1 //===--- SemaLambda.cpp - Semantic Analysis for C++11 Lambdas -------------===//
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 semantic analysis for C++ lambda expressions.
10 //
11 //===----------------------------------------------------------------------===//
12 #include "clang/Sema/DeclSpec.h"
13 #include "TypeLocBuilder.h"
14 #include "clang/AST/ASTLambda.h"
15 #include "clang/AST/ExprCXX.h"
16 #include "clang/Basic/TargetInfo.h"
17 #include "clang/Sema/Initialization.h"
18 #include "clang/Sema/Lookup.h"
19 #include "clang/Sema/Scope.h"
20 #include "clang/Sema/ScopeInfo.h"
21 #include "clang/Sema/SemaInternal.h"
22 #include "clang/Sema/SemaLambda.h"
23 #include "llvm/ADT/STLExtras.h"
24 using namespace clang;
25 using namespace sema;
26
27 /// Examines the FunctionScopeInfo stack to determine the nearest
28 /// enclosing lambda (to the current lambda) that is 'capture-ready' for
29 /// the variable referenced in the current lambda (i.e. \p VarToCapture).
30 /// If successful, returns the index into Sema's FunctionScopeInfo stack
31 /// of the capture-ready lambda's LambdaScopeInfo.
32 ///
33 /// Climbs down the stack of lambdas (deepest nested lambda - i.e. current
34 /// lambda - is on top) to determine the index of the nearest enclosing/outer
35 /// lambda that is ready to capture the \p VarToCapture being referenced in
36 /// the current lambda.
37 /// As we climb down the stack, we want the index of the first such lambda -
38 /// that is the lambda with the highest index that is 'capture-ready'.
39 ///
40 /// A lambda 'L' is capture-ready for 'V' (var or this) if:
41 /// - its enclosing context is non-dependent
42 /// - and if the chain of lambdas between L and the lambda in which
43 /// V is potentially used (i.e. the lambda at the top of the scope info
44 /// stack), can all capture or have already captured V.
45 /// If \p VarToCapture is 'null' then we are trying to capture 'this'.
46 ///
47 /// Note that a lambda that is deemed 'capture-ready' still needs to be checked
48 /// for whether it is 'capture-capable' (see
49 /// getStackIndexOfNearestEnclosingCaptureCapableLambda), before it can truly
50 /// capture.
51 ///
52 /// \param FunctionScopes - Sema's stack of nested FunctionScopeInfo's (which a
53 /// LambdaScopeInfo inherits from). The current/deepest/innermost lambda
54 /// is at the top of the stack and has the highest index.
55 /// \param VarToCapture - the variable to capture. If NULL, capture 'this'.
56 ///
57 /// \returns An Optional<unsigned> Index that if evaluates to 'true' contains
58 /// the index (into Sema's FunctionScopeInfo stack) of the innermost lambda
59 /// which is capture-ready. If the return value evaluates to 'false' then
60 /// no lambda is capture-ready for \p VarToCapture.
61
62 static inline Optional<unsigned>
getStackIndexOfNearestEnclosingCaptureReadyLambda(ArrayRef<const clang::sema::FunctionScopeInfo * > FunctionScopes,VarDecl * VarToCapture)63 getStackIndexOfNearestEnclosingCaptureReadyLambda(
64 ArrayRef<const clang::sema::FunctionScopeInfo *> FunctionScopes,
65 VarDecl *VarToCapture) {
66 // Label failure to capture.
67 const Optional<unsigned> NoLambdaIsCaptureReady;
68
69 // Ignore all inner captured regions.
70 unsigned CurScopeIndex = FunctionScopes.size() - 1;
71 while (CurScopeIndex > 0 && isa<clang::sema::CapturedRegionScopeInfo>(
72 FunctionScopes[CurScopeIndex]))
73 --CurScopeIndex;
74 assert(
75 isa<clang::sema::LambdaScopeInfo>(FunctionScopes[CurScopeIndex]) &&
76 "The function on the top of sema's function-info stack must be a lambda");
77
78 // If VarToCapture is null, we are attempting to capture 'this'.
79 const bool IsCapturingThis = !VarToCapture;
80 const bool IsCapturingVariable = !IsCapturingThis;
81
82 // Start with the current lambda at the top of the stack (highest index).
83 DeclContext *EnclosingDC =
84 cast<sema::LambdaScopeInfo>(FunctionScopes[CurScopeIndex])->CallOperator;
85
86 do {
87 const clang::sema::LambdaScopeInfo *LSI =
88 cast<sema::LambdaScopeInfo>(FunctionScopes[CurScopeIndex]);
89 // IF we have climbed down to an intervening enclosing lambda that contains
90 // the variable declaration - it obviously can/must not capture the
91 // variable.
92 // Since its enclosing DC is dependent, all the lambdas between it and the
93 // innermost nested lambda are dependent (otherwise we wouldn't have
94 // arrived here) - so we don't yet have a lambda that can capture the
95 // variable.
96 if (IsCapturingVariable &&
97 VarToCapture->getDeclContext()->Equals(EnclosingDC))
98 return NoLambdaIsCaptureReady;
99
100 // For an enclosing lambda to be capture ready for an entity, all
101 // intervening lambda's have to be able to capture that entity. If even
102 // one of the intervening lambda's is not capable of capturing the entity
103 // then no enclosing lambda can ever capture that entity.
104 // For e.g.
105 // const int x = 10;
106 // [=](auto a) { #1
107 // [](auto b) { #2 <-- an intervening lambda that can never capture 'x'
108 // [=](auto c) { #3
109 // f(x, c); <-- can not lead to x's speculative capture by #1 or #2
110 // }; }; };
111 // If they do not have a default implicit capture, check to see
112 // if the entity has already been explicitly captured.
113 // If even a single dependent enclosing lambda lacks the capability
114 // to ever capture this variable, there is no further enclosing
115 // non-dependent lambda that can capture this variable.
116 if (LSI->ImpCaptureStyle == sema::LambdaScopeInfo::ImpCap_None) {
117 if (IsCapturingVariable && !LSI->isCaptured(VarToCapture))
118 return NoLambdaIsCaptureReady;
119 if (IsCapturingThis && !LSI->isCXXThisCaptured())
120 return NoLambdaIsCaptureReady;
121 }
122 EnclosingDC = getLambdaAwareParentOfDeclContext(EnclosingDC);
123
124 assert(CurScopeIndex);
125 --CurScopeIndex;
126 } while (!EnclosingDC->isTranslationUnit() &&
127 EnclosingDC->isDependentContext() &&
128 isLambdaCallOperator(EnclosingDC));
129
130 assert(CurScopeIndex < (FunctionScopes.size() - 1));
131 // If the enclosingDC is not dependent, then the immediately nested lambda
132 // (one index above) is capture-ready.
133 if (!EnclosingDC->isDependentContext())
134 return CurScopeIndex + 1;
135 return NoLambdaIsCaptureReady;
136 }
137
138 /// Examines the FunctionScopeInfo stack to determine the nearest
139 /// enclosing lambda (to the current lambda) that is 'capture-capable' for
140 /// the variable referenced in the current lambda (i.e. \p VarToCapture).
141 /// If successful, returns the index into Sema's FunctionScopeInfo stack
142 /// of the capture-capable lambda's LambdaScopeInfo.
143 ///
144 /// Given the current stack of lambdas being processed by Sema and
145 /// the variable of interest, to identify the nearest enclosing lambda (to the
146 /// current lambda at the top of the stack) that can truly capture
147 /// a variable, it has to have the following two properties:
148 /// a) 'capture-ready' - be the innermost lambda that is 'capture-ready':
149 /// - climb down the stack (i.e. starting from the innermost and examining
150 /// each outer lambda step by step) checking if each enclosing
151 /// lambda can either implicitly or explicitly capture the variable.
152 /// Record the first such lambda that is enclosed in a non-dependent
153 /// context. If no such lambda currently exists return failure.
154 /// b) 'capture-capable' - make sure the 'capture-ready' lambda can truly
155 /// capture the variable by checking all its enclosing lambdas:
156 /// - check if all outer lambdas enclosing the 'capture-ready' lambda
157 /// identified above in 'a' can also capture the variable (this is done
158 /// via tryCaptureVariable for variables and CheckCXXThisCapture for
159 /// 'this' by passing in the index of the Lambda identified in step 'a')
160 ///
161 /// \param FunctionScopes - Sema's stack of nested FunctionScopeInfo's (which a
162 /// LambdaScopeInfo inherits from). The current/deepest/innermost lambda
163 /// is at the top of the stack.
164 ///
165 /// \param VarToCapture - the variable to capture. If NULL, capture 'this'.
166 ///
167 ///
168 /// \returns An Optional<unsigned> Index that if evaluates to 'true' contains
169 /// the index (into Sema's FunctionScopeInfo stack) of the innermost lambda
170 /// which is capture-capable. If the return value evaluates to 'false' then
171 /// no lambda is capture-capable for \p VarToCapture.
172
getStackIndexOfNearestEnclosingCaptureCapableLambda(ArrayRef<const sema::FunctionScopeInfo * > FunctionScopes,VarDecl * VarToCapture,Sema & S)173 Optional<unsigned> clang::getStackIndexOfNearestEnclosingCaptureCapableLambda(
174 ArrayRef<const sema::FunctionScopeInfo *> FunctionScopes,
175 VarDecl *VarToCapture, Sema &S) {
176
177 const Optional<unsigned> NoLambdaIsCaptureCapable;
178
179 const Optional<unsigned> OptionalStackIndex =
180 getStackIndexOfNearestEnclosingCaptureReadyLambda(FunctionScopes,
181 VarToCapture);
182 if (!OptionalStackIndex)
183 return NoLambdaIsCaptureCapable;
184
185 const unsigned IndexOfCaptureReadyLambda = OptionalStackIndex.getValue();
186 assert(((IndexOfCaptureReadyLambda != (FunctionScopes.size() - 1)) ||
187 S.getCurGenericLambda()) &&
188 "The capture ready lambda for a potential capture can only be the "
189 "current lambda if it is a generic lambda");
190
191 const sema::LambdaScopeInfo *const CaptureReadyLambdaLSI =
192 cast<sema::LambdaScopeInfo>(FunctionScopes[IndexOfCaptureReadyLambda]);
193
194 // If VarToCapture is null, we are attempting to capture 'this'
195 const bool IsCapturingThis = !VarToCapture;
196 const bool IsCapturingVariable = !IsCapturingThis;
197
198 if (IsCapturingVariable) {
199 // Check if the capture-ready lambda can truly capture the variable, by
200 // checking whether all enclosing lambdas of the capture-ready lambda allow
201 // the capture - i.e. make sure it is capture-capable.
202 QualType CaptureType, DeclRefType;
203 const bool CanCaptureVariable =
204 !S.tryCaptureVariable(VarToCapture,
205 /*ExprVarIsUsedInLoc*/ SourceLocation(),
206 clang::Sema::TryCapture_Implicit,
207 /*EllipsisLoc*/ SourceLocation(),
208 /*BuildAndDiagnose*/ false, CaptureType,
209 DeclRefType, &IndexOfCaptureReadyLambda);
210 if (!CanCaptureVariable)
211 return NoLambdaIsCaptureCapable;
212 } else {
213 // Check if the capture-ready lambda can truly capture 'this' by checking
214 // whether all enclosing lambdas of the capture-ready lambda can capture
215 // 'this'.
216 const bool CanCaptureThis =
217 !S.CheckCXXThisCapture(
218 CaptureReadyLambdaLSI->PotentialThisCaptureLocation,
219 /*Explicit*/ false, /*BuildAndDiagnose*/ false,
220 &IndexOfCaptureReadyLambda);
221 if (!CanCaptureThis)
222 return NoLambdaIsCaptureCapable;
223 }
224 return IndexOfCaptureReadyLambda;
225 }
226
227 static inline TemplateParameterList *
getGenericLambdaTemplateParameterList(LambdaScopeInfo * LSI,Sema & SemaRef)228 getGenericLambdaTemplateParameterList(LambdaScopeInfo *LSI, Sema &SemaRef) {
229 if (!LSI->GLTemplateParameterList && !LSI->TemplateParams.empty()) {
230 LSI->GLTemplateParameterList = TemplateParameterList::Create(
231 SemaRef.Context,
232 /*Template kw loc*/ SourceLocation(),
233 /*L angle loc*/ LSI->ExplicitTemplateParamsRange.getBegin(),
234 LSI->TemplateParams,
235 /*R angle loc*/LSI->ExplicitTemplateParamsRange.getEnd(),
236 LSI->RequiresClause.get());
237 }
238 return LSI->GLTemplateParameterList;
239 }
240
createLambdaClosureType(SourceRange IntroducerRange,TypeSourceInfo * Info,bool KnownDependent,LambdaCaptureDefault CaptureDefault)241 CXXRecordDecl *Sema::createLambdaClosureType(SourceRange IntroducerRange,
242 TypeSourceInfo *Info,
243 bool KnownDependent,
244 LambdaCaptureDefault CaptureDefault) {
245 DeclContext *DC = CurContext;
246 while (!(DC->isFunctionOrMethod() || DC->isRecord() || DC->isFileContext()))
247 DC = DC->getParent();
248 bool IsGenericLambda = getGenericLambdaTemplateParameterList(getCurLambda(),
249 *this);
250 // Start constructing the lambda class.
