r360974 - Refactor constant evaluation of typeid(T) to track a symbolic type_info
Chris Bieneman via cfe-commits
cfe-commits at lists.llvm.org
Thu May 16 22:44:30 PDT 2019
I did some digging before reverting. The bots your patch is failing on are 32-bit CPUs. It looks like your static_assert is assuming 8-byte aligned pointers, so it always fails on the 32-bit builders.
-Chris
> On May 16, 2019, at 10:14 PM, Chris Bieneman <chris.bieneman at me.com> wrote:
>
> Sorry to do this, but I'm also reverting r360977, because it seems to be on top of this one.
>
> -Chris
>
>> On May 16, 2019, at 9:58 PM, Chris Bieneman via cfe-commits <cfe-commits at lists.llvm.org> wrote:
>>
>> Hey Richard,
>>
>> This change is tripping up a bunch of the bots:
>>
>> http://lab.llvm.org:8011/builders/clang-cmake-armv8-lld/builds/1397
>>
>> I'm going to revert it so that we don't leave the bots broken overnight.
>>
>> -Chris
>>
>>> On May 16, 2019, at 6:46 PM, Richard Smith via cfe-commits <cfe-commits at lists.llvm.org> wrote:
>>>
>>> Author: rsmith
>>> Date: Thu May 16 18:46:05 2019
>>> New Revision: 360974
>>>
>>> URL: http://llvm.org/viewvc/llvm-project?rev=360974&view=rev
>>> Log:
>>> Refactor constant evaluation of typeid(T) to track a symbolic type_info
>>> object rather than tracking the originating expression.
>>>
>>> This is groundwork for supporting polymorphic typeid expressions. (Note
>>> that this somewhat regresses our support for DR1968, but it turns out
>>> that that never actually worked anyway, at least in non-trivial cases.)
>>>
>>> Modified:
>>> cfe/trunk/include/clang/AST/APValue.h
>>> cfe/trunk/include/clang/Basic/DiagnosticASTKinds.td
>>> cfe/trunk/lib/AST/APValue.cpp
>>> cfe/trunk/lib/AST/ExprConstant.cpp
>>> cfe/trunk/lib/CodeGen/CGExprConstant.cpp
>>> cfe/trunk/lib/Sema/SemaTemplate.cpp
>>> cfe/trunk/test/CXX/drs/dr19xx.cpp
>>> cfe/trunk/test/Parser/MicrosoftExtensions.cpp
>>> cfe/trunk/test/SemaCXX/builtin-constant-p.cpp
>>> cfe/trunk/test/SemaCXX/typeid.cpp
>>> cfe/trunk/www/cxx_dr_status.html
>>>
>>> Modified: cfe/trunk/include/clang/AST/APValue.h
>>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/AST/APValue.h?rev=360974&r1=360973&r2=360974&view=diff
>>> ==============================================================================
>>> --- cfe/trunk/include/clang/AST/APValue.h (original)
>>> +++ cfe/trunk/include/clang/AST/APValue.h Thu May 16 18:46:05 2019
>>> @@ -24,14 +24,52 @@ namespace clang {
>>> class AddrLabelExpr;
>>> class ASTContext;
>>> class CharUnits;
>>> + class CXXRecordDecl;
>>> + class Decl;
>>> class DiagnosticBuilder;
>>> class Expr;
>>> class FieldDecl;
>>> - class Decl;
>>> + struct PrintingPolicy;
>>> + class Type;
>>> class ValueDecl;
>>> - class CXXRecordDecl;
>>> - class QualType;
>>>
>>> +/// Symbolic representation of typeid(T) for some type T.
