nils.hoelscher
/
llvm-for-llvmta
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity
llvm-for-llvmta/tools/clang/lib/Sema/SemaCoroutine.cpp

1723 lines
64 KiB
C++
Raw Blame History

This file contains ambiguous Unicode characters

This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

//===-- SemaCoroutine.cpp - Semantic Analysis for Coroutines --------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements semantic analysis for C++ Coroutines.
//
// This file contains references to sections of the Coroutines TS, which
// can be found at http://wg21.link/coroutines.
//
//===----------------------------------------------------------------------===//
#include "CoroutineStmtBuilder.h"
#include "clang/AST/ASTLambda.h"
#include "clang/AST/Decl.h"
#include "clang/AST/ExprCXX.h"
#include "clang/AST/StmtCXX.h"
#include "clang/Basic/Builtins.h"
#include "clang/Lex/Preprocessor.h"
#include "clang/Sema/Initialization.h"
#include "clang/Sema/Overload.h"
#include "clang/Sema/ScopeInfo.h"
#include "clang/Sema/SemaInternal.h"
#include "llvm/ADT/SmallSet.h"
using namespace clang;
using namespace sema;
static LookupResult lookupMember(Sema &S, const char *Name, CXXRecordDecl *RD,
SourceLocation Loc, bool &Res) {
DeclarationName DN = S.PP.getIdentifierInfo(Name);
LookupResult LR(S, DN, Loc, Sema::LookupMemberName);
// Suppress diagnostics when a private member is selected. The same warnings
// will be produced again when building the call.
LR.suppressDiagnostics();
Res = S.LookupQualifiedName(LR, RD);
return LR;
}
static bool lookupMember(Sema &S, const char *Name, CXXRecordDecl *RD,
SourceLocation Loc) {
bool Res;
lookupMember(S, Name, RD, Loc, Res);
return Res;
}
/// Look up the std::coroutine_traits<...>::promise_type for the given
/// function type.
static QualType lookupPromiseType(Sema &S, const FunctionDecl *FD,
SourceLocation KwLoc) {
const FunctionProtoType *FnType = FD->getType()->castAs<FunctionProtoType>();
const SourceLocation FuncLoc = FD->getLocation();
// FIXME: Cache std::coroutine_traits once we've found it.
NamespaceDecl *StdExp = S.lookupStdExperimentalNamespace();
if (!StdExp) {
S.Diag(KwLoc, diag::err_implied_coroutine_type_not_found)
<< "std::experimental::coroutine_traits";
return QualType();
}
ClassTemplateDecl *CoroTraits = S.lookupCoroutineTraits(KwLoc, FuncLoc);
if (!CoroTraits) {
return QualType();
}
// Form template argument list for coroutine_traits<R, P1, P2, ...> according
// to [dcl.fct.def.coroutine]3
TemplateArgumentListInfo Args(KwLoc, KwLoc);
auto AddArg = [&](QualType T) {
Args.addArgument(TemplateArgumentLoc(
TemplateArgument(T), S.Context.getTrivialTypeSourceInfo(T, KwLoc)));
};
AddArg(FnType->getReturnType());
// If the function is a non-static member function, add the type
// of the implicit object parameter before the formal parameters.
if (auto *MD = dyn_cast<CXXMethodDecl>(FD)) {
if (MD->isInstance()) {
// [over.match.funcs]4
// For non-static member functions, the type of the implicit object
// parameter is
// -- "lvalue reference to cv X" for functions declared without a
// ref-qualifier or with the & ref-qualifier
// -- "rvalue reference to cv X" for functions declared with the &&
// ref-qualifier
QualType T = MD->getThisType()->castAs<PointerType>()->getPointeeType();
T = FnType->getRefQualifier() == RQ_RValue
? S.Context.getRValueReferenceType(T)
: S.Context.getLValueReferenceType(T, /*SpelledAsLValue*/ true);
AddArg(T);
}
}
for (QualType T : FnType->getParamTypes())
AddArg(T);
// Build the template-id.
QualType CoroTrait =
S.CheckTemplateIdType(TemplateName(CoroTraits), KwLoc, Args);
if (CoroTrait.isNull())
return QualType();
if (S.RequireCompleteType(KwLoc, CoroTrait,
diag::err_coroutine_type_missing_specialization))
return QualType();
auto *RD = CoroTrait->getAsCXXRecordDecl();
assert(RD && "specialization of class template is not a class?");
// Look up the ::promise_type member.
LookupResult R(S, &S.PP.getIdentifierTable().get("promise_type"), KwLoc,
Sema::LookupOrdinaryName);
S.LookupQualifiedName(R, RD);
auto *Promise = R.getAsSingle<TypeDecl>();
if (!Promise) {
S.Diag(FuncLoc,
diag::err_implied_std_coroutine_traits_promise_type_not_found)
<< RD;
return QualType();
}
// The promise type is required to be a class type.
QualType PromiseType = S.Context.getTypeDeclType(Promise);
auto buildElaboratedType = [&]() {
auto *NNS = NestedNameSpecifier::Create(S.Context, nullptr, StdExp);
NNS = NestedNameSpecifier::Create(S.Context, NNS, false,
CoroTrait.getTypePtr());
return S.Context.getElaboratedType(ETK_None, NNS, PromiseType);
};
if (!PromiseType->getAsCXXRecordDecl()) {
S.Diag(FuncLoc,
diag::err_implied_std_coroutine_traits_promise_type_not_class)
<< buildElaboratedType();
return QualType();
}
if (S.RequireCompleteType(FuncLoc, buildElaboratedType(),
diag::err_coroutine_promise_type_incomplete))
return QualType();
return PromiseType;
}
/// Look up the std::experimental::coroutine_handle<PromiseType>.
static QualType lookupCoroutineHandleType(Sema &S, QualType PromiseType,
SourceLocation Loc) {
if (PromiseType.isNull())
return QualType();
NamespaceDecl *StdExp = S.lookupStdExperimentalNamespace();
assert(StdExp && "Should already be diagnosed");
LookupResult Result(S, &S.PP.getIdentifierTable().get("coroutine_handle"),
Loc, Sema::LookupOrdinaryName);
if (!S.LookupQualifiedName(Result, StdExp)) {
S.Diag(Loc, diag::err_implied_coroutine_type_not_found)
<< "std::experimental::coroutine_handle";
return QualType();
}
ClassTemplateDecl *CoroHandle = Result.getAsSingle<ClassTemplateDecl>();
if (!CoroHandle) {
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_coroutine_handle);
return QualType();
}
// Form template argument list for coroutine_handle<Promise>.
TemplateArgumentListInfo Args(Loc, Loc);
Args.addArgument(TemplateArgumentLoc(
TemplateArgument(PromiseType),
S.Context.getTrivialTypeSourceInfo(PromiseType, Loc)));
// Build the template-id.
QualType CoroHandleType =
S.CheckTemplateIdType(TemplateName(CoroHandle), Loc, Args);
if (CoroHandleType.isNull())
return QualType();
if (S.RequireCompleteType(Loc, CoroHandleType,
diag::err_coroutine_type_missing_specialization))
return QualType();
return CoroHandleType;
}
static bool isValidCoroutineContext(Sema &S, SourceLocation Loc,
StringRef Keyword) {
// [expr.await]p2 dictates that 'co_await' and 'co_yield' must be used within
// a function body.
// FIXME: This also covers [expr.await]p2: "An await-expression shall not
// appear in a default argument." But the diagnostic QoI here could be
// improved to inform the user that default arguments specifically are not
// allowed.
auto *FD = dyn_cast<FunctionDecl>(S.CurContext);
if (!FD) {
S.Diag(Loc, isa<ObjCMethodDecl>(S.CurContext)
? diag::err_coroutine_objc_method
: diag::err_coroutine_outside_function) << Keyword;
return false;
}
// An enumeration for mapping the diagnostic type to the correct diagnostic
// selection index.
enum InvalidFuncDiag {
DiagCtor = 0,
DiagDtor,
DiagMain,
DiagConstexpr,
DiagAutoRet,
DiagVarargs,
DiagConsteval,
};
bool Diagnosed = false;
auto DiagInvalid = [&](InvalidFuncDiag ID) {
S.Diag(Loc, diag::err_coroutine_invalid_func_context) << ID << Keyword;
Diagnosed = true;
return false;
};
// Diagnose when a constructor, destructor
// or the function 'main' are declared as a coroutine.
auto *MD = dyn_cast<CXXMethodDecl>(FD);
// [class.ctor]p11: "A constructor shall not be a coroutine."
if (MD && isa<CXXConstructorDecl>(MD))
return DiagInvalid(DiagCtor);
// [class.dtor]p17: "A destructor shall not be a coroutine."
else if (MD && isa<CXXDestructorDecl>(MD))
return DiagInvalid(DiagDtor);
// [basic.start.main]p3: "The function main shall not be a coroutine."
else if (FD->isMain())
return DiagInvalid(DiagMain);
// Emit a diagnostics for each of the following conditions which is not met.