251 CXXRecordDecl *Class = CXXRecordDecl::CreateLambda(Context, DC, Info,
252 IntroducerRange.getBegin(),
253 KnownDependent,
254 IsGenericLambda,
255 CaptureDefault);
256 DC->addDecl(Class);
257
258 return Class;
259 }
260
261 /// Determine whether the given context is or is enclosed in an inline
262 /// function.
isInInlineFunction(const DeclContext * DC)263 static bool isInInlineFunction(const DeclContext *DC) {
264 while (!DC->isFileContext()) {
265 if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(DC))
266 if (FD->isInlined())
267 return true;
268
269 DC = DC->getLexicalParent();
270 }
271
272 return false;
273 }
274
275 std::tuple<MangleNumberingContext *, Decl *>
getCurrentMangleNumberContext(const DeclContext * DC)276 Sema::getCurrentMangleNumberContext(const DeclContext *DC) {
277 // Compute the context for allocating mangling numbers in the current
278 // expression, if the ABI requires them.
279 Decl *ManglingContextDecl = ExprEvalContexts.back().ManglingContextDecl;
280
281 enum ContextKind {
282 Normal,
283 DefaultArgument,
284 DataMember,
285 StaticDataMember,
286 InlineVariable,
287 VariableTemplate
288 } Kind = Normal;
289
290 // Default arguments of member function parameters that appear in a class
291 // definition, as well as the initializers of data members, receive special
292 // treatment. Identify them.
293 if (ManglingContextDecl) {
294 if (ParmVarDecl *Param = dyn_cast<ParmVarDecl>(ManglingContextDecl)) {
295 if (const DeclContext *LexicalDC
296 = Param->getDeclContext()->getLexicalParent())
297 if (LexicalDC->isRecord())
298 Kind = DefaultArgument;
299 } else if (VarDecl *Var = dyn_cast<VarDecl>(ManglingContextDecl)) {
300 if (Var->getDeclContext()->isRecord())
301 Kind = StaticDataMember;
302 else if (Var->getMostRecentDecl()->isInline())
303 Kind = InlineVariable;
304 else if (Var->getDescribedVarTemplate())
305 Kind = VariableTemplate;
306 else if (auto *VTS = dyn_cast<VarTemplateSpecializationDecl>(Var)) {
307 if (!VTS->isExplicitSpecialization())
308 Kind = VariableTemplate;
309 }
310 } else if (isa<FieldDecl>(ManglingContextDecl)) {
311 Kind = DataMember;
312 }
313 }
314
315 // Itanium ABI [5.1.7]:
316 // In the following contexts [...] the one-definition rule requires closure
317 // types in different translation units to "correspond":
318 bool IsInNonspecializedTemplate =
319 inTemplateInstantiation() || CurContext->isDependentContext();
320 switch (Kind) {
321 case Normal: {
322 // -- the bodies of non-exported nonspecialized template functions
323 // -- the bodies of inline functions
324 if ((IsInNonspecializedTemplate &&
325 !(ManglingContextDecl && isa<ParmVarDecl>(ManglingContextDecl))) ||
326 isInInlineFunction(CurContext)) {
327 while (auto *CD = dyn_cast<CapturedDecl>(DC))
328 DC = CD->getParent();
329 return std::make_tuple(&Context.getManglingNumberContext(DC), nullptr);
330 }
331
332 return std::make_tuple(nullptr, nullptr);
333 }
334
335 case StaticDataMember:
336 // -- the initializers of nonspecialized static members of template classes
337 if (!IsInNonspecializedTemplate)
338 return std::make_tuple(nullptr, ManglingContextDecl);
339 // Fall through to get the current context.
340 LLVM_FALLTHROUGH;
341
342 case DataMember:
343 // -- the in-class initializers of class members
344 case DefaultArgument:
345 // -- default arguments appearing in class definitions
346 case InlineVariable:
347 // -- the initializers of inline variables
348 case VariableTemplate:
349 // -- the initializers of templated variables
350 return std::make_tuple(
351 &Context.getManglingNumberContext(ASTContext::NeedExtraManglingDecl,
352 ManglingContextDecl),
353 ManglingContextDecl);
354 }
355
356 llvm_unreachable("unexpected context");
357 }
358
startLambdaDefinition(CXXRecordDecl * Class,SourceRange IntroducerRange,TypeSourceInfo * MethodTypeInfo,SourceLocation EndLoc,ArrayRef<ParmVarDecl * > Params,ConstexprSpecKind ConstexprKind,Expr * TrailingRequiresClause)359 CXXMethodDecl *Sema::startLambdaDefinition(CXXRecordDecl *Class,
360 SourceRange IntroducerRange,
361 TypeSourceInfo *MethodTypeInfo,
362 SourceLocation EndLoc,
363 ArrayRef<ParmVarDecl *> Params,
364 ConstexprSpecKind ConstexprKind,
365 Expr *TrailingRequiresClause) {
366 QualType MethodType = MethodTypeInfo->getType();
367 TemplateParameterList *TemplateParams =
368 getGenericLambdaTemplateParameterList(getCurLambda(), *this);
369 // If a lambda appears in a dependent context or is a generic lambda (has
370 // template parameters) and has an 'auto' return type, deduce it to a
371 // dependent type.
372 if (Class->isDependentContext() || TemplateParams) {
373 const FunctionProtoType *FPT = MethodType->castAs<FunctionProtoType>();
374 QualType Result = FPT->getReturnType();
375 if (Result->isUndeducedType()) {
376 Result = SubstAutoType(Result, Context.DependentTy);
377 MethodType = Context.getFunctionType(Result, FPT->getParamTypes(),
378 FPT->getExtProtoInfo());
379 }
380 }
381
382 // C++11 [expr.prim.lambda]p5:
383 // The closure type for a lambda-expression has a public inline function
384 // call operator (13.5.4) whose parameters and return type are described by
385 // the lambda-expression's parameter-declaration-clause and
386 // trailing-return-type respectively.
387 DeclarationName MethodName
388 = Context.DeclarationNames.getCXXOperatorName(OO_Call);
389 DeclarationNameLoc MethodNameLoc;
390 MethodNameLoc.CXXOperatorName.BeginOpNameLoc
391 = IntroducerRange.getBegin().getRawEncoding();
392 MethodNameLoc.CXXOperatorName.EndOpNameLoc
393 = IntroducerRange.getEnd().getRawEncoding();
394 CXXMethodDecl *Method = CXXMethodDecl::Create(
395 Context, Class, EndLoc,
396 DeclarationNameInfo(MethodName, IntroducerRange.getBegin(),
397 MethodNameLoc),
398 MethodType, MethodTypeInfo, SC_None,
399 /*isInline=*/true, ConstexprKind, EndLoc, TrailingRequiresClause);
400 Method->setAccess(AS_public);
401 if (!TemplateParams)
402 Class->addDecl(Method);
403
404 // Temporarily set the lexical declaration context to the current
405 // context, so that the Scope stack matches the lexical nesting.
406 Method->setLexicalDeclContext(CurContext);
407 // Create a function template if we have a template parameter list
408 FunctionTemplateDecl *const TemplateMethod = TemplateParams ?
409 FunctionTemplateDecl::Create(Context, Class,
410 Method->getLocation(), MethodName,
411 TemplateParams,
412 Method) : nullptr;
413 if (TemplateMethod) {
414 TemplateMethod->setAccess(AS_public);
415 Method->setDescribedFunctionTemplate(TemplateMethod);
416 Class->addDecl(TemplateMethod);
417 TemplateMethod->setLexicalDeclContext(CurContext);
418 }
419
420 // Add parameters.
421 if (!Params.empty()) {
422 Method->setParams(Params);
423 CheckParmsForFunctionDef(Params,
424 /*CheckParameterNames=*/false);
425
426 for (auto P : Method->parameters())
427 P->setOwningFunction(Method);
428 }
429
430 return Method;
431 }
432
handleLambdaNumbering(CXXRecordDecl * Class,CXXMethodDecl * Method,Optional<std::tuple<bool,unsigned,unsigned,Decl * >> Mangling)433 void Sema::handleLambdaNumbering(
434 CXXRecordDecl *Class, CXXMethodDecl *Method,
435 Optional<std::tuple<bool, unsigned, unsigned, Decl *>> Mangling) {
436 if (Mangling) {
437 bool HasKnownInternalLinkage;
438 unsigned ManglingNumber, DeviceManglingNumber;
439 Decl *ManglingContextDecl;
440 std::tie(HasKnownInternalLinkage, ManglingNumber, DeviceManglingNumber,
441 ManglingContextDecl) = Mangling.getValue();
442 Class->setLambdaMangling(ManglingNumber, ManglingContextDecl,
443 HasKnownInternalLinkage);
444 Class->setDeviceLambdaManglingNumber(DeviceManglingNumber);
445 return;
446 }
447
448 auto getMangleNumberingContext =
449 [this](CXXRecordDecl *Class,
450 Decl *ManglingContextDecl) -> MangleNumberingContext * {
451 // Get mangle numbering context if there's any extra decl context.
452 if (ManglingContextDecl)
453 return &Context.getManglingNumberContext(
454 ASTContext::NeedExtraManglingDecl, ManglingContextDecl);
455 // Otherwise, from that lambda's decl context.
456 auto DC = Class->getDeclContext();
457 while (auto *CD = dyn_cast<CapturedDecl>(DC))
458 DC = CD->getParent();
459 return &Context.getManglingNumberContext(DC);
460 };
461
462 MangleNumberingContext *MCtx;
463 Decl *ManglingContextDecl;
464 std::tie(MCtx, ManglingContextDecl) =
465 getCurrentMangleNumberContext(Class->getDeclContext());
466 bool HasKnownInternalLinkage = false;
467 if (!MCtx && getLangOpts().CUDA) {
468 // Force lambda numbering in CUDA/HIP as we need to name lambdas following
469 // ODR. Both device- and host-compilation need to have a consistent naming
470 // on kernel functions. As lambdas are potential part of these `__global__`
471 // function names, they needs numbering following ODR.
472 MCtx = getMangleNumberingContext(Class, ManglingContextDecl);
473 assert(MCtx && "Retrieving mangle numbering context failed!");
474 HasKnownInternalLinkage = true;
475 }
476 if (MCtx) {
477 unsigned ManglingNumber = MCtx->getManglingNumber(Method);
478 Class->setLambdaMangling(ManglingNumber, ManglingContextDecl,
479 HasKnownInternalLinkage);
480 Class->setDeviceLambdaManglingNumber(MCtx->getDeviceManglingNumber(Method));
481 }
482 }
483
buildLambdaScope(LambdaScopeInfo * LSI,CXXMethodDecl * CallOperator,SourceRange IntroducerRange,LambdaCaptureDefault CaptureDefault,SourceLocation CaptureDefaultLoc,bool ExplicitParams,bool ExplicitResultType,bool Mutable)484 void Sema::buildLambdaScope(LambdaScopeInfo *LSI,
485 CXXMethodDecl *CallOperator,
486 SourceRange IntroducerRange,
487 LambdaCaptureDefault CaptureDefault,
488 SourceLocation CaptureDefaultLoc,
489 bool ExplicitParams,
490 bool ExplicitResultType,
491 bool Mutable) {
492 LSI->CallOperator = CallOperator;
493 CXXRecordDecl *LambdaClass = CallOperator->getParent();
494 LSI->Lambda = LambdaClass;
495 if (CaptureDefault == LCD_ByCopy)
496 LSI->ImpCaptureStyle = LambdaScopeInfo::ImpCap_LambdaByval;
497 else if (CaptureDefault == LCD_ByRef)
498 LSI->ImpCaptureStyle = LambdaScopeInfo::ImpCap_LambdaByref;
499 LSI->CaptureDefaultLoc = CaptureDefaultLoc;
500 LSI->IntroducerRange = IntroducerRange;
501 LSI->ExplicitParams = ExplicitParams;
502 LSI->Mutable = Mutable;
503
504 if (ExplicitResultType) {
505 LSI->ReturnType = CallOperator->getReturnType();
506
507 if (!LSI->ReturnType->isDependentType() &&
508 !LSI->ReturnType->isVoidType()) {
509 if (RequireCompleteType(CallOperator->getBeginLoc(), LSI->ReturnType,
510 diag::err_lambda_incomplete_result)) {
511 // Do nothing.
