Bug Summary

File:clang/lib/Sema/SemaCoroutine.cpp
Warning:line 680, column 13
Called C++ object pointer is null

Annotated Source Code

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clang -cc1 -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -disable-llvm-verifier -discard-value-names -main-file-name SemaCoroutine.cpp -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -setup-static-analyzer -analyzer-config-compatibility-mode=true -mrelocation-model pic -pic-level 2 -mframe-pointer=none -relaxed-aliasing -fmath-errno -fno-rounding-math -mconstructor-aliases -munwind-tables -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -ffunction-sections -fdata-sections -fcoverage-compilation-dir=/build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/build-llvm/tools/clang/lib/Sema -resource-dir /usr/lib/llvm-14/lib/clang/14.0.0 -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/build-llvm/tools/clang/lib/Sema -I /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/clang/lib/Sema -I /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/clang/include -I /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/build-llvm/tools/clang/include -I /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/build-llvm/include -I /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/llvm/include -D NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/x86_64-linux-gnu/c++/10 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10/backward -internal-isystem /usr/lib/llvm-14/lib/clang/14.0.0/include -internal-isystem /usr/local/include -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../x86_64-linux-gnu/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -O2 -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-maybe-uninitialized -Wno-class-memaccess -Wno-redundant-move -Wno-pessimizing-move -Wno-noexcept-type -Wno-comment -std=c++14 -fdeprecated-macro -fdebug-compilation-dir=/build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/build-llvm/tools/clang/lib/Sema -fdebug-prefix-map=/build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e=. -ferror-limit 19 -fvisibility-inlines-hidden -stack-protector 2 -fgnuc-version=4.2.1 -vectorize-loops -vectorize-slp -analyzer-output=html -analyzer-config stable-report-filename=true -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/scan-build-2021-09-04-040900-46481-1 -x c++ /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/clang/lib/Sema/SemaCoroutine.cpp
1//===-- SemaCoroutine.cpp - Semantic Analysis for Coroutines --------------===//
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++ Coroutines.
10//
11// This file contains references to sections of the Coroutines TS, which
12// can be found at http://wg21.link/coroutines.
13//
14//===----------------------------------------------------------------------===//
15
16#include "CoroutineStmtBuilder.h"
17#include "clang/AST/ASTLambda.h"
18#include "clang/AST/Decl.h"
19#include "clang/AST/ExprCXX.h"
20#include "clang/AST/StmtCXX.h"
21#include "clang/Basic/Builtins.h"
22#include "clang/Lex/Preprocessor.h"
23#include "clang/Sema/Initialization.h"
24#include "clang/Sema/Overload.h"
25#include "clang/Sema/ScopeInfo.h"
26#include "clang/Sema/SemaInternal.h"
27#include "llvm/ADT/SmallSet.h"
28
29using namespace clang;
30using namespace sema;
31
32static LookupResult lookupMember(Sema &S, const char *Name, CXXRecordDecl *RD,
33 SourceLocation Loc, bool &Res) {
34 DeclarationName DN = S.PP.getIdentifierInfo(Name);
35 LookupResult LR(S, DN, Loc, Sema::LookupMemberName);
36 // Suppress diagnostics when a private member is selected. The same warnings
37 // will be produced again when building the call.
38 LR.suppressDiagnostics();
39 Res = S.LookupQualifiedName(LR, RD);
40 return LR;
41}
42
43static bool lookupMember(Sema &S, const char *Name, CXXRecordDecl *RD,
44 SourceLocation Loc) {
45 bool Res;
46 lookupMember(S, Name, RD, Loc, Res);
47 return Res;
48}
49
50/// Look up the std::coroutine_traits<...>::promise_type for the given
51/// function type.
52static QualType lookupPromiseType(Sema &S, const FunctionDecl *FD,
53 SourceLocation KwLoc) {
54 const FunctionProtoType *FnType = FD->getType()->castAs<FunctionProtoType>();
55 const SourceLocation FuncLoc = FD->getLocation();
56 // FIXME: Cache std::coroutine_traits once we've found it.
57 NamespaceDecl *StdExp = S.lookupStdExperimentalNamespace();
58 if (!StdExp) {
59 S.Diag(KwLoc, diag::err_implied_coroutine_type_not_found)
60 << "std::experimental::coroutine_traits";
61 return QualType();
62 }
63
64 ClassTemplateDecl *CoroTraits = S.lookupCoroutineTraits(KwLoc, FuncLoc);
65 if (!CoroTraits) {
66 return QualType();
67 }
68
69 // Form template argument list for coroutine_traits<R, P1, P2, ...> according
70 // to [dcl.fct.def.coroutine]3
71 TemplateArgumentListInfo Args(KwLoc, KwLoc);
72 auto AddArg = [&](QualType T) {
73 Args.addArgument(TemplateArgumentLoc(
74 TemplateArgument(T), S.Context.getTrivialTypeSourceInfo(T, KwLoc)));
75 };
76 AddArg(FnType->getReturnType());
77 // If the function is a non-static member function, add the type
78 // of the implicit object parameter before the formal parameters.
79 if (auto *MD = dyn_cast<CXXMethodDecl>(FD)) {
80 if (MD->isInstance()) {
81 // [over.match.funcs]4
82 // For non-static member functions, the type of the implicit object
83 // parameter is
84 // -- "lvalue reference to cv X" for functions declared without a
85 // ref-qualifier or with the & ref-qualifier
86 // -- "rvalue reference to cv X" for functions declared with the &&
87 // ref-qualifier
88 QualType T = MD->getThisType()->castAs<PointerType>()->getPointeeType();
89 T = FnType->getRefQualifier() == RQ_RValue
90 ? S.Context.getRValueReferenceType(T)
91 : S.Context.getLValueReferenceType(T, /*SpelledAsLValue*/ true);
92 AddArg(T);
93 }
94 }
95 for (QualType T : FnType->getParamTypes())
96 AddArg(T);
97
98 // Build the template-id.
99 QualType CoroTrait =
100 S.CheckTemplateIdType(TemplateName(CoroTraits), KwLoc, Args);
101 if (CoroTrait.isNull())
102 return QualType();
103 if (S.RequireCompleteType(KwLoc, CoroTrait,
104 diag::err_coroutine_type_missing_specialization))
105 return QualType();
106
107 auto *RD = CoroTrait->getAsCXXRecordDecl();
108 assert(RD && "specialization of class template is not a class?")(static_cast<void> (0));
109
110 // Look up the ::promise_type member.
111 LookupResult R(S, &S.PP.getIdentifierTable().get("promise_type"), KwLoc,
112 Sema::LookupOrdinaryName);
113 S.LookupQualifiedName(R, RD);
114 auto *Promise = R.getAsSingle<TypeDecl>();
115 if (!Promise) {
116 S.Diag(FuncLoc,
117 diag::err_implied_std_coroutine_traits_promise_type_not_found)
118 << RD;
119 return QualType();
120 }
121 // The promise type is required to be a class type.
122 QualType PromiseType = S.Context.getTypeDeclType(Promise);
123
124 auto buildElaboratedType = [&]() {
125 auto *NNS = NestedNameSpecifier::Create(S.Context, nullptr, StdExp);
126 NNS = NestedNameSpecifier::Create(S.Context, NNS, false,
127 CoroTrait.getTypePtr());
128 return S.Context.getElaboratedType(ETK_None, NNS, PromiseType);
129 };
130
131 if (!PromiseType->getAsCXXRecordDecl()) {
132 S.Diag(FuncLoc,
133 diag::err_implied_std_coroutine_traits_promise_type_not_class)
134 << buildElaboratedType();
135 return QualType();
136 }
137 if (S.RequireCompleteType(FuncLoc, buildElaboratedType(),
138 diag::err_coroutine_promise_type_incomplete))
139 return QualType();
140
141 return PromiseType;
142}
143
144/// Look up the std::experimental::coroutine_handle<PromiseType>.
145static QualType lookupCoroutineHandleType(Sema &S, QualType PromiseType,
146 SourceLocation Loc) {
147 if (PromiseType.isNull())
148 return QualType();
149
150 NamespaceDecl *StdExp = S.lookupStdExperimentalNamespace();
151 assert(StdExp && "Should already be diagnosed")(static_cast<void> (0));
152
153 LookupResult Result(S, &S.PP.getIdentifierTable().get("coroutine_handle"),
154 Loc, Sema::LookupOrdinaryName);
155 if (!S.LookupQualifiedName(Result, StdExp)) {
156 S.Diag(Loc, diag::err_implied_coroutine_type_not_found)
157 << "std::experimental::coroutine_handle";
158 return QualType();
159 }
160
161 ClassTemplateDecl *CoroHandle = Result.getAsSingle<ClassTemplateDecl>();
162 if (!CoroHandle) {
163 Result.suppressDiagnostics();
164 // We found something weird. Complain about the first thing we found.
165 NamedDecl *Found = *Result.begin();
166 S.Diag(Found->getLocation(), diag::err_malformed_std_coroutine_handle);
167 return QualType();
168 }
169
170 // Form template argument list for coroutine_handle<Promise>.
171 TemplateArgumentListInfo Args(Loc, Loc);
172 Args.addArgument(TemplateArgumentLoc(
173 TemplateArgument(PromiseType),
174 S.Context.getTrivialTypeSourceInfo(PromiseType, Loc)));
175
176 // Build the template-id.
177 QualType CoroHandleType =
178 S.CheckTemplateIdType(TemplateName(CoroHandle), Loc, Args);
179 if (CoroHandleType.isNull())
180 return QualType();
181 if (S.RequireCompleteType(Loc, CoroHandleType,
182 diag::err_coroutine_type_missing_specialization))
183 return QualType();
184
185 return CoroHandleType;
186}
187
188static bool isValidCoroutineContext(Sema &S, SourceLocation Loc,
189 StringRef Keyword) {
190 // [expr.await]p2 dictates that 'co_await' and 'co_yield' must be used within
191 // a function body.
192 // FIXME: This also covers [expr.await]p2: "An await-expression shall not
193 // appear in a default argument." But the diagnostic QoI here could be
194 // improved to inform the user that default arguments specifically are not
195 // allowed.
