Implement DR1330 in C++11 mode, to support libstdc++4.7 which uses it.
We have a new flavor of exception specification, EST_Uninstantiated. A function
type with this exception specification carries a pointer to a FunctionDecl, and
the exception specification for that FunctionDecl is instantiated (if needed)
and used in the place of the function type's exception specification.
When a function template declaration with a non-trivial exception specification
is instantiated, the specialization's exception specification is set to this
new 'uninstantiated' kind rather than being instantiated immediately.
Expr::CanThrow has migrated onto Sema, so it can instantiate exception specs
on-demand. Also, any odr-use of a function triggers the instantiation of its
exception specification (the exception specification could be needed by IRGen).
In passing, fix two places where a DeclRefExpr was created but the corresponding
function was not actually marked odr-used. We used to get away with this, but
don't any more.
Also fix a bug where instantiating an exception specification which refers to
function parameters resulted in a crash. We still have the same bug in default
arguments, which I'll be looking into next.
This, plus a tiny patch to fix libstdc++'s common_type, is enough for clang to
parse (and, in very limited testing, support) all of libstdc++4.7's standard
headers.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@154886 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaExceptionSpec.cpp b/lib/Sema/SemaExceptionSpec.cpp
index 42221f8..14b2434 100644
--- a/lib/Sema/SemaExceptionSpec.cpp
+++ b/lib/Sema/SemaExceptionSpec.cpp
@@ -96,6 +96,26 @@
return FnT->hasExceptionSpec();
}
+const FunctionProtoType *
+Sema::ResolveExceptionSpec(SourceLocation Loc, const FunctionProtoType *FPT) {
+ // FIXME: If FD is a special member, we should delay computing its exception
+ // specification until this point.
+ if (FPT->getExceptionSpecType() != EST_Uninstantiated)
+ return FPT;
+
+ FunctionDecl *SourceDecl = FPT->getExceptionSpecDecl();
+ const FunctionProtoType *SourceFPT =
+ SourceDecl->getType()->castAs<FunctionProtoType>();
+
+ if (SourceFPT->getExceptionSpecType() != EST_Uninstantiated)
+ return SourceFPT;
+
+ // Instantiate the exception specification now.
+ InstantiateExceptionSpec(Loc, SourceDecl);
+
+ return SourceDecl->getType()->castAs<FunctionProtoType>();
+}
+
bool Sema::CheckEquivalentExceptionSpec(FunctionDecl *Old, FunctionDecl *New) {
OverloadedOperatorKind OO = New->getDeclName().getCXXOverloadedOperator();
bool IsOperatorNew = OO == OO_New || OO == OO_Array_New;
@@ -104,7 +124,7 @@
unsigned DiagID = diag::err_mismatched_exception_spec;
if (getLangOpts().MicrosoftExt)
DiagID = diag::warn_mismatched_exception_spec;
-
+
if (!CheckEquivalentExceptionSpec(PDiag(DiagID),
PDiag(diag::note_previous_declaration),
Old->getType()->getAs<FunctionProtoType>(),
@@ -295,6 +315,13 @@
if (MissingEmptyExceptionSpecification)
*MissingEmptyExceptionSpecification = false;
+ Old = ResolveExceptionSpec(NewLoc, Old);
+ if (!Old)
+ return false;
+ New = ResolveExceptionSpec(NewLoc, New);
+ if (!New)
+ return false;
+
// C++0x [except.spec]p3: Two exception-specifications are compatible if:
// - both are non-throwing, regardless of their form,
// - both have the form noexcept(constant-expression) and the constant-
@@ -318,6 +345,7 @@
ExceptionSpecificationType NewEST = New->getExceptionSpecType();
assert(OldEST != EST_Delayed && NewEST != EST_Delayed &&
+ OldEST != EST_Uninstantiated && NewEST != EST_Uninstantiated &&
"Shouldn't see unknown exception specifications here");
// Shortcut the case where both have no spec.
@@ -483,6 +511,14 @@
if (!SubLoc.isValid())
SubLoc = SuperLoc;
+ // Resolve the exception specifications, if needed.
+ Superset = ResolveExceptionSpec(SuperLoc, Superset);
+ if (!Superset)
+ return false;
+ Subset = ResolveExceptionSpec(SubLoc, Subset);
+ if (!Subset)
+ return false;
+
ExceptionSpecificationType SuperEST = Superset->getExceptionSpecType();
// If superset contains everything, we're done.
@@ -507,6 +543,7 @@
ExceptionSpecificationType SubEST = Subset->getExceptionSpecType();
assert(SuperEST != EST_Delayed && SubEST != EST_Delayed &&
+ SuperEST != EST_Uninstantiated && SubEST != EST_Uninstantiated &&
"Shouldn't see unknown exception specifications here");
// It does not. If the subset contains everything, we've failed.
