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llvm-project/clang/lib/Sema/SemaCoroutine.cpp

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//===--- SemaCoroutines.cpp - Semantic Analysis for Coroutines ------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements semantic analysis for C++ Coroutines.
//
//===----------------------------------------------------------------------===//
#include "clang/Sema/SemaInternal.h"
#include "clang/AST/Decl.h"
#include "clang/AST/ExprCXX.h"
#include "clang/AST/StmtCXX.h"
#include "clang/Lex/Preprocessor.h"
#include "clang/Sema/Initialization.h"
#include "clang/Sema/Overload.h"
using namespace clang;
using namespace sema;
static bool lookupMember(Sema &S, const char *Name, CXXRecordDecl *RD,
SourceLocation Loc) {
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();
return S.LookupQualifiedName(LR, RD);
}
/// Look up the std::coroutine_traits<...>::promise_type for the given
/// function type.
static QualType lookupPromiseType(Sema &S, const FunctionProtoType *FnType,
SourceLocation KwLoc,
SourceLocation FuncLoc) {
// 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();
}
LookupResult Result(S, &S.PP.getIdentifierTable().get("coroutine_traits"),
FuncLoc, Sema::LookupOrdinaryName);
if (!S.LookupQualifiedName(Result, StdExp)) {
S.Diag(KwLoc, diag::err_implied_coroutine_type_not_found)
<< "std::experimental::coroutine_traits";
return QualType();
}
ClassTemplateDecl *CoroTraits = Result.getAsSingle<ClassTemplateDecl>();
if (!CoroTraits) {
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_traits);
return QualType();
}
// Form template argument list for coroutine_traits<R, P1, P2, ...>.
TemplateArgumentListInfo Args(KwLoc, KwLoc);
Args.addArgument(TemplateArgumentLoc(
TemplateArgument(FnType->getReturnType()),
S.Context.getTrivialTypeSourceInfo(FnType->getReturnType(), KwLoc)));
// FIXME: If the function is a non-static member function, add the type
// of the implicit object parameter before the formal parameters.
for (QualType T : FnType->getParamTypes())
Args.addArgument(TemplateArgumentLoc(
TemplateArgument(T), S.Context.getTrivialTypeSourceInfo(T, KwLoc)));
// 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::coroutine_traits<...>::promise_type for the given
/// function type.
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) {
// 'co_await' and 'co_yield' are not permitted in unevaluated operands.
if (S.isUnevaluatedContext()) {
S.Diag(Loc, diag::err_coroutine_unevaluated_context) << Keyword;
return false;
}
// Any other usage must be within a function.
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,
DiagCopyAssign,
DiagMoveAssign,
DiagMain,
DiagConstexpr,
DiagAutoRet,
DiagVarargs,
};
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, copy/move assignment operator,
// or the function 'main' are declared as a coroutine.
auto *MD = dyn_cast<CXXMethodDecl>(FD);
if (MD && isa<CXXConstructorDecl>(MD))
return DiagInvalid(DiagCtor);
else if (MD && isa<CXXDestructorDecl>(MD))
return DiagInvalid(DiagDtor);
else if (MD && MD->isCopyAssignmentOperator())
return DiagInvalid(DiagCopyAssign);
else if (MD && MD->isMoveAssignmentOperator())
return DiagInvalid(DiagMoveAssign);
else if (FD->isMain())
return DiagInvalid(DiagMain);
// Emit a diagnostics for each of the following conditions which is not met.
if (FD->isConstexpr())
DiagInvalid(DiagConstexpr);
if (FD->getReturnType()->isUndeducedType())
DiagInvalid(DiagAutoRet);
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.ActOnCallExpr(/*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.ActOnCallExpr(nullptr, FromAddr.get(), Loc, FramePtr, Loc);
}
struct ReadySuspendResumeResult {
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();
return S.ActOnCallExpr(nullptr, Result.get(), Loc, Args, Loc, nullptr);
}
/// Build calls to await_ready, await_suspend, and await_resume for a 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 invalid until we see otherwise.
ReadySuspendResumeResult Calls = {{}, Operand, /*IsInvalid=*/true};
ExprResult CoroHandleRes = buildCoroutineHandle(S, CoroPromise->getType(), Loc);
if (CoroHandleRes.isInvalid())
return Calls;
Expr *CoroHandle = CoroHandleRes.get();
const StringRef Funcs[] = {"await_ready", "await_suspend", "await_resume"};
MultiExprArg Args[] = {None, CoroHandle, None};
for (size_t I = 0, N = llvm::array_lengthof(Funcs); I != N; ++I) {
ExprResult Result = buildMemberCall(S, Operand, Loc, Funcs[I], Args[I]);
if (Result.isInvalid())
return Calls;
Calls.Results[I] = Result.get();
}
Calls.IsInvalid = false;
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();
// Call 'yield_value', passing in E.