>>> +class TypeInfoLValue {
>>> + const Type *T;
>>> +
>>> +public:
>>> + TypeInfoLValue() : T() {}
>>> + explicit TypeInfoLValue(const Type *T);
>>> +
>>> + const Type *getType() const { return T; }
>>> + explicit operator bool() const { return T; }
>>> +
>>> + void *getOpaqueValue() { return const_cast<Type*>(T); }
>>> + static TypeInfoLValue getFromOpaqueValue(void *Value) {
>>> + TypeInfoLValue V;
>>> + V.T = reinterpret_cast<const Type*>(Value);
>>> + return V;
>>> + }
>>> +
>>> + void print(llvm::raw_ostream &Out, const PrintingPolicy &Policy) const;
>>> +};
>>> +}
>>> +
>>> +namespace llvm {
>>> +template<> struct PointerLikeTypeTraits<clang::TypeInfoLValue> {
>>> + static void *getAsVoidPointer(clang::TypeInfoLValue V) {
>>> + return V.getOpaqueValue();
>>> + }
>>> + static clang::TypeInfoLValue getFromVoidPointer(void *P) {
>>> + return clang::TypeInfoLValue::getFromOpaqueValue(P);
>>> + }
>>> + // Validated by static_assert in APValue.cpp; hardcoded to avoid needing
>>> + // to include Type.h.
>>> + static constexpr int NumLowBitsAvailable = 3;
>>> +};
>>> +}
>>> +
>>> +namespace clang {
>>> /// APValue - This class implements a discriminated union of [uninitialized]
>>> /// [APSInt] [APFloat], [Complex APSInt] [Complex APFloat], [Expr + Offset],
>>> /// [Vector: N * APValue], [Array: N * APValue]
>>> @@ -57,13 +95,18 @@ public:
>>>
>>> class LValueBase {
>>> public:
>>> - typedef llvm::PointerUnion<const ValueDecl *, const Expr *> PtrTy;
>>> + typedef llvm::PointerUnion<const ValueDecl *, const Expr *, TypeInfoLValue>
>>> + PtrTy;
>>>
>>> - LValueBase() : CallIndex(0), Version(0) {}
>>> + LValueBase() : Local{} {}
>>>
>>> template <class T>
>>> - LValueBase(T P, unsigned I = 0, unsigned V = 0)
>>> - : Ptr(P), CallIndex(I), Version(V) {}
>>> + LValueBase(T P, unsigned I = 0, unsigned V = 0) : Ptr(P), Local{I, V} {
>>> + assert(!is<TypeInfoLValue>() &&
>>> + "don't use this constructor to form a type_info lvalue");
>>> + }
>>> +
>>> + static LValueBase getTypeInfo(TypeInfoLValue LV, QualType TypeInfo);
>>>
>>> template <class T>
>>> bool is() const { return Ptr.is<T>(); }
>>> @@ -78,28 +121,15 @@ public:
>>>
>>> bool isNull() const;
>>>
>>> - explicit operator bool () const;
>>> + explicit operator bool() const;
>>>
>>> - PtrTy getPointer() const {
>>> - return Ptr;
>>> - }
>>> + PtrTy getPointer() const { return Ptr; }
>>>
>>> - unsigned getCallIndex() const {
>>> - return CallIndex;
>>> - }
>>> + unsigned getCallIndex() const;
>>> + unsigned getVersion() const;
>>> + QualType getTypeInfoType() const;
>>>
>>> - void setCallIndex(unsigned Index) {
>>> - CallIndex = Index;
>>> - }
>>> -
>>> - unsigned getVersion() const {
>>> - return Version;
>>> - }
>>> -
>>> - friend bool operator==(const LValueBase &LHS, const LValueBase &RHS) {
>>> - return LHS.Ptr == RHS.Ptr && LHS.CallIndex == RHS.CallIndex &&
>>> - LHS.Version == RHS.Version;
>>> - }
>>> + friend bool operator==(const LValueBase &LHS, const LValueBase &RHS);
>>> friend bool operator!=(const LValueBase &LHS, const LValueBase &RHS) {
>>> return !(LHS == RHS);
>>> }
>>> @@ -107,7 +137,14 @@ public:
>>>
>>> private:
>>> PtrTy Ptr;
>>> - unsigned CallIndex, Version;
>>> + struct LocalState {
>>> + unsigned CallIndex, Version;
>>> + };
>>> + union {
>>> + LocalState Local;
>>> + /// The type std::type_info, if this is a TypeInfoLValue.