196 auto *FD = dyn_cast<FunctionDecl>(S.CurContext);
197 if (!FD) {
198 S.Diag(Loc, isa<ObjCMethodDecl>(S.CurContext)
199 ? diag::err_coroutine_objc_method
200 : diag::err_coroutine_outside_function) << Keyword;
201 return false;
202 }
203
204 // An enumeration for mapping the diagnostic type to the correct diagnostic
205 // selection index.
206 enum InvalidFuncDiag {
207 DiagCtor = 0,
208 DiagDtor,
209 DiagMain,
210 DiagConstexpr,
211 DiagAutoRet,
212 DiagVarargs,
213 DiagConsteval,
214 };
215 bool Diagnosed = false;
216 auto DiagInvalid = [&](InvalidFuncDiag ID) {
217 S.Diag(Loc, diag::err_coroutine_invalid_func_context) << ID << Keyword;
218 Diagnosed = true;
219 return false;
220 };
221
222 // Diagnose when a constructor, destructor
223 // or the function 'main' are declared as a coroutine.
224 auto *MD = dyn_cast<CXXMethodDecl>(FD);
225 // [class.ctor]p11: "A constructor shall not be a coroutine."
226 if (MD && isa<CXXConstructorDecl>(MD))
227 return DiagInvalid(DiagCtor);
228 // [class.dtor]p17: "A destructor shall not be a coroutine."
229 else if (MD && isa<CXXDestructorDecl>(MD))
230 return DiagInvalid(DiagDtor);
231 // [basic.start.main]p3: "The function main shall not be a coroutine."
232 else if (FD->isMain())
233 return DiagInvalid(DiagMain);
234
235 // Emit a diagnostics for each of the following conditions which is not met.
236 // [expr.const]p2: "An expression e is a core constant expression unless the
237 // evaluation of e [...] would evaluate one of the following expressions:
238 // [...] an await-expression [...] a yield-expression."
239 if (FD->isConstexpr())
240 DiagInvalid(FD->isConsteval() ? DiagConsteval : DiagConstexpr);
241 // [dcl.spec.auto]p15: "A function declared with a return type that uses a
242 // placeholder type shall not be a coroutine."
243 if (FD->getReturnType()->isUndeducedType())
244 DiagInvalid(DiagAutoRet);
245 // [dcl.fct.def.coroutine]p1: "The parameter-declaration-clause of the
246 // coroutine shall not terminate with an ellipsis that is not part of a
247 // parameter-declaration."
248 if (FD->isVariadic())
249 DiagInvalid(DiagVarargs);
250
251 return !Diagnosed;
252}
253
254static ExprResult buildOperatorCoawaitLookupExpr(Sema &SemaRef, Scope *S,
255 SourceLocation Loc) {
256 DeclarationName OpName =
257 SemaRef.Context.DeclarationNames.getCXXOperatorName(OO_Coawait);
258 LookupResult Operators(SemaRef, OpName, SourceLocation(),
259 Sema::LookupOperatorName);
260 SemaRef.LookupName(Operators, S);
261
262 assert(!Operators.isAmbiguous() && "Operator lookup cannot be ambiguous")(static_cast<void> (0));
263 const auto &Functions = Operators.asUnresolvedSet();
264 bool IsOverloaded =
265 Functions.size() > 1 ||
266 (Functions.size() == 1 && isa<FunctionTemplateDecl>(*Functions.begin()));
267 Expr *CoawaitOp = UnresolvedLookupExpr::Create(
268 SemaRef.Context, /*NamingClass*/ nullptr, NestedNameSpecifierLoc(),
269 DeclarationNameInfo(OpName, Loc), /*RequiresADL*/ true, IsOverloaded,
270 Functions.begin(), Functions.end());
271 assert(CoawaitOp)(static_cast<void> (0));
272 return CoawaitOp;
273}
274
275/// Build a call to 'operator co_await' if there is a suitable operator for
276/// the given expression.
277static ExprResult buildOperatorCoawaitCall(Sema &SemaRef, SourceLocation Loc,
278 Expr *E,
279 UnresolvedLookupExpr *Lookup) {
280 UnresolvedSet<16> Functions;
281 Functions.append(Lookup->decls_begin(), Lookup->decls_end());
282 return SemaRef.CreateOverloadedUnaryOp(Loc, UO_Coawait, Functions, E);
283}
284
285static ExprResult buildOperatorCoawaitCall(Sema &SemaRef, Scope *S,
286 SourceLocation Loc, Expr *E) {
287 ExprResult R = buildOperatorCoawaitLookupExpr(SemaRef, S, Loc);
288 if (R.isInvalid())
289 return ExprError();
290 return buildOperatorCoawaitCall(SemaRef, Loc, E,
291 cast<UnresolvedLookupExpr>(R.get()));
292}
293
294static ExprResult buildCoroutineHandle(Sema &S, QualType PromiseType,
295 SourceLocation Loc) {
296 QualType CoroHandleType = lookupCoroutineHandleType(S, PromiseType, Loc);
297 if (CoroHandleType.isNull())
298 return ExprError();
299
300 DeclContext *LookupCtx = S.computeDeclContext(CoroHandleType);
301 LookupResult Found(S, &S.PP.getIdentifierTable().get("from_address"), Loc,
302 Sema::LookupOrdinaryName);
303 if (!S.LookupQualifiedName(Found, LookupCtx)) {
304 S.Diag(Loc, diag::err_coroutine_handle_missing_member)
305 << "from_address";
306 return ExprError();
307 }
308
309 Expr *FramePtr =
310 S.BuildBuiltinCallExpr(Loc, Builtin::BI__builtin_coro_frame, {});
311
312 CXXScopeSpec SS;
313 ExprResult FromAddr =
314 S.BuildDeclarationNameExpr(SS, Found, /*NeedsADL=*/false);
315 if (FromAddr.isInvalid())
316 return ExprError();
317
318 return S.BuildCallExpr(nullptr, FromAddr.get(), Loc, FramePtr, Loc);
319}
320
321struct ReadySuspendResumeResult {
322 enum AwaitCallType { ACT_Ready, ACT_Suspend, ACT_Resume };
323 Expr *Results[3];
324 OpaqueValueExpr *OpaqueValue;
325 bool IsInvalid;
326};
327
328static ExprResult buildMemberCall(Sema &S, Expr *Base, SourceLocation Loc,
329 StringRef Name, MultiExprArg Args) {
330 DeclarationNameInfo NameInfo(&S.PP.getIdentifierTable().get(Name), Loc);
331
332 // FIXME: Fix BuildMemberReferenceExpr to take a const CXXScopeSpec&.
333 CXXScopeSpec SS;
334 ExprResult Result = S.BuildMemberReferenceExpr(
335 Base, Base->getType(), Loc, /*IsPtr=*/false, SS,
336 SourceLocation(), nullptr, NameInfo, /*TemplateArgs=*/nullptr,
337 /*Scope=*/nullptr);
338 if (Result.isInvalid())
339 return ExprError();
340
341 // We meant exactly what we asked for. No need for typo correction.
342 if (auto *TE = dyn_cast<TypoExpr>(Result.get())) {
343 S.clearDelayedTypo(TE);
344 S.Diag(Loc, diag::err_no_member)
345 << NameInfo.getName() << Base->getType()->getAsCXXRecordDecl()
346 << Base->getSourceRange();
347 return ExprError();
348 }
349
350 return S.BuildCallExpr(nullptr, Result.get(), Loc, Args, Loc, nullptr);
351}
352
353// See if return type is coroutine-handle and if so, invoke builtin coro-resume
354// on its address. This is to enable experimental support for coroutine-handle
355// returning await_suspend that results in a guaranteed tail call to the target
356// coroutine.
357static Expr *maybeTailCall(Sema &S, QualType RetType, Expr *E,
358 SourceLocation Loc) {
359 if (RetType->isReferenceType())
360 return nullptr;
361 Type const *T = RetType.getTypePtr();
362 if (!T->isClassType() && !T->isStructureType())
363 return nullptr;
364
365 // FIXME: Add convertability check to coroutine_handle<>. Possibly via
366 // EvaluateBinaryTypeTrait(BTT_IsConvertible, ...) which is at the moment
367 // a private function in SemaExprCXX.cpp
368
369 ExprResult AddressExpr = buildMemberCall(S, E, Loc, "address", None);
370 if (AddressExpr.isInvalid())
371 return nullptr;
372
373 Expr *JustAddress = AddressExpr.get();
374
375 // Check that the type of AddressExpr is void*
376 if (!JustAddress->getType().getTypePtr()->isVoidPointerType())
377 S.Diag(cast<CallExpr>(JustAddress)->getCalleeDecl()->getLocation(),
378 diag::warn_coroutine_handle_address_invalid_return_type)
379 << JustAddress->getType();
380
381 // Clean up temporary objects so that they don't live across suspension points
382 // unnecessarily. We choose to clean up before the call to
383 // __builtin_coro_resume so that the cleanup code are not inserted in-between
384 // the resume call and return instruction, which would interfere with the
385 // musttail call contract.
386 JustAddress = S.MaybeCreateExprWithCleanups(JustAddress);
387 return S.BuildBuiltinCallExpr(Loc, Builtin::BI__builtin_coro_resume,
388 JustAddress);
389}
390
391/// Build calls to await_ready, await_suspend, and await_resume for a co_await
392/// expression.
393/// The generated AST tries to clean up temporary objects as early as
394/// possible so that they don't live across suspension points if possible.
395/// Having temporary objects living across suspension points unnecessarily can
396/// lead to large frame size, and also lead to memory corruptions if the
397/// coroutine frame is destroyed after coming back from suspension. This is done
398/// by wrapping both the await_ready call and the await_suspend call with
399/// ExprWithCleanups. In the end of this function, we also need to explicitly
400/// set cleanup state so that the CoawaitExpr is also wrapped with an
401/// ExprWithCleanups to clean up the awaiter associated with the co_await
402/// expression.
403static ReadySuspendResumeResult buildCoawaitCalls(Sema &S, VarDecl *CoroPromise,
404 SourceLocation Loc, Expr *E) {
405 OpaqueValueExpr *Operand = new (S.Context)
406 OpaqueValueExpr(Loc, E->getType(), VK_LValue, E->getObjectKind(), E);
407
408 // Assume valid until we see otherwise.