// [expr.const]p2: "An expression e is a core constant expression unless the
// evaluation of e [...] would evaluate one of the following expressions:
// [...] an await-expression [...] a yield-expression."
if (FD->isConstexpr())
DiagInvalid(FD->isConsteval() ? DiagConsteval : DiagConstexpr);
// [dcl.spec.auto]p15: "A function declared with a return type that uses a
// placeholder type shall not be a coroutine."
if (FD->getReturnType()->isUndeducedType())
DiagInvalid(DiagAutoRet);
// [dcl.fct.def.coroutine]p1: "The parameter-declaration-clause of the
// coroutine shall not terminate with an ellipsis that is not part of a
// parameter-declaration."
if (FD->isVariadic())
DiagInvalid(DiagVarargs);
return !Diagnosed;
}
static ExprResult buildOperatorCoawaitLookupExpr(Sema &SemaRef, Scope *S,
SourceLocation Loc) {
DeclarationName OpName =
SemaRef.Context.DeclarationNames.getCXXOperatorName(OO_Coawait);
LookupResult Operators(SemaRef, OpName, SourceLocation(),
Sema::LookupOperatorName);
SemaRef.LookupName(Operators, S);
assert(!Operators.isAmbiguous() && "Operator lookup cannot be ambiguous");
const auto &Functions = Operators.asUnresolvedSet();
bool IsOverloaded =
Functions.size() > 1 ||
(Functions.size() == 1 && isa<FunctionTemplateDecl>(*Functions.begin()));
Expr *CoawaitOp = UnresolvedLookupExpr::Create(
SemaRef.Context, /*NamingClass*/ nullptr, NestedNameSpecifierLoc(),
DeclarationNameInfo(OpName, Loc), /*RequiresADL*/ true, IsOverloaded,
Functions.begin(), Functions.end());
assert(CoawaitOp);
return CoawaitOp;
}
/// Build a call to 'operator co_await' if there is a suitable operator for
/// the given expression.
static ExprResult buildOperatorCoawaitCall(Sema &SemaRef, SourceLocation Loc,
Expr *E,
UnresolvedLookupExpr *Lookup) {
UnresolvedSet<16> Functions;
Functions.append(Lookup->decls_begin(), Lookup->decls_end());
return SemaRef.CreateOverloadedUnaryOp(Loc, UO_Coawait, Functions, E);
}
static ExprResult buildOperatorCoawaitCall(Sema &SemaRef, Scope *S,
SourceLocation Loc, Expr *E) {
ExprResult R = buildOperatorCoawaitLookupExpr(SemaRef, S, Loc);
if (R.isInvalid())
return ExprError();
return buildOperatorCoawaitCall(SemaRef, Loc, E,
cast<UnresolvedLookupExpr>(R.get()));
}
static Expr *buildBuiltinCall(Sema &S, SourceLocation Loc, Builtin::ID Id,
MultiExprArg CallArgs) {
StringRef Name = S.Context.BuiltinInfo.getName(Id);
LookupResult R(S, &S.Context.Idents.get(Name), Loc, Sema::LookupOrdinaryName);
S.LookupName(R, S.TUScope, /*AllowBuiltinCreation=*/true);
auto *BuiltInDecl = R.getAsSingle<FunctionDecl>();
assert(BuiltInDecl && "failed to find builtin declaration");
ExprResult DeclRef =
S.BuildDeclRefExpr(BuiltInDecl, BuiltInDecl->getType(), VK_LValue, Loc);
assert(DeclRef.isUsable() && "Builtin reference cannot fail");
ExprResult Call =
S.BuildCallExpr(/*Scope=*/nullptr, DeclRef.get(), Loc, CallArgs, Loc);
assert(!Call.isInvalid() && "Call to builtin cannot fail!");
return Call.get();
}
static ExprResult buildCoroutineHandle(Sema &S, QualType PromiseType,
SourceLocation Loc) {
QualType CoroHandleType = lookupCoroutineHandleType(S, PromiseType, Loc);
if (CoroHandleType.isNull())
return ExprError();
DeclContext *LookupCtx = S.computeDeclContext(CoroHandleType);
LookupResult Found(S, &S.PP.getIdentifierTable().get("from_address"), Loc,
Sema::LookupOrdinaryName);
if (!S.LookupQualifiedName(Found, LookupCtx)) {
S.Diag(Loc, diag::err_coroutine_handle_missing_member)
<< "from_address";
return ExprError();
}
Expr *FramePtr =
buildBuiltinCall(S, Loc, Builtin::BI__builtin_coro_frame, {});
CXXScopeSpec SS;
ExprResult FromAddr =
S.BuildDeclarationNameExpr(SS, Found, /*NeedsADL=*/false);
if (FromAddr.isInvalid())
return ExprError();
return S.BuildCallExpr(nullptr, FromAddr.get(), Loc, FramePtr, Loc);
}
struct ReadySuspendResumeResult {
enum AwaitCallType { ACT_Ready, ACT_Suspend, ACT_Resume };
Expr *Results[3];
OpaqueValueExpr *OpaqueValue;
bool IsInvalid;
};
static ExprResult buildMemberCall(Sema &S, Expr *Base, SourceLocation Loc,
StringRef Name, MultiExprArg Args) {
DeclarationNameInfo NameInfo(&S.PP.getIdentifierTable().get(Name), Loc);
// FIXME: Fix BuildMemberReferenceExpr to take a const CXXScopeSpec&.
CXXScopeSpec SS;
ExprResult Result = S.BuildMemberReferenceExpr(
Base, Base->getType(), Loc, /*IsPtr=*/false, SS,
SourceLocation(), nullptr, NameInfo, /*TemplateArgs=*/nullptr,
/*Scope=*/nullptr);
if (Result.isInvalid())
return ExprError();
// We meant exactly what we asked for. No need for typo correction.
if (auto *TE = dyn_cast<TypoExpr>(Result.get())) {
S.clearDelayedTypo(TE);
S.Diag(Loc, diag::err_no_member)
<< NameInfo.getName() << Base->getType()->getAsCXXRecordDecl()
<< Base->getSourceRange();
return ExprError();
}
return S.BuildCallExpr(nullptr, Result.get(), Loc, Args, Loc, nullptr);
}
// See if return type is coroutine-handle and if so, invoke builtin coro-resume
// on its address. This is to enable experimental support for coroutine-handle
// returning await_suspend that results in a guaranteed tail call to the target
// coroutine.
static Expr *maybeTailCall(Sema &S, QualType RetType, Expr *E,
SourceLocation Loc) {
if (RetType->isReferenceType())
return nullptr;
Type const *T = RetType.getTypePtr();
if (!T->isClassType() && !T->isStructureType())
return nullptr;
// FIXME: Add convertability check to coroutine_handle<>. Possibly via
// EvaluateBinaryTypeTrait(BTT_IsConvertible, ...) which is at the moment
// a private function in SemaExprCXX.cpp
ExprResult AddressExpr = buildMemberCall(S, E, Loc, "address", None);
if (AddressExpr.isInvalid())
return nullptr;
Expr *JustAddress = AddressExpr.get();
// Check that the type of AddressExpr is void*
if (!JustAddress->getType().getTypePtr()->isVoidPointerType())
S.Diag(cast<CallExpr>(JustAddress)->getCalleeDecl()->getLocation(),
diag::warn_coroutine_handle_address_invalid_return_type)
<< JustAddress->getType();
// Clean up temporary objects so that they don't live across suspension points
// unnecessarily. We choose to clean up before the call to
// __builtin_coro_resume so that the cleanup code are not inserted in-between
// the resume call and return instruction, which would interfere with the
// musttail call contract.
JustAddress = S.MaybeCreateExprWithCleanups(JustAddress);
return buildBuiltinCall(S, Loc, Builtin::BI__builtin_coro_resume,
JustAddress);
}
/// Build calls to await_ready, await_suspend, and await_resume for a co_await
/// expression.