@@ -726,4 +763,324 @@
New->getLocation());
}
+static CanThrowResult canSubExprsThrow(Sema &S, const Expr *CE) {
+ Expr *E = const_cast<Expr*>(CE);
+ CanThrowResult R = CT_Cannot;
+ for (Expr::child_range I = E->children(); I && R != CT_Can; ++I)
+ R = mergeCanThrow(R, S.canThrow(cast<Expr>(*I)));
+ return R;
+}
+
+static CanThrowResult canCalleeThrow(Sema &S, const Expr *E,
+ const Decl *D,
+ bool NullThrows = true) {
+ if (!D)
+ return NullThrows ? CT_Can : CT_Cannot;
+
+ // See if we can get a function type from the decl somehow.
+ const ValueDecl *VD = dyn_cast<ValueDecl>(D);
+ if (!VD) // If we have no clue what we're calling, assume the worst.
+ return CT_Can;
+
+ // As an extension, we assume that __attribute__((nothrow)) functions don't
+ // throw.
+ if (isa<FunctionDecl>(D) && D->hasAttr<NoThrowAttr>())
+ return CT_Cannot;
+
+ QualType T = VD->getType();
+ const FunctionProtoType *FT;
+ if ((FT = T->getAs<FunctionProtoType>())) {
+ } else if (const PointerType *PT = T->getAs<PointerType>())
+ FT = PT->getPointeeType()->getAs<FunctionProtoType>();
+ else if (const ReferenceType *RT = T->getAs<ReferenceType>())
+ FT = RT->getPointeeType()->getAs<FunctionProtoType>();
+ else if (const MemberPointerType *MT = T->getAs<MemberPointerType>())
+ FT = MT->getPointeeType()->getAs<FunctionProtoType>();
+ else if (const BlockPointerType *BT = T->getAs<BlockPointerType>())
+ FT = BT->getPointeeType()->getAs<FunctionProtoType>();
+
+ if (!FT)
+ return CT_Can;
+
+ FT = S.ResolveExceptionSpec(E->getLocStart(), FT);
+ if (!FT)
+ return CT_Can;
+
+ if (FT->getExceptionSpecType() == EST_Delayed) {
+ // FIXME: Try to resolve a delayed exception spec in ResolveExceptionSpec.
+ assert(isa<CXXConstructorDecl>(D) &&
+ "only constructor exception specs can be unknown");
+ S.Diag(E->getLocStart(), diag::err_exception_spec_unknown)
+ << E->getSourceRange();
+ return CT_Can;
+ }
+
+ return FT->isNothrow(S.Context) ? CT_Cannot : CT_Can;
+}
+
+static CanThrowResult canDynamicCastThrow(const CXXDynamicCastExpr *DC) {
+ if (DC->isTypeDependent())
+ return CT_Dependent;
+
+ if (!DC->getTypeAsWritten()->isReferenceType())
+ return CT_Cannot;
+
+ if (DC->getSubExpr()->isTypeDependent())
+ return CT_Dependent;
+
+ return DC->getCastKind() == clang::CK_Dynamic? CT_Can : CT_Cannot;
+}
+
+static CanThrowResult canTypeidThrow(Sema &S, const CXXTypeidExpr *DC) {
+ if (DC->isTypeOperand())
+ return CT_Cannot;
+
+ Expr *Op = DC->getExprOperand();
+ if (Op->isTypeDependent())
+ return CT_Dependent;
+
+ const RecordType *RT = Op->getType()->getAs<RecordType>();
+ if (!RT)
+ return CT_Cannot;
+
+ if (!cast<CXXRecordDecl>(RT->getDecl())->isPolymorphic())
+ return CT_Cannot;
+
+ if (Op->Classify(S.Context).isPRValue())
+ return CT_Cannot;
+
+ return CT_Can;
+}
+
+CanThrowResult Sema::canThrow(const Expr *E) {
+ // C++ [expr.unary.noexcept]p3:
+ // [Can throw] if in a potentially-evaluated context the expression would
+ // contain:
+ switch (E->getStmtClass()) {
+ case Expr::CXXThrowExprClass:
+ // - a potentially evaluated throw-expression
+ return CT_Can;
+
+ case Expr::CXXDynamicCastExprClass: {
+ // - a potentially evaluated dynamic_cast expression dynamic_cast<T>(v),
+ // where T is a reference type, that requires a run-time check
+ CanThrowResult CT = canDynamicCastThrow(cast<CXXDynamicCastExpr>(E));
+ if (CT == CT_Can)
+ return CT;
+ return mergeCanThrow(CT, canSubExprsThrow(*this, E));
+ }
+
+ case Expr::CXXTypeidExprClass:
+ // - a potentially evaluated typeid expression applied to a glvalue
+ // expression whose type is a polymorphic class type
+ return canTypeidThrow(*this, cast<CXXTypeidExpr>(E));
+