409 // Further operations are responsible for setting IsInalid to true.
410 ReadySuspendResumeResult Calls = {{}, Operand, /*IsInvalid=*/false};
411
412 using ACT = ReadySuspendResumeResult::AwaitCallType;
413
414 auto BuildSubExpr = [&](ACT CallType, StringRef Func,
415 MultiExprArg Arg) -> Expr * {
416 ExprResult Result = buildMemberCall(S, Operand, Loc, Func, Arg);
417 if (Result.isInvalid()) {
418 Calls.IsInvalid = true;
419 return nullptr;
420 }
421 Calls.Results[CallType] = Result.get();
422 return Result.get();
423 };
424
425 CallExpr *AwaitReady =
426 cast_or_null<CallExpr>(BuildSubExpr(ACT::ACT_Ready, "await_ready", None));
427 if (!AwaitReady)
428 return Calls;
429 if (!AwaitReady->getType()->isDependentType()) {
430 // [expr.await]p3 [...]
431 // — await-ready is the expression e.await_ready(), contextually converted
432 // to bool.
433 ExprResult Conv = S.PerformContextuallyConvertToBool(AwaitReady);
434 if (Conv.isInvalid()) {
435 S.Diag(AwaitReady->getDirectCallee()->getBeginLoc(),
436 diag::note_await_ready_no_bool_conversion);
437 S.Diag(Loc, diag::note_coroutine_promise_call_implicitly_required)
438 << AwaitReady->getDirectCallee() << E->getSourceRange();
439 Calls.IsInvalid = true;
440 } else
441 Calls.Results[ACT::ACT_Ready] = S.MaybeCreateExprWithCleanups(Conv.get());
442 }
443
444 ExprResult CoroHandleRes =
445 buildCoroutineHandle(S, CoroPromise->getType(), Loc);
446 if (CoroHandleRes.isInvalid()) {
447 Calls.IsInvalid = true;
448 return Calls;
449 }
450 Expr *CoroHandle = CoroHandleRes.get();
451 CallExpr *AwaitSuspend = cast_or_null<CallExpr>(
452 BuildSubExpr(ACT::ACT_Suspend, "await_suspend", CoroHandle));
453 if (!AwaitSuspend)
454 return Calls;
455 if (!AwaitSuspend->getType()->isDependentType()) {
456 // [expr.await]p3 [...]
457 // - await-suspend is the expression e.await_suspend(h), which shall be
458 // a prvalue of type void, bool, or std::coroutine_handle<Z> for some
459 // type Z.
460 QualType RetType = AwaitSuspend->getCallReturnType(S.Context);
461
462 // Experimental support for coroutine_handle returning await_suspend.
463 if (Expr *TailCallSuspend =
464 maybeTailCall(S, RetType, AwaitSuspend, Loc))
465 // Note that we don't wrap the expression with ExprWithCleanups here
466 // because that might interfere with tailcall contract (e.g. inserting
467 // clean up instructions in-between tailcall and return). Instead
468 // ExprWithCleanups is wrapped within maybeTailCall() prior to the resume
469 // call.
470 Calls.Results[ACT::ACT_Suspend] = TailCallSuspend;
471 else {
472 // non-class prvalues always have cv-unqualified types
473 if (RetType->isReferenceType() ||
474 (!RetType->isBooleanType() && !RetType->isVoidType())) {
475 S.Diag(AwaitSuspend->getCalleeDecl()->getLocation(),
476 diag::err_await_suspend_invalid_return_type)
477 << RetType;
478 S.Diag(Loc, diag::note_coroutine_promise_call_implicitly_required)
479 << AwaitSuspend->getDirectCallee();
480 Calls.IsInvalid = true;
481 } else
482 Calls.Results[ACT::ACT_Suspend] =
483 S.MaybeCreateExprWithCleanups(AwaitSuspend);
484 }
485 }
486
487 BuildSubExpr(ACT::ACT_Resume, "await_resume", None);
488
489 // Make sure the awaiter object gets a chance to be cleaned up.
490 S.Cleanup.setExprNeedsCleanups(true);
491
492 return Calls;
493}
494
495static ExprResult buildPromiseCall(Sema &S, VarDecl *Promise,
496 SourceLocation Loc, StringRef Name,
497 MultiExprArg Args) {
498
499 // Form a reference to the promise.
500 ExprResult PromiseRef = S.BuildDeclRefExpr(
501 Promise, Promise->getType().getNonReferenceType(), VK_LValue, Loc);
502 if (PromiseRef.isInvalid())
503 return ExprError();
504
505 return buildMemberCall(S, PromiseRef.get(), Loc, Name, Args);
506}
507
508VarDecl *Sema::buildCoroutinePromise(SourceLocation Loc) {
509 assert(isa<FunctionDecl>(CurContext) && "not in a function scope")(static_cast<void> (0));
510 auto *FD = cast<FunctionDecl>(CurContext);
511 bool IsThisDependentType = [&] {
512 if (auto *MD = dyn_cast_or_null<CXXMethodDecl>(FD))
513 return MD->isInstance() && MD->getThisType()->isDependentType();
514 else
515 return false;
516 }();
517
518 QualType T = FD->getType()->isDependentType() || IsThisDependentType
519 ? Context.DependentTy
520 : lookupPromiseType(*this, FD, Loc);
521 if (T.isNull())
522 return nullptr;
523
524 auto *VD = VarDecl::Create(Context, FD, FD->getLocation(), FD->getLocation(),
525 &PP.getIdentifierTable().get("__promise"), T,
526 Context.getTrivialTypeSourceInfo(T, Loc), SC_None);
527 VD->setImplicit();
528 CheckVariableDeclarationType(VD);
529 if (VD->isInvalidDecl())
530 return nullptr;
531
532 auto *ScopeInfo = getCurFunction();
533
534 // Build a list of arguments, based on the coroutine function's arguments,
535 // that if present will be passed to the promise type's constructor.
536 llvm::SmallVector<Expr *, 4> CtorArgExprs;
537
538 // Add implicit object parameter.
539 if (auto *MD = dyn_cast<CXXMethodDecl>(FD)) {
540 if (MD->isInstance() && !isLambdaCallOperator(MD)) {
541 ExprResult ThisExpr = ActOnCXXThis(Loc);
542 if (ThisExpr.isInvalid())
543 return nullptr;
544 ThisExpr = CreateBuiltinUnaryOp(Loc, UO_Deref, ThisExpr.get());
545 if (ThisExpr.isInvalid())
546 return nullptr;
547 CtorArgExprs.push_back(ThisExpr.get());
548 }
549 }
550
551 // Add the coroutine function's parameters.
552 auto &Moves = ScopeInfo->CoroutineParameterMoves;
553 for (auto *PD : FD->parameters()) {
554 if (PD->getType()->isDependentType())
555 continue;
556
557 auto RefExpr = ExprEmpty();
558 auto Move = Moves.find(PD);
559 assert(Move != Moves.end() &&(static_cast<void> (0))
560 "Coroutine function parameter not inserted into move map")(static_cast<void> (0));
561 // If a reference to the function parameter exists in the coroutine
562 // frame, use that reference.
563 auto *MoveDecl =
564 cast<VarDecl>(cast<DeclStmt>(Move->second)->getSingleDecl());
565 RefExpr =
566 BuildDeclRefExpr(MoveDecl, MoveDecl->getType().getNonReferenceType(),
567 ExprValueKind::VK_LValue, FD->getLocation());
568 if (RefExpr.isInvalid())
569 return nullptr;
570 CtorArgExprs.push_back(RefExpr.get());
571 }
572
573 // If we have a non-zero number of constructor arguments, try to use them.
574 // Otherwise, fall back to the promise type's default constructor.
575 if (!CtorArgExprs.empty()) {
576 // Create an initialization sequence for the promise type using the
577 // constructor arguments, wrapped in a parenthesized list expression.
578 Expr *PLE = ParenListExpr::Create(Context, FD->getLocation(),
579 CtorArgExprs, FD->getLocation());
580 InitializedEntity Entity = InitializedEntity::InitializeVariable(VD);
581 InitializationKind Kind = InitializationKind::CreateForInit(
582 VD->getLocation(), /*DirectInit=*/true, PLE);
583 InitializationSequence InitSeq(*this, Entity, Kind, CtorArgExprs,
584 /*TopLevelOfInitList=*/false,
585 /*TreatUnavailableAsInvalid=*/false);
586
587 // Attempt to initialize the promise type with the arguments.
588 // If that fails, fall back to the promise type's default constructor.
589 if (InitSeq) {
590 ExprResult Result = InitSeq.Perform(*this, Entity, Kind, CtorArgExprs);
591 if (Result.isInvalid()) {
592 VD->setInvalidDecl();
593 } else if (Result.get()) {
594 VD->setInit(MaybeCreateExprWithCleanups(Result.get()));
595 VD->setInitStyle(VarDecl::CallInit);
596 CheckCompleteVariableDeclaration(VD);
597 }
598 } else
599 ActOnUninitializedDecl(VD);
600 } else
601 ActOnUninitializedDecl(VD);
602
603 FD->addDecl(VD);
604 return VD;
605}
606
607/// Check that this is a context in which a coroutine suspension can appear.
608static FunctionScopeInfo *checkCoroutineContext(Sema &S, SourceLocation Loc,
609 StringRef Keyword,
610 bool IsImplicit = false) {
611 if (!isValidCoroutineContext(S, Loc, Keyword))
612 return nullptr;
613
614 assert(isa<FunctionDecl>(S.CurContext) && "not in a function scope")(static_cast<void> (0));
615
616 auto *ScopeInfo = S.getCurFunction();
617 assert(ScopeInfo && "missing function scope for function")(static_cast<void> (0));
618
619 if (ScopeInfo->FirstCoroutineStmtLoc.isInvalid() && !IsImplicit)
620 ScopeInfo->setFirstCoroutineStmt(Loc, Keyword);
621
622 if (ScopeInfo->CoroutinePromise)
623 return ScopeInfo;
624
625 if (!S.buildCoroutineParameterMoves(Loc))
626 return nullptr;
627
628 ScopeInfo->CoroutinePromise = S.buildCoroutinePromise(Loc);
629 if (!ScopeInfo->CoroutinePromise)
630 return nullptr;
631
632 return ScopeInfo;
633}
634
635/// Recursively check \p E and all its children to see if any call target
636/// (including constructor call) is declared noexcept. Also any value returned
637/// from the call has a noexcept destructor.