>>> + void *TypeInfoType;
>>> + };
>>> };
>>>
>>> /// A FieldDecl or CXXRecordDecl, along with a flag indicating whether we
>>>
>>> Modified: cfe/trunk/include/clang/Basic/DiagnosticASTKinds.td
>>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticASTKinds.td?rev=360974&r1=360973&r2=360974&view=diff
>>> ==============================================================================
>>> --- cfe/trunk/include/clang/Basic/DiagnosticASTKinds.td (original)
>>> +++ cfe/trunk/include/clang/Basic/DiagnosticASTKinds.td Thu May 16 18:46:05 2019
>>> @@ -160,6 +160,9 @@ def note_constexpr_access_static_tempora
>>> "dynamic_cast of}0 temporary "
>>> "is not allowed in a constant expression outside the expression that "
>>> "created the temporary">;
>>> +def note_constexpr_access_unreadable_object : Note<
>>> + "%select{read of|assignment to|increment of|decrement of|member call on|"
>>> + "dynamic_cast of}0 object '%1' whose value is not known">;
>>> def note_constexpr_modify_global : Note<
>>> "a constant expression cannot modify an object that is visible outside "
>>> "that expression">;
>>>
>>> Modified: cfe/trunk/lib/AST/APValue.cpp
>>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/APValue.cpp?rev=360974&r1=360973&r2=360974&view=diff
>>> ==============================================================================
>>> --- cfe/trunk/lib/AST/APValue.cpp (original)
>>> +++ cfe/trunk/lib/AST/APValue.cpp Thu May 16 18:46:05 2019
>>> @@ -20,6 +20,56 @@
>>> #include "llvm/Support/raw_ostream.h"
>>> using namespace clang;
>>>
>>> +/// The identity of a type_info object depends on the canonical unqualified
>>> +/// type only.
>>> +TypeInfoLValue::TypeInfoLValue(const Type *T)
>>> + : T(T->getCanonicalTypeUnqualified().getTypePtr()) {}
>>> +
>>> +void TypeInfoLValue::print(llvm::raw_ostream &Out,
>>> + const PrintingPolicy &Policy) const {
>>> + Out << "typeid(";
>>> + QualType(getType(), 0).print(Out, Policy);
>>> + Out << ")";
>>> +}
>>> +
>>> +static_assert(
>>> + 1 << llvm::PointerLikeTypeTraits<TypeInfoLValue>::NumLowBitsAvailable <=
>>> + alignof(const Type *),
>>> + "Type is insufficiently aligned");
>>> +
>>> +APValue::LValueBase APValue::LValueBase::getTypeInfo(TypeInfoLValue LV,
>>> + QualType TypeInfo) {
>>> + LValueBase Base;
>>> + Base.Ptr = LV;
>>> + Base.TypeInfoType = TypeInfo.getAsOpaquePtr();
>>> + return Base;
>>> +}
>>> +
>>> +unsigned APValue::LValueBase::getCallIndex() const {
>>> + return is<TypeInfoLValue>() ? 0 : Local.CallIndex;
>>> +}
>>> +
>>> +unsigned APValue::LValueBase::getVersion() const {
>>> + return is<TypeInfoLValue>() ? 0 : Local.Version;
>>> +}
>>> +
>>> +QualType APValue::LValueBase::getTypeInfoType() const {
>>> + assert(is<TypeInfoLValue>() && "not a type_info lvalue");
>>> + return QualType::getFromOpaquePtr(TypeInfoType);
>>> +}
>>> +
>>> +namespace clang {
>>> +bool operator==(const APValue::LValueBase &LHS,
>>> + const APValue::LValueBase &RHS) {
>>> + if (LHS.Ptr != RHS.Ptr)
>>> + return false;
>>> + if (LHS.is<TypeInfoLValue>())
>>> + return true;
>>> + return LHS.Local.CallIndex == RHS.Local.CallIndex &&