+ // - a potentially evaluated call to a function, member function, function
+ // pointer, or member function pointer that does not have a non-throwing
+ // exception-specification
+ case Expr::CallExprClass:
+ case Expr::CXXMemberCallExprClass:
+ case Expr::CXXOperatorCallExprClass:
+ case Expr::UserDefinedLiteralClass: {
+ const CallExpr *CE = cast<CallExpr>(E);
+ CanThrowResult CT;
+ if (E->isTypeDependent())
+ CT = CT_Dependent;
+ else if (isa<CXXPseudoDestructorExpr>(CE->getCallee()->IgnoreParens()))
+ CT = CT_Cannot;
+ else
+ CT = canCalleeThrow(*this, E, CE->getCalleeDecl());
+ if (CT == CT_Can)
+ return CT;
+ return mergeCanThrow(CT, canSubExprsThrow(*this, E));
+ }
+
+ case Expr::CXXConstructExprClass:
+ case Expr::CXXTemporaryObjectExprClass: {
+ CanThrowResult CT = canCalleeThrow(*this, E,
+ cast<CXXConstructExpr>(E)->getConstructor());
+ if (CT == CT_Can)
+ return CT;
+ return mergeCanThrow(CT, canSubExprsThrow(*this, E));
+ }
+
+ case Expr::LambdaExprClass: {
+ const LambdaExpr *Lambda = cast<LambdaExpr>(E);
+ CanThrowResult CT = CT_Cannot;
+ for (LambdaExpr::capture_init_iterator Cap = Lambda->capture_init_begin(),
+ CapEnd = Lambda->capture_init_end();
+ Cap != CapEnd; ++Cap)
+ CT = mergeCanThrow(CT, canThrow(*Cap));
+ return CT;
+ }
+
+ case Expr::CXXNewExprClass: {
+ CanThrowResult CT;
+ if (E->isTypeDependent())
+ CT = CT_Dependent;
+ else
+ CT = canCalleeThrow(*this, E, cast<CXXNewExpr>(E)->getOperatorNew());
+ if (CT == CT_Can)
+ return CT;
+ return mergeCanThrow(CT, canSubExprsThrow(*this, E));
+ }
+
+ case Expr::CXXDeleteExprClass: {
+ CanThrowResult CT;
+ QualType DTy = cast<CXXDeleteExpr>(E)->getDestroyedType();
+ if (DTy.isNull() || DTy->isDependentType()) {
+ CT = CT_Dependent;
+ } else {
+ CT = canCalleeThrow(*this, E,
+ cast<CXXDeleteExpr>(E)->getOperatorDelete());
+ if (const RecordType *RT = DTy->getAs<RecordType>()) {
+ const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl());
+ CT = mergeCanThrow(CT, canCalleeThrow(*this, E, RD->getDestructor()));
+ }
+ if (CT == CT_Can)
+ return CT;
+ }
+ return mergeCanThrow(CT, canSubExprsThrow(*this, E));
+ }
+
+ case Expr::CXXBindTemporaryExprClass: {
+ // The bound temporary has to be destroyed again, which might throw.
+ CanThrowResult CT = canCalleeThrow(*this, E,
+ cast<CXXBindTemporaryExpr>(E)->getTemporary()->getDestructor());
+ if (CT == CT_Can)
+ return CT;
+ return mergeCanThrow(CT, canSubExprsThrow(*this, E));
+ }
+
+ // ObjC message sends are like function calls, but never have exception
+ // specs.
+ case Expr::ObjCMessageExprClass:
+ case Expr::ObjCPropertyRefExprClass:
+ case Expr::ObjCSubscriptRefExprClass:
+ return CT_Can;
+
+ // All the ObjC literals that are implemented as calls are
+ // potentially throwing unless we decide to close off that
+ // possibility.
+ case Expr::ObjCArrayLiteralClass:
+ case Expr::ObjCDictionaryLiteralClass:
+ case Expr::ObjCNumericLiteralClass:
+ return CT_Can;
+
+ // Many other things have subexpressions, so we have to test those.
+ // Some are simple:
+ case Expr::ConditionalOperatorClass:
+ case Expr::CompoundLiteralExprClass:
+ case Expr::CXXConstCastExprClass:
+ case Expr::CXXDefaultArgExprClass:
+ case Expr::CXXReinterpretCastExprClass:
+ case Expr::DesignatedInitExprClass:
+ case Expr::ExprWithCleanupsClass:
+ case Expr::ExtVectorElementExprClass:
+ case Expr::InitListExprClass:
+ case Expr::MemberExprClass:
+ case Expr::ObjCIsaExprClass:
+ case Expr::ObjCIvarRefExprClass:
+ case Expr::ParenExprClass:
+ case Expr::ParenListExprClass:
+ case Expr::ShuffleVectorExprClass:
+ case Expr::VAArgExprClass:
+ return canSubExprsThrow(*this, E);
+
+ // Some might be dependent for other reasons.