638static void checkNoThrow(Sema &S, const Stmt *E,
639 llvm::SmallPtrSetImpl<const Decl *> &ThrowingDecls) {
640 auto checkDeclNoexcept = [&](const Decl *D, bool IsDtor = false) {
641 // In the case of dtor, the call to dtor is implicit and hence we should
642 // pass nullptr to canCalleeThrow.
643 if (Sema::canCalleeThrow(S, IsDtor ? nullptr : cast<Expr>(E), D)) {
644 if (const auto *FD = dyn_cast<FunctionDecl>(D)) {
645 // co_await promise.final_suspend() could end up calling
646 // __builtin_coro_resume for symmetric transfer if await_suspend()
647 // returns a handle. In that case, even __builtin_coro_resume is not
648 // declared as noexcept and may throw, it does not throw _into_ the
649 // coroutine that just suspended, but rather throws back out from
650 // whoever called coroutine_handle::resume(), hence we claim that
651 // logically it does not throw.
652 if (FD->getBuiltinID() == Builtin::BI__builtin_coro_resume)
653 return;
654 }
655 if (ThrowingDecls.empty()) {
656 // First time seeing an error, emit the error message.
657 S.Diag(cast<FunctionDecl>(S.CurContext)->getLocation(),
658 diag::err_coroutine_promise_final_suspend_requires_nothrow);
659 }
660 ThrowingDecls.insert(D);
661 }
662 };
663 auto SC = E->getStmtClass();
664 if (SC == Expr::CXXConstructExprClass) {
11
Assuming 'SC' is not equal to CXXConstructExprClass
665 auto const *Ctor = cast<CXXConstructExpr>(E)->getConstructor();
666 checkDeclNoexcept(Ctor);
667 // Check the corresponding destructor of the constructor.
668 checkDeclNoexcept(Ctor->getParent()->getDestructor(), true);
669 } else if (SC == Expr::CallExprClass || SC == Expr::CXXMemberCallExprClass ||
12
Assuming 'SC' is equal to CallExprClass
670 SC == Expr::CXXOperatorCallExprClass) {
671 if (!cast<CallExpr>(E)->isTypeDependent()) {
13
'E' is a 'CallExpr'
14
Assuming the condition is true
15
Taking true branch
672 checkDeclNoexcept(cast<CallExpr>(E)->getCalleeDecl());
16
'E' is a 'CallExpr'
673 auto ReturnType = cast<CallExpr>(E)->getCallReturnType(S.getASTContext());
17
'E' is a 'CallExpr'
674 // Check the destructor of the call return type, if any.
675 if (ReturnType.isDestructedType() ==
18
Assuming the condition is true
19
Taking true branch
676 QualType::DestructionKind::DK_cxx_destructor) {
677 const auto *T =
678 cast<RecordType>(ReturnType.getCanonicalType().getTypePtr());
20
The object is a 'RecordType'
679 checkDeclNoexcept(
680 dyn_cast<CXXRecordDecl>(T->getDecl())->getDestructor(), true);
21
Assuming the object is not a 'CXXRecordDecl'
22
Called C++ object pointer is null
681 }
682 }
683 }
684 for (const auto *Child : E->children()) {
685 if (!Child)
686 continue;
687 checkNoThrow(S, Child, ThrowingDecls);
688 }
689}
690
691bool Sema::checkFinalSuspendNoThrow(const Stmt *FinalSuspend) {
692 llvm::SmallPtrSet<const Decl *, 4> ThrowingDecls;
693 // We first collect all declarations that should not throw but not declared
694 // with noexcept. We then sort them based on the location before printing.
695 // This is to avoid emitting the same note multiple times on the same
696 // declaration, and also provide a deterministic order for the messages.
697 checkNoThrow(*this, FinalSuspend, ThrowingDecls);
10
Calling 'checkNoThrow'
698 auto SortedDecls = llvm::SmallVector<const Decl *, 4>{ThrowingDecls.begin(),
699 ThrowingDecls.end()};
700 sort(SortedDecls, [](const Decl *A, const Decl *B) {
701 return A->getEndLoc() < B->getEndLoc();
702 });
703 for (const auto *D : SortedDecls) {
704 Diag(D->getEndLoc(), diag::note_coroutine_function_declare_noexcept);
705 }
706 return ThrowingDecls.empty();
707}
708
709bool Sema::ActOnCoroutineBodyStart(Scope *SC, SourceLocation KWLoc,
710 StringRef Keyword) {
711 if (!checkCoroutineContext(*this, KWLoc, Keyword))
2
Taking false branch
712 return false;
713 auto *ScopeInfo = getCurFunction();
714 assert(ScopeInfo->CoroutinePromise)(static_cast<void> (0));
715
716 // If we have existing coroutine statements then we have already built
717 // the initial and final suspend points.
718 if (!ScopeInfo->NeedsCoroutineSuspends)
3
Assuming field 'NeedsCoroutineSuspends' is true
4
Taking false branch
719 return true;
720
721 ScopeInfo->setNeedsCoroutineSuspends(false);
722
723 auto *Fn = cast<FunctionDecl>(CurContext);
5
Field 'CurContext' is a 'FunctionDecl'
724 SourceLocation Loc = Fn->getLocation();
725 // Build the initial suspend point
726 auto buildSuspends = [&](StringRef Name) mutable -> StmtResult {
727 ExprResult Suspend =
728 buildPromiseCall(*this, ScopeInfo->CoroutinePromise, Loc, Name, None);
729 if (Suspend.isInvalid())
730 return StmtError();
731 Suspend = buildOperatorCoawaitCall(*this, SC, Loc, Suspend.get());
732 if (Suspend.isInvalid())
733 return StmtError();
734 Suspend = BuildResolvedCoawaitExpr(Loc, Suspend.get(),
735 /*IsImplicit*/ true);
736 Suspend = ActOnFinishFullExpr(Suspend.get(), /*DiscardedValue*/ false);
737 if (Suspend.isInvalid()) {
738 Diag(Loc, diag::note_coroutine_promise_suspend_implicitly_required)
739 << ((Name == "initial_suspend") ? 0 : 1);
740 Diag(KWLoc, diag::note_declared_coroutine_here) << Keyword;
741 return StmtError();
742 }
743 return cast<Stmt>(Suspend.get());
744 };
745
746 StmtResult InitSuspend = buildSuspends("initial_suspend");
747 if (InitSuspend.isInvalid())
6
Assuming the condition is false
7
Taking false branch
748 return true;
749
750 StmtResult FinalSuspend = buildSuspends("final_suspend");
751 if (FinalSuspend.isInvalid() || !checkFinalSuspendNoThrow(FinalSuspend.get()))
8
Assuming the condition is false
9
Calling 'Sema::checkFinalSuspendNoThrow'
752 return true;
753
754 ScopeInfo->setCoroutineSuspends(InitSuspend.get(), FinalSuspend.get());
755
756 return true;
757}
758
759// Recursively walks up the scope hierarchy until either a 'catch' or a function
760// scope is found, whichever comes first.
761static bool isWithinCatchScope(Scope *S) {
762 // 'co_await' and 'co_yield' keywords are disallowed within catch blocks, but
763 // lambdas that use 'co_await' are allowed. The loop below ends when a
764 // function scope is found in order to ensure the following behavior:
765 //
766 // void foo() { // <- function scope
767 // try { //
768 // co_await x; // <- 'co_await' is OK within a function scope
769 // } catch { // <- catch scope
770 // co_await x; // <- 'co_await' is not OK within a catch scope
771 // []() { // <- function scope
772 // co_await x; // <- 'co_await' is OK within a function scope
773 // }();
774 // }
775 // }
776 while (S && !(S->getFlags() & Scope::FnScope)) {
777 if (S->getFlags() & Scope::CatchScope)
778 return true;
779 S = S->getParent();
780 }
781 return false;
782}
783
784// [expr.await]p2, emphasis added: "An await-expression shall appear only in
785// a *potentially evaluated* expression within the compound-statement of a
786// function-body *outside of a handler* [...] A context within a function
787// where an await-expression can appear is called a suspension context of the
788// function."
789static void checkSuspensionContext(Sema &S, SourceLocation Loc,
790 StringRef Keyword) {
791 // First emphasis of [expr.await]p2: must be a potentially evaluated context.
792 // That is, 'co_await' and 'co_yield' cannot appear in subexpressions of
793 // \c sizeof.
794 if (S.isUnevaluatedContext())
795 S.Diag(Loc, diag::err_coroutine_unevaluated_context) << Keyword;
796
797 // Second emphasis of [expr.await]p2: must be outside of an exception handler.
