Index: include/clang/Basic/DiagnosticSemaKinds.td =================================================================== --- include/clang/Basic/DiagnosticSemaKinds.td +++ include/clang/Basic/DiagnosticSemaKinds.td @@ -8851,6 +8851,11 @@ def err_implied_coroutine_type_not_found : Error< "%0 type was not found; include before defining " "a coroutine">; +def err_implicit_coroutine_std_nothrow_type_not_found : Error< + "std::nothrow was not found; include before defining a coroutine which " + "uses get_return_object_on_allocation_failure()">; +def err_malformed_std_nothrow : Error< + "std::nothrow must be a valid variable declaration">; def err_malformed_std_coroutine_handle : Error< "std::experimental::coroutine_handle must be a class template">; def err_coroutine_handle_missing_member : Error< @@ -8870,7 +8875,7 @@ "%0 declares both 'return_value' and 'return_void'">; def note_coroutine_promise_implicit_await_transform_required_here : Note< "call to 'await_transform' implicitly required by 'co_await' here">; -def note_coroutine_promise_call_implicitly_required : Note< +def note_coroutine_promise_suspend_implicitly_required : Note< "call to '%select{initial_suspend|final_suspend}0' implicitly " "required by the %select{initial suspend point|final suspend point}0">; def err_coroutine_promise_unhandled_exception_required : Error< @@ -8880,6 +8885,11 @@ InGroup; def err_coroutine_promise_get_return_object_on_allocation_failure : Error< "%0: 'get_return_object_on_allocation_failure()' must be a static member function">; +def err_coroutine_promise_new_requires_nothrow : Error< + "%0 is required to have a non-throwing noexcept specification when the promise " + "type declares 'get_return_object_on_allocation_failure()'">; +def note_coroutine_promise_call_implicitly_required : Note< + "call to %0 implicitly required by coroutine function here">; } let CategoryName = "Documentation Issue" in { Index: lib/Sema/SemaCoroutine.cpp =================================================================== --- lib/Sema/SemaCoroutine.cpp +++ lib/Sema/SemaCoroutine.cpp @@ -454,7 +454,7 @@ /*IsImplicit*/ true); Suspend = S.ActOnFinishFullExpr(Suspend.get()); if (Suspend.isInvalid()) { - S.Diag(Loc, diag::note_coroutine_promise_call_implicitly_required) + S.Diag(Loc, diag::note_coroutine_promise_suspend_implicitly_required) << ((Name == "initial_suspend") ? 0 : 1); S.Diag(KWLoc, diag::note_declared_coroutine_here) << Keyword; return StmtError(); @@ -660,6 +660,37 @@ return Res; } +/// Look up the std::nothrow object. +static Expr *buildStdNoThrowDeclRef(Sema &S, SourceLocation Loc) { + NamespaceDecl *Std = S.getStdNamespace(); + assert(Std && "Should already be diagnosed"); + + LookupResult Result(S, &S.PP.getIdentifierTable().get("nothrow"), Loc, + Sema::LookupOrdinaryName); + if (!S.LookupQualifiedName(Result, Std)) { + // FIXME: should have been included already. + // If we require it to include then this diagnostic is no longer + // needed. + S.Diag(Loc, diag::err_implicit_coroutine_std_nothrow_type_not_found); + return nullptr; + } + + auto *VD = Result.getAsSingle(); + if (!VD) { + Result.suppressDiagnostics(); + // We found something weird. Complain about the first thing we found. + NamedDecl *Found = *Result.begin(); + S.Diag(Found->getLocation(), diag::err_malformed_std_nothrow); + return nullptr; + } + + ExprResult DR = S.BuildDeclRefExpr(VD, VD->getType(), VK_LValue, Loc); + if (DR.isInvalid()) + return nullptr; + + return DR.get(); +} + // Find an appropriate delete for the promise. static FunctionDecl *findDeleteForPromise(Sema &S, SourceLocation Loc, QualType PromiseType) { @@ -815,23 +846,51 @@ if (S.RequireCompleteType(Loc, PromiseType, diag::err_incomplete_type)) return false; - // FIXME: Add nothrow_t placement arg for global alloc - // if ReturnStmtOnAllocFailure != nullptr. + const