512 }
513 }
514 } else {
515 LSI->HasImplicitReturnType = true;
516 }
517 }
518
finishLambdaExplicitCaptures(LambdaScopeInfo * LSI)519 void Sema::finishLambdaExplicitCaptures(LambdaScopeInfo *LSI) {
520 LSI->finishedExplicitCaptures();
521 }
522
ActOnLambdaExplicitTemplateParameterList(SourceLocation LAngleLoc,ArrayRef<NamedDecl * > TParams,SourceLocation RAngleLoc,ExprResult RequiresClause)523 void Sema::ActOnLambdaExplicitTemplateParameterList(SourceLocation LAngleLoc,
524 ArrayRef<NamedDecl *> TParams,
525 SourceLocation RAngleLoc,
526 ExprResult RequiresClause) {
527 LambdaScopeInfo *LSI = getCurLambda();
528 assert(LSI && "Expected a lambda scope");
529 assert(LSI->NumExplicitTemplateParams == 0 &&
530 "Already acted on explicit template parameters");
531 assert(LSI->TemplateParams.empty() &&
532 "Explicit template parameters should come "
533 "before invented (auto) ones");
534 assert(!TParams.empty() &&
535 "No template parameters to act on");
536 LSI->TemplateParams.append(TParams.begin(), TParams.end());
537 LSI->NumExplicitTemplateParams = TParams.size();
538 LSI->ExplicitTemplateParamsRange = {LAngleLoc, RAngleLoc};
539 LSI->RequiresClause = RequiresClause;
540 }
541
addLambdaParameters(ArrayRef<LambdaIntroducer::LambdaCapture> Captures,CXXMethodDecl * CallOperator,Scope * CurScope)542 void Sema::addLambdaParameters(
543 ArrayRef<LambdaIntroducer::LambdaCapture> Captures,
544 CXXMethodDecl *CallOperator, Scope *CurScope) {
545 // Introduce our parameters into the function scope
546 for (unsigned p = 0, NumParams = CallOperator->getNumParams();
547 p < NumParams; ++p) {
548 ParmVarDecl *Param = CallOperator->getParamDecl(p);
549
550 // If this has an identifier, add it to the scope stack.
551 if (CurScope && Param->getIdentifier()) {
552 bool Error = false;
553 // Resolution of CWG 2211 in C++17 renders shadowing ill-formed, but we
554 // retroactively apply it.
555 for (const auto &Capture : Captures) {
556 if (Capture.Id == Param->getIdentifier()) {
557 Error = true;
558 Diag(Param->getLocation(), diag::err_parameter_shadow_capture);
559 Diag(Capture.Loc, diag::note_var_explicitly_captured_here)
560 << Capture.Id << true;
561 }
562 }
563 if (!Error)
564 CheckShadow(CurScope, Param);
565
566 PushOnScopeChains(Param, CurScope);
567 }
568 }
569 }
570
571 /// If this expression is an enumerator-like expression of some type
572 /// T, return the type T; otherwise, return null.
573 ///
574 /// Pointer comparisons on the result here should always work because
575 /// it's derived from either the parent of an EnumConstantDecl
576 /// (i.e. the definition) or the declaration returned by
577 /// EnumType::getDecl() (i.e. the definition).
findEnumForBlockReturn(Expr * E)578 static EnumDecl *findEnumForBlockReturn(Expr *E) {
579 // An expression is an enumerator-like expression of type T if,
580 // ignoring parens and parens-like expressions:
581 E = E->IgnoreParens();
582
583 // - it is an enumerator whose enum type is T or
584 if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E)) {
585 if (EnumConstantDecl *D
586 = dyn_cast<EnumConstantDecl>(DRE->getDecl())) {
587 return cast<EnumDecl>(D->getDeclContext());
588 }
589 return nullptr;
590 }
591
592 // - it is a comma expression whose RHS is an enumerator-like
593 // expression of type T or
594 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) {
595 if (BO->getOpcode() == BO_Comma)
596 return findEnumForBlockReturn(BO->getRHS());
597 return nullptr;
598 }
599
600 // - it is a statement-expression whose value expression is an
601 // enumerator-like expression of type T or
602 if (StmtExpr *SE = dyn_cast<StmtExpr>(E)) {
603 if (Expr *last = dyn_cast_or_null<Expr>(SE->getSubStmt()->body_back()))
604 return findEnumForBlockReturn(last);
605 return nullptr;
606 }
607
608 // - it is a ternary conditional operator (not the GNU ?:
609 // extension) whose second and third operands are
610 // enumerator-like expressions of type T or
611 if (ConditionalOperator *CO = dyn_cast<ConditionalOperator>(E)) {
612 if (EnumDecl *ED = findEnumForBlockReturn(CO->getTrueExpr()))
613 if (ED == findEnumForBlockReturn(CO->getFalseExpr()))
614 return ED;
615 return nullptr;
616 }
617
618 // (implicitly:)
619 // - it is an implicit integral conversion applied to an
620 // enumerator-like expression of type T or
621 if (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(E)) {
622 // We can sometimes see integral conversions in valid
623 // enumerator-like expressions.
624 if (ICE->getCastKind() == CK_IntegralCast)
625 return findEnumForBlockReturn(ICE->getSubExpr());
626
627 // Otherwise, just rely on the type.
628 }
629
630 // - it is an expression of that formal enum type.
631 if (const EnumType *ET = E->getType()->getAs<EnumType>()) {
632 return ET->getDecl();
633 }
634
635 // Otherwise, nope.
636 return nullptr;
637 }
638
639 /// Attempt to find a type T for which the returned expression of the
640 /// given statement is an enumerator-like expression of that type.
findEnumForBlockReturn(ReturnStmt * ret)641 static EnumDecl *findEnumForBlockReturn(ReturnStmt *ret) {
642 if (Expr *retValue = ret->getRetValue())
643 return findEnumForBlockReturn(retValue);
644 return nullptr;
645 }
646
647 /// Attempt to find a common type T for which all of the returned
648 /// expressions in a block are enumerator-like expressions of that
649 /// type.
findCommonEnumForBlockReturns(ArrayRef<ReturnStmt * > returns)650 static EnumDecl *findCommonEnumForBlockReturns(ArrayRef<ReturnStmt*> returns) {
651 ArrayRef<ReturnStmt*>::iterator i = returns.begin(), e = returns.end();
652
653 // Try to find one for the first return.
654 EnumDecl *ED = findEnumForBlockReturn(*i);
655 if (!ED) return nullptr;
656
657 // Check that the rest of the returns have the same enum.
658 for (++i; i != e; ++i) {
659 if (findEnumForBlockReturn(*i) != ED)
660 return nullptr;
661 }
662
663 // Never infer an anonymous enum type.
664 if (!ED->hasNameForLinkage()) return nullptr;
665
666 return ED;
667 }
668
669 /// Adjust the given return statements so that they formally return
670 /// the given type. It should require, at most, an IntegralCast.
adjustBlockReturnsToEnum(Sema & S,ArrayRef<ReturnStmt * > returns,QualType returnType)671 static void adjustBlockReturnsToEnum(Sema &S, ArrayRef<ReturnStmt*> returns,
672 QualType returnType) {
673 for (ArrayRef<ReturnStmt*>::iterator
674 i = returns.begin(), e = returns.end(); i != e; ++i) {
675 ReturnStmt *ret = *i;
676 Expr *retValue = ret->getRetValue();
677 if (S.Context.hasSameType(retValue->getType(), returnType))
678 continue;
679
680 // Right now we only support integral fixup casts.
681 assert(returnType->isIntegralOrUnscopedEnumerationType());
682 assert(retValue->getType()->isIntegralOrUnscopedEnumerationType());
683
684 ExprWithCleanups *cleanups = dyn_cast<ExprWithCleanups>(retValue);
685
686 Expr *E = (cleanups ? cleanups->getSubExpr() : retValue);
687 E = ImplicitCastExpr::Create(S.Context, returnType, CK_IntegralCast, E,
688 /*base path*/ nullptr, VK_RValue,
689 FPOptionsOverride());
690 if (cleanups) {
691 cleanups->setSubExpr(E);
692 } else {
693 ret->setRetValue(E);
694 }
695 }
696 }
697
deduceClosureReturnType(CapturingScopeInfo & CSI)698 void Sema::deduceClosureReturnType(CapturingScopeInfo &CSI) {
699 assert(CSI.HasImplicitReturnType);
700 // If it was ever a placeholder, it had to been deduced to DependentTy.
701 assert(CSI.ReturnType.isNull() || !CSI.ReturnType->isUndeducedType());
702 assert((!isa<LambdaScopeInfo>(CSI) || !getLangOpts().CPlusPlus14) &&
703 "lambda expressions use auto deduction in C++14 onwards");
704
705 // C++ core issue 975:
706 // If a lambda-expression does not include a trailing-return-type,
707 // it is as if the trailing-return-type denotes the following type:
708 // - if there are no return statements in the compound-statement,
709 // or all return statements return either an expression of type
710 // void or no expression or braced-init-list, the type void;
711 // - otherwise, if all return statements return an expression
712 // and the types of the returned expressions after
713 // lvalue-to-rvalue conversion (4.1 [conv.lval]),
714 // array-to-pointer conversion (4.2 [conv.array]), and
715 // function-to-pointer conversion (4.3 [conv.func]) are the
716 // same, that common type;
717 // - otherwise, the program is ill-formed.
718 //
719 // C++ core issue 1048 additionally removes top-level cv-qualifiers
720 // from the types of returned expressions to match the C++14 auto
721 // deduction rules.
722 //
723 // In addition, in blocks in non-C++ modes, if all of the return
724 // statements are enumerator-like expressions of some type T, where
725 // T has a name for linkage, then we infer the return type of the
726 // block to be that type.
727
728 // First case: no return statements, implicit void return type.
729 ASTContext &Ctx = getASTContext();
730 if (CSI.Returns.empty()) {
731 // It's possible there were simply no /valid/ return statements.
732 // In this case, the first one we found may have at least given us a type.
733 if (CSI.ReturnType.isNull())
734 CSI.ReturnType = Ctx.VoidTy;
735 return;
736 }
737
738 // Second case: at least one return statement has dependent type.
739 // Delay type checking until instantiation.
740 assert(!CSI.ReturnType.isNull() && "We should have a tentative return type.");
741 if (CSI.ReturnType->isDependentType())
742 return;
743
744 // Try to apply the enum-fuzz rule.
745 if (!getLangOpts().CPlusPlus) {
746 assert(isa<BlockScopeInfo>(CSI));
747 const EnumDecl *ED = findCommonEnumForBlockReturns(CSI.Returns);
748 if (ED) {
749 CSI.ReturnType = Context.getTypeDeclType(ED);
750 adjustBlockReturnsToEnum(*this, CSI.Returns, CSI.ReturnType);
751 return;
752 }
753 }
754
755 // Third case: only one return statement. Don't bother doing extra work!
756 if (CSI.Returns.size() == 1)
757 return;
758
759 // General case: many return statements.
760 // Check that they all have compatible return types.
761
762 // We require the return types to strictly match here.
763 // Note that we've already done the required promotions as part of
764 // processing the return statement.
765 for (const ReturnStmt *RS : CSI.Returns) {
766 const Expr *RetE = RS->getRetValue();
767
768 QualType ReturnType =
769 (RetE ? RetE->getType() : Context.VoidTy).getUnqualifiedType();
770 if (Context.getCanonicalFunctionResultType(ReturnType) ==
771 Context.getCanonicalFunctionResultType(CSI.ReturnType)) {
772 // Use the return type with the strictest possible nullability annotation.
773 auto RetTyNullability = ReturnType->getNullability(Ctx);
774 auto BlockNullability = CSI.ReturnType->getNullability(Ctx);
775 if (BlockNullability &&
776 (!RetTyNullability ||
777 hasWeakerNullability(*RetTyNullability, *BlockNullability)))
778 CSI.ReturnType = ReturnType;
779 continue;
780 }
781
782 // FIXME: This is a poor diagnostic for ReturnStmts without expressions.
783 // TODO: It's possible that the *first* return is the divergent one.
784 Diag(RS->getBeginLoc(),
785 diag::err_typecheck_missing_return_type_incompatible)
786 << ReturnType << CSI.ReturnType << isa<LambdaScopeInfo>(CSI);
787 // Continue iterating so that we keep emitting diagnostics.
788 }
789 }
790
buildLambdaInitCaptureInitialization(SourceLocation Loc,bool ByRef,SourceLocation EllipsisLoc,Optional<unsigned> NumExpansions,IdentifierInfo * Id,bool IsDirectInit,Expr * & Init)791 QualType Sema::buildLambdaInitCaptureInitialization(
792 SourceLocation Loc, bool ByRef, SourceLocation EllipsisLoc,
793 Optional<unsigned> NumExpansions, IdentifierInfo *Id, bool IsDirectInit,
794 Expr *&Init) {
795 // Create an 'auto' or 'auto&' TypeSourceInfo that we can use to
796 // deduce against.