798 if (isWithinCatchScope(S.getCurScope()))
799 S.Diag(Loc, diag::err_coroutine_within_handler) << Keyword;
800}
801
802ExprResult Sema::ActOnCoawaitExpr(Scope *S, SourceLocation Loc, Expr *E) {
803 if (!ActOnCoroutineBodyStart(S, Loc, "co_await")) {
804 CorrectDelayedTyposInExpr(E);
805 return ExprError();
806 }
807
808 checkSuspensionContext(*this, Loc, "co_await");
809
810 if (E->getType()->isPlaceholderType()) {
811 ExprResult R = CheckPlaceholderExpr(E);
812 if (R.isInvalid()) return ExprError();
813 E = R.get();
814 }
815 ExprResult Lookup = buildOperatorCoawaitLookupExpr(*this, S, Loc);
816 if (Lookup.isInvalid())
817 return ExprError();
818 return BuildUnresolvedCoawaitExpr(Loc, E,
819 cast<UnresolvedLookupExpr>(Lookup.get()));
820}
821
822ExprResult Sema::BuildUnresolvedCoawaitExpr(SourceLocation Loc, Expr *E,
823 UnresolvedLookupExpr *Lookup) {
824 auto *FSI = checkCoroutineContext(*this, Loc, "co_await");
825 if (!FSI)
826 return ExprError();
827
828 if (E->getType()->isPlaceholderType()) {
829 ExprResult R = CheckPlaceholderExpr(E);
830 if (R.isInvalid())
831 return ExprError();
832 E = R.get();
833 }
834
835 auto *Promise = FSI->CoroutinePromise;
836 if (Promise->getType()->isDependentType()) {
837 Expr *Res =
838 new (Context) DependentCoawaitExpr(Loc, Context.DependentTy, E, Lookup);
839 return Res;
840 }
841
842 auto *RD = Promise->getType()->getAsCXXRecordDecl();
843 if (lookupMember(*this, "await_transform", RD, Loc)) {
844 ExprResult R = buildPromiseCall(*this, Promise, Loc, "await_transform", E);
845 if (R.isInvalid()) {
846 Diag(Loc,
847 diag::note_coroutine_promise_implicit_await_transform_required_here)
848 << E->getSourceRange();
849 return ExprError();
850 }
851 E = R.get();
852 }
853 ExprResult Awaitable = buildOperatorCoawaitCall(*this, Loc, E, Lookup);
854 if (Awaitable.isInvalid())
855 return ExprError();
856
857 return BuildResolvedCoawaitExpr(Loc, Awaitable.get());
858}
859
860ExprResult Sema::BuildResolvedCoawaitExpr(SourceLocation Loc, Expr *E,
861 bool IsImplicit) {
862 auto *Coroutine = checkCoroutineContext(*this, Loc, "co_await", IsImplicit);
863 if (!Coroutine)
864 return ExprError();
865
866 if (E->getType()->isPlaceholderType()) {
867 ExprResult R = CheckPlaceholderExpr(E);
868 if (R.isInvalid()) return ExprError();
869 E = R.get();
870 }
871
872 if (E->getType()->isDependentType()) {
873 Expr *Res = new (Context)
874 CoawaitExpr(Loc, Context.DependentTy, E, IsImplicit);
875 return Res;
876 }
877
878 // If the expression is a temporary, materialize it as an lvalue so that we
879 // can use it multiple times.
880 if (E->isPRValue())
881 E = CreateMaterializeTemporaryExpr(E->getType(), E, true);
882
883 // The location of the `co_await` token cannot be used when constructing
884 // the member call expressions since it's before the location of `Expr`, which
885 // is used as the start of the member call expression.
886 SourceLocation CallLoc = E->getExprLoc();
887
888 // Build the await_ready, await_suspend, await_resume calls.
889 ReadySuspendResumeResult RSS = buildCoawaitCalls(
890 *this, Coroutine->CoroutinePromise, CallLoc, E);
891 if (RSS.IsInvalid)
892 return ExprError();
893
894 Expr *Res =
895 new (Context) CoawaitExpr(Loc, E, RSS.Results[0], RSS.Results[1],
896 RSS.Results[2], RSS.OpaqueValue, IsImplicit);
897
898 return Res;
899}
900
901ExprResult Sema::ActOnCoyieldExpr(Scope *S, SourceLocation Loc, Expr *E) {
902 if (!ActOnCoroutineBodyStart(S, Loc, "co_yield")) {
903 CorrectDelayedTyposInExpr(E);
904 return ExprError();
905 }
906
907 checkSuspensionContext(*this, Loc, "co_yield");
908
909 // Build yield_value call.
910 ExprResult Awaitable = buildPromiseCall(
911 *this, getCurFunction()->CoroutinePromise, Loc, "yield_value", E);
912 if (Awaitable.isInvalid())
913 return ExprError();
914
915 // Build 'operator co_await' call.
916 Awaitable = buildOperatorCoawaitCall(*this, S, Loc, Awaitable.get());
917 if (Awaitable.isInvalid())
918 return ExprError();
919
920 return BuildCoyieldExpr(Loc, Awaitable.get());
921}
922ExprResult Sema::BuildCoyieldExpr(SourceLocation Loc, Expr *E) {
923 auto *Coroutine = checkCoroutineContext(*this, Loc, "co_yield");
924 if (!Coroutine)
925 return ExprError();
926
927 if (E->getType()->isPlaceholderType()) {
928 ExprResult R = CheckPlaceholderExpr(E);
929 if (R.isInvalid()) return ExprError();
930 E = R.get();
931 }
932
933 if (E->getType()->isDependentType()) {
934 Expr *Res = new (Context) CoyieldExpr(Loc, Context.DependentTy, E);
935 return Res;
936 }
937
938 // If the expression is a temporary, materialize it as an lvalue so that we
939 // can use it multiple times.
940 if (E->isPRValue())
941 E = CreateMaterializeTemporaryExpr(E->getType(), E, true);
942
943 // Build the await_ready, await_suspend, await_resume calls.
944 ReadySuspendResumeResult RSS = buildCoawaitCalls(
945 *this, Coroutine->CoroutinePromise, Loc, E);
946 if (RSS.IsInvalid)
947 return ExprError();
948
949 Expr *Res =
950 new (Context) CoyieldExpr(Loc, E, RSS.Results[0], RSS.Results[1],
951 RSS.Results[2], RSS.OpaqueValue);
952
953 return Res;
954}
955
956StmtResult Sema::ActOnCoreturnStmt(Scope *S, SourceLocation Loc, Expr *E) {
957 if (!ActOnCoroutineBodyStart(S, Loc, "co_return")) {
1
Calling 'Sema::ActOnCoroutineBodyStart'
958 CorrectDelayedTyposInExpr(E);
959 return StmtError();
960 }
961 return BuildCoreturnStmt(Loc, E);
962}
963
964StmtResult Sema::BuildCoreturnStmt(SourceLocation Loc, Expr *E,
965 bool IsImplicit) {
966 auto *FSI = checkCoroutineContext(*this, Loc, "co_return", IsImplicit);
967 if (!FSI)
968 return StmtError();
969
970 if (E && E->getType()->isPlaceholderType() &&
971 !E->getType()->isSpecificPlaceholderType(BuiltinType::Overload)) {
972 ExprResult R = CheckPlaceholderExpr(E);
973 if (R.isInvalid()) return StmtError();
974 E = R.get();
975 }
976
977 VarDecl *Promise = FSI->CoroutinePromise;
978 ExprResult PC;
979 if (E && (isa<InitListExpr>(E) || !E->getType()->isVoidType())) {
980 getNamedReturnInfo(E, SimplerImplicitMoveMode::ForceOn);
981 PC = buildPromiseCall(*this, Promise, Loc, "return_value", E);
982 } else {
983 E = MakeFullDiscardedValueExpr(E).get();
984 PC = buildPromiseCall(*this, Promise, Loc, "return_void", None);
985 }
986 if (PC.isInvalid())
987 return StmtError();
988
989 Expr *PCE = ActOnFinishFullExpr(PC.get(), /*DiscardedValue*/ false).get();
990
991 Stmt *Res = new (Context) CoreturnStmt(Loc, E, PCE, IsImplicit);
992 return Res;
993}
994
995/// Look up the std::nothrow object.
996static Expr *buildStdNoThrowDeclRef(Sema &S, SourceLocation Loc) {
997 NamespaceDecl *Std = S.getStdNamespace();
998 assert(Std && "Should already be diagnosed")(static_cast<void> (0));
999
1000 LookupResult Result(S, &S.PP.getIdentifierTable().get("nothrow"), Loc,
1001 Sema::LookupOrdinaryName);
1002 if (!S.LookupQualifiedName(Result, Std)) {
1003 // FIXME: <experimental/coroutine> should have been included already.
1004 // If we require it to include <new> then this diagnostic is no longer
1005 // needed.
1006 S.Diag(Loc, diag::err_implicit_coroutine_std_nothrow_type_not_found);
1007 return nullptr;
1008 }
1009
1010 auto *VD = Result.getAsSingle<VarDecl>();
1011 if (!VD) {
1012 Result.suppressDiagnostics();
1013 // We found something weird. Complain about the first thing we found.
1014 NamedDecl *Found = *Result.begin();
1015 S.Diag(Found->getLocation(), diag::err_malformed_std_nothrow);
1016 return nullptr;
1017 }
1018
1019 ExprResult DR = S.BuildDeclRefExpr(VD, VD->getType(), VK_LValue, Loc);
1020 if (DR.isInvalid())
1021 return nullptr;
1022
1023 return DR.get();
1024}
1025
1026// Find an appropriate delete for the promise.
1027static FunctionDecl *findDeleteForPromise(Sema &S, SourceLocation Loc,
1028 QualType PromiseType) {
1029 FunctionDecl *OperatorDelete = nullptr;
1030
1031 DeclarationName DeleteName =
1032 S.Context.DeclarationNames.getCXXOperatorName(OO_Delete);
1033
1034 auto *PointeeRD = PromiseType->getAsCXXRecordDecl();
1035 assert(PointeeRD && "PromiseType must be a CxxRecordDecl type")(static_cast<void> (0));
1036
1037 if (S.FindDeallocationFunction(Loc, PointeeRD, DeleteName, OperatorDelete))
1038 return nullptr;
1039
1040 if (!OperatorDelete) {
1041 // Look for a global declaration.
1042 const bool CanProvideSize = S.isCompleteType(Loc, PromiseType);
1043 const bool Overaligned = false;
1044 OperatorDelete = S.FindUsualDeallocationFunction(Loc, CanProvideSize,
1045 Overaligned, DeleteName);
1046 }
1047 S.MarkFunctionReferenced(Loc, OperatorDelete);
1048 return OperatorDelete;
1049}
1050
1051
1052void Sema::CheckCompletedCoroutineBody(FunctionDecl *FD, Stmt *&Body) {
1053 FunctionScopeInfo *Fn = getCurFunction();
1054 assert(Fn && Fn->isCoroutine() && "not a coroutine")(static_cast<void> (0));
1055 if (!Body) {
1056 assert(FD->isInvalidDecl() &&(static_cast<void> (0))
1057 "a null body is only allowed for invalid declarations")(static_cast<void> (0));
1058 return;
1059 }
1060 // We have a function that uses coroutine keywords, but we failed to build
1061 // the promise type.