>>> + LHS.Local.Version == RHS.Local.Version;
>>> +}
>>> +}
>>> +
>>> namespace {
>>> struct LVBase {
>>> APValue::LValueBase Base;
>>> @@ -60,6 +110,8 @@ llvm::DenseMapInfo<clang::APValue::LValu
>>>
>>> namespace clang {
>>> llvm::hash_code hash_value(const APValue::LValueBase &Base) {
>>> + if (Base.is<TypeInfoLValue>())
>>> + return llvm::hash_value(Base.getOpaqueValue());
>>> return llvm::hash_combine(Base.getOpaqueValue(), Base.getCallIndex(),
>>> Base.getVersion());
>>> }
>>> @@ -470,7 +522,9 @@ void APValue::printPretty(raw_ostream &O
>>>
>>> if (const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>())
>>> Out << *VD;
>>> - else {
>>> + else if (TypeInfoLValue TI = Base.dyn_cast<TypeInfoLValue>()) {
>>> + TI.print(Out, Ctx.getPrintingPolicy());
>>> + } else {
>>> assert(Base.get<const Expr *>() != nullptr &&
>>> "Expecting non-null Expr");
>>> Base.get<const Expr*>()->printPretty(Out, nullptr,
>>> @@ -495,6 +549,9 @@ void APValue::printPretty(raw_ostream &O
>>> if (const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>()) {
>>> Out << *VD;
>>> ElemTy = VD->getType();
>>> + } else if (TypeInfoLValue TI = Base.dyn_cast<TypeInfoLValue>()) {
>>> + TI.print(Out, Ctx.getPrintingPolicy());
>>> + ElemTy = Base.getTypeInfoType();
>>> } else {
>>> const Expr *E = Base.get<const Expr*>();
>>> assert(E != nullptr && "Expecting non-null Expr");
>>>
>>> Modified: cfe/trunk/lib/AST/ExprConstant.cpp
>>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/ExprConstant.cpp?rev=360974&r1=360973&r2=360974&view=diff
>>> ==============================================================================
>>> --- cfe/trunk/lib/AST/ExprConstant.cpp (original)
>>> +++ cfe/trunk/lib/AST/ExprConstant.cpp Thu May 16 18:46:05 2019
>>> @@ -87,6 +87,9 @@ namespace {
>>> return D->getType();
>>> }
>>>
>>> + if (TypeInfoLValue TI = B.dyn_cast<TypeInfoLValue>())
>>> + return B.getTypeInfoType();
>>> +
>>> const Expr *Base = B.get<const Expr*>();
>>>
>>> // For a materialized temporary, the type of the temporary we materialized
>>> @@ -1783,6 +1786,9 @@ static bool IsGlobalLValue(APValue::LVal
>>> return isa<FunctionDecl>(D);
>>> }
>>>
>>> + if (B.is<TypeInfoLValue>())
>>> + return true;
>>> +
>>> const Expr *E = B.get<const Expr*>();
>>> switch (E->getStmtClass()) {
>>> default:
>>> @@ -1800,7 +1806,6 @@ static bool IsGlobalLValue(APValue::LVal
>>> case Expr::PredefinedExprClass:
>>> case Expr::ObjCStringLiteralClass:
>>> case Expr::ObjCEncodeExprClass:
>>> - case Expr::CXXTypeidExprClass:
>>> case Expr::CXXUuidofExprClass:
>>> return true;
>>> case Expr::ObjCBoxedExprClass:
>>> @@ -1878,9 +1883,9 @@ static void NoteLValueLocation(EvalInfo
>>> const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>();
>>> if (VD)
>>> Info.Note(VD->getLocation(), diag::note_declared_at);
>>> - else
>>> - Info.Note(Base.get<const Expr*>()->getExprLoc(),
>>> - diag::note_constexpr_temporary_here);
>>> + else if (const Expr *E = Base.dyn_cast<const Expr*>())
>>> + Info.Note(E->getExprLoc(), diag::note_constexpr_temporary_here);
>>> + // We have no information to show for a typeid(T) object.
