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