1062 if (!Fn->CoroutinePromise)
1063 return FD->setInvalidDecl();
1064
1065 if (isa<CoroutineBodyStmt>(Body)) {
1066 // Nothing todo. the body is already a transformed coroutine body statement.
1067 return;
1068 }
1069
1070 // Coroutines [stmt.return]p1:
1071 // A return statement shall not appear in a coroutine.
1072 if (Fn->FirstReturnLoc.isValid()) {
1073 assert(Fn->FirstCoroutineStmtLoc.isValid() &&(static_cast<void> (0))
1074 "first coroutine location not set")(static_cast<void> (0));
1075 Diag(Fn->FirstReturnLoc, diag::err_return_in_coroutine);
1076 Diag(Fn->FirstCoroutineStmtLoc, diag::note_declared_coroutine_here)
1077 << Fn->getFirstCoroutineStmtKeyword();
1078 }
1079 CoroutineStmtBuilder Builder(*this, *FD, *Fn, Body);
1080 if (Builder.isInvalid() || !Builder.buildStatements())
1081 return FD->setInvalidDecl();
1082
1083 // Build body for the coroutine wrapper statement.
1084 Body = CoroutineBodyStmt::Create(Context, Builder);
1085}
1086
1087CoroutineStmtBuilder::CoroutineStmtBuilder(Sema &S, FunctionDecl &FD,
1088 sema::FunctionScopeInfo &Fn,
1089 Stmt *Body)
1090 : S(S), FD(FD), Fn(Fn), Loc(FD.getLocation()),
1091 IsPromiseDependentType(
1092 !Fn.CoroutinePromise ||
1093 Fn.CoroutinePromise->getType()->isDependentType()) {
1094 this->Body = Body;
1095
1096 for (auto KV : Fn.CoroutineParameterMoves)
1097 this->ParamMovesVector.push_back(KV.second);
1098 this->ParamMoves = this->ParamMovesVector;
1099
1100 if (!IsPromiseDependentType) {
1101 PromiseRecordDecl = Fn.CoroutinePromise->getType()->getAsCXXRecordDecl();
1102 assert(PromiseRecordDecl && "Type should have already been checked")(static_cast<void> (0));
1103 }
1104 this->IsValid = makePromiseStmt() && makeInitialAndFinalSuspend();
1105}
1106
1107bool CoroutineStmtBuilder::buildStatements() {
1108 assert(this->IsValid && "coroutine already invalid")(static_cast<void> (0));
1109 this->IsValid = makeReturnObject();
1110 if (this->IsValid && !IsPromiseDependentType)
1111 buildDependentStatements();
1112 return this->IsValid;
1113}
1114
1115bool CoroutineStmtBuilder::buildDependentStatements() {
1116 assert(this->IsValid && "coroutine already invalid")(static_cast<void> (0));
1117 assert(!this->IsPromiseDependentType &&(static_cast<void> (0))
1118 "coroutine cannot have a dependent promise type")(static_cast<void> (0));
1119 this->IsValid = makeOnException() && makeOnFallthrough() &&
1120 makeGroDeclAndReturnStmt() && makeReturnOnAllocFailure() &&
1121 makeNewAndDeleteExpr();
1122 return this->IsValid;
1123}
1124
1125bool CoroutineStmtBuilder::makePromiseStmt() {
1126 // Form a declaration statement for the promise declaration, so that AST
1127 // visitors can more easily find it.
1128 StmtResult PromiseStmt =
1129 S.ActOnDeclStmt(S.ConvertDeclToDeclGroup(Fn.CoroutinePromise), Loc, Loc);
1130 if (PromiseStmt.isInvalid())
1131 return false;
1132
1133 this->Promise = PromiseStmt.get();
1134 return true;
1135}
1136
1137bool CoroutineStmtBuilder::makeInitialAndFinalSuspend() {
1138 if (Fn.hasInvalidCoroutineSuspends())
1139 return false;
1140 this->InitialSuspend = cast<Expr>(Fn.CoroutineSuspends.first);
1141 this->FinalSuspend = cast<Expr>(Fn.CoroutineSuspends.second);
1142 return true;
1143}
1144
1145static bool diagReturnOnAllocFailure(Sema &S, Expr *E,
1146 CXXRecordDecl *PromiseRecordDecl,
1147 FunctionScopeInfo &Fn) {
1148 auto Loc = E->getExprLoc();
1149 if (auto *DeclRef = dyn_cast_or_null<DeclRefExpr>(E)) {
1150 auto *Decl = DeclRef->getDecl();
1151 if (CXXMethodDecl *Method = dyn_cast_or_null<CXXMethodDecl>(Decl)) {
1152 if (Method->isStatic())
1153 return true;
1154 else
1155 Loc = Decl->getLocation();
1156 }
1157 }
1158
1159 S.Diag(
1160 Loc,
1161 diag::err_coroutine_promise_get_return_object_on_allocation_failure)
1162 << PromiseRecordDecl;
1163 S.Diag(Fn.FirstCoroutineStmtLoc, diag::note_declared_coroutine_here)
1164 << Fn.getFirstCoroutineStmtKeyword();
1165 return false;
1166}
1167
1168bool CoroutineStmtBuilder::makeReturnOnAllocFailure() {
1169 assert(!IsPromiseDependentType &&(static_cast<void> (0))
1170 "cannot make statement while the promise type is dependent")(static_cast<void> (0));
1171
1172 // [dcl.fct.def.coroutine]/8
1173 // The unqualified-id get_return_object_on_allocation_failure is looked up in
1174 // the scope of class P by class member access lookup (3.4.5). ...
1175 // If an allocation function returns nullptr, ... the coroutine return value
1176 // is obtained by a call to ... get_return_object_on_allocation_failure().
1177
1178 DeclarationName DN =
1179 S.PP.getIdentifierInfo("get_return_object_on_allocation_failure");
1180 LookupResult Found(S, DN, Loc, Sema::LookupMemberName);
1181 if (!S.LookupQualifiedName(Found, PromiseRecordDecl))
1182 return true;
1183
1184 CXXScopeSpec SS;
1185 ExprResult DeclNameExpr =
1186 S.BuildDeclarationNameExpr(SS, Found, /*NeedsADL=*/false);
1187 if (DeclNameExpr.isInvalid())
1188 return false;
1189
1190 if (!diagReturnOnAllocFailure(S, DeclNameExpr.get(), PromiseRecordDecl, Fn))
1191 return false;
1192
1193 ExprResult ReturnObjectOnAllocationFailure =
1194 S.BuildCallExpr(nullptr, DeclNameExpr.get(), Loc, {}, Loc);
1195 if (ReturnObjectOnAllocationFailure.isInvalid())
1196 return false;
1197
1198 StmtResult ReturnStmt =
1199 S.BuildReturnStmt(Loc, ReturnObjectOnAllocationFailure.get());
1200 if (ReturnStmt.isInvalid()) {
1201 S.Diag(Found.getFoundDecl()->getLocation(), diag::note_member_declared_here)
1202 << DN;
1203 S.Diag(Fn.FirstCoroutineStmtLoc, diag::note_declared_coroutine_here)
1204 << Fn.getFirstCoroutineStmtKeyword();
1205 return false;
1206 }
1207
1208 this->ReturnStmtOnAllocFailure = ReturnStmt.get();
1209 return true;
1210}
1211
1212bool CoroutineStmtBuilder::makeNewAndDeleteExpr() {
1213 // Form and check allocation and deallocation calls.
1214 assert(!IsPromiseDependentType &&(static_cast<void> (0))
1215 "cannot make statement while the promise type is dependent")(static_cast<void> (0));
1216 QualType PromiseType = Fn.CoroutinePromise->getType();
1217
1218 if (S.RequireCompleteType(Loc, PromiseType, diag::err_incomplete_type))
1219 return false;
1220
1221 const bool RequiresNoThrowAlloc = ReturnStmtOnAllocFailure != nullptr;
1222
1223 // [dcl.fct.def.coroutine]/7
1224 // Lookup allocation functions using a parameter list composed of the
1225 // requested size of the coroutine state being allocated, followed by
1226 // the coroutine function's arguments. If a matching allocation function
1227 // exists, use it. Otherwise, use an allocation function that just takes
1228 // the requested size.
1229
1230 FunctionDecl *OperatorNew = nullptr;
1231 FunctionDecl *OperatorDelete = nullptr;
1232 FunctionDecl *UnusedResult = nullptr;
1233 bool PassAlignment = false;
1234 SmallVector<Expr *, 1> PlacementArgs;
1235
1236 // [dcl.fct.def.coroutine]/7
1237 // "The allocation function’s name is looked up in the scope of P.
1238 // [...] If the lookup finds an allocation function in the scope of P,
1239 // overload resolution is performed on a function call created by assembling
1240 // an argument list. The first argument is the amount of space requested,
1241 // and has type std::size_t. The lvalues p1 ... pn are the succeeding
1242 // arguments."
1243 //
1244 // ...where "p1 ... pn" are defined earlier as:
1245 //
1246 // [dcl.fct.def.coroutine]/3
1247 // "For a coroutine f that is a non-static member function, let P1 denote the
1248 // type of the implicit object parameter (13.3.1) and P2 ... Pn be the types
1249 // of the function parameters; otherwise let P1 ... Pn be the types of the
1250 // function parameters. Let p1 ... pn be lvalues denoting those objects."
1251 if (auto *MD = dyn_cast<CXXMethodDecl>(&FD)) {
1252 if (MD->isInstance() && !isLambdaCallOperator(MD)) {
1253 ExprResult ThisExpr = S.ActOnCXXThis(Loc);
1254 if (ThisExpr.isInvalid())
1255 return false;
1256 ThisExpr = S.CreateBuiltinUnaryOp(Loc, UO_Deref, ThisExpr.get());
1257 if (ThisExpr.isInvalid())
1258 return false;
1259 PlacementArgs.push_back(ThisExpr.get());
1260 }
1261 }
1262 for (auto *PD : FD.parameters()) {
1263 if (PD->getType()->isDependentType())
1264 continue;
1265
1266 // Build a reference to the parameter.