797 QualType DeductType = Context.getAutoDeductType();
798 TypeLocBuilder TLB;
799 AutoTypeLoc TL = TLB.push<AutoTypeLoc>(DeductType);
800 TL.setNameLoc(Loc);
801 if (ByRef) {
802 DeductType = BuildReferenceType(DeductType, true, Loc, Id);
803 assert(!DeductType.isNull() && "can't build reference to auto");
804 TLB.push<ReferenceTypeLoc>(DeductType).setSigilLoc(Loc);
805 }
806 if (EllipsisLoc.isValid()) {
807 if (Init->containsUnexpandedParameterPack()) {
808 Diag(EllipsisLoc, getLangOpts().CPlusPlus20
809 ? diag::warn_cxx17_compat_init_capture_pack
810 : diag::ext_init_capture_pack);
811 DeductType = Context.getPackExpansionType(DeductType, NumExpansions,
812 /*ExpectPackInType=*/false);
813 TLB.push<PackExpansionTypeLoc>(DeductType).setEllipsisLoc(EllipsisLoc);
814 } else {
815 // Just ignore the ellipsis for now and form a non-pack variable. We'll
816 // diagnose this later when we try to capture it.
817 }
818 }
819 TypeSourceInfo *TSI = TLB.getTypeSourceInfo(Context, DeductType);
820
821 // Deduce the type of the init capture.
822 QualType DeducedType = deduceVarTypeFromInitializer(
823 /*VarDecl*/nullptr, DeclarationName(Id), DeductType, TSI,
824 SourceRange(Loc, Loc), IsDirectInit, Init);
825 if (DeducedType.isNull())
826 return QualType();
827
828 // Are we a non-list direct initialization?
829 ParenListExpr *CXXDirectInit = dyn_cast<ParenListExpr>(Init);
830
831 // Perform initialization analysis and ensure any implicit conversions
832 // (such as lvalue-to-rvalue) are enforced.
833 InitializedEntity Entity =
834 InitializedEntity::InitializeLambdaCapture(Id, DeducedType, Loc);
835 InitializationKind Kind =
836 IsDirectInit
837 ? (CXXDirectInit ? InitializationKind::CreateDirect(
838 Loc, Init->getBeginLoc(), Init->getEndLoc())
839 : InitializationKind::CreateDirectList(Loc))
840 : InitializationKind::CreateCopy(Loc, Init->getBeginLoc());
841
842 MultiExprArg Args = Init;
843 if (CXXDirectInit)
844 Args =
845 MultiExprArg(CXXDirectInit->getExprs(), CXXDirectInit->getNumExprs());
846 QualType DclT;
847 InitializationSequence InitSeq(*this, Entity, Kind, Args);
848 ExprResult Result = InitSeq.Perform(*this, Entity, Kind, Args, &DclT);
849
850 if (Result.isInvalid())
851 return QualType();
852
853 Init = Result.getAs<Expr>();
854 return DeducedType;
855 }
856
createLambdaInitCaptureVarDecl(SourceLocation Loc,QualType InitCaptureType,SourceLocation EllipsisLoc,IdentifierInfo * Id,unsigned InitStyle,Expr * Init)857 VarDecl *Sema::createLambdaInitCaptureVarDecl(SourceLocation Loc,
858 QualType InitCaptureType,
859 SourceLocation EllipsisLoc,
860 IdentifierInfo *Id,
861 unsigned InitStyle, Expr *Init) {
862 // FIXME: Retain the TypeSourceInfo from buildLambdaInitCaptureInitialization
863 // rather than reconstructing it here.
864 TypeSourceInfo *TSI = Context.getTrivialTypeSourceInfo(InitCaptureType, Loc);
865 if (auto PETL = TSI->getTypeLoc().getAs<PackExpansionTypeLoc>())
866 PETL.setEllipsisLoc(EllipsisLoc);
867
868 // Create a dummy variable representing the init-capture. This is not actually
869 // used as a variable, and only exists as a way to name and refer to the
870 // init-capture.
871 // FIXME: Pass in separate source locations for '&' and identifier.
872 VarDecl *NewVD = VarDecl::Create(Context, CurContext, Loc,
873 Loc, Id, InitCaptureType, TSI, SC_Auto);
874 NewVD->setInitCapture(true);
875 NewVD->setReferenced(true);
876 // FIXME: Pass in a VarDecl::InitializationStyle.
877 NewVD->setInitStyle(static_cast<VarDecl::InitializationStyle>(InitStyle));
878 NewVD->markUsed(Context);
879 NewVD->setInit(Init);
880 if (NewVD->isParameterPack())
881 getCurLambda()->LocalPacks.push_back(NewVD);
882 return NewVD;
883 }
884
addInitCapture(LambdaScopeInfo * LSI,VarDecl * Var)885 void Sema::addInitCapture(LambdaScopeInfo *LSI, VarDecl *Var) {
886 assert(Var->isInitCapture() && "init capture flag should be set");
887 LSI->addCapture(Var, /*isBlock*/false, Var->getType()->isReferenceType(),
888 /*isNested*/false, Var->getLocation(), SourceLocation(),
889 Var->getType(), /*Invalid*/false);
890 }
891
ActOnStartOfLambdaDefinition(LambdaIntroducer & Intro,Declarator & ParamInfo,Scope * CurScope)892 void Sema::ActOnStartOfLambdaDefinition(LambdaIntroducer &Intro,
893 Declarator &ParamInfo,
894 Scope *CurScope) {
895 LambdaScopeInfo *const LSI = getCurLambda();
896 assert(LSI && "LambdaScopeInfo should be on stack!");
897
898 // Determine if we're within a context where we know that the lambda will
899 // be dependent, because there are template parameters in scope.
900 bool KnownDependent;
901 if (LSI->NumExplicitTemplateParams > 0) {
902 auto *TemplateParamScope = CurScope->getTemplateParamParent();
903 assert(TemplateParamScope &&
904 "Lambda with explicit template param list should establish a "
905 "template param scope");
906 assert(TemplateParamScope->getParent());
907 KnownDependent = TemplateParamScope->getParent()
908 ->getTemplateParamParent() != nullptr;
909 } else {
910 KnownDependent = CurScope->getTemplateParamParent() != nullptr;
911 }
912
913 // Determine the signature of the call operator.
914 TypeSourceInfo *MethodTyInfo;
915 bool ExplicitParams = true;
916 bool ExplicitResultType = true;
917 bool ContainsUnexpandedParameterPack = false;
918 SourceLocation EndLoc;
919 SmallVector<ParmVarDecl *, 8> Params;
920 if (ParamInfo.getNumTypeObjects() == 0) {
921 // C++11 [expr.prim.lambda]p4:
922 // If a lambda-expression does not include a lambda-declarator, it is as
923 // if the lambda-declarator were ().
924 FunctionProtoType::ExtProtoInfo EPI(Context.getDefaultCallingConvention(
925 /*IsVariadic=*/false, /*IsCXXMethod=*/true));
926 EPI.HasTrailingReturn = true;
927 EPI.TypeQuals.addConst();
928 LangAS AS = getDefaultCXXMethodAddrSpace();
929 if (AS != LangAS::Default)
930 EPI.TypeQuals.addAddressSpace(AS);
931
932 // C++1y [expr.prim.lambda]:
933 // The lambda return type is 'auto', which is replaced by the
934 // trailing-return type if provided and/or deduced from 'return'
935 // statements
936 // We don't do this before C++1y, because we don't support deduced return
937 // types there.
938 QualType DefaultTypeForNoTrailingReturn =
939 getLangOpts().CPlusPlus14 ? Context.getAutoDeductType()
940 : Context.DependentTy;
941 QualType MethodTy =
942 Context.getFunctionType(DefaultTypeForNoTrailingReturn, None, EPI);
943 MethodTyInfo = Context.getTrivialTypeSourceInfo(MethodTy);
944 ExplicitParams = false;
945 ExplicitResultType = false;
946 EndLoc = Intro.Range.getEnd();
947 } else {
948 assert(ParamInfo.isFunctionDeclarator() &&
949 "lambda-declarator is a function");
950 DeclaratorChunk::FunctionTypeInfo &FTI = ParamInfo.getFunctionTypeInfo();
951
952 // C++11 [expr.prim.lambda]p5:
953 // This function call operator is declared const (9.3.1) if and only if
954 // the lambda-expression's parameter-declaration-clause is not followed
955 // by mutable. It is neither virtual nor declared volatile. [...]
956 if (!FTI.hasMutableQualifier()) {
957 FTI.getOrCreateMethodQualifiers().SetTypeQual(DeclSpec::TQ_const,
958 SourceLocation());
959 }
960
961 MethodTyInfo = GetTypeForDeclarator(ParamInfo, CurScope);
962 assert(MethodTyInfo && "no type from lambda-declarator");
963 EndLoc = ParamInfo.getSourceRange().getEnd();
964
965 ExplicitResultType = FTI.hasTrailingReturnType();
966
967 if (FTIHasNonVoidParameters(FTI)) {
968 Params.reserve(FTI.NumParams);
969 for (unsigned i = 0, e = FTI.NumParams; i != e; ++i)
970 Params.push_back(cast<ParmVarDecl>(FTI.Params[i].Param));
971 }
972
973 // Check for unexpanded parameter packs in the method type.
974 if (MethodTyInfo->getType()->containsUnexpandedParameterPack())
975 DiagnoseUnexpandedParameterPack(Intro.Range.getBegin(), MethodTyInfo,
976 UPPC_DeclarationType);
977 }
978
979 CXXRecordDecl *Class = createLambdaClosureType(Intro.Range, MethodTyInfo,
980 KnownDependent, Intro.Default);
981 CXXMethodDecl *Method =
982 startLambdaDefinition(Class, Intro.Range, MethodTyInfo, EndLoc, Params,
983 ParamInfo.getDeclSpec().getConstexprSpecifier(),
984 ParamInfo.getTrailingRequiresClause());
985 if (ExplicitParams)
986 CheckCXXDefaultArguments(Method);
987
988 // This represents the function body for the lambda function, check if we
989 // have to apply optnone due to a pragma.
990 AddRangeBasedOptnone(Method);
991
992 // code_seg attribute on lambda apply to the method.
993 if (Attr *A = getImplicitCodeSegOrSectionAttrForFunction(Method, /*IsDefinition=*/true))
994 Method->addAttr(A);
995
996 // Attributes on the lambda apply to the method.
997 ProcessDeclAttributes(CurScope, Method, ParamInfo);
998
999 // CUDA lambdas get implicit host and device attributes.
1000 if (getLangOpts().CUDA)
1001 CUDASetLambdaAttrs(Method);
1002
1003 // OpenMP lambdas might get assumumption attributes.
1004 if (LangOpts.OpenMP)
1005 ActOnFinishedFunctionDefinitionInOpenMPAssumeScope(Method);
1006
1007 // Number the lambda for linkage purposes if necessary.
1008 handleLambdaNumbering(Class, Method);
1009
1010 // Introduce the function call operator as the current declaration context.
1011 PushDeclContext(CurScope, Method);
1012
1013 // Build the lambda scope.
1014 buildLambdaScope(LSI, Method, Intro.Range, Intro.Default, Intro.DefaultLoc,
1015 ExplicitParams, ExplicitResultType, !Method->isConst());
1016
1017 // C++11 [expr.prim.lambda]p9:
1018 // A lambda-expression whose smallest enclosing scope is a block scope is a
1019 // local lambda expression; any other lambda expression shall not have a
1020 // capture-default or simple-capture in its lambda-introducer.
1021 //
1022 // For simple-captures, this is covered by the check below that any named
1023 // entity is a variable that can be captured.
1024 //
1025 // For DR1632, we also allow a capture-default in any context where we can
1026 // odr-use 'this' (in particular, in a default initializer for a non-static
1027 // data member).
1028 if (Intro.Default != LCD_None && !Class->getParent()->isFunctionOrMethod() &&
1029 (getCurrentThisType().isNull() ||
1030 CheckCXXThisCapture(SourceLocation(), /*Explicit*/true,
1031 /*BuildAndDiagnose*/false)))
1032 Diag(Intro.DefaultLoc, diag::err_capture_default_non_local);
1033
1034 // Distinct capture names, for diagnostics.
1035 llvm::SmallSet<IdentifierInfo*, 8> CaptureNames;
1036
1037 // Handle explicit captures.