/// The generated AST tries to clean up temporary objects as early as
/// possible so that they don't live across suspension points if possible.
/// Having temporary objects living across suspension points unnecessarily can
/// lead to large frame size, and also lead to memory corruptions if the
/// coroutine frame is destroyed after coming back from suspension. This is done
/// by wrapping both the await_ready call and the await_suspend call with
/// ExprWithCleanups. In the end of this function, we also need to explicitly
/// set cleanup state so that the CoawaitExpr is also wrapped with an
/// ExprWithCleanups to clean up the awaiter associated with the co_await
/// expression.
static ReadySuspendResumeResult buildCoawaitCalls(Sema &S, VarDecl *CoroPromise,
SourceLocation Loc, Expr *E) {
OpaqueValueExpr *Operand = new (S.Context)
OpaqueValueExpr(Loc, E->getType(), VK_LValue, E->getObjectKind(), E);
// Assume valid until we see otherwise.
// Further operations are responsible for setting IsInalid to true.
ReadySuspendResumeResult Calls = {{}, Operand, /*IsInvalid=*/false};
using ACT = ReadySuspendResumeResult::AwaitCallType;
auto BuildSubExpr = [&](ACT CallType, StringRef Func,
MultiExprArg Arg) -> Expr * {
ExprResult Result = buildMemberCall(S, Operand, Loc, Func, Arg);
if (Result.isInvalid()) {
Calls.IsInvalid = true;
return nullptr;
}
Calls.Results[CallType] = Result.get();
return Result.get();
};
CallExpr *AwaitReady =
cast_or_null<CallExpr>(BuildSubExpr(ACT::ACT_Ready, "await_ready", None));
if (!AwaitReady)
return Calls;
if (!AwaitReady->getType()->isDependentType()) {
// [expr.await]p3 [...]
// — await-ready is the expression e.await_ready(), contextually converted
// to bool.
ExprResult Conv = S.PerformContextuallyConvertToBool(AwaitReady);
if (Conv.isInvalid()) {
S.Diag(AwaitReady->getDirectCallee()->getBeginLoc(),
diag::note_await_ready_no_bool_conversion);
S.Diag(Loc, diag::note_coroutine_promise_call_implicitly_required)
<< AwaitReady->getDirectCallee() << E->getSourceRange();
Calls.IsInvalid = true;
} else
Calls.Results[ACT::ACT_Ready] = S.MaybeCreateExprWithCleanups(Conv.get());
}
ExprResult CoroHandleRes =
buildCoroutineHandle(S, CoroPromise->getType(), Loc);
if (CoroHandleRes.isInvalid()) {
Calls.IsInvalid = true;
return Calls;
}
Expr *CoroHandle = CoroHandleRes.get();
CallExpr *AwaitSuspend = cast_or_null<CallExpr>(
BuildSubExpr(ACT::ACT_Suspend, "await_suspend", CoroHandle));
if (!AwaitSuspend)
return Calls;
if (!AwaitSuspend->getType()->isDependentType()) {
// [expr.await]p3 [...]
// - await-suspend is the expression e.await_suspend(h), which shall be
// a prvalue of type void, bool, or std::coroutine_handle<Z> for some
// type Z.
QualType RetType = AwaitSuspend->getCallReturnType(S.Context);
// Experimental support for coroutine_handle returning await_suspend.
if (Expr *TailCallSuspend =
maybeTailCall(S, RetType, AwaitSuspend, Loc))
// Note that we don't wrap the expression with ExprWithCleanups here
// because that might interfere with tailcall contract (e.g. inserting
// clean up instructions in-between tailcall and return). Instead
// ExprWithCleanups is wrapped within maybeTailCall() prior to the resume
// call.
Calls.Results[ACT::ACT_Suspend] = TailCallSuspend;
else {
// non-class prvalues always have cv-unqualified types
if (RetType->isReferenceType() ||
(!RetType->isBooleanType() && !RetType->isVoidType())) {
S.Diag(AwaitSuspend->getCalleeDecl()->getLocation(),
diag::err_await_suspend_invalid_return_type)
<< RetType;
S.Diag(Loc, diag::note_coroutine_promise_call_implicitly_required)
<< AwaitSuspend->getDirectCallee();
Calls.IsInvalid = true;
} else
Calls.Results[ACT::ACT_Suspend] =
S.MaybeCreateExprWithCleanups(AwaitSuspend);
}
}
BuildSubExpr(ACT::ACT_Resume, "await_resume", None);
// Make sure the awaiter object gets a chance to be cleaned up.
S.Cleanup.setExprNeedsCleanups(true);
return Calls;
}
static ExprResult buildPromiseCall(Sema &S, VarDecl *Promise,
SourceLocation Loc, StringRef Name,
MultiExprArg Args) {
// Form a reference to the promise.
ExprResult PromiseRef = S.BuildDeclRefExpr(
Promise, Promise->getType().getNonReferenceType(), VK_LValue, Loc);
if (PromiseRef.isInvalid())
return ExprError();
return buildMemberCall(S, PromiseRef.get(), Loc, Name, Args);
}
VarDecl *Sema::buildCoroutinePromise(SourceLocation Loc) {
assert(isa<FunctionDecl>(CurContext) && "not in a function scope");
auto *FD = cast<FunctionDecl>(CurContext);
bool IsThisDependentType = [&] {
if (auto *MD = dyn_cast_or_null<CXXMethodDecl>(FD))
return MD->isInstance() && MD->getThisType()->isDependentType();
else
return false;
}();
QualType T = FD->getType()->isDependentType() || IsThisDependentType
? Context.DependentTy
: lookupPromiseType(*this, FD, Loc);
if (T.isNull())
return nullptr;
auto *VD = VarDecl::Create(Context, FD, FD->getLocation(), FD->getLocation(),
&PP.getIdentifierTable().get("__promise"), T,
Context.getTrivialTypeSourceInfo(T, Loc), SC_None);
VD->setImplicit();
CheckVariableDeclarationType(VD);
if (VD->isInvalidDecl())
return nullptr;
auto *ScopeInfo = getCurFunction();
// Build a list of arguments, based on the coroutine function's arguments,
// that if present will be passed to the promise type's constructor.
llvm::SmallVector<Expr *, 4> CtorArgExprs;
// Add implicit object parameter.
if (auto *MD = dyn_cast<CXXMethodDecl>(FD)) {
if (MD->isInstance() && !isLambdaCallOperator(MD)) {
ExprResult ThisExpr = ActOnCXXThis(Loc);
if (ThisExpr.isInvalid())
return nullptr;
ThisExpr = CreateBuiltinUnaryOp(Loc, UO_Deref, ThisExpr.get());
if (ThisExpr.isInvalid())
return nullptr;
CtorArgExprs.push_back(ThisExpr.get());
}
}
// Add the coroutine function's parameters.
auto &Moves = ScopeInfo->CoroutineParameterMoves;
for (auto *PD : FD->parameters()) {
if (PD->getType()->isDependentType())
continue;
auto RefExpr = ExprEmpty();
auto Move = Moves.find(PD);
assert(Move != Moves.end() &&
"Coroutine function parameter not inserted into move map");
// If a reference to the function parameter exists in the coroutine
// frame, use that reference.
auto *MoveDecl =
cast<VarDecl>(cast<DeclStmt>(Move->second)->getSingleDecl());
RefExpr =
BuildDeclRefExpr(MoveDecl, MoveDecl->getType().getNonReferenceType(),
ExprValueKind::VK_LValue, FD->getLocation());
if (RefExpr.isInvalid())
return nullptr;
CtorArgExprs.push_back(RefExpr.get());
}
// If we have a non-zero number of constructor arguments, try to use them.
// Otherwise, fall back to the promise type's default constructor.
if (!CtorArgExprs.empty()) {
// Create an initialization sequence for the promise type using the
// constructor arguments, wrapped in a parenthesized list expression.
Expr *PLE = ParenListExpr::Create(Context, FD->getLocation(),
CtorArgExprs, FD->getLocation());
InitializedEntity Entity = InitializedEntity::InitializeVariable(VD);
InitializationKind Kind = InitializationKind::CreateForInit(
VD->getLocation(), /*DirectInit=*/true, PLE);
InitializationSequence InitSeq(*this, Entity, Kind, CtorArgExprs,
/*TopLevelOfInitList=*/false,
/*TreatUnavailableAsInvalid=*/false);
// Attempt to initialize the promise type with the arguments.