bool RequiresNoThrowAlloc = ReturnStmtOnAllocFailure != nullptr; + // FIXME: Add support for stateful allocators. FunctionDecl *OperatorNew = nullptr; FunctionDecl *OperatorDelete = nullptr; FunctionDecl *UnusedResult = nullptr; bool PassAlignment = false; + MultiExprArg PlacementArgs = None; S.FindAllocationFunctions(Loc, SourceRange(), /*UseGlobal*/ false, PromiseType, - /*isArray*/ false, PassAlignment, - /*PlacementArgs*/ None, OperatorNew, UnusedResult); + /*isArray*/ false, PassAlignment, PlacementArgs, + OperatorNew, UnusedResult); + + bool IsGlobalOverload = + OperatorNew && !isa(OperatorNew->getDeclContext()); + // If we didn't find a class-local new declaration and non-throwing new + // was is required then we need to lookup the non-throwing global operator + // instead. + if (RequiresNoThrowAlloc && (!OperatorNew || IsGlobalOverload)) { + auto *StdNoThrow = buildStdNoThrowDeclRef(S, Loc); + if (!StdNoThrow) + return false; + PlacementArgs = MultiExprArg(StdNoThrow); + OperatorNew = nullptr; + S.FindAllocationFunctions(Loc, SourceRange(), + /*UseGlobal*/ true, PromiseType, + /*isArray*/ false, PassAlignment, PlacementArgs, + OperatorNew, UnusedResult); + } - OperatorDelete = findDeleteForPromise(S, Loc, PromiseType); + if (OperatorNew && RequiresNoThrowAlloc) { + const auto *FT = OperatorNew->getType()->getAs(); + if (!FT->isNothrow(S.Context, /*ResultIfDependent*/ false)) { + S.Diag(OperatorNew->getLocation(), + diag::err_coroutine_promise_new_requires_nothrow) + << OperatorNew; + S.Diag(Loc, diag::note_coroutine_promise_call_implicitly_required) + << OperatorNew; + return false; + } + } - if (!OperatorDelete || !OperatorNew) + if ((OperatorDelete = findDeleteForPromise(S, Loc, PromiseType)) == nullptr) return false; Expr *FramePtr = @@ -847,8 +906,12 @@ if (NewRef.isInvalid()) return false; + SmallVector NewArgs{FrameSize}; + for (auto Arg : PlacementArgs) + NewArgs.push_back(Arg); + ExprResult NewExpr = - S.ActOnCallExpr(S.getCurScope(), NewRef.get(), Loc, FrameSize, Loc); + S.ActOnCallExpr(S.getCurScope(), NewRef.get(), Loc, NewArgs, Loc); if (NewExpr.isInvalid()) return false; Index: test/SemaCXX/coroutines.cpp =================================================================== --- test/SemaCXX/coroutines.cpp +++ test/SemaCXX/coroutines.cpp @@ -654,6 +654,20 @@ co_return; //expected-note {{function is a coroutine due to use of 'co_return' here}} } +namespace std { + struct nothrow_t {}; + constexpr nothrow_t nothrow = {}; +} + +using SizeT = decltype(sizeof(int)); + +void* operator new(SizeT __sz, const std::nothrow_t&) noexcept; +void operator delete(void* __p, const std::nothrow_t&) noexcept; + +void* operator new[](SizeT __sz, const std::nothrow_t&) noexcept; +void operator delete[](void* __p, const std::nothrow_t&) noexcept; + + struct promise_on_alloc_failure_tag {}; template<> @@ -694,3 +708,25 @@ } template coro dependent_private_alloc_failure_handler(bad_promise_11); // expected-note@-1 {{requested here}} + + +struct bad_promise_12 { + coro get_return_object(); + suspend_always initial_suspend(); + suspend_always final_suspend(); + void unhandled_exception(); + void return_void(); + static coro get_return_object_on_allocation_failure(); + + static void* operator new(SizeT); + // expected-error@-1 2 {{'operator new' is required to have a non-throwing noexcept specification when the promise type declares 'get_return_object_on_allocation_failure()'}} +}; +coro throwing_in_class_new() { // expected-note {{call to 'operator new' implicitly required by coroutine function here}} + co_return; +} + +template +coro dependent_throwing_in_class_new(T) { // expected-note {{call to 'operator new' implicitly required by coroutine function here}} + co_return; +} +template coro dependent_throwing_in_class_new(bad_promise_12); // expected-note {{requested here}}