>>> }
>>>
>>> /// Check that this reference or pointer core constant expression is a valid
>>> @@ -3404,7 +3409,7 @@ static CompleteObject findCompleteObject
>>>
>>> if (!Frame) {
>>> if (const MaterializeTemporaryExpr *MTE =
>>> - dyn_cast<MaterializeTemporaryExpr>(Base)) {
>>> + dyn_cast_or_null<MaterializeTemporaryExpr>(Base)) {
>>> assert(MTE->getStorageDuration() == SD_Static &&
>>> "should have a frame for a non-global materialized temporary");
>>>
>>> @@ -3439,7 +3444,13 @@ static CompleteObject findCompleteObject
>>> } else {
>>> if (!IsAccess)
>>> return CompleteObject(LVal.getLValueBase(), nullptr, BaseType);
>>> - Info.FFDiag(E);
>>> + APValue Val;
>>> + LVal.moveInto(Val);
>>> + Info.FFDiag(E, diag::note_constexpr_access_unreadable_object)
>>> + << AK
>>> + << Val.getAsString(Info.Ctx,
>>> + Info.Ctx.getLValueReferenceType(LValType));
>>> + NoteLValueLocation(Info, LVal.Base);
>>> return CompleteObject();
>>> }
>>> } else {
>>> @@ -5777,13 +5788,13 @@ public:
>>> // - Literals
>>> // * CompoundLiteralExpr in C (and in global scope in C++)
>>> // * StringLiteral
>>> -// * CXXTypeidExpr
>>> // * PredefinedExpr
>>> // * ObjCStringLiteralExpr
>>> // * ObjCEncodeExpr
>>> // * AddrLabelExpr
>>> // * BlockExpr
>>> // * CallExpr for a MakeStringConstant builtin
>>> +// - typeid(T) expressions, as TypeInfoLValues
>>> // - Locals and temporaries
>>> // * MaterializeTemporaryExpr
>>> // * Any Expr, with a CallIndex indicating the function in which the temporary
>>> @@ -6018,8 +6029,14 @@ LValueExprEvaluator::VisitCompoundLitera
>>> }
>>>
>>> bool LValueExprEvaluator::VisitCXXTypeidExpr(const CXXTypeidExpr *E) {
>>> - if (!E->isPotentiallyEvaluated())
>>> - return Success(E);
>>> + if (!E->isPotentiallyEvaluated()) {
>>> + TypeInfoLValue TypeInfo;
>>> + if (E->isTypeOperand())
>>> + TypeInfo = TypeInfoLValue(E->getTypeOperand(Info.Ctx).getTypePtr());
>>> + else
>>> + TypeInfo = TypeInfoLValue(E->getExprOperand()->getType().getTypePtr());
>>> + return Success(APValue::LValueBase::getTypeInfo(TypeInfo, E->getType()));
>>> + }
>>>
>>> Info.FFDiag(E, diag::note_constexpr_typeid_polymorphic)
>>> << E->getExprOperand()->getType()
>>> @@ -6615,9 +6632,11 @@ bool PointerExprEvaluator::VisitBuiltinC
>>> if (const ValueDecl *VD =
>>> OffsetResult.Base.dyn_cast<const ValueDecl*>()) {
>>> BaseAlignment = Info.Ctx.getDeclAlign(VD);
>>> + } else if (const Expr *E = OffsetResult.Base.dyn_cast<const Expr *>()) {
>>> + BaseAlignment = GetAlignOfExpr(Info, E, UETT_AlignOf);
>>> } else {
>>> - BaseAlignment = GetAlignOfExpr(
>>> - Info, OffsetResult.Base.get<const Expr *>(), UETT_AlignOf);
>>> + BaseAlignment = GetAlignOfType(
>>> + Info, OffsetResult.Base.getTypeInfoType(), UETT_AlignOf);
>>> }
>>>
>>> if (BaseAlignment < Align) {
>>> @@ -8335,6 +8354,10 @@ static bool EvaluateBuiltinConstantPForL
>>> if (!isa<StringLiteral>(E))
>>> return false;
>>> return LV.getLValueOffset().isZero();
>>> + } else if (Base.is<TypeInfoLValue>()) {
>>> + // Surprisingly, GCC considers __builtin_constant_p(&typeid(int)) to
>>> + // evaluate to true.
>>> + return true;
>>> } else {
>>> // Any other base is not constant enough for GCC.
>>> return false;
>>> @@ -8399,6 +8422,8 @@ static QualType getObjectType(APValue::L
>>> } else if (const Expr *E = B.get<const Expr*>()) {
>>> if (isa<CompoundLiteralExpr>(E))
>>> return E->getType();
>>> + } else if (B.is<TypeInfoLValue>()) {
>>> + return B.getTypeInfoType();
>>> }
>>>
>>> return QualType();
>>>
>>> Modified: cfe/trunk/lib/CodeGen/CGExprConstant.cpp
>>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGExprConstant.cpp?rev=360974&r1=360973&r2=360974&view=diff
>>> ==============================================================================
>>> --- cfe/trunk/lib/CodeGen/CGExprConstant.cpp (original)
>>> +++ cfe/trunk/lib/CodeGen/CGExprConstant.cpp Thu May 16 18:46:05 2019
>>> @@ -1735,6 +1735,17 @@ ConstantLValueEmitter::tryEmitBase(const
>>> return nullptr;
>>> }
>>>
>>> + // Handle typeid(T).