// If that fails, fall back to the promise type's default constructor.
if (InitSeq) {
ExprResult Result = InitSeq.Perform(*this, Entity, Kind, CtorArgExprs);
if (Result.isInvalid()) {
VD->setInvalidDecl();
} else if (Result.get()) {
VD->setInit(MaybeCreateExprWithCleanups(Result.get()));
VD->setInitStyle(VarDecl::CallInit);
CheckCompleteVariableDeclaration(VD);
}
} else
ActOnUninitializedDecl(VD);
} else
ActOnUninitializedDecl(VD);
FD->addDecl(VD);
return VD;
}
/// Check that this is a context in which a coroutine suspension can appear.
static FunctionScopeInfo *checkCoroutineContext(Sema &S, SourceLocation Loc,
StringRef Keyword,
bool IsImplicit = false) {
if (!isValidCoroutineContext(S, Loc, Keyword))
return nullptr;
assert(isa<FunctionDecl>(S.CurContext) && "not in a function scope");
auto *ScopeInfo = S.getCurFunction();
assert(ScopeInfo && "missing function scope for function");
if (ScopeInfo->FirstCoroutineStmtLoc.isInvalid() && !IsImplicit)
ScopeInfo->setFirstCoroutineStmt(Loc, Keyword);
if (ScopeInfo->CoroutinePromise)
return ScopeInfo;
if (!S.buildCoroutineParameterMoves(Loc))
return nullptr;
ScopeInfo->CoroutinePromise = S.buildCoroutinePromise(Loc);
if (!ScopeInfo->CoroutinePromise)
return nullptr;
return ScopeInfo;
}
/// Recursively check \p E and all its children to see if any call target
/// (including constructor call) is declared noexcept. Also any value returned
/// from the call has a noexcept destructor.
static void checkNoThrow(Sema &S, const Stmt *E,
llvm::SmallPtrSetImpl<const Decl *> &ThrowingDecls) {
auto checkDeclNoexcept = [&](const Decl *D, bool IsDtor = false) {
// In the case of dtor, the call to dtor is implicit and hence we should
// pass nullptr to canCalleeThrow.
if (Sema::canCalleeThrow(S, IsDtor ? nullptr : cast<Expr>(E), D)) {
if (const auto *FD = dyn_cast<FunctionDecl>(D)) {
// co_await promise.final_suspend() could end up calling
// __builtin_coro_resume for symmetric transfer if await_suspend()
// returns a handle. In that case, even __builtin_coro_resume is not
// declared as noexcept and may throw, it does not throw _into_ the
// coroutine that just suspended, but rather throws back out from
// whoever called coroutine_handle::resume(), hence we claim that
// logically it does not throw.
if (FD->getBuiltinID() == Builtin::BI__builtin_coro_resume)
return;
}
if (ThrowingDecls.empty()) {
// First time seeing an error, emit the error message.
S.Diag(cast<FunctionDecl>(S.CurContext)->getLocation(),
diag::err_coroutine_promise_final_suspend_requires_nothrow);
}
ThrowingDecls.insert(D);
}
};
auto SC = E->getStmtClass();
if (SC == Expr::CXXConstructExprClass) {
auto const *Ctor = cast<CXXConstructExpr>(E)->getConstructor();
checkDeclNoexcept(Ctor);
// Check the corresponding destructor of the constructor.
checkDeclNoexcept(Ctor->getParent()->getDestructor(), true);
} else if (SC == Expr::CallExprClass || SC == Expr::CXXMemberCallExprClass ||
SC == Expr::CXXOperatorCallExprClass) {
if (!cast<CallExpr>(E)->isTypeDependent()) {
checkDeclNoexcept(cast<CallExpr>(E)->getCalleeDecl());
auto ReturnType = cast<CallExpr>(E)->getCallReturnType(S.getASTContext());
// Check the destructor of the call return type, if any.
if (ReturnType.isDestructedType() ==
QualType::DestructionKind::DK_cxx_destructor) {
const auto *T =
cast<RecordType>(ReturnType.getCanonicalType().getTypePtr());
checkDeclNoexcept(
dyn_cast<CXXRecordDecl>(T->getDecl())->getDestructor(), true);
}
}
}
for (const auto *Child : E->children()) {
if (!Child)
continue;
checkNoThrow(S, Child, ThrowingDecls);
}
}
bool Sema::checkFinalSuspendNoThrow(const Stmt *FinalSuspend) {
llvm::SmallPtrSet<const Decl *, 4> ThrowingDecls;
// We first collect all declarations that should not throw but not declared
// with noexcept. We then sort them based on the location before printing.
// This is to avoid emitting the same note multiple times on the same
// declaration, and also provide a deterministic order for the messages.
checkNoThrow(*this, FinalSuspend, ThrowingDecls);
auto SortedDecls = llvm::SmallVector<const Decl *, 4>{ThrowingDecls.begin(),
ThrowingDecls.end()};
sort(SortedDecls, [](const Decl *A, const Decl *B) {
return A->getEndLoc() < B->getEndLoc();
});
for (const auto *D : SortedDecls) {
Diag(D->getEndLoc(), diag::note_coroutine_function_declare_noexcept);
}
return ThrowingDecls.empty();
}
bool Sema::ActOnCoroutineBodyStart(Scope *SC, SourceLocation KWLoc,
StringRef Keyword) {
if (!checkCoroutineContext(*this, KWLoc, Keyword))
return false;
auto *ScopeInfo = getCurFunction();
assert(ScopeInfo->CoroutinePromise);
// If we have existing coroutine statements then we have already built
// the initial and final suspend points.
if (!ScopeInfo->NeedsCoroutineSuspends)
return true;
ScopeInfo->setNeedsCoroutineSuspends(false);
auto *Fn = cast<FunctionDecl>(CurContext);
SourceLocation Loc = Fn->getLocation();
// Build the initial suspend point
auto buildSuspends = [&](StringRef Name) mutable -> StmtResult {
ExprResult Suspend =
buildPromiseCall(*this, ScopeInfo->CoroutinePromise, Loc, Name, None);
if (Suspend.isInvalid())
return StmtError();
Suspend = buildOperatorCoawaitCall(*this, SC, Loc, Suspend.get());
if (Suspend.isInvalid())
return StmtError();
Suspend = BuildResolvedCoawaitExpr(Loc, Suspend.get(),
/*IsImplicit*/ true);
Suspend = ActOnFinishFullExpr(Suspend.get(), /*DiscardedValue*/ false);
if (Suspend.isInvalid()) {
Diag(Loc, diag::note_coroutine_promise_suspend_implicitly_required)
<< ((Name == "initial_suspend") ? 0 : 1);
Diag(KWLoc, diag::note_declared_coroutine_here) << Keyword;
return StmtError();
}
return cast<Stmt>(Suspend.get());
};
StmtResult InitSuspend = buildSuspends("initial_suspend");
if (InitSuspend.isInvalid())
return true;
StmtResult FinalSuspend = buildSuspends("final_suspend");
if (FinalSuspend.isInvalid() || !checkFinalSuspendNoThrow(FinalSuspend.get()))
return true;
ScopeInfo->setCoroutineSuspends(InitSuspend.get(), FinalSuspend.get());
return true;
}
// Recursively walks up the scope hierarchy until either a 'catch' or a function
// scope is found, whichever comes first.
static bool isWithinCatchScope(Scope *S) {
// 'co_await' and 'co_yield' keywords are disallowed within catch blocks, but
// lambdas that use 'co_await' are allowed. The loop below ends when a
// function scope is found in order to ensure the following behavior:
//
// void foo() { // <- function scope
// try { //
// co_await x; // <- 'co_await' is OK within a function scope
// } catch { // <- catch scope
// co_await x; // <- 'co_await' is not OK within a catch scope
// []() { // <- function scope
// co_await x; // <- 'co_await' is OK within a function scope
// }();
// }
// }
while (S && !(S->getFlags() & Scope::FnScope)) {
if (S->getFlags() & Scope::CatchScope)
return true;
S = S->getParent();
}
return false;
}
// [expr.await]p2, emphasis added: "An await-expression shall appear only in
// a *potentially evaluated* expression within the compound-statement of a
// function-body *outside of a handler* [...] A context within a function
// where an await-expression can appear is called a suspension context of the
// function."
static void checkSuspensionContext(Sema &S, SourceLocation Loc,
StringRef Keyword) {
// First emphasis of [expr.await]p2: must be a potentially evaluated context.