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);
QualType T =
FD->getType()->isDependentType()
? Context.DependentTy
: lookupPromiseType(*this, FD->getType()->castAs<FunctionProtoType>(),
Loc, FD->getLocation());
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);
CheckVariableDeclarationType(VD);
if (VD->isInvalidDecl())
return nullptr;
ActOnUninitializedDecl(VD);
assert(!VD->isInvalidDecl());
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;
ScopeInfo->CoroutinePromise = S.buildCoroutinePromise(Loc);
if (!ScopeInfo->CoroutinePromise)
return nullptr;
return ScopeInfo;
}
static bool actOnCoroutineBodyStart(Sema &S, Scope *SC, SourceLocation KWLoc,
StringRef Keyword) {
if (!checkCoroutineContext(S, KWLoc, Keyword))
return false;
auto *ScopeInfo = S.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>(S.CurContext);
SourceLocation Loc = Fn->getLocation();
// Build the initial suspend point
auto buildSuspends = [&](StringRef Name) mutable -> StmtResult {
ExprResult Suspend =
buildPromiseCall(S, ScopeInfo->CoroutinePromise, Loc, Name, None);
if (Suspend.isInvalid())
return StmtError();
Suspend = buildOperatorCoawaitCall(S, SC, Loc, Suspend.get());
if (Suspend.isInvalid())
return StmtError();
Suspend = S.BuildResolvedCoawaitExpr(Loc, Suspend.get(),
/*IsImplicit*/ true);
Suspend = S.ActOnFinishFullExpr(Suspend.get());
if (Suspend.isInvalid()) {
S.Diag(Loc, diag::note_coroutine_promise_call_implicitly_required)
<< ((Name == "initial_suspend") ? 0 : 1);
S.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())
return true;
ScopeInfo->setCoroutineSuspends(InitSuspend.get(), FinalSuspend.get());
return true;
}
ExprResult Sema::ActOnCoawaitExpr(Scope *S, SourceLocation Loc, Expr *E) {
if (!actOnCoroutineBodyStart(*this, S, Loc, "co_await")) {
CorrectDelayedTyposInExpr(E);
return ExprError();
}
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);
// 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) 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(*this, S, Loc, "co_yield")) {
CorrectDelayedTyposInExpr(E);
return ExprError();
}
// 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(*this, 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();
}
// 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()).get();
Stmt *Res = new (Context) CoreturnStmt(Loc, E, PCE, IsImplicit);
return Res;
}
static ExprResult buildStdCurrentExceptionCall(Sema &S, SourceLocation Loc) {
NamespaceDecl *Std = S.getStdNamespace();
if (!Std) {
S.Diag(Loc, diag::err_implied_std_current_exception_not_found);
return ExprError();
}
LookupResult Result(S, &S.PP.getIdentifierTable().get("current_exception"),
Loc, Sema::LookupOrdinaryName);
if (!S.LookupQualifiedName(Result, Std)) {
S.Diag(Loc, diag::err_implied_std_current_exception_not_found);
return ExprError();
}
// FIXME The STL is free to provide more than one overload.
FunctionDecl *FD = Result.getAsSingle<FunctionDecl>();
if (!FD) {
S.Diag(Loc, diag::err_malformed_std_current_exception);
return ExprError();
}
ExprResult Res = S.BuildDeclRefExpr(FD, FD->getType(), VK_LValue, Loc);
Res = S.ActOnCallExpr(/*Scope*/ nullptr, Res.get(), Loc, None, Loc);
if (Res.isInvalid()) {
S.Diag(Loc, diag::err_malformed_std_current_exception);
return ExprError();
}
return Res;
}
// 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;
}
namespace {
class SubStmtBuilder : public CoroutineBodyStmt::CtorArgs {
Sema &S;
FunctionDecl &FD;
FunctionScopeInfo &Fn;
bool IsValid;
SourceLocation Loc;
QualType RetType;
SmallVector<Stmt *, 4> ParamMovesVector;
const bool IsPromiseDependentType;
CXXRecordDecl *PromiseRecordDecl = nullptr;
public:
SubStmtBuilder(Sema &S, FunctionDecl &FD, FunctionScopeInfo &Fn, Stmt *Body)
: S(S), FD(FD), Fn(Fn), Loc(FD.getLocation()),
IsPromiseDependentType(
!Fn.CoroutinePromise ||
Fn.CoroutinePromise->getType()->isDependentType()) {
this->Body = Body;
if (!IsPromiseDependentType) {
PromiseRecordDecl = Fn.CoroutinePromise->getType()->getAsCXXRecordDecl();
assert(PromiseRecordDecl && "Type should have already been checked");
}
this->IsValid = makePromiseStmt() && makeInitialAndFinalSuspend() &&
makeOnException() && makeOnFallthrough() &&
makeNewAndDeleteExpr() && makeReturnObject() &&
makeParamMoves();
}
bool isInvalid() const { return !this->IsValid; }
bool makePromiseStmt();
bool makeInitialAndFinalSuspend();
bool makeNewAndDeleteExpr();
bool makeOnFallthrough();
bool makeOnException();
bool makeReturnObject();
bool makeParamMoves();
};
}
void Sema::CheckCompletedCoroutineBody(FunctionDecl *FD, Stmt *&Body) {
FunctionScopeInfo *Fn = getCurFunction();
assert(Fn && Fn->CoroutinePromise && "not a coroutine");
if (!Body) {
assert(FD->isInvalidDecl() &&
"a null body is only allowed for invalid declarations");
return;
}
if (isa<CoroutineBodyStmt>(Body)) {
// FIXME(EricWF): 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();
}
SubStmtBuilder Builder(*this, *FD, *Fn, Body);
if (Builder.isInvalid())
return FD->setInvalidDecl();
// Build body for the coroutine wrapper statement.