>>> + if (TypeInfoLValue TI = base.dyn_cast<TypeInfoLValue>()) {
>>> + llvm::Type *StdTypeInfoPtrTy =
>>> + CGM.getTypes().ConvertType(base.getTypeInfoType())->getPointerTo();
>>> + llvm::Constant *TypeInfo =
>>> + CGM.GetAddrOfRTTIDescriptor(QualType(TI.getType(), 0));
>>> + if (TypeInfo->getType() != StdTypeInfoPtrTy)
>>> + TypeInfo = llvm::ConstantExpr::getBitCast(TypeInfo, StdTypeInfoPtrTy);
>>> + return TypeInfo;
>>> + }
>>> +
>>> // Otherwise, it must be an expression.
>>> return Visit(base.get<const Expr*>());
>>> }
>>>
>>> Modified: cfe/trunk/lib/Sema/SemaTemplate.cpp
>>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaTemplate.cpp?rev=360974&r1=360973&r2=360974&view=diff
>>> ==============================================================================
>>> --- cfe/trunk/lib/Sema/SemaTemplate.cpp (original)
>>> +++ cfe/trunk/lib/Sema/SemaTemplate.cpp Thu May 16 18:46:05 2019
>>> @@ -6424,8 +6424,11 @@ ExprResult Sema::CheckTemplateArgument(N
>>> // -- a string literal
>>> // -- the result of a typeid expression, or
>>> // -- a predefined __func__ variable
>>> - if (auto *E = Value.getLValueBase().dyn_cast<const Expr*>()) {
>>> - if (isa<CXXUuidofExpr>(E)) {
>>> + APValue::LValueBase Base = Value.getLValueBase();
>>> + auto *VD = const_cast<ValueDecl *>(Base.dyn_cast<const ValueDecl *>());
>>> + if (Base && !VD) {
>>> + auto *E = Base.dyn_cast<const Expr *>();
>>> + if (E && isa<CXXUuidofExpr>(E)) {
>>> Converted = TemplateArgument(ArgResult.get()->IgnoreImpCasts());
>>> break;
>>> }
>>> @@ -6433,8 +6436,6 @@ ExprResult Sema::CheckTemplateArgument(N
>>> << Arg->getSourceRange();
>>> return ExprError();
>>> }
>>> - auto *VD = const_cast<ValueDecl *>(
>>> - Value.getLValueBase().dyn_cast<const ValueDecl *>());
>>> // -- a subobject
>>> if (Value.hasLValuePath() && Value.getLValuePath().size() == 1 &&
>>> VD && VD->getType()->isArrayType() &&
>>>
>>> Modified: cfe/trunk/test/CXX/drs/dr19xx.cpp
>>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CXX/drs/dr19xx.cpp?rev=360974&r1=360973&r2=360974&view=diff
>>> ==============================================================================
>>> --- cfe/trunk/test/CXX/drs/dr19xx.cpp (original)
>>> +++ cfe/trunk/test/CXX/drs/dr19xx.cpp Thu May 16 18:46:05 2019
>>> @@ -167,9 +167,14 @@ namespace dr1959 { // dr1959: 3.9
>>> #endif
>>> }
>>>
>>> -namespace dr1968 { // dr1968: yes
>>> +namespace dr1968 { // dr1968: no
>>> #if __cplusplus >= 201103L
>>> - static_assert(&typeid(int) == &typeid(int), ""); // expected-error{{not an integral constant expression}}
>>> + // FIXME: According to DR1968, both of these should be considered
>>> + // non-constant.
