EllipsisLoc, tok::kw_true);
1071 case BO_Comma:
1072 ScalarType = Context.VoidTy;
1073 break;
1074
1075 default:
1076 return Diag(EllipsisLoc, diag::err_fold_expression_empty)
1077 << BinaryOperator::getOpcodeStr(Operator);
1078 }
1079
1080 return new (Context) CXXScalarValueInitExpr(
1081 ScalarType, Context.getTrivialTypeSourceInfo(ScalarType, EllipsisLoc),
1082 EllipsisLoc);
1083}