1267 auto PDLoc = PD->getLocation();
1268 ExprResult PDRefExpr =
1269 S.BuildDeclRefExpr(PD, PD->getOriginalType().getNonReferenceType(),
1270 ExprValueKind::VK_LValue, PDLoc);
1271 if (PDRefExpr.isInvalid())
1272 return false;
1273
1274 PlacementArgs.push_back(PDRefExpr.get());
1275 }
1276 S.FindAllocationFunctions(Loc, SourceRange(), /*NewScope*/ Sema::AFS_Class,
1277 /*DeleteScope*/ Sema::AFS_Both, PromiseType,
1278 /*isArray*/ false, PassAlignment, PlacementArgs,
1279 OperatorNew, UnusedResult, /*Diagnose*/ false);
1280
1281 // [dcl.fct.def.coroutine]/7
1282 // "If no matching function is found, overload resolution is performed again
1283 // on a function call created by passing just the amount of space required as
1284 // an argument of type std::size_t."
1285 if (!OperatorNew && !PlacementArgs.empty()) {
1286 PlacementArgs.clear();
1287 S.FindAllocationFunctions(Loc, SourceRange(), /*NewScope*/ Sema::AFS_Class,
1288 /*DeleteScope*/ Sema::AFS_Both, PromiseType,
1289 /*isArray*/ false, PassAlignment, PlacementArgs,
1290 OperatorNew, UnusedResult, /*Diagnose*/ false);
1291 }
1292
1293 // [dcl.fct.def.coroutine]/7
1294 // "The allocation function’s name is looked up in the scope of P. If this
1295 // lookup fails, the allocation function’s name is looked up in the global
1296 // scope."
1297 if (!OperatorNew) {
1298 S.FindAllocationFunctions(Loc, SourceRange(), /*NewScope*/ Sema::AFS_Global,
1299 /*DeleteScope*/ Sema::AFS_Both, PromiseType,
1300 /*isArray*/ false, PassAlignment, PlacementArgs,
1301 OperatorNew, UnusedResult);
1302 }
1303
1304 bool IsGlobalOverload =
1305 OperatorNew && !isa<CXXRecordDecl>(OperatorNew->getDeclContext());
1306 // If we didn't find a class-local new declaration and non-throwing new
1307 // was is required then we need to lookup the non-throwing global operator
1308 // instead.
1309 if (RequiresNoThrowAlloc && (!OperatorNew || IsGlobalOverload)) {
1310 auto *StdNoThrow = buildStdNoThrowDeclRef(S, Loc);
1311 if (!StdNoThrow)
1312 return false;
1313 PlacementArgs = {StdNoThrow};
1314 OperatorNew = nullptr;
1315 S.FindAllocationFunctions(Loc, SourceRange(), /*NewScope*/ Sema::AFS_Both,
1316 /*DeleteScope*/ Sema::AFS_Both, PromiseType,
1317 /*isArray*/ false, PassAlignment, PlacementArgs,
1318 OperatorNew, UnusedResult);
1319 }
1320
1321 if (!OperatorNew)
1322 return false;
1323
1324 if (RequiresNoThrowAlloc) {
1325 const auto *FT = OperatorNew->getType()->castAs<FunctionProtoType>();
1326 if (!FT->isNothrow(/*ResultIfDependent*/ false)) {
1327 S.Diag(OperatorNew->getLocation(),
1328 diag::err_coroutine_promise_new_requires_nothrow)
1329 << OperatorNew;
1330 S.Diag(Loc, diag::note_coroutine_promise_call_implicitly_required)
1331 << OperatorNew;
1332 return false;
1333 }
1334 }
1335
1336 if ((OperatorDelete = findDeleteForPromise(S, Loc, PromiseType)) == nullptr)
1337 return false;
1338
1339 Expr *FramePtr =
1340 S.BuildBuiltinCallExpr(Loc, Builtin::BI__builtin_coro_frame, {});
1341
1342 Expr *FrameSize =
1343 S.BuildBuiltinCallExpr(Loc, Builtin::BI__builtin_coro_size, {});
1344
1345 // Make new call.
1346
1347 ExprResult NewRef =
1348 S.BuildDeclRefExpr(OperatorNew, OperatorNew->getType(), VK_LValue, Loc);
1349 if (NewRef.isInvalid())
1350 return false;
1351
1352 SmallVector<Expr *, 2> NewArgs(1, FrameSize);
1353 for (auto Arg : PlacementArgs)
1354 NewArgs.push_back(Arg);
1355
1356 ExprResult NewExpr =
1357 S.BuildCallExpr(S.getCurScope(), NewRef.get(), Loc, NewArgs, Loc);
1358 NewExpr = S.ActOnFinishFullExpr(NewExpr.get(), /*DiscardedValue*/ false);
1359 if (NewExpr.isInvalid())
1360 return false;
1361
1362 // Make delete call.
1363
1364 QualType OpDeleteQualType = OperatorDelete->getType();
1365
1366 ExprResult DeleteRef =
1367 S.BuildDeclRefExpr(OperatorDelete, OpDeleteQualType, VK_LValue, Loc);
1368 if (DeleteRef.isInvalid())
1369 return false;
1370
1371 Expr *CoroFree =
1372 S.BuildBuiltinCallExpr(Loc, Builtin::BI__builtin_coro_free, {FramePtr});
1373
1374 SmallVector<Expr *, 2> DeleteArgs{CoroFree};
1375
1376 // Check if we need to pass the size.
1377 const auto *OpDeleteType =
1378 OpDeleteQualType.getTypePtr()->castAs<FunctionProtoType>();
1379 if (OpDeleteType->getNumParams() > 1)
1380 DeleteArgs.push_back(FrameSize);
1381
1382 ExprResult DeleteExpr =
1383 S.BuildCallExpr(S.getCurScope(), DeleteRef.get(), Loc, DeleteArgs, Loc);
1384 DeleteExpr =
1385 S.ActOnFinishFullExpr(DeleteExpr.get(), /*DiscardedValue*/ false);
1386 if (DeleteExpr.isInvalid())
1387 return false;
1388
1389 this->Allocate = NewExpr.get();
1390 this->Deallocate = DeleteExpr.get();
1391
1392 return true;
1393}
1394
1395bool CoroutineStmtBuilder::makeOnFallthrough() {
1396 assert(!IsPromiseDependentType &&(static_cast<void> (0))
1397 "cannot make statement while the promise type is dependent")(static_cast<void> (0));
1398
1399 // [dcl.fct.def.coroutine]/4
1400 // The unqualified-ids 'return_void' and 'return_value' are looked up in
1401 // the scope of class P. If both are found, the program is ill-formed.
1402 bool HasRVoid, HasRValue;
1403 LookupResult LRVoid =
1404 lookupMember(S, "return_void", PromiseRecordDecl, Loc, HasRVoid);
1405 LookupResult LRValue =
1406 lookupMember(S, "return_value", PromiseRecordDecl, Loc, HasRValue);
1407
1408 StmtResult Fallthrough;
1409 if (HasRVoid && HasRValue) {
1410 // FIXME Improve this diagnostic
1411 S.Diag(FD.getLocation(),
1412 diag::err_coroutine_promise_incompatible_return_functions)
1413 << PromiseRecordDecl;
1414 S.Diag(LRVoid.getRepresentativeDecl()->getLocation(),
1415 diag::note_member_first_declared_here)
1416 << LRVoid.getLookupName();
1417 S.Diag(LRValue.getRepresentativeDecl()->getLocation(),
1418 diag::note_member_first_declared_here)
1419 << LRValue.getLookupName();
1420 return false;
1421 } else if (!HasRVoid && !HasRValue) {
1422 // FIXME: The PDTS currently specifies this case as UB, not ill-formed.
1423 // However we still diagnose this as an error since until the PDTS is fixed.
1424 S.Diag(FD.getLocation(),
1425 diag::err_coroutine_promise_requires_return_function)
1426 << PromiseRecordDecl;
1427 S.Diag(PromiseRecordDecl->getLocation(), diag::note_defined_here)
1428 << PromiseRecordDecl;
1429 return false;
1430 } else if (HasRVoid) {
1431 // If the unqualified-id return_void is found, flowing off the end of a
1432 // coroutine is equivalent to a co_return with no operand. Otherwise,
1433 // flowing off the end of a coroutine results in undefined behavior.
1434 Fallthrough = S.BuildCoreturnStmt(FD.getLocation(), nullptr,
1435 /*IsImplicit*/false);
1436 Fallthrough = S.ActOnFinishFullStmt(Fallthrough.get());
1437 if (Fallthrough.isInvalid())
1438 return false;
1439 }
1440
1441 this->OnFallthrough = Fallthrough.get();
1442 return true;
1443}
1444
1445bool CoroutineStmtBuilder::makeOnException() {
1446 // Try to form 'p.unhandled_exception();'
1447 assert(!IsPromiseDependentType &&(static_cast<void> (0))
1448 "cannot make statement while the promise type is dependent")(static_cast<void> (0));
1449
1450 const bool RequireUnhandledException = S.getLangOpts().CXXExceptions;
1451
1452 if (!lookupMember(S, "unhandled_exception", PromiseRecordDecl, Loc)) {
1453 auto DiagID =
1454 RequireUnhandledException
1455 ? diag::err_coroutine_promise_unhandled_exception_required
1456 : diag::
1457 warn_coroutine_promise_unhandled_exception_required_with_exceptions;
1458 S.Diag(Loc, DiagID) << PromiseRecordDecl;
1459 S.Diag(PromiseRecordDecl->getLocation(), diag::note_defined_here)
1460 << PromiseRecordDecl;
1461 return !RequireUnhandledException;
1462 }
1463
1464 // If exceptions are disabled, don't try to build OnException.
1465 if (!S.getLangOpts().CXXExceptions)
1466 return true;
1467
1468 ExprResult UnhandledException = buildPromiseCall(S, Fn.CoroutinePromise, Loc,
1469 "unhandled_exception", None);
1470 UnhandledException = S.ActOnFinishFullExpr(UnhandledException.get(), Loc,
1471 /*DiscardedValue*/ false);
1472 if (UnhandledException.isInvalid())
1473 return false;
1474
1475 // Since the body of the coroutine will be wrapped in try-catch, it will
1476 // be incompatible with SEH __try if present in a function.