// That is, 'co_await' and 'co_yield' cannot appear in subexpressions of
// \c sizeof.
if (S.isUnevaluatedContext())
S.Diag(Loc, diag::err_coroutine_unevaluated_context) << Keyword;
// Second emphasis of [expr.await]p2: must be outside of an exception handler.
if (isWithinCatchScope(S.getCurScope()))
S.Diag(Loc, diag::err_coroutine_within_handler) << Keyword;
}
ExprResult Sema::ActOnCoawaitExpr(Scope *S, SourceLocation Loc, Expr *E) {
if (!ActOnCoroutineBodyStart(S, Loc, "co_await")) {
CorrectDelayedTyposInExpr(E);
return ExprError();
}
checkSuspensionContext(*this, Loc, "co_await");
if (E->getType()->isPlaceholderType()) {
ExprResult R = CheckPlaceholderExpr(E);
if (R.isInvalid()) return ExprError();
E = R.get();
}
ExprResult Lookup = buildOperatorCoawaitLookupExpr(*this, S, Loc);
if (Lookup.isInvalid())
return ExprError();
return BuildUnresolvedCoawaitExpr(Loc, E,
cast<UnresolvedLookupExpr>(Lookup.get()));
}
ExprResult Sema::BuildUnresolvedCoawaitExpr(SourceLocation Loc, Expr *E,
UnresolvedLookupExpr *Lookup) {
auto *FSI = checkCoroutineContext(*this, Loc, "co_await");
if (!FSI)
return ExprError();
if (E->getType()->isPlaceholderType()) {
ExprResult R = CheckPlaceholderExpr(E);
if (R.isInvalid())
return ExprError();
E = R.get();
}
auto *Promise = FSI->CoroutinePromise;
if (Promise->getType()->isDependentType()) {
Expr *Res =
new (Context) DependentCoawaitExpr(Loc, Context.DependentTy, E, Lookup);
return Res;
}
auto *RD = Promise->getType()->getAsCXXRecordDecl();
if (lookupMember(*this, "await_transform", RD, Loc)) {
ExprResult R = buildPromiseCall(*this, Promise, Loc, "await_transform", E);
if (R.isInvalid()) {
Diag(Loc,
diag::note_coroutine_promise_implicit_await_transform_required_here)
<< E->getSourceRange();
return ExprError();
}
E = R.get();
}
ExprResult Awaitable = buildOperatorCoawaitCall(*this, Loc, E, Lookup);
if (Awaitable.isInvalid())
return ExprError();
return BuildResolvedCoawaitExpr(Loc, Awaitable.get());
}
ExprResult Sema::BuildResolvedCoawaitExpr(SourceLocation Loc, Expr *E,
bool IsImplicit) {
auto *Coroutine = checkCoroutineContext(*this, Loc, "co_await", IsImplicit);
if (!Coroutine)
return ExprError();
if (E->getType()->isPlaceholderType()) {
ExprResult R = CheckPlaceholderExpr(E);
if (R.isInvalid()) return ExprError();
E = R.get();
}
if (E->getType()->isDependentType()) {
Expr *Res = new (Context)
CoawaitExpr(Loc, Context.DependentTy, E, IsImplicit);
return Res;
}
// If the expression is a temporary, materialize it as an lvalue so that we
// can use it multiple times.
if (E->getValueKind() == VK_RValue)
E = CreateMaterializeTemporaryExpr(E->getType(), E, true);
// The location of the `co_await` token cannot be used when constructing
// the member call expressions since it's before the location of `Expr`, which
// is used as the start of the member call expression.
SourceLocation CallLoc = E->getExprLoc();
// Build the await_ready, await_suspend, await_resume calls.
ReadySuspendResumeResult RSS = buildCoawaitCalls(
*this, Coroutine->CoroutinePromise, CallLoc, E);
if (RSS.IsInvalid)
return ExprError();
Expr *Res =
new (Context) CoawaitExpr(Loc, E, RSS.Results[0], RSS.Results[1],
RSS.Results[2], RSS.OpaqueValue, IsImplicit);
return Res;
}
ExprResult Sema::ActOnCoyieldExpr(Scope *S, SourceLocation Loc, Expr *E) {
if (!ActOnCoroutineBodyStart(S, Loc, "co_yield")) {
CorrectDelayedTyposInExpr(E);
return ExprError();
}
checkSuspensionContext(*this, Loc, "co_yield");
// Build yield_value call.
ExprResult Awaitable = buildPromiseCall(
*this, getCurFunction()->CoroutinePromise, Loc, "yield_value", E);
if (Awaitable.isInvalid())
return ExprError();
// Build 'operator co_await' call.
Awaitable = buildOperatorCoawaitCall(*this, S, Loc, Awaitable.get());
if (Awaitable.isInvalid())
return ExprError();
return BuildCoyieldExpr(Loc, Awaitable.get());
}
ExprResult Sema::BuildCoyieldExpr(SourceLocation Loc, Expr *E) {
auto *Coroutine = checkCoroutineContext(*this, Loc, "co_yield");
if (!Coroutine)
return ExprError();
if (E->getType()->isPlaceholderType()) {
ExprResult R = CheckPlaceholderExpr(E);
if (R.isInvalid()) return ExprError();
E = R.get();
}
if (E->getType()->isDependentType()) {
Expr *Res = new (Context) CoyieldExpr(Loc, Context.DependentTy, E);
return Res;
}
// If the expression is a temporary, materialize it as an lvalue so that we
// can use it multiple times.
if (E->getValueKind() == VK_RValue)
E = CreateMaterializeTemporaryExpr(E->getType(), E, true);
// Build the await_ready, await_suspend, await_resume calls.
ReadySuspendResumeResult RSS = buildCoawaitCalls(
*this, Coroutine->CoroutinePromise, Loc, E);
if (RSS.IsInvalid)
return ExprError();
Expr *Res =
new (Context) CoyieldExpr(Loc, E, RSS.Results[0], RSS.Results[1],
RSS.Results[2], RSS.OpaqueValue);
return Res;
}
StmtResult Sema::ActOnCoreturnStmt(Scope *S, SourceLocation Loc, Expr *E) {
if (!ActOnCoroutineBodyStart(S, Loc, "co_return")) {
CorrectDelayedTyposInExpr(E);
return StmtError();
}
return BuildCoreturnStmt(Loc, E);
}
StmtResult Sema::BuildCoreturnStmt(SourceLocation Loc, Expr *E,
bool IsImplicit) {
auto *FSI = checkCoroutineContext(*this, Loc, "co_return", IsImplicit);
if (!FSI)
return StmtError();
if (E && E->getType()->isPlaceholderType() &&
!E->getType()->isSpecificPlaceholderType(BuiltinType::Overload)) {
ExprResult R = CheckPlaceholderExpr(E);
if (R.isInvalid()) return StmtError();
E = R.get();
}
// Move the return value if we can
if (E) {
auto NRVOCandidate = this->getCopyElisionCandidate(E->getType(), E, CES_AsIfByStdMove);
if (NRVOCandidate) {
InitializedEntity Entity =
InitializedEntity::InitializeResult(Loc, E->getType(), NRVOCandidate);
ExprResult MoveResult = this->PerformMoveOrCopyInitialization(
Entity, NRVOCandidate, E->getType(), E);
if (MoveResult.get())
E = MoveResult.get();
}
}
// FIXME: If the operand is a reference to a variable that's about to go out
// of scope, we should treat the operand as an xvalue for this overload
// resolution.
VarDecl *Promise = FSI->CoroutinePromise;
ExprResult PC;
if (E && (isa<InitListExpr>(E) || !E->getType()->isVoidType())) {
PC = buildPromiseCall(*this, Promise, Loc, "return_value", E);
} else {
E = MakeFullDiscardedValueExpr(E).get();
PC = buildPromiseCall(*this, Promise, Loc, "return_void", None);
}
if (PC.isInvalid())
return StmtError();
Expr *PCE = ActOnFinishFullExpr(PC.get(), /*DiscardedValue*/ false).get();
Stmt *Res = new (Context) CoreturnStmt(Loc, E, PCE, IsImplicit);
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: <experimental/coroutine> should have been included already.