1038 SourceLocation PrevCaptureLoc
1039 = Intro.Default == LCD_None? Intro.Range.getBegin() : Intro.DefaultLoc;
1040 for (auto C = Intro.Captures.begin(), E = Intro.Captures.end(); C != E;
1041 PrevCaptureLoc = C->Loc, ++C) {
1042 if (C->Kind == LCK_This || C->Kind == LCK_StarThis) {
1043 if (C->Kind == LCK_StarThis)
1044 Diag(C->Loc, !getLangOpts().CPlusPlus17
1045 ? diag::ext_star_this_lambda_capture_cxx17
1046 : diag::warn_cxx14_compat_star_this_lambda_capture);
1047
1048 // C++11 [expr.prim.lambda]p8:
1049 // An identifier or this shall not appear more than once in a
1050 // lambda-capture.
1051 if (LSI->isCXXThisCaptured()) {
1052 Diag(C->Loc, diag::err_capture_more_than_once)
1053 << "'this'" << SourceRange(LSI->getCXXThisCapture().getLocation())
1054 << FixItHint::CreateRemoval(
1055 SourceRange(getLocForEndOfToken(PrevCaptureLoc), C->Loc));
1056 continue;
1057 }
1058
1059 // C++2a [expr.prim.lambda]p8:
1060 // If a lambda-capture includes a capture-default that is =,
1061 // each simple-capture of that lambda-capture shall be of the form
1062 // "&identifier", "this", or "* this". [ Note: The form [&,this] is
1063 // redundant but accepted for compatibility with ISO C++14. --end note ]
1064 if (Intro.Default == LCD_ByCopy && C->Kind != LCK_StarThis)
1065 Diag(C->Loc, !getLangOpts().CPlusPlus20
1066 ? diag::ext_equals_this_lambda_capture_cxx20
1067 : diag::warn_cxx17_compat_equals_this_lambda_capture);
1068
1069 // C++11 [expr.prim.lambda]p12:
1070 // If this is captured by a local lambda expression, its nearest
1071 // enclosing function shall be a non-static member function.
1072 QualType ThisCaptureType = getCurrentThisType();
1073 if (ThisCaptureType.isNull()) {
1074 Diag(C->Loc, diag::err_this_capture) << true;
1075 continue;
1076 }
1077
1078 CheckCXXThisCapture(C->Loc, /*Explicit=*/true, /*BuildAndDiagnose*/ true,
1079 /*FunctionScopeIndexToStopAtPtr*/ nullptr,
1080 C->Kind == LCK_StarThis);
1081 if (!LSI->Captures.empty())
1082 LSI->ExplicitCaptureRanges[LSI->Captures.size() - 1] = C->ExplicitRange;
1083 continue;
1084 }
1085
1086 assert(C->Id && "missing identifier for capture");
1087
1088 if (C->Init.isInvalid())
1089 continue;
1090
1091 VarDecl *Var = nullptr;
1092 if (C->Init.isUsable()) {
1093 Diag(C->Loc, getLangOpts().CPlusPlus14
1094 ? diag::warn_cxx11_compat_init_capture
1095 : diag::ext_init_capture);
1096
1097 // If the initializer expression is usable, but the InitCaptureType
1098 // is not, then an error has occurred - so ignore the capture for now.
1099 // for e.g., [n{0}] { }; <-- if no <initializer_list> is included.
1100 // FIXME: we should create the init capture variable and mark it invalid
1101 // in this case.
1102 if (C->InitCaptureType.get().isNull())
1103 continue;
1104
1105 if (C->Init.get()->containsUnexpandedParameterPack() &&
1106 !C->InitCaptureType.get()->getAs<PackExpansionType>())
1107 DiagnoseUnexpandedParameterPack(C->Init.get(), UPPC_Initializer);
1108
1109 unsigned InitStyle;
1110 switch (C->InitKind) {
1111 case LambdaCaptureInitKind::NoInit:
1112 llvm_unreachable("not an init-capture?");
1113 case LambdaCaptureInitKind::CopyInit:
1114 InitStyle = VarDecl::CInit;
1115 break;
1116 case LambdaCaptureInitKind::DirectInit:
1117 InitStyle = VarDecl::CallInit;
1118 break;
1119 case LambdaCaptureInitKind::ListInit:
1120 InitStyle = VarDecl::ListInit;
1121 break;
1122 }
1123 Var = createLambdaInitCaptureVarDecl(C->Loc, C->InitCaptureType.get(),
1124 C->EllipsisLoc, C->Id, InitStyle,
1125 C->Init.get());
1126 // C++1y [expr.prim.lambda]p11:
1127 // An init-capture behaves as if it declares and explicitly
1128 // captures a variable [...] whose declarative region is the
1129 // lambda-expression's compound-statement
1130 if (Var)
1131 PushOnScopeChains(Var, CurScope, false);
1132 } else {
1133 assert(C->InitKind == LambdaCaptureInitKind::NoInit &&
1134 "init capture has valid but null init?");
1135
1136 // C++11 [expr.prim.lambda]p8:
1137 // If a lambda-capture includes a capture-default that is &, the
1138 // identifiers in the lambda-capture shall not be preceded by &.
1139 // If a lambda-capture includes a capture-default that is =, [...]
1140 // each identifier it contains shall be preceded by &.
1141 if (C->Kind == LCK_ByRef && Intro.Default == LCD_ByRef) {
1142 Diag(C->Loc, diag::err_reference_capture_with_reference_default)
1143 << FixItHint::CreateRemoval(
1144 SourceRange(getLocForEndOfToken(PrevCaptureLoc), C->Loc));
1145 continue;
1146 } else if (C->Kind == LCK_ByCopy && Intro.Default == LCD_ByCopy) {
1147 Diag(C->Loc, diag::err_copy_capture_with_copy_default)
1148 << FixItHint::CreateRemoval(
1149 SourceRange(getLocForEndOfToken(PrevCaptureLoc), C->Loc));
1150 continue;
1151 }
1152
1153 // C++11 [expr.prim.lambda]p10:
1154 // The identifiers in a capture-list are looked up using the usual
1155 // rules for unqualified name lookup (3.4.1)
1156 DeclarationNameInfo Name(C->Id, C->Loc);
1157 LookupResult R(*this, Name, LookupOrdinaryName);
1158 LookupName(R, CurScope);
1159 if (R.isAmbiguous())
1160 continue;
1161 if (R.empty()) {
1162 // FIXME: Disable corrections that would add qualification?
1163 CXXScopeSpec ScopeSpec;
1164 DeclFilterCCC<VarDecl> Validator{};
1165 if (DiagnoseEmptyLookup(CurScope, ScopeSpec, R, Validator))
1166 continue;
1167 }
1168
1169 Var = R.getAsSingle<VarDecl>();
1170 if (Var && DiagnoseUseOfDecl(Var, C->Loc))
1171 continue;
1172 }
1173
1174 // C++11 [expr.prim.lambda]p8:
1175 // An identifier or this shall not appear more than once in a
1176 // lambda-capture.
1177 if (!CaptureNames.insert(C->Id).second) {
1178 if (Var && LSI->isCaptured(Var)) {
1179 Diag(C->Loc, diag::err_capture_more_than_once)
1180 << C->Id << SourceRange(LSI->getCapture(Var).getLocation())
1181 << FixItHint::CreateRemoval(
1182 SourceRange(getLocForEndOfToken(PrevCaptureLoc), C->Loc));
1183 } else
1184 // Previous capture captured something different (one or both was
1185 // an init-cpature): no fixit.
1186 Diag(C->Loc, diag::err_capture_more_than_once) << C->Id;
1187 continue;
1188 }
1189
1190 // C++11 [expr.prim.lambda]p10:
1191 // [...] each such lookup shall find a variable with automatic storage
1192 // duration declared in the reaching scope of the local lambda expression.
1193 // Note that the 'reaching scope' check happens in tryCaptureVariable().
1194 if (!Var) {
1195 Diag(C->Loc, diag::err_capture_does_not_name_variable) << C->Id;
1196 continue;
1197 }
1198
1199 // Ignore invalid decls; they'll just confuse the code later.
1200 if (Var->isInvalidDecl())
1201 continue;
1202
1203 if (!Var->hasLocalStorage()) {
1204 Diag(C->Loc, diag::err_capture_non_automatic_variable) << C->Id;
1205 Diag(Var->getLocation(), diag::note_previous_decl) << C->Id;
1206 continue;
1207 }
1208
1209 // C++11 [expr.prim.lambda]p23:
1210 // A capture followed by an ellipsis is a pack expansion (14.5.3).
1211 SourceLocation EllipsisLoc;
1212 if (C->EllipsisLoc.isValid()) {
1213 if (Var->isParameterPack()) {
1214 EllipsisLoc = C->EllipsisLoc;
1215 } else {
1216 Diag(C->EllipsisLoc, diag::err_pack_expansion_without_parameter_packs)
1217 << (C->Init.isUsable() ? C->Init.get()->getSourceRange()
1218 : SourceRange(C->Loc));
1219
1220 // Just ignore the ellipsis.
1221 }
1222 } else if (Var->isParameterPack()) {
1223 ContainsUnexpandedParameterPack = true;
1224 }
1225
1226 if (C->Init.isUsable()) {
1227 addInitCapture(LSI, Var);
1228 } else {
1229 TryCaptureKind Kind = C->Kind == LCK_ByRef ? TryCapture_ExplicitByRef :
1230 TryCapture_ExplicitByVal;
1231 tryCaptureVariable(Var, C->Loc, Kind, EllipsisLoc);
1232 }
1233 if (!LSI->Captures.empty())
1234 LSI->ExplicitCaptureRanges[LSI->Captures.size() - 1] = C->ExplicitRange;
1235 }
1236 finishLambdaExplicitCaptures(LSI);
1237
1238 LSI->ContainsUnexpandedParameterPack |= ContainsUnexpandedParameterPack;
1239
1240 // Add lambda parameters into scope.
1241 addLambdaParameters(Intro.Captures, Method, CurScope);
1242
1243 // Enter a new evaluation context to insulate the lambda from any
1244 // cleanups from the enclosing full-expression.
1245 PushExpressionEvaluationContext(
1246 LSI->CallOperator->isConsteval()
1247 ? ExpressionEvaluationContext::ConstantEvaluated
1248 : ExpressionEvaluationContext::PotentiallyEvaluated);
1249 }
1250
ActOnLambdaError(SourceLocation StartLoc,Scope * CurScope,bool IsInstantiation)1251 void Sema::ActOnLambdaError(SourceLocation StartLoc, Scope *CurScope,
1252 bool IsInstantiation) {
1253 LambdaScopeInfo *LSI = cast<LambdaScopeInfo>(FunctionScopes.back());
1254
1255 // Leave the expression-evaluation context.
1256 DiscardCleanupsInEvaluationContext();
1257 PopExpressionEvaluationContext();
1258
1259 // Leave the context of the lambda.
1260 if (!IsInstantiation)
1261 PopDeclContext();
1262
1263 // Finalize the lambda.
1264 CXXRecordDecl *Class = LSI->Lambda;
1265 Class->setInvalidDecl();
1266 SmallVector<Decl*, 4> Fields(Class->fields());
1267 ActOnFields(nullptr, Class->getLocation(), Class, Fields, SourceLocation(),
1268 SourceLocation(), ParsedAttributesView());
1269 CheckCompletedCXXClass(nullptr, Class);
1270
1271 PopFunctionScopeInfo();
1272 }
1273
1274 template <typename Func>
repeatForLambdaConversionFunctionCallingConvs(Sema & S,const FunctionProtoType & CallOpProto,Func F)1275 static void repeatForLambdaConversionFunctionCallingConvs(
1276 Sema &S, const FunctionProtoType &CallOpProto, Func F) {
1277 CallingConv DefaultFree = S.Context.getDefaultCallingConvention(
1278 CallOpProto.isVariadic(), /*IsCXXMethod=*/false);
1279 CallingConv DefaultMember = S.Context.getDefaultCallingConvention(
1280 CallOpProto.isVariadic(), /*IsCXXMethod=*/true);
1281 CallingConv CallOpCC = CallOpProto.getCallConv();
1282
1283 /// Implement emitting a version of the operator for many of the calling
1284 /// conventions for MSVC, as described here:
1285 /// https://devblogs.microsoft.com/oldnewthing/20150220-00/?p=44623.
1286 /// Experimentally, we determined that cdecl, stdcall, fastcall, and
1287 /// vectorcall are generated by MSVC when it is supported by the target.
1288 /// Additionally, we are ensuring that the default-free/default-member and
1289 /// call-operator calling convention are generated as well.
1290 /// NOTE: We intentionally generate a 'thiscall' on Win32 implicitly from the
1291 /// 'member default', despite MSVC not doing so. We do this in order to ensure
1292 /// that someone who intentionally places 'thiscall' on the lambda call
1293 /// operator will still get that overload, since we don't have the a way of
1294 /// detecting the attribute by the time we get here.