>>> + static_assert(&typeid(int) == &typeid(int), "");
>>> +
>>> + constexpr const std::type_info *f() { return &typeid(int); }
>>> + static_assert(f() == f(), "");
>>> #endif
>>> }
>>>
>>>
>>> Modified: cfe/trunk/test/Parser/MicrosoftExtensions.cpp
>>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Parser/MicrosoftExtensions.cpp?rev=360974&r1=360973&r2=360974&view=diff
>>> ==============================================================================
>>> --- cfe/trunk/test/Parser/MicrosoftExtensions.cpp (original)
>>> +++ cfe/trunk/test/Parser/MicrosoftExtensions.cpp Thu May 16 18:46:05 2019
>>> @@ -138,6 +138,8 @@ typedef COM_CLASS_TEMPLATE_REF<struct_wi
>>> COM_CLASS_TEMPLATE_REF<int, __uuidof(struct_with_uuid)> good_template_arg;
>>>
>>> COM_CLASS_TEMPLATE<int, __uuidof(struct_with_uuid)> bad_template_arg; // expected-error {{non-type template argument of type 'const _GUID' is not a constant expression}}
>>> +// expected-note at -1 {{read of object '__uuidof(struct_with_uuid)' whose value is not known}}
>>> +// expected-note at -2 {{temporary created here}}
>>>
>>> namespace PR16911 {
>>> struct __declspec(uuid("{12345678-1234-1234-1234-1234567890aB}")) uuid;
>>>
>>> Modified: cfe/trunk/test/SemaCXX/builtin-constant-p.cpp
>>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/builtin-constant-p.cpp?rev=360974&r1=360973&r2=360974&view=diff
>>> ==============================================================================
>>> --- cfe/trunk/test/SemaCXX/builtin-constant-p.cpp (original)
>>> +++ cfe/trunk/test/SemaCXX/builtin-constant-p.cpp Thu May 16 18:46:05 2019
>>> @@ -130,3 +130,8 @@ constexpr int mutate6(bool mutate) {
>>> static_assert(mutate6(false) == 11);
>>> // Mutation of state outside __builtin_constant_p: evaluates to false.
>>> static_assert(mutate6(true) == 10);
>>> +
>>> +// GCC strangely returns true for the address of a type_info object, despite it
>>> +// not being a pointer to the start of a string literal.
>>> +namespace std { struct type_info; }
>>> +static_assert(__builtin_constant_p(&typeid(int)));
>>>
>>> Modified: cfe/trunk/test/SemaCXX/typeid.cpp
>>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/typeid.cpp?rev=360974&r1=360973&r2=360974&view=diff
>>> ==============================================================================
>>> --- cfe/trunk/test/SemaCXX/typeid.cpp (original)
>>> +++ cfe/trunk/test/SemaCXX/typeid.cpp Thu May 16 18:46:05 2019
>>> @@ -6,7 +6,7 @@ void f()
>>> }
>>>
>>> namespace std {
>>> - class type_info;
>>> + struct type_info { const char *name; };
>>> }
>>>
>>> void g()
>>> @@ -27,3 +27,6 @@ void h(int i) {
>>> typeid(V); // expected-error{{'typeid' of variably modified type 'char [i]'}}
>>> typeid(char [i]); // expected-error{{'typeid' of variably modified type 'char [i]'}}
>>> }
>>> +
>>> +// expected-note at +1 {{read of object 'typeid(int).name' whose value is not known}}
>>> +constexpr const char *name = typeid(int).name; // expected-error {{constant expression}}
>>>
>>> Modified: cfe/trunk/www/cxx_dr_status.html
>>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/www/cxx_dr_status.html?rev=360974&r1=360973&r2=360974&view=diff
>>> ==============================================================================
>>> --- cfe/trunk/www/cxx_dr_status.html (original)
>>> +++ cfe/trunk/www/cxx_dr_status.html Thu May 16 18:46:05 2019
>>> @@ -11623,7 +11623,7 @@ and <I>POD class</I></td>
>>> <td><a href="http://wg21.link/cwg1968">1968</a></td>
>>> <td>NAD</td>
>>> <td>Address of <TT>typeid</TT> in constant expressions</td>
>>> - <td class="full" align="center">Yes</td>
>>> + <td class="none" align="center">No</td>
>>> </tr>
>>> <tr class="open" id="1969">
>>> <td><a href="http://wg21.link/cwg1969">1969</a></td>
>>>
>>>
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