1477 if (!S.getLangOpts().Borland && Fn.FirstSEHTryLoc.isValid()) {
1478 S.Diag(Fn.FirstSEHTryLoc, diag::err_seh_in_a_coroutine_with_cxx_exceptions);
1479 S.Diag(Fn.FirstCoroutineStmtLoc, diag::note_declared_coroutine_here)
1480 << Fn.getFirstCoroutineStmtKeyword();
1481 return false;
1482 }
1483
1484 this->OnException = UnhandledException.get();
1485 return true;
1486}
1487
1488bool CoroutineStmtBuilder::makeReturnObject() {
1489 // Build implicit 'p.get_return_object()' expression and form initialization
1490 // of return type from it.
1491 ExprResult ReturnObject =
1492 buildPromiseCall(S, Fn.CoroutinePromise, Loc, "get_return_object", None);
1493 if (ReturnObject.isInvalid())
1494 return false;
1495
1496 this->ReturnValue = ReturnObject.get();
1497 return true;
1498}
1499
1500static void noteMemberDeclaredHere(Sema &S, Expr *E, FunctionScopeInfo &Fn) {
1501 if (auto *MbrRef = dyn_cast<CXXMemberCallExpr>(E)) {
1502 auto *MethodDecl = MbrRef->getMethodDecl();
1503 S.Diag(MethodDecl->getLocation(), diag::note_member_declared_here)
1504 << MethodDecl;
1505 }
1506 S.Diag(Fn.FirstCoroutineStmtLoc, diag::note_declared_coroutine_here)
1507 << Fn.getFirstCoroutineStmtKeyword();
1508}
1509
1510bool CoroutineStmtBuilder::makeGroDeclAndReturnStmt() {
1511 assert(!IsPromiseDependentType &&(static_cast<void> (0))
1512 "cannot make statement while the promise type is dependent")(static_cast<void> (0));
1513 assert(this->ReturnValue && "ReturnValue must be already formed")(static_cast<void> (0));
1514
1515 QualType const GroType = this->ReturnValue->getType();
1516 assert(!GroType->isDependentType() &&(static_cast<void> (0))
1517 "get_return_object type must no longer be dependent")(static_cast<void> (0));
1518
1519 QualType const FnRetType = FD.getReturnType();
1520 assert(!FnRetType->isDependentType() &&(static_cast<void> (0))
1521 "get_return_object type must no longer be dependent")(static_cast<void> (0));
1522
1523 if (FnRetType->isVoidType()) {
1524 ExprResult Res =
1525 S.ActOnFinishFullExpr(this->ReturnValue, Loc, /*DiscardedValue*/ false);
1526 if (Res.isInvalid())
1527 return false;
1528
1529 this->ResultDecl = Res.get();
1530 return true;
1531 }
1532
1533 if (GroType->isVoidType()) {
1534 // Trigger a nice error message.
1535 InitializedEntity Entity =
1536 InitializedEntity::InitializeResult(Loc, FnRetType, false);
1537 S.PerformCopyInitialization(Entity, SourceLocation(), ReturnValue);
1538 noteMemberDeclaredHere(S, ReturnValue, Fn);
1539 return false;
1540 }
1541
1542 auto *GroDecl = VarDecl::Create(
1543 S.Context, &FD, FD.getLocation(), FD.getLocation(),
1544 &S.PP.getIdentifierTable().get("__coro_gro"), GroType,
1545 S.Context.getTrivialTypeSourceInfo(GroType, Loc), SC_None);
1546 GroDecl->setImplicit();
1547
1548 S.CheckVariableDeclarationType(GroDecl);
1549 if (GroDecl->isInvalidDecl())
1550 return false;
1551
1552 InitializedEntity Entity = InitializedEntity::InitializeVariable(GroDecl);
1553 ExprResult Res =
1554 S.PerformCopyInitialization(Entity, SourceLocation(), ReturnValue);
1555 if (Res.isInvalid())
1556 return false;
1557
1558 Res = S.ActOnFinishFullExpr(Res.get(), /*DiscardedValue*/ false);
1559 if (Res.isInvalid())
1560 return false;
1561
1562 S.AddInitializerToDecl(GroDecl, Res.get(),
1563 /*DirectInit=*/false);
1564
1565 S.FinalizeDeclaration(GroDecl);
1566
1567 // Form a declaration statement for the return declaration, so that AST
1568 // visitors can more easily find it.
1569 StmtResult GroDeclStmt =
1570 S.ActOnDeclStmt(S.ConvertDeclToDeclGroup(GroDecl), Loc, Loc);
1571 if (GroDeclStmt.isInvalid())
1572 return false;
1573
1574 this->ResultDecl = GroDeclStmt.get();
1575
1576 ExprResult declRef = S.BuildDeclRefExpr(GroDecl, GroType, VK_LValue, Loc);
1577 if (declRef.isInvalid())
1578 return false;
1579
1580 StmtResult ReturnStmt = S.BuildReturnStmt(Loc, declRef.get());
1581 if (ReturnStmt.isInvalid()) {
1582 noteMemberDeclaredHere(S, ReturnValue, Fn);
1583 return false;
1584 }
1585 if (cast<clang::ReturnStmt>(ReturnStmt.get())->getNRVOCandidate() == GroDecl)
1586 GroDecl->setNRVOVariable(true);
1587
1588 this->ReturnStmt = ReturnStmt.get();
1589 return true;
1590}
1591
1592// Create a static_cast\<T&&>(expr).
1593static Expr *castForMoving(Sema &S, Expr *E, QualType T = QualType()) {
1594 if (T.isNull())
1595 T = E->getType();
1596 QualType TargetType = S.BuildReferenceType(
1597 T, /*SpelledAsLValue*/ false, SourceLocation(), DeclarationName());
1598 SourceLocation ExprLoc = E->getBeginLoc();
1599 TypeSourceInfo *TargetLoc =
1600 S.Context.getTrivialTypeSourceInfo(TargetType, ExprLoc);
1601
1602 return S
1603 .BuildCXXNamedCast(ExprLoc, tok::kw_static_cast, TargetLoc, E,
1604 SourceRange(ExprLoc, ExprLoc), E->getSourceRange())
1605 .get();
1606}
1607
1608/// Build a variable declaration for move parameter.
1609static VarDecl *buildVarDecl(Sema &S, SourceLocation Loc, QualType Type,
1610 IdentifierInfo *II) {
1611 TypeSourceInfo *TInfo = S.Context.getTrivialTypeSourceInfo(Type, Loc);
1612 VarDecl *Decl = VarDecl::Create(S.Context, S.CurContext, Loc, Loc, II, Type,
1613 TInfo, SC_None);
1614 Decl->setImplicit();
1615 return Decl;
1616}
1617
1618// Build statements that move coroutine function parameters to the coroutine
1619// frame, and store them on the function scope info.
1620bool Sema::buildCoroutineParameterMoves(SourceLocation Loc) {
1621 assert(isa<FunctionDecl>(CurContext) && "not in a function scope")(static_cast<void> (0));
1622 auto *FD = cast<FunctionDecl>(CurContext);
1623
1624 auto *ScopeInfo = getCurFunction();
1625 if (!ScopeInfo->CoroutineParameterMoves.empty())
1626 return false;
1627
1628 for (auto *PD : FD->parameters()) {
1629 if (PD->getType()->isDependentType())
1630 continue;
1631
1632 ExprResult PDRefExpr =
1633 BuildDeclRefExpr(PD, PD->getType().getNonReferenceType(),
1634 ExprValueKind::VK_LValue, Loc); // FIXME: scope?
1635 if (PDRefExpr.isInvalid())
1636 return false;
1637
1638 Expr *CExpr = nullptr;
1639 if (PD->getType()->getAsCXXRecordDecl() ||
1640 PD->getType()->isRValueReferenceType())
1641 CExpr = castForMoving(*this, PDRefExpr.get());
1642 else
1643 CExpr = PDRefExpr.get();
1644
1645 auto D = buildVarDecl(*this, Loc, PD->getType(), PD->getIdentifier());
1646 AddInitializerToDecl(D, CExpr, /*DirectInit=*/true);
1647
1648 // Convert decl to a statement.
1649 StmtResult Stmt = ActOnDeclStmt(ConvertDeclToDeclGroup(D), Loc, Loc);
1650 if (Stmt.isInvalid())
1651 return false;
1652
1653 ScopeInfo->CoroutineParameterMoves.insert(std::make_pair(PD, Stmt.get()));
1654 }
1655 return true;
1656}
1657
1658StmtResult Sema::BuildCoroutineBodyStmt(CoroutineBodyStmt::CtorArgs Args) {
1659 CoroutineBodyStmt *Res = CoroutineBodyStmt::Create(Context, Args);
1660 if (!Res)
1661 return StmtError();
1662 return Res;
1663}
1664
1665ClassTemplateDecl *Sema::lookupCoroutineTraits(SourceLocation KwLoc,
1666 SourceLocation FuncLoc) {
1667 if (!StdCoroutineTraitsCache) {
1668 if (auto StdExp = lookupStdExperimentalNamespace()) {
1669 LookupResult Result(*this,
1670 &PP.getIdentifierTable().get("coroutine_traits"),
1671 FuncLoc, LookupOrdinaryName);
1672 if (!LookupQualifiedName(Result, StdExp)) {
1673 Diag(KwLoc, diag::err_implied_coroutine_type_not_found)
1674 << "std::experimental::coroutine_traits";
1675 return nullptr;
1676 }
1677 if (!(StdCoroutineTraitsCache =
1678 Result.getAsSingle<ClassTemplateDecl>())) {
1679 Result.suppressDiagnostics();
1680 NamedDecl *Found = *Result.begin();
1681 Diag(Found->getLocation(), diag::err_malformed_std_coroutine_traits);
1682 return nullptr;
1683 }
1684 }
1685 }
1686 return StdCoroutineTraitsCache;
1687}