1295 if (S.getLangOpts().MSVCCompat) {
1296 CallingConv Convs[] = {
1297 CC_C, CC_X86StdCall, CC_X86FastCall, CC_X86VectorCall,
1298 DefaultFree, DefaultMember, CallOpCC};
1299 llvm::sort(Convs);
1300 llvm::iterator_range<CallingConv *> Range(
1301 std::begin(Convs), std::unique(std::begin(Convs), std::end(Convs)));
1302 const TargetInfo &TI = S.getASTContext().getTargetInfo();
1303
1304 for (CallingConv C : Range) {
1305 if (TI.checkCallingConvention(C) == TargetInfo::CCCR_OK)
1306 F(C);
1307 }
1308 return;
1309 }
1310
1311 if (CallOpCC == DefaultMember && DefaultMember != DefaultFree) {
1312 F(DefaultFree);
1313 F(DefaultMember);
1314 } else {
1315 F(CallOpCC);
1316 }
1317 }
1318
1319 // Returns the 'standard' calling convention to be used for the lambda
1320 // conversion function, that is, the 'free' function calling convention unless
1321 // it is overridden by a non-default calling convention attribute.
1322 static CallingConv
getLambdaConversionFunctionCallConv(Sema & S,const FunctionProtoType * CallOpProto)1323 getLambdaConversionFunctionCallConv(Sema &S,
1324 const FunctionProtoType *CallOpProto) {
1325 CallingConv DefaultFree = S.Context.getDefaultCallingConvention(
1326 CallOpProto->isVariadic(), /*IsCXXMethod=*/false);
1327 CallingConv DefaultMember = S.Context.getDefaultCallingConvention(
1328 CallOpProto->isVariadic(), /*IsCXXMethod=*/true);
1329 CallingConv CallOpCC = CallOpProto->getCallConv();
1330
1331 // If the call-operator hasn't been changed, return both the 'free' and
1332 // 'member' function calling convention.
1333 if (CallOpCC == DefaultMember && DefaultMember != DefaultFree)
1334 return DefaultFree;
1335 return CallOpCC;
1336 }
1337
getLambdaConversionFunctionResultType(const FunctionProtoType * CallOpProto,CallingConv CC)1338 QualType Sema::getLambdaConversionFunctionResultType(
1339 const FunctionProtoType *CallOpProto, CallingConv CC) {
1340 const FunctionProtoType::ExtProtoInfo CallOpExtInfo =
1341 CallOpProto->getExtProtoInfo();
1342 FunctionProtoType::ExtProtoInfo InvokerExtInfo = CallOpExtInfo;
1343 InvokerExtInfo.ExtInfo = InvokerExtInfo.ExtInfo.withCallingConv(CC);
1344 InvokerExtInfo.TypeQuals = Qualifiers();
1345 assert(InvokerExtInfo.RefQualifier == RQ_None &&
1346 "Lambda's call operator should not have a reference qualifier");
1347 return Context.getFunctionType(CallOpProto->getReturnType(),
1348 CallOpProto->getParamTypes(), InvokerExtInfo);
1349 }
1350
1351 /// Add a lambda's conversion to function pointer, as described in
1352 /// C++11 [expr.prim.lambda]p6.
addFunctionPointerConversion(Sema & S,SourceRange IntroducerRange,CXXRecordDecl * Class,CXXMethodDecl * CallOperator,QualType InvokerFunctionTy)1353 static void addFunctionPointerConversion(Sema &S, SourceRange IntroducerRange,
1354 CXXRecordDecl *Class,
1355 CXXMethodDecl *CallOperator,
1356 QualType InvokerFunctionTy) {
1357 // This conversion is explicitly disabled if the lambda's function has
1358 // pass_object_size attributes on any of its parameters.
1359 auto HasPassObjectSizeAttr = [](const ParmVarDecl *P) {
1360 return P->hasAttr<PassObjectSizeAttr>();
1361 };
1362 if (llvm::any_of(CallOperator->parameters(), HasPassObjectSizeAttr))
1363 return;
1364
1365 // Add the conversion to function pointer.
1366 QualType PtrToFunctionTy = S.Context.getPointerType(InvokerFunctionTy);
1367
1368 // Create the type of the conversion function.
1369 FunctionProtoType::ExtProtoInfo ConvExtInfo(
1370 S.Context.getDefaultCallingConvention(
1371 /*IsVariadic=*/false, /*IsCXXMethod=*/true));
1372 // The conversion function is always const and noexcept.
1373 ConvExtInfo.TypeQuals = Qualifiers();
1374 ConvExtInfo.TypeQuals.addConst();
1375 ConvExtInfo.ExceptionSpec.Type = EST_BasicNoexcept;
1376 QualType ConvTy =
1377 S.Context.getFunctionType(PtrToFunctionTy, None, ConvExtInfo);
1378
1379 SourceLocation Loc = IntroducerRange.getBegin();
1380 DeclarationName ConversionName
1381 = S.Context.DeclarationNames.getCXXConversionFunctionName(
1382 S.Context.getCanonicalType(PtrToFunctionTy));
1383 DeclarationNameLoc ConvNameLoc;
1384 // Construct a TypeSourceInfo for the conversion function, and wire
1385 // all the parameters appropriately for the FunctionProtoTypeLoc
1386 // so that everything works during transformation/instantiation of
1387 // generic lambdas.
1388 // The main reason for wiring up the parameters of the conversion
1389 // function with that of the call operator is so that constructs
1390 // like the following work:
1391 // auto L = [](auto b) { <-- 1
1392 // return [](auto a) -> decltype(a) { <-- 2
1393 // return a;
1394 // };
1395 // };
1396 // int (*fp)(int) = L(5);
1397 // Because the trailing return type can contain DeclRefExprs that refer
1398 // to the original call operator's variables, we hijack the call
1399 // operators ParmVarDecls below.
1400 TypeSourceInfo *ConvNamePtrToFunctionTSI =
1401 S.Context.getTrivialTypeSourceInfo(PtrToFunctionTy, Loc);
1402 ConvNameLoc.NamedType.TInfo = ConvNamePtrToFunctionTSI;
1403
1404 // The conversion function is a conversion to a pointer-to-function.
1405 TypeSourceInfo *ConvTSI = S.Context.getTrivialTypeSourceInfo(ConvTy, Loc);
1406 FunctionProtoTypeLoc ConvTL =
1407 ConvTSI->getTypeLoc().getAs<FunctionProtoTypeLoc>();
1408 // Get the result of the conversion function which is a pointer-to-function.
1409 PointerTypeLoc PtrToFunctionTL =
1410 ConvTL.getReturnLoc().getAs<PointerTypeLoc>();
1411 // Do the same for the TypeSourceInfo that is used to name the conversion
1412 // operator.
1413 PointerTypeLoc ConvNamePtrToFunctionTL =
1414 ConvNamePtrToFunctionTSI->getTypeLoc().getAs<PointerTypeLoc>();
1415
1416 // Get the underlying function types that the conversion function will
1417 // be converting to (should match the type of the call operator).
1418 FunctionProtoTypeLoc CallOpConvTL =
1419 PtrToFunctionTL.getPointeeLoc().getAs<FunctionProtoTypeLoc>();
1420 FunctionProtoTypeLoc CallOpConvNameTL =
1421 ConvNamePtrToFunctionTL.getPointeeLoc().getAs<FunctionProtoTypeLoc>();
1422
1423 // Wire up the FunctionProtoTypeLocs with the call operator's parameters.
1424 // These parameter's are essentially used to transform the name and
1425 // the type of the conversion operator. By using the same parameters
1426 // as the call operator's we don't have to fix any back references that
1427 // the trailing return type of the call operator's uses (such as
1428 // decltype(some_type<decltype(a)>::type{} + decltype(a){}) etc.)
1429 // - we can simply use the return type of the call operator, and
1430 // everything should work.
1431 SmallVector<ParmVarDecl *, 4> InvokerParams;
1432 for (unsigned I = 0, N = CallOperator->getNumParams(); I != N; ++I) {
1433 ParmVarDecl *From = CallOperator->getParamDecl(I);
1434
1435 InvokerParams.push_back(ParmVarDecl::Create(
1436 S.Context,
1437 // Temporarily add to the TU. This is set to the invoker below.
1438 S.Context.getTranslationUnitDecl(), From->getBeginLoc(),
1439 From->getLocation(), From->getIdentifier(), From->getType(),
1440 From->getTypeSourceInfo(), From->getStorageClass(),
1441 /*DefArg=*/nullptr));
1442 CallOpConvTL.setParam(I, From);
1443 CallOpConvNameTL.setParam(I, From);
1444 }
1445
1446 CXXConversionDecl *Conversion = CXXConversionDecl::Create(
1447 S.Context, Class, Loc,
1448 DeclarationNameInfo(ConversionName, Loc, ConvNameLoc), ConvTy, ConvTSI,
1449 /*isInline=*/true, ExplicitSpecifier(),
1450 S.getLangOpts().CPlusPlus17 ? ConstexprSpecKind::Constexpr
1451 : ConstexprSpecKind::Unspecified,
1452 CallOperator->getBody()->getEndLoc());
1453 Conversion->setAccess(AS_public);
1454 Conversion->setImplicit(true);
1455
1456 if (Class->isGenericLambda()) {
1457 // Create a template version of the conversion operator, using the template
1458 // parameter list of the function call operator.
1459 FunctionTemplateDecl *TemplateCallOperator =
1460 CallOperator->getDescribedFunctionTemplate();
1461 FunctionTemplateDecl *ConversionTemplate =
1462 FunctionTemplateDecl::Create(S.Context, Class,
1463 Loc, ConversionName,
1464 TemplateCallOperator->getTemplateParameters(),
1465 Conversion);
1466 ConversionTemplate->setAccess(AS_public);
1467 ConversionTemplate->setImplicit(true);
1468 Conversion->setDescribedFunctionTemplate(ConversionTemplate);
1469 Class->addDecl(ConversionTemplate);
1470 } else
1471 Class->addDecl(Conversion);
1472 // Add a non-static member function that will be the result of
1473 // the conversion with a certain unique ID.
1474 DeclarationName InvokerName = &S.Context.Idents.get(
1475 getLambdaStaticInvokerName());
1476 // FIXME: Instead of passing in the CallOperator->getTypeSourceInfo()
1477 // we should get a prebuilt TrivialTypeSourceInfo from Context
1478 // using FunctionTy & Loc and get its TypeLoc as a FunctionProtoTypeLoc
1479 // then rewire the parameters accordingly, by hoisting up the InvokeParams
1480 // loop below and then use its Params to set Invoke->setParams(...) below.
1481 // This would avoid the 'const' qualifier of the calloperator from
1482 // contaminating the type of the invoker, which is currently adjusted
1483 // in SemaTemplateDeduction.cpp:DeduceTemplateArguments. Fixing the
1484 // trailing return type of the invoker would require a visitor to rebuild
1485 // the trailing return type and adjusting all back DeclRefExpr's to refer
1486 // to the new static invoker parameters - not the call operator's.
1487 CXXMethodDecl *Invoke = CXXMethodDecl::Create(
1488 S.Context, Class, Loc, DeclarationNameInfo(InvokerName, Loc),
1489 InvokerFunctionTy, CallOperator->getTypeSourceInfo(), SC_Static,
1490 /*isInline=*/true, ConstexprSpecKind::Unspecified,
1491 CallOperator->getBody()->getEndLoc());
1492 for (unsigned I = 0, N = CallOperator->getNumParams(); I != N; ++I)
1493 InvokerParams[I]->setOwningFunction(Invoke);
1494 Invoke->setParams(InvokerParams);
1495 Invoke->setAccess(AS_private);
1496 Invoke->setImplicit(true);
1497 if (Class->isGenericLambda()) {
1498 FunctionTemplateDecl *TemplateCallOperator =
1499 CallOperator->getDescribedFunctionTemplate();
1500 FunctionTemplateDecl *StaticInvokerTemplate = FunctionTemplateDecl::Create(
1501 S.Context, Class, Loc, InvokerName,
1502 TemplateCallOperator->getTemplateParameters(),
1503 Invoke);
1504 StaticInvokerTemplate->setAccess(AS_private);
1505 StaticInvokerTemplate->setImplicit(true);
1506 Invoke->setDescribedFunctionTemplate(StaticInvokerTemplate);
1507 Class->addDecl(StaticInvokerTemplate);
1508 } else
1509 Class->addDecl(Invoke);
1510 }
1511
1512 /// Add a lambda's conversion to function pointers, as described in
1513 /// C++11 [expr.prim.lambda]p6. Note that in most cases, this should emit only a
1514 /// single pointer conversion. In the event that the default calling convention
1515 /// for free and member functions is different, it will emit both conventions.