// If we require it to include <new> 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<VarDecl>();
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) {
FunctionDecl *OperatorDelete = nullptr;
DeclarationName DeleteName =
S.Context.DeclarationNames.getCXXOperatorName(OO_Delete);
auto *PointeeRD = PromiseType->getAsCXXRecordDecl();
assert(PointeeRD && "PromiseType must be a CxxRecordDecl type");
if (S.FindDeallocationFunction(Loc, PointeeRD, DeleteName, OperatorDelete))
return nullptr;
if (!OperatorDelete) {
// Look for a global declaration.
const bool CanProvideSize = S.isCompleteType(Loc, PromiseType);
const bool Overaligned = false;
OperatorDelete = S.FindUsualDeallocationFunction(Loc, CanProvideSize,
Overaligned, DeleteName);
}
S.MarkFunctionReferenced(Loc, OperatorDelete);
return OperatorDelete;
}
void Sema::CheckCompletedCoroutineBody(FunctionDecl *FD, Stmt *&Body) {
FunctionScopeInfo *Fn = getCurFunction();
assert(Fn && Fn->isCoroutine() && "not a coroutine");
if (!Body) {
assert(FD->isInvalidDecl() &&
"a null body is only allowed for invalid declarations");
return;
}
// We have a function that uses coroutine keywords, but we failed to build
// the promise type.
if (!Fn->CoroutinePromise)
return FD->setInvalidDecl();
if (isa<CoroutineBodyStmt>(Body)) {
// Nothing todo. the body is already a transformed coroutine body statement.
return;
}
// Coroutines [stmt.return]p1:
// A return statement shall not appear in a coroutine.
if (Fn->FirstReturnLoc.isValid()) {
assert(Fn->FirstCoroutineStmtLoc.isValid() &&
"first coroutine location not set");
Diag(Fn->FirstReturnLoc, diag::err_return_in_coroutine);
Diag(Fn->FirstCoroutineStmtLoc, diag::note_declared_coroutine_here)
<< Fn->getFirstCoroutineStmtKeyword();
}
CoroutineStmtBuilder Builder(*this, *FD, *Fn, Body);
if (Builder.isInvalid() || !Builder.buildStatements())
return FD->setInvalidDecl();
// Build body for the coroutine wrapper statement.
Body = CoroutineBodyStmt::Create(Context, Builder);
}
CoroutineStmtBuilder::CoroutineStmtBuilder(Sema &S, FunctionDecl &FD,
sema::FunctionScopeInfo &Fn,
Stmt *Body)
: S(S), FD(FD), Fn(Fn), Loc(FD.getLocation()),
IsPromiseDependentType(
!Fn.CoroutinePromise ||
Fn.CoroutinePromise->getType()->isDependentType()) {
this->Body = Body;
for (auto KV : Fn.CoroutineParameterMoves)
this->ParamMovesVector.push_back(KV.second);
this->ParamMoves = this->ParamMovesVector;
if (!IsPromiseDependentType) {
PromiseRecordDecl = Fn.CoroutinePromise->getType()->getAsCXXRecordDecl();
assert(PromiseRecordDecl && "Type should have already been checked");
}
this->IsValid = makePromiseStmt() && makeInitialAndFinalSuspend();
}
bool CoroutineStmtBuilder::buildStatements() {
assert(this->IsValid && "coroutine already invalid");
this->IsValid = makeReturnObject();
if (this->IsValid && !IsPromiseDependentType)
buildDependentStatements();
return this->IsValid;
}
bool CoroutineStmtBuilder::buildDependentStatements() {
assert(this->IsValid && "coroutine already invalid");
assert(!this->IsPromiseDependentType &&
"coroutine cannot have a dependent promise type");
this->IsValid = makeOnException() && makeOnFallthrough() &&
makeGroDeclAndReturnStmt() && makeReturnOnAllocFailure() &&
makeNewAndDeleteExpr();
return this->IsValid;
}
bool CoroutineStmtBuilder::makePromiseStmt() {
// Form a declaration statement for the promise declaration, so that AST
// visitors can more easily find it.
StmtResult PromiseStmt =
S.ActOnDeclStmt(S.ConvertDeclToDeclGroup(Fn.CoroutinePromise), Loc, Loc);
if (PromiseStmt.isInvalid())
return false;
this->Promise = PromiseStmt.get();
return true;
}
bool CoroutineStmtBuilder::makeInitialAndFinalSuspend() {
if (Fn.hasInvalidCoroutineSuspends())
return false;
this->InitialSuspend = cast<Expr>(Fn.CoroutineSuspends.first);
this->FinalSuspend = cast<Expr>(Fn.CoroutineSuspends.second);
return true;
}
static bool diagReturnOnAllocFailure(Sema &S, Expr *E,
CXXRecordDecl *PromiseRecordDecl,
FunctionScopeInfo &Fn) {
auto Loc = E->getExprLoc();
if (auto *DeclRef = dyn_cast_or_null<DeclRefExpr>(E)) {
auto *Decl = DeclRef->getDecl();
if (CXXMethodDecl *Method = dyn_cast_or_null<CXXMethodDecl>(Decl)) {
if (Method->isStatic())
return true;
else
Loc = Decl->getLocation();
}
}
S.Diag(
Loc,
diag::err_coroutine_promise_get_return_object_on_allocation_failure)
<< PromiseRecordDecl;
S.Diag(Fn.FirstCoroutineStmtLoc, diag::note_declared_coroutine_here)
<< Fn.getFirstCoroutineStmtKeyword();
return false;
}
bool CoroutineStmtBuilder::makeReturnOnAllocFailure() {
assert(!IsPromiseDependentType &&
"cannot make statement while the promise type is dependent");
// [dcl.fct.def.coroutine]/8
// The unqualified-id get_return_object_on_allocation_failure is looked up in
// the scope of class P by class member access lookup (3.4.5). ...
// If an allocation function returns nullptr, ... the coroutine return value
// is obtained by a call to ... get_return_object_on_allocation_failure().
DeclarationName DN =
S.PP.getIdentifierInfo("get_return_object_on_allocation_failure");
LookupResult Found(S, DN, Loc, Sema::LookupMemberName);
if (!S.LookupQualifiedName(Found, PromiseRecordDecl))
return true;
CXXScopeSpec SS;
ExprResult DeclNameExpr =
S.BuildDeclarationNameExpr(SS, Found, /*NeedsADL=*/false);
if (DeclNameExpr.isInvalid())
return false;
if (!diagReturnOnAllocFailure(S, DeclNameExpr.get(), PromiseRecordDecl, Fn))
return false;
ExprResult ReturnObjectOnAllocationFailure =
S.BuildCallExpr(nullptr, DeclNameExpr.get(), Loc, {}, Loc);
if (ReturnObjectOnAllocationFailure.isInvalid())
return false;
StmtResult ReturnStmt =
S.BuildReturnStmt(Loc, ReturnObjectOnAllocationFailure.get());
if (ReturnStmt.isInvalid()) {
S.Diag(Found.getFoundDecl()->getLocation(), diag::note_member_declared_here)
<< DN;
S.Diag(Fn.FirstCoroutineStmtLoc, diag::note_declared_coroutine_here)
<< Fn.getFirstCoroutineStmtKeyword();
return false;
}
this->ReturnStmtOnAllocFailure = ReturnStmt.get();
return true;
}
bool CoroutineStmtBuilder::makeNewAndDeleteExpr() {
// Form and check allocation and deallocation calls.
assert(!IsPromiseDependentType &&
"cannot make statement while the promise type is dependent");
QualType PromiseType = Fn.CoroutinePromise->getType();
if (S.RequireCompleteType(Loc, PromiseType, diag::err_incomplete_type))
return false;
const bool RequiresNoThrowAlloc = ReturnStmtOnAllocFailure != nullptr;
// [dcl.fct.def.coroutine]/7
// Lookup allocation functions using a parameter list composed of the
// requested size of the coroutine state being allocated, followed by
// the coroutine function's arguments. If a matching allocation function
// exists, use it. Otherwise, use an allocation function that just takes
// the requested size.
FunctionDecl *OperatorNew = nullptr;
FunctionDecl *OperatorDelete = nullptr;
FunctionDecl *UnusedResult = nullptr;
bool PassAlignment = false;
SmallVector<Expr *, 1> PlacementArgs;
// [dcl.fct.def.coroutine]/7
// "The allocation function’s name is looked up in the scope of P.
// [...] If the lookup finds an allocation function in the scope of P,
// overload resolution is performed on a function call created by assembling
// an argument list. The first argument is the amount of space requested,
// and has type std::size_t. The lvalues p1 ... pn are the succeeding
// arguments."