Body = CoroutineBodyStmt::Create(Context, Builder);
}
bool SubStmtBuilder::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 SubStmtBuilder::makeInitialAndFinalSuspend() {
if (Fn.hasInvalidCoroutineSuspends())
return false;
this->InitialSuspend = cast<Expr>(Fn.CoroutineSuspends.first);
this->FinalSuspend = cast<Expr>(Fn.CoroutineSuspends.second);
return true;
}
bool SubStmtBuilder::makeNewAndDeleteExpr() {
// Form and check allocation and deallocation calls.
QualType PromiseType = Fn.CoroutinePromise->getType();
if (PromiseType->isDependentType())
return true;
if (S.RequireCompleteType(Loc, PromiseType, diag::err_incomplete_type))
return false;
// FIXME: Add support for get_return_object_on_allocation failure.
// FIXME: Add support for stateful allocators.
FunctionDecl *OperatorNew = nullptr;
FunctionDecl *OperatorDelete = nullptr;
FunctionDecl *UnusedResult = nullptr;
bool PassAlignment = false;
S.FindAllocationFunctions(Loc, SourceRange(),
/*UseGlobal*/ false, PromiseType,
/*isArray*/ false, PassAlignment,
/*PlacementArgs*/ None, OperatorNew, UnusedResult);
OperatorDelete = findDeleteForPromise(S, Loc, PromiseType);
if (!OperatorDelete || !OperatorNew)
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;
ExprResult NewExpr =
S.ActOnCallExpr(S.getCurScope(), NewRef.get(), Loc, FrameSize, Loc);
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()->getAs<FunctionProtoType>();
if (OpDeleteType->getNumParams() > 1)
DeleteArgs.push_back(FrameSize);
ExprResult DeleteExpr =
S.ActOnCallExpr(S.getCurScope(), DeleteRef.get(), Loc, DeleteArgs, Loc);
if (DeleteExpr.isInvalid())
return false;
this->Allocate = NewExpr.get();
this->Deallocate = DeleteExpr.get();
return true;
}
bool SubStmtBuilder::makeOnFallthrough() {
if (!PromiseRecordDecl)
return true;
// [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.
const bool HasRVoid = lookupMember(S, "return_void", PromiseRecordDecl, Loc);
const bool HasRValue = lookupMember(S, "return_value", PromiseRecordDecl, Loc);
StmtResult Fallthrough;
if (HasRVoid && HasRValue) {
// FIXME Improve this diagnostic
S.Diag(FD.getLocation(), diag::err_coroutine_promise_return_ill_formed)
<< 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 SubStmtBuilder::makeOnException() {
// Try to form 'p.set_exception(std::current_exception());' to handle
// uncaught exceptions.
// TODO: Post WG21 Issaquah 2016 renamed set_exception to unhandled_exception
// TODO: and dropped exception_ptr parameter. Make it so.
if (!PromiseRecordDecl)
return true;
// If exceptions are disabled, don't try to build OnException.
if (!S.getLangOpts().CXXExceptions)
return true;
ExprResult SetException;
// [dcl.fct.def.coroutine]/3
// The unqualified-id set_exception is found in the scope of P by class
// member access lookup (3.4.5).
if (lookupMember(S, "set_exception", PromiseRecordDecl, Loc)) {
// Form the call 'p.set_exception(std::current_exception())'
SetException = buildStdCurrentExceptionCall(S, Loc);
if (SetException.isInvalid())
return false;
Expr *E = SetException.get();
SetException = buildPromiseCall(S, Fn.CoroutinePromise, Loc, "set_exception", E);
SetException = S.ActOnFinishFullExpr(SetException.get(), Loc);
if (SetException.isInvalid())
return false;
}
this->OnException = SetException.get();
return true;
}
bool SubStmtBuilder::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;
QualType RetType = FD.getReturnType();
if (!RetType->isDependentType()) {
InitializedEntity Entity =
InitializedEntity::InitializeResult(Loc, RetType, false);
ReturnObject = S.PerformMoveOrCopyInitialization(Entity, nullptr, RetType,
ReturnObject.get());
if (ReturnObject.isInvalid())
return false;
}
ReturnObject = S.ActOnFinishFullExpr(ReturnObject.get(), Loc);
if (ReturnObject.isInvalid())
return false;
this->ReturnValue = ReturnObject.get();
return true;
}
bool SubStmtBuilder::makeParamMoves() {
// FIXME: Perform move-initialization of parameters into frame-local copies.
return true;
}
StmtResult Sema::BuildCoroutineBodyStmt(CoroutineBodyStmt::CtorArgs Args) {
CoroutineBodyStmt *Res = CoroutineBodyStmt::Create(Context, Args);
if (!Res)
return StmtError();
return Res;
}
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