addFunctionPointerConversions(Sema & S,SourceRange IntroducerRange,CXXRecordDecl * Class,CXXMethodDecl * CallOperator)1516 static void addFunctionPointerConversions(Sema &S, SourceRange IntroducerRange,
1517 CXXRecordDecl *Class,
1518 CXXMethodDecl *CallOperator) {
1519 const FunctionProtoType *CallOpProto =
1520 CallOperator->getType()->castAs<FunctionProtoType>();
1521
1522 repeatForLambdaConversionFunctionCallingConvs(
1523 S, *CallOpProto, [&](CallingConv CC) {
1524 QualType InvokerFunctionTy =
1525 S.getLambdaConversionFunctionResultType(CallOpProto, CC);
1526 addFunctionPointerConversion(S, IntroducerRange, Class, CallOperator,
1527 InvokerFunctionTy);
1528 });
1529 }
1530
1531 /// Add a lambda's conversion to block pointer.
addBlockPointerConversion(Sema & S,SourceRange IntroducerRange,CXXRecordDecl * Class,CXXMethodDecl * CallOperator)1532 static void addBlockPointerConversion(Sema &S,
1533 SourceRange IntroducerRange,
1534 CXXRecordDecl *Class,
1535 CXXMethodDecl *CallOperator) {
1536 const FunctionProtoType *CallOpProto =
1537 CallOperator->getType()->castAs<FunctionProtoType>();
1538 QualType FunctionTy = S.getLambdaConversionFunctionResultType(
1539 CallOpProto, getLambdaConversionFunctionCallConv(S, CallOpProto));
1540 QualType BlockPtrTy = S.Context.getBlockPointerType(FunctionTy);
1541
1542 FunctionProtoType::ExtProtoInfo ConversionEPI(
1543 S.Context.getDefaultCallingConvention(
1544 /*IsVariadic=*/false, /*IsCXXMethod=*/true));
1545 ConversionEPI.TypeQuals = Qualifiers();
1546 ConversionEPI.TypeQuals.addConst();
1547 QualType ConvTy = S.Context.getFunctionType(BlockPtrTy, None, ConversionEPI);
1548
1549 SourceLocation Loc = IntroducerRange.getBegin();
1550 DeclarationName Name
1551 = S.Context.DeclarationNames.getCXXConversionFunctionName(
1552 S.Context.getCanonicalType(BlockPtrTy));
1553 DeclarationNameLoc NameLoc;
1554 NameLoc.NamedType.TInfo = S.Context.getTrivialTypeSourceInfo(BlockPtrTy, Loc);
1555 CXXConversionDecl *Conversion = CXXConversionDecl::Create(
1556 S.Context, Class, Loc, DeclarationNameInfo(Name, Loc, NameLoc), ConvTy,
1557 S.Context.getTrivialTypeSourceInfo(ConvTy, Loc),
1558 /*isInline=*/true, ExplicitSpecifier(), ConstexprSpecKind::Unspecified,
1559 CallOperator->getBody()->getEndLoc());
1560 Conversion->setAccess(AS_public);
1561 Conversion->setImplicit(true);
1562 Class->addDecl(Conversion);
1563 }
1564
BuildCaptureInit(const Capture & Cap,SourceLocation ImplicitCaptureLoc,bool IsOpenMPMapping)1565 ExprResult Sema::BuildCaptureInit(const Capture &Cap,
1566 SourceLocation ImplicitCaptureLoc,
1567 bool IsOpenMPMapping) {
1568 // VLA captures don't have a stored initialization expression.
1569 if (Cap.isVLATypeCapture())
1570 return ExprResult();
1571
1572 // An init-capture is initialized directly from its stored initializer.
1573 if (Cap.isInitCapture())
1574 return Cap.getVariable()->getInit();
1575
1576 // For anything else, build an initialization expression. For an implicit
1577 // capture, the capture notionally happens at the capture-default, so use
1578 // that location here.
1579 SourceLocation Loc =
1580 ImplicitCaptureLoc.isValid() ? ImplicitCaptureLoc : Cap.getLocation();
1581
1582 // C++11 [expr.prim.lambda]p21:
1583 // When the lambda-expression is evaluated, the entities that
1584 // are captured by copy are used to direct-initialize each
1585 // corresponding non-static data member of the resulting closure
1586 // object. (For array members, the array elements are
1587 // direct-initialized in increasing subscript order.) These
1588 // initializations are performed in the (unspecified) order in
1589 // which the non-static data members are declared.
1590
1591 // C++ [expr.prim.lambda]p12:
1592 // An entity captured by a lambda-expression is odr-used (3.2) in
1593 // the scope containing the lambda-expression.
1594 ExprResult Init;
1595 IdentifierInfo *Name = nullptr;
1596 if (Cap.isThisCapture()) {
1597 QualType ThisTy = getCurrentThisType();
1598 Expr *This = BuildCXXThisExpr(Loc, ThisTy, ImplicitCaptureLoc.isValid());
1599 if (Cap.isCopyCapture())
1600 Init = CreateBuiltinUnaryOp(Loc, UO_Deref, This);
1601 else
1602 Init = This;
1603 } else {
1604 assert(Cap.isVariableCapture() && "unknown kind of capture");
1605 VarDecl *Var = Cap.getVariable();
1606 Name = Var->getIdentifier();
1607 Init = BuildDeclarationNameExpr(
1608 CXXScopeSpec(), DeclarationNameInfo(Var->getDeclName(), Loc), Var);
1609 }
1610
1611 // In OpenMP, the capture kind doesn't actually describe how to capture:
1612 // variables are "mapped" onto the device in a process that does not formally
1613 // make a copy, even for a "copy capture".
1614 if (IsOpenMPMapping)
1615 return Init;
1616
1617 if (Init.isInvalid())
1618 return ExprError();
1619
1620 Expr *InitExpr = Init.get();
1621 InitializedEntity Entity = InitializedEntity::InitializeLambdaCapture(
1622 Name, Cap.getCaptureType(), Loc);
1623 InitializationKind InitKind =
1624 InitializationKind::CreateDirect(Loc, Loc, Loc);
1625 InitializationSequence InitSeq(*this, Entity, InitKind, InitExpr);
1626 return InitSeq.Perform(*this, Entity, InitKind, InitExpr);
1627 }
1628
ActOnLambdaExpr(SourceLocation StartLoc,Stmt * Body,Scope * CurScope)1629 ExprResult Sema::ActOnLambdaExpr(SourceLocation StartLoc, Stmt *Body,
1630 Scope *CurScope) {
1631 LambdaScopeInfo LSI = *cast<LambdaScopeInfo>(FunctionScopes.back());
1632 ActOnFinishFunctionBody(LSI.CallOperator, Body);
1633 return BuildLambdaExpr(StartLoc, Body->getEndLoc(), &LSI);
1634 }
1635
1636 static LambdaCaptureDefault
mapImplicitCaptureStyle(CapturingScopeInfo::ImplicitCaptureStyle ICS)1637 mapImplicitCaptureStyle(CapturingScopeInfo::ImplicitCaptureStyle ICS) {
1638 switch (ICS) {
1639 case CapturingScopeInfo::ImpCap_None:
1640 return LCD_None;
1641 case CapturingScopeInfo::ImpCap_LambdaByval:
1642 return LCD_ByCopy;
1643 case CapturingScopeInfo::ImpCap_CapturedRegion:
1644 case CapturingScopeInfo::ImpCap_LambdaByref:
1645 return LCD_ByRef;
1646 case CapturingScopeInfo::ImpCap_Block:
1647 llvm_unreachable("block capture in lambda");
1648 }
1649 llvm_unreachable("Unknown implicit capture style");
1650 }
1651
CaptureHasSideEffects(const Capture & From)1652 bool Sema::CaptureHasSideEffects(const Capture &From) {
1653 if (From.isInitCapture()) {
1654 Expr *Init = From.getVariable()->getInit();
1655 if (Init && Init->HasSideEffects(Context))
1656 return true;
1657 }
1658
1659 if (!From.isCopyCapture())
1660 return false;
1661
1662 const QualType T = From.isThisCapture()
1663 ? getCurrentThisType()->getPointeeType()
1664 : From.getCaptureType();
1665
1666 if (T.isVolatileQualified())
1667 return true;
1668
1669 const Type *BaseT = T->getBaseElementTypeUnsafe();
1670 if (const CXXRecordDecl *RD = BaseT->getAsCXXRecordDecl())
1671 return !RD->isCompleteDefinition() || !RD->hasTrivialCopyConstructor() ||
1672 !RD->hasTrivialDestructor();
1673
1674 return false;
1675 }
1676
DiagnoseUnusedLambdaCapture(SourceRange CaptureRange,const Capture & From)1677 bool Sema::DiagnoseUnusedLambdaCapture(SourceRange CaptureRange,
1678 const Capture &From) {
1679 if (CaptureHasSideEffects(From))
1680 return false;
1681
1682 if (From.isVLATypeCapture())
1683 return false;
1684
1685 auto diag = Diag(From.getLocation(), diag::warn_unused_lambda_capture);
1686 if (From.isThisCapture())
1687 diag << "'this'";
1688 else
1689 diag << From.getVariable();
1690 diag << From.isNonODRUsed();
1691 diag << FixItHint::CreateRemoval(CaptureRange);
1692 return true;
1693 }
1694
1695 /// Create a field within the lambda class or captured statement record for the
1696 /// given capture.
BuildCaptureField(RecordDecl * RD,const sema::Capture & Capture)1697 FieldDecl *Sema::BuildCaptureField(RecordDecl *RD,
1698 const sema::Capture &Capture) {
1699 SourceLocation Loc = Capture.getLocation();
1700 QualType FieldType = Capture.getCaptureType();
1701
1702 TypeSourceInfo *TSI = nullptr;
1703 if (Capture.isVariableCapture()) {
1704 auto *Var = Capture.getVariable();
1705 if (Var->isInitCapture())
1706 TSI = Capture.getVariable()->getTypeSourceInfo();
1707 }
1708
1709 // FIXME: Should we really be doing this? A null TypeSourceInfo seems more
1710 // appropriate, at least for an implicit capture.
1711 if (!TSI)
1712 TSI = Context.getTrivialTypeSourceInfo(FieldType, Loc);
1713
1714 // Build the non-static data member.
1715 FieldDecl *Field =
1716 FieldDecl::Create(Context, RD, /*StartLoc=*/Loc, /*IdLoc=*/Loc,
1717 /*Id=*/nullptr, FieldType, TSI, /*BW=*/nullptr,
1718 /*Mutable=*/false, ICIS_NoInit);
1719 // If the variable being captured has an invalid type, mark the class as
1720 // invalid as well.
1721 if (!FieldType->isDependentType()) {
1722 if (RequireCompleteSizedType(Loc, FieldType,
1723 diag::err_field_incomplete_or_sizeless)) {
1724 RD->setInvalidDecl();
1725 Field->setInvalidDecl();
1726 } else {
1727 NamedDecl *Def;
1728 FieldType->isIncompleteType(&Def);
1729 if (Def && Def->isInvalidDecl()) {
1730 RD->setInvalidDecl();
1731 Field->setInvalidDecl();
1732 }
1733 }
1734 }
1735 Field->setImplicit(true);
1736 Field->setAccess(AS_private);
1737 RD->addDecl(Field);
1738
1739 if (Capture.isVLATypeCapture())
1740 Field->setCapturedVLAType(Capture.getCapturedVLAType());
1741
1742 return Field;
1743 }
1744
BuildLambdaExpr(SourceLocation StartLoc,SourceLocation EndLoc,LambdaScopeInfo * LSI)1745 ExprResult Sema::BuildLambdaExpr(SourceLocation StartLoc, SourceLocation EndLoc,
1746 LambdaScopeInfo *LSI) {
1747 // Collect information from the lambda scope.
1748 SmallVector<LambdaCapture, 4> Captures;
1749 SmallVector<Expr *, 4> CaptureInits;
1750 SourceLocation CaptureDefaultLoc = LSI->CaptureDefaultLoc;
1751 LambdaCaptureDefault CaptureDefault =
1752 mapImplicitCaptureStyle(LSI->ImpCaptureStyle);
1753 CXXRecordDecl *Class;
1754 CXXMethodDecl *CallOperator;
1755 SourceRange IntroducerRange;
1756 bool ExplicitParams;
1757 bool ExplicitResultType;
1758 CleanupInfo LambdaCleanup;
1759 bool ContainsUnexpandedParameterPack;
1760 bool IsGenericLambda;
1761 {
1762 CallOperator = LSI->CallOperator;
1763 Class = LSI->Lambda;
1764 IntroducerRange = LSI->IntroducerRange;
1765 ExplicitParams = LSI->ExplicitParams;
1766 ExplicitResultType = !LSI->HasImplicitReturnType;
1767 LambdaCleanup = LSI->Cleanup;
1768 ContainsUnexpandedParameterPack = LSI->ContainsUnexpandedParameterPack;
1769 IsGenericLambda = Class->isGenericLambda();
1770
1771 CallOperator->setLexicalDeclContext(Class);
1772 Decl *TemplateOrNonTemplateCallOperatorDecl =
1773 CallOperator->getDescribedFunctionTemplate()
1774 ? CallOperator->getDescribedFunctionTemplate()
1775 : cast<Decl>(CallOperator);
1776
1777 // FIXME: Is this really the best choice? Keeping the lexical decl context
1778 // set as CurContext seems more faithful to the source.