//
// ...where "p1 ... pn" are defined earlier as:
//
// [dcl.fct.def.coroutine]/3
// "For a coroutine f that is a non-static member function, let P1 denote the
// type of the implicit object parameter (13.3.1) and P2 ... Pn be the types
// of the function parameters; otherwise let P1 ... Pn be the types of the
// function parameters. Let p1 ... pn be lvalues denoting those objects."
if (auto *MD = dyn_cast<CXXMethodDecl>(&FD)) {
if (MD->isInstance() && !isLambdaCallOperator(MD)) {
ExprResult ThisExpr = S.ActOnCXXThis(Loc);
if (ThisExpr.isInvalid())
return false;
ThisExpr = S.CreateBuiltinUnaryOp(Loc, UO_Deref, ThisExpr.get());
if (ThisExpr.isInvalid())
return false;
PlacementArgs.push_back(ThisExpr.get());
}
}
for (auto *PD : FD.parameters()) {
if (PD->getType()->isDependentType())
continue;
// Build a reference to the parameter.
auto PDLoc = PD->getLocation();
ExprResult PDRefExpr =
S.BuildDeclRefExpr(PD, PD->getOriginalType().getNonReferenceType(),
ExprValueKind::VK_LValue, PDLoc);
if (PDRefExpr.isInvalid())
return false;
PlacementArgs.push_back(PDRefExpr.get());
}
S.FindAllocationFunctions(Loc, SourceRange(), /*NewScope*/ Sema::AFS_Class,
/*DeleteScope*/ Sema::AFS_Both, PromiseType,
/*isArray*/ false, PassAlignment, PlacementArgs,
OperatorNew, UnusedResult, /*Diagnose*/ false);
// [dcl.fct.def.coroutine]/7
// "If no matching function is found, overload resolution is performed again
// on a function call created by passing just the amount of space required as
// an argument of type std::size_t."
if (!OperatorNew && !PlacementArgs.empty()) {
PlacementArgs.clear();
S.FindAllocationFunctions(Loc, SourceRange(), /*NewScope*/ Sema::AFS_Class,
/*DeleteScope*/ Sema::AFS_Both, PromiseType,
/*isArray*/ false, PassAlignment, PlacementArgs,
OperatorNew, UnusedResult, /*Diagnose*/ false);
}
// [dcl.fct.def.coroutine]/7
// "The allocation function’s name is looked up in the scope of P. If this
// lookup fails, the allocation function’s name is looked up in the global
// scope."
if (!OperatorNew) {
S.FindAllocationFunctions(Loc, SourceRange(), /*NewScope*/ Sema::AFS_Global,
/*DeleteScope*/ Sema::AFS_Both, PromiseType,
/*isArray*/ false, PassAlignment, PlacementArgs,
OperatorNew, UnusedResult);
}
bool IsGlobalOverload =
OperatorNew && !isa<CXXRecordDecl>(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 = {StdNoThrow};
OperatorNew = nullptr;
S.FindAllocationFunctions(Loc, SourceRange(), /*NewScope*/ Sema::AFS_Both,
/*DeleteScope*/ Sema::AFS_Both, PromiseType,
/*isArray*/ false, PassAlignment, PlacementArgs,
OperatorNew, UnusedResult);
}
if (!OperatorNew)
return false;
if (RequiresNoThrowAlloc) {
const auto *FT = OperatorNew->getType()->castAs<FunctionProtoType>();
if (!FT->isNothrow(/*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 = findDeleteForPromise(S, Loc, PromiseType)) == nullptr)
return false;
Expr *FramePtr =
buildBuiltinCall(S, Loc, Builtin::BI__builtin_coro_frame, {});
Expr *FrameSize =
buildBuiltinCall(S, Loc, Builtin::BI__builtin_coro_size, {});
// Make new call.
ExprResult NewRef =
S.BuildDeclRefExpr(OperatorNew, OperatorNew->getType(), VK_LValue, Loc);
if (NewRef.isInvalid())
return false;
SmallVector<Expr *, 2> NewArgs(1, FrameSize);
for (auto Arg : PlacementArgs)
NewArgs.push_back(Arg);
ExprResult NewExpr =
S.BuildCallExpr(S.getCurScope(), NewRef.get(), Loc, NewArgs, Loc);
NewExpr = S.ActOnFinishFullExpr(NewExpr.get(), /*DiscardedValue*/ false);
if (NewExpr.isInvalid())
return false;
// Make delete call.
QualType OpDeleteQualType = OperatorDelete->getType();
ExprResult DeleteRef =
S.BuildDeclRefExpr(OperatorDelete, OpDeleteQualType, VK_LValue, Loc);
if (DeleteRef.isInvalid())
return false;
Expr *CoroFree =
buildBuiltinCall(S, Loc, Builtin::BI__builtin_coro_free, {FramePtr});
SmallVector<Expr *, 2> DeleteArgs{CoroFree};
// Check if we need to pass the size.
const auto *OpDeleteType =
OpDeleteQualType.getTypePtr()->castAs<FunctionProtoType>();
if (OpDeleteType->getNumParams() > 1)
DeleteArgs.push_back(FrameSize);
ExprResult DeleteExpr =
S.BuildCallExpr(S.getCurScope(), DeleteRef.get(), Loc, DeleteArgs, Loc);
DeleteExpr =
S.ActOnFinishFullExpr(DeleteExpr.get(), /*DiscardedValue*/ false);
if (DeleteExpr.isInvalid())
return false;
this->Allocate = NewExpr.get();
this->Deallocate = DeleteExpr.get();
return true;
}
bool CoroutineStmtBuilder::makeOnFallthrough() {
assert(!IsPromiseDependentType &&
"cannot make statement while the promise type is dependent");
// [dcl.fct.def.coroutine]/4
// The unqualified-ids 'return_void' and 'return_value' are looked up in
// the scope of class P. If both are found, the program is ill-formed.
bool HasRVoid, HasRValue;
LookupResult LRVoid =
lookupMember(S, "return_void", PromiseRecordDecl, Loc, HasRVoid);
LookupResult LRValue =
lookupMember(S, "return_value", PromiseRecordDecl, Loc, HasRValue);
StmtResult Fallthrough;
if (HasRVoid && HasRValue) {
// FIXME Improve this diagnostic
S.Diag(FD.getLocation(),
diag::err_coroutine_promise_incompatible_return_functions)
<< PromiseRecordDecl;
S.Diag(LRVoid.getRepresentativeDecl()->getLocation(),
diag::note_member_first_declared_here)
<< LRVoid.getLookupName();
S.Diag(LRValue.getRepresentativeDecl()->getLocation(),
diag::note_member_first_declared_here)
<< LRValue.getLookupName();
return false;
} else if (!HasRVoid && !HasRValue) {
// FIXME: The PDTS currently specifies this case as UB, not ill-formed.
// However we still diagnose this as an error since until the PDTS is fixed.
S.Diag(FD.getLocation(),
diag::err_coroutine_promise_requires_return_function)
<< PromiseRecordDecl;
S.Diag(PromiseRecordDecl->getLocation(), diag::note_defined_here)
<< PromiseRecordDecl;
return false;
} else if (HasRVoid) {
// If the unqualified-id return_void is found, flowing off the end of a
// coroutine is equivalent to a co_return with no operand. Otherwise,
// flowing off the end of a coroutine results in undefined behavior.
Fallthrough = S.BuildCoreturnStmt(FD.getLocation(), nullptr,
/*IsImplicit*/false);
Fallthrough = S.ActOnFinishFullStmt(Fallthrough.get());
if (Fallthrough.isInvalid())
return false;
}
this->OnFallthrough = Fallthrough.get();
return true;
}
bool CoroutineStmtBuilder::makeOnException() {
// Try to form 'p.unhandled_exception();'
assert(!IsPromiseDependentType &&
"cannot make statement while the promise type is dependent");
const bool RequireUnhandledException = S.getLangOpts().CXXExceptions;
if (!lookupMember(S, "unhandled_exception", PromiseRecordDecl, Loc)) {
auto DiagID =
RequireUnhandledException
? diag::err_coroutine_promise_unhandled_exception_required
: diag::
warn_coroutine_promise_unhandled_exception_required_with_exceptions;
S.Diag(Loc, DiagID) << PromiseRecordDecl;
S.Diag(PromiseRecordDecl->getLocation(), diag::note_defined_here)
<< PromiseRecordDecl;
return !RequireUnhandledException;
}
// If exceptions are disabled, don't try to build OnException.
if (!S.getLangOpts().CXXExceptions)
return true;
ExprResult UnhandledException = buildPromiseCall(S, Fn.CoroutinePromise, Loc,
"unhandled_exception", None);
UnhandledException = S.ActOnFinishFullExpr(UnhandledException.get(), Loc,
/*DiscardedValue*/ false);
if (UnhandledException.isInvalid())
return false;
// Since the body of the coroutine will be wrapped in try-catch, it will
// be incompatible with SEH __try if present in a function.
if (!S.getLangOpts().Borland && Fn.FirstSEHTryLoc.isValid()) {
S.Diag(Fn.FirstSEHTryLoc, diag::err_seh_in_a_coroutine_with_cxx_exceptions);
S.Diag(Fn.FirstCoroutineStmtLoc, diag::note_declared_coroutine_here)
<< Fn.getFirstCoroutineStmtKeyword();
return false;
}
this->OnException = UnhandledException.get();
return true;
}
bool CoroutineStmtBuilder::makeReturnObject() {
// Build implicit 'p.get_return_object()' expression and form initialization
// of return type from it.