+ case Expr::ArraySubscriptExprClass:
+ case Expr::BinaryOperatorClass:
+ case Expr::CompoundAssignOperatorClass:
+ case Expr::CStyleCastExprClass:
+ case Expr::CXXStaticCastExprClass:
+ case Expr::CXXFunctionalCastExprClass:
+ case Expr::ImplicitCastExprClass:
+ case Expr::MaterializeTemporaryExprClass:
+ case Expr::UnaryOperatorClass: {
+ CanThrowResult CT = E->isTypeDependent() ? CT_Dependent : CT_Cannot;
+ return mergeCanThrow(CT, canSubExprsThrow(*this, E));
+ }
+
+ // FIXME: We should handle StmtExpr, but that opens a MASSIVE can of worms.
+ case Expr::StmtExprClass:
+ return CT_Can;
+
+ case Expr::ChooseExprClass:
+ if (E->isTypeDependent() || E->isValueDependent())
+ return CT_Dependent;
+ return canThrow(cast<ChooseExpr>(E)->getChosenSubExpr(Context));
+
+ case Expr::GenericSelectionExprClass:
+ if (cast<GenericSelectionExpr>(E)->isResultDependent())
+ return CT_Dependent;
+ return canThrow(cast<GenericSelectionExpr>(E)->getResultExpr());
+
+ // Some expressions are always dependent.
+ case Expr::CXXDependentScopeMemberExprClass:
+ case Expr::CXXUnresolvedConstructExprClass:
+ case Expr::DependentScopeDeclRefExprClass:
+ return CT_Dependent;
+
+ case Expr::AsTypeExprClass:
+ case Expr::BinaryConditionalOperatorClass:
+ case Expr::BlockExprClass:
+ case Expr::CUDAKernelCallExprClass:
+ case Expr::DeclRefExprClass:
+ case Expr::ObjCBridgedCastExprClass:
+ case Expr::ObjCIndirectCopyRestoreExprClass:
+ case Expr::ObjCProtocolExprClass:
+ case Expr::ObjCSelectorExprClass:
+ case Expr::OffsetOfExprClass:
+ case Expr::PackExpansionExprClass:
+ case Expr::PseudoObjectExprClass:
+ case Expr::SubstNonTypeTemplateParmExprClass:
+ case Expr::SubstNonTypeTemplateParmPackExprClass:
+ case Expr::UnaryExprOrTypeTraitExprClass:
+ case Expr::UnresolvedLookupExprClass:
+ case Expr::UnresolvedMemberExprClass:
+ // FIXME: Can any of the above throw? If so, when?
+ return CT_Cannot;
+
+ case Expr::AddrLabelExprClass:
+ case Expr::ArrayTypeTraitExprClass:
+ case Expr::AtomicExprClass:
+ case Expr::BinaryTypeTraitExprClass:
+ case Expr::TypeTraitExprClass:
+ case Expr::CXXBoolLiteralExprClass:
+ case Expr::CXXNoexceptExprClass:
+ case Expr::CXXNullPtrLiteralExprClass:
+ case Expr::CXXPseudoDestructorExprClass:
+ case Expr::CXXScalarValueInitExprClass:
+ case Expr::CXXThisExprClass:
+ case Expr::CXXUuidofExprClass:
+ case Expr::CharacterLiteralClass:
+ case Expr::ExpressionTraitExprClass:
+ case Expr::FloatingLiteralClass:
+ case Expr::GNUNullExprClass:
+ case Expr::ImaginaryLiteralClass:
+ case Expr::ImplicitValueInitExprClass:
+ case Expr::IntegerLiteralClass:
+ case Expr::ObjCEncodeExprClass:
+ case Expr::ObjCStringLiteralClass:
+ case Expr::ObjCBoolLiteralExprClass:
+ case Expr::OpaqueValueExprClass:
+ case Expr::PredefinedExprClass:
+ case Expr::SizeOfPackExprClass:
+ case Expr::StringLiteralClass:
+ case Expr::UnaryTypeTraitExprClass:
+ // These expressions can never throw.
+ return CT_Cannot;
+
+#define STMT(CLASS, PARENT) case Expr::CLASS##Class:
+#define STMT_RANGE(Base, First, Last)
+#define LAST_STMT_RANGE(BASE, FIRST, LAST)
+#define EXPR(CLASS, PARENT)
+#define ABSTRACT_STMT(STMT)
+#include "clang/AST/StmtNodes.inc"
+ case Expr::NoStmtClass:
+ llvm_unreachable("Invalid class for expression");
+ }
+ llvm_unreachable("Bogus StmtClass");
+}
+
} // end namespace clang