1779 TemplateOrNonTemplateCallOperatorDecl->setLexicalDeclContext(Class);
1780
1781 PopExpressionEvaluationContext();
1782
1783 // True if the current capture has a used capture or default before it.
1784 bool CurHasPreviousCapture = CaptureDefault != LCD_None;
1785 SourceLocation PrevCaptureLoc = CurHasPreviousCapture ?
1786 CaptureDefaultLoc : IntroducerRange.getBegin();
1787
1788 for (unsigned I = 0, N = LSI->Captures.size(); I != N; ++I) {
1789 const Capture &From = LSI->Captures[I];
1790
1791 if (From.isInvalid())
1792 return ExprError();
1793
1794 assert(!From.isBlockCapture() && "Cannot capture __block variables");
1795 bool IsImplicit = I >= LSI->NumExplicitCaptures;
1796 SourceLocation ImplicitCaptureLoc =
1797 IsImplicit ? CaptureDefaultLoc : SourceLocation();
1798
1799 // Use source ranges of explicit captures for fixits where available.
1800 SourceRange CaptureRange = LSI->ExplicitCaptureRanges[I];
1801
1802 // Warn about unused explicit captures.
1803 bool IsCaptureUsed = true;
1804 if (!CurContext->isDependentContext() && !IsImplicit &&
1805 !From.isODRUsed()) {
1806 // Initialized captures that are non-ODR used may not be eliminated.
1807 // FIXME: Where did the IsGenericLambda here come from?
1808 bool NonODRUsedInitCapture =
1809 IsGenericLambda && From.isNonODRUsed() && From.isInitCapture();
1810 if (!NonODRUsedInitCapture) {
1811 bool IsLast = (I + 1) == LSI->NumExplicitCaptures;
1812 SourceRange FixItRange;
1813 if (CaptureRange.isValid()) {
1814 if (!CurHasPreviousCapture && !IsLast) {
1815 // If there are no captures preceding this capture, remove the
1816 // following comma.
1817 FixItRange = SourceRange(CaptureRange.getBegin(),
1818 getLocForEndOfToken(CaptureRange.getEnd()));
1819 } else {
1820 // Otherwise, remove the comma since the last used capture.
1821 FixItRange = SourceRange(getLocForEndOfToken(PrevCaptureLoc),
1822 CaptureRange.getEnd());
1823 }
1824 }
1825
1826 IsCaptureUsed = !DiagnoseUnusedLambdaCapture(FixItRange, From);
1827 }
1828 }
1829
1830 if (CaptureRange.isValid()) {
1831 CurHasPreviousCapture |= IsCaptureUsed;
1832 PrevCaptureLoc = CaptureRange.getEnd();
1833 }
1834
1835 // Map the capture to our AST representation.
1836 LambdaCapture Capture = [&] {
1837 if (From.isThisCapture()) {
1838 // Capturing 'this' implicitly with a default of '[=]' is deprecated,
1839 // because it results in a reference capture. Don't warn prior to
1840 // C++2a; there's nothing that can be done about it before then.
1841 if (getLangOpts().CPlusPlus20 && IsImplicit &&
1842 CaptureDefault == LCD_ByCopy) {
1843 Diag(From.getLocation(), diag::warn_deprecated_this_capture);
1844 Diag(CaptureDefaultLoc, diag::note_deprecated_this_capture)
1845 << FixItHint::CreateInsertion(
1846 getLocForEndOfToken(CaptureDefaultLoc), ", this");
1847 }
1848 return LambdaCapture(From.getLocation(), IsImplicit,
1849 From.isCopyCapture() ? LCK_StarThis : LCK_This);
1850 } else if (From.isVLATypeCapture()) {
1851 return LambdaCapture(From.getLocation(), IsImplicit, LCK_VLAType);
1852 } else {
1853 assert(From.isVariableCapture() && "unknown kind of capture");
1854 VarDecl *Var = From.getVariable();
1855 LambdaCaptureKind Kind =
1856 From.isCopyCapture() ? LCK_ByCopy : LCK_ByRef;
1857 return LambdaCapture(From.getLocation(), IsImplicit, Kind, Var,
1858 From.getEllipsisLoc());
1859 }
1860 }();
1861
1862 // Form the initializer for the capture field.
1863 ExprResult Init = BuildCaptureInit(From, ImplicitCaptureLoc);
1864
1865 // FIXME: Skip this capture if the capture is not used, the initializer
1866 // has no side-effects, the type of the capture is trivial, and the
1867 // lambda is not externally visible.
1868
1869 // Add a FieldDecl for the capture and form its initializer.
1870 BuildCaptureField(Class, From);
1871 Captures.push_back(Capture);
1872 CaptureInits.push_back(Init.get());
1873
1874 if (LangOpts.CUDA)
1875 CUDACheckLambdaCapture(CallOperator, From);
1876 }
1877
1878 Class->setCaptures(Context, Captures);
1879
1880 // C++11 [expr.prim.lambda]p6:
1881 // The closure type for a lambda-expression with no lambda-capture
1882 // has a public non-virtual non-explicit const conversion function
1883 // to pointer to function having the same parameter and return
1884 // types as the closure type's function call operator.
1885 if (Captures.empty() && CaptureDefault == LCD_None)
1886 addFunctionPointerConversions(*this, IntroducerRange, Class,
1887 CallOperator);
1888
1889 // Objective-C++:
1890 // The closure type for a lambda-expression has a public non-virtual
1891 // non-explicit const conversion function to a block pointer having the
1892 // same parameter and return types as the closure type's function call
1893 // operator.
1894 // FIXME: Fix generic lambda to block conversions.
1895 if (getLangOpts().Blocks && getLangOpts().ObjC && !IsGenericLambda)
1896 addBlockPointerConversion(*this, IntroducerRange, Class, CallOperator);
1897
1898 // Finalize the lambda class.
1899 SmallVector<Decl*, 4> Fields(Class->fields());
1900 ActOnFields(nullptr, Class->getLocation(), Class, Fields, SourceLocation(),
1901 SourceLocation(), ParsedAttributesView());
1902 CheckCompletedCXXClass(nullptr, Class);
1903 }
1904
1905 Cleanup.mergeFrom(LambdaCleanup);
1906
1907 LambdaExpr *Lambda = LambdaExpr::Create(Context, Class, IntroducerRange,
1908 CaptureDefault, CaptureDefaultLoc,
1909 ExplicitParams, ExplicitResultType,
1910 CaptureInits, EndLoc,
1911 ContainsUnexpandedParameterPack);
1912 // If the lambda expression's call operator is not explicitly marked constexpr
1913 // and we are not in a dependent context, analyze the call operator to infer
1914 // its constexpr-ness, suppressing diagnostics while doing so.
1915 if (getLangOpts().CPlusPlus17 && !CallOperator->isInvalidDecl() &&
1916 !CallOperator->isConstexpr() &&
1917 !isa<CoroutineBodyStmt>(CallOperator->getBody()) &&
1918 !Class->getDeclContext()->isDependentContext()) {
1919 CallOperator->setConstexprKind(
1920 CheckConstexprFunctionDefinition(CallOperator,
1921 CheckConstexprKind::CheckValid)
1922 ? ConstexprSpecKind::Constexpr
1923 : ConstexprSpecKind::Unspecified);
1924 }
1925
1926 // Emit delayed shadowing warnings now that the full capture list is known.
1927 DiagnoseShadowingLambdaDecls(LSI);
1928
1929 if (!CurContext->isDependentContext()) {
1930 switch (ExprEvalContexts.back().Context) {
1931 // C++11 [expr.prim.lambda]p2:
1932 // A lambda-expression shall not appear in an unevaluated operand
1933 // (Clause 5).
1934 case ExpressionEvaluationContext::Unevaluated:
1935 case ExpressionEvaluationContext::UnevaluatedList:
1936 case ExpressionEvaluationContext::UnevaluatedAbstract:
1937 // C++1y [expr.const]p2:
1938 // A conditional-expression e is a core constant expression unless the
1939 // evaluation of e, following the rules of the abstract machine, would
1940 // evaluate [...] a lambda-expression.
1941 //
1942 // This is technically incorrect, there are some constant evaluated contexts
1943 // where this should be allowed. We should probably fix this when DR1607 is
1944 // ratified, it lays out the exact set of conditions where we shouldn't
1945 // allow a lambda-expression.
1946 case ExpressionEvaluationContext::ConstantEvaluated:
1947 // We don't actually diagnose this case immediately, because we
1948 // could be within a context where we might find out later that
1949 // the expression is potentially evaluated (e.g., for typeid).
1950 ExprEvalContexts.back().Lambdas.push_back(Lambda);
1951 break;
1952
1953 case ExpressionEvaluationContext::DiscardedStatement:
1954 case ExpressionEvaluationContext::PotentiallyEvaluated:
1955 case ExpressionEvaluationContext::PotentiallyEvaluatedIfUsed:
1956 break;
1957 }
1958 }
1959
1960 return MaybeBindToTemporary(Lambda);
1961 }
1962
BuildBlockForLambdaConversion(SourceLocation CurrentLocation,SourceLocation ConvLocation,CXXConversionDecl * Conv,Expr * Src)1963 ExprResult Sema::BuildBlockForLambdaConversion(SourceLocation CurrentLocation,
1964 SourceLocation ConvLocation,
1965 CXXConversionDecl *Conv,
1966 Expr *Src) {
1967 // Make sure that the lambda call operator is marked used.
1968 CXXRecordDecl *Lambda = Conv->getParent();
1969 CXXMethodDecl *CallOperator
1970 = cast<CXXMethodDecl>(
1971 Lambda->lookup(
1972 Context.DeclarationNames.getCXXOperatorName(OO_Call)).front());
1973 CallOperator->setReferenced();
1974 CallOperator->markUsed(Context);
1975
1976 ExprResult Init = PerformCopyInitialization(
1977 InitializedEntity::InitializeLambdaToBlock(ConvLocation, Src->getType(),
1978 /*NRVO=*/false),
1979 CurrentLocation, Src);
1980 if (!Init.isInvalid())
1981 Init = ActOnFinishFullExpr(Init.get(), /*DiscardedValue*/ false);
1982
1983 if (Init.isInvalid())
1984 return ExprError();
1985
1986 // Create the new block to be returned.
1987 BlockDecl *Block = BlockDecl::Create(Context, CurContext, ConvLocation);
1988
1989 // Set the type information.
1990 Block->setSignatureAsWritten(CallOperator->getTypeSourceInfo());
1991 Block->setIsVariadic(CallOperator->isVariadic());
1992 Block->setBlockMissingReturnType(false);
1993
1994 // Add parameters.
1995 SmallVector<ParmVarDecl *, 4> BlockParams;
1996 for (unsigned I = 0, N = CallOperator->getNumParams(); I != N; ++I) {
1997 ParmVarDecl *From = CallOperator->getParamDecl(I);
1998 BlockParams.push_back(ParmVarDecl::Create(
1999 Context, Block, From->getBeginLoc(), From->getLocation(),
2000 From->getIdentifier(), From->getType(), From->getTypeSourceInfo(),
2001 From->getStorageClass(),
2002 /*DefArg=*/nullptr));
2003 }
2004 Block->setParams(BlockParams);
2005
2006 Block->setIsConversionFromLambda(true);
2007
2008 // Add capture. The capture uses a fake variable, which doesn't correspond
2009 // to any actual memory location. However, the initializer copy-initializes
2010 // the lambda object.
2011 TypeSourceInfo *CapVarTSI =
2012 Context.getTrivialTypeSourceInfo(Src->getType());
2013 VarDecl *CapVar = VarDecl::Create(Context, Block, ConvLocation,
2014 ConvLocation, nullptr,
2015 Src->getType(), CapVarTSI,
2016 SC_None);
2017 BlockDecl::Capture Capture(/*variable=*/CapVar, /*byRef=*/false,
2018 /*nested=*/false, /*copy=*/Init.get());
2019 Block->setCaptures(Context, Capture, /*CapturesCXXThis=*/false);
2020
2021 // Add a fake function body to the block. IR generation is responsible
2022 // for filling in the actual body, which cannot be expressed as an AST.
2023 Block->setBody(new (Context) CompoundStmt(ConvLocation));
2024
2025 // Create the block literal expression.
2026 Expr *BuildBlock = new (Context) BlockExpr(Block, Conv->getConversionType());
2027 ExprCleanupObjects.push_back(Block);
2028 Cleanup.setExprNeedsCleanups(true);
2029
2030 return BuildBlock;
2031 }
2032