ExprResult ReturnObject =
buildPromiseCall(S, Fn.CoroutinePromise, Loc, "get_return_object", None);
if (ReturnObject.isInvalid())
return false;
this->ReturnValue = ReturnObject.get();
return true;
}
static void noteMemberDeclaredHere(Sema &S, Expr *E, FunctionScopeInfo &Fn) {
if (auto *MbrRef = dyn_cast<CXXMemberCallExpr>(E)) {
auto *MethodDecl = MbrRef->getMethodDecl();
S.Diag(MethodDecl->getLocation(), diag::note_member_declared_here)
<< MethodDecl;
}
S.Diag(Fn.FirstCoroutineStmtLoc, diag::note_declared_coroutine_here)
<< Fn.getFirstCoroutineStmtKeyword();
}
bool CoroutineStmtBuilder::makeGroDeclAndReturnStmt() {
assert(!IsPromiseDependentType &&
"cannot make statement while the promise type is dependent");
assert(this->ReturnValue && "ReturnValue must be already formed");
QualType const GroType = this->ReturnValue->getType();
assert(!GroType->isDependentType() &&
"get_return_object type must no longer be dependent");
QualType const FnRetType = FD.getReturnType();
assert(!FnRetType->isDependentType() &&
"get_return_object type must no longer be dependent");
if (FnRetType->isVoidType()) {
ExprResult Res =
S.ActOnFinishFullExpr(this->ReturnValue, Loc, /*DiscardedValue*/ false);
if (Res.isInvalid())
return false;
this->ResultDecl = Res.get();
return true;
}
if (GroType->isVoidType()) {
// Trigger a nice error message.
InitializedEntity Entity =
InitializedEntity::InitializeResult(Loc, FnRetType, false);
S.PerformMoveOrCopyInitialization(Entity, nullptr, FnRetType, ReturnValue);
noteMemberDeclaredHere(S, ReturnValue, Fn);
return false;
}
auto *GroDecl = VarDecl::Create(
S.Context, &FD, FD.getLocation(), FD.getLocation(),
&S.PP.getIdentifierTable().get("__coro_gro"), GroType,
S.Context.getTrivialTypeSourceInfo(GroType, Loc), SC_None);
GroDecl->setImplicit();
S.CheckVariableDeclarationType(GroDecl);
if (GroDecl->isInvalidDecl())
return false;
InitializedEntity Entity = InitializedEntity::InitializeVariable(GroDecl);
ExprResult Res = S.PerformMoveOrCopyInitialization(Entity, nullptr, GroType,
this->ReturnValue);
if (Res.isInvalid())
return false;
Res = S.ActOnFinishFullExpr(Res.get(), /*DiscardedValue*/ false);
if (Res.isInvalid())
return false;
S.AddInitializerToDecl(GroDecl, Res.get(),
/*DirectInit=*/false);
S.FinalizeDeclaration(GroDecl);
// Form a declaration statement for the return declaration, so that AST
// visitors can more easily find it.
StmtResult GroDeclStmt =
S.ActOnDeclStmt(S.ConvertDeclToDeclGroup(GroDecl), Loc, Loc);
if (GroDeclStmt.isInvalid())
return false;
this->ResultDecl = GroDeclStmt.get();
ExprResult declRef = S.BuildDeclRefExpr(GroDecl, GroType, VK_LValue, Loc);
if (declRef.isInvalid())
return false;
StmtResult ReturnStmt = S.BuildReturnStmt(Loc, declRef.get());
if (ReturnStmt.isInvalid()) {
noteMemberDeclaredHere(S, ReturnValue, Fn);
return false;
}
if (cast<clang::ReturnStmt>(ReturnStmt.get())->getNRVOCandidate() == GroDecl)
GroDecl->setNRVOVariable(true);
this->ReturnStmt = ReturnStmt.get();
return true;
}
// Create a static_cast\<T&&>(expr).
static Expr *castForMoving(Sema &S, Expr *E, QualType T = QualType()) {
if (T.isNull())
T = E->getType();
QualType TargetType = S.BuildReferenceType(
T, /*SpelledAsLValue*/ false, SourceLocation(), DeclarationName());
SourceLocation ExprLoc = E->getBeginLoc();
TypeSourceInfo *TargetLoc =
S.Context.getTrivialTypeSourceInfo(TargetType, ExprLoc);
return S
.BuildCXXNamedCast(ExprLoc, tok::kw_static_cast, TargetLoc, E,
SourceRange(ExprLoc, ExprLoc), E->getSourceRange())
.get();
}
/// Build a variable declaration for move parameter.
static VarDecl *buildVarDecl(Sema &S, SourceLocation Loc, QualType Type,
IdentifierInfo *II) {
TypeSourceInfo *TInfo = S.Context.getTrivialTypeSourceInfo(Type, Loc);
VarDecl *Decl = VarDecl::Create(S.Context, S.CurContext, Loc, Loc, II, Type,
TInfo, SC_None);
Decl->setImplicit();
return Decl;
}
// Build statements that move coroutine function parameters to the coroutine
// frame, and store them on the function scope info.
bool Sema::buildCoroutineParameterMoves(SourceLocation Loc) {
assert(isa<FunctionDecl>(CurContext) && "not in a function scope");
auto *FD = cast<FunctionDecl>(CurContext);
auto *ScopeInfo = getCurFunction();
if (!ScopeInfo->CoroutineParameterMoves.empty())
return false;
for (auto *PD : FD->parameters()) {
if (PD->getType()->isDependentType())
continue;
ExprResult PDRefExpr =
BuildDeclRefExpr(PD, PD->getType().getNonReferenceType(),
ExprValueKind::VK_LValue, Loc); // FIXME: scope?
if (PDRefExpr.isInvalid())
return false;
Expr *CExpr = nullptr;
if (PD->getType()->getAsCXXRecordDecl() ||
PD->getType()->isRValueReferenceType())
CExpr = castForMoving(*this, PDRefExpr.get());
else
CExpr = PDRefExpr.get();
auto D = buildVarDecl(*this, Loc, PD->getType(), PD->getIdentifier());
AddInitializerToDecl(D, CExpr, /*DirectInit=*/true);
// Convert decl to a statement.
StmtResult Stmt = ActOnDeclStmt(ConvertDeclToDeclGroup(D), Loc, Loc);
if (Stmt.isInvalid())
return false;
ScopeInfo->CoroutineParameterMoves.insert(std::make_pair(PD, Stmt.get()));
}
return true;
}
StmtResult Sema::BuildCoroutineBodyStmt(CoroutineBodyStmt::CtorArgs Args) {
CoroutineBodyStmt *Res = CoroutineBodyStmt::Create(Context, Args);
if (!Res)
return StmtError();
return Res;
}
ClassTemplateDecl *Sema::lookupCoroutineTraits(SourceLocation KwLoc,
SourceLocation FuncLoc) {
if (!StdCoroutineTraitsCache) {
if (auto StdExp = lookupStdExperimentalNamespace()) {
LookupResult Result(*this,
&PP.getIdentifierTable().get("coroutine_traits"),
FuncLoc, LookupOrdinaryName);
if (!LookupQualifiedName(Result, StdExp)) {
Diag(KwLoc, diag::err_implied_coroutine_type_not_found)
<< "std::experimental::coroutine_traits";
return nullptr;
}
if (!(StdCoroutineTraitsCache =
Result.getAsSingle<ClassTemplateDecl>())) {
Result.suppressDiagnostics();
NamedDecl *Found = *Result.begin();
Diag(Found->getLocation(), diag::err_malformed_std_coroutine_traits);
return nullptr;
}
}
}
return StdCoroutineTraitsCache;
}
Reference in New Issue View Git Blame Copy Permalink