[clang] 740a164 - PR46377: Fix dependence calculation for function types and typedef

Nico Weber via cfe-commits cfe-commits at lists.llvm.org
Fri Jul 31 16:22:50 PDT 2020


Heads-up: This causes Chromium's build to fail with

clang-cl:
/usr/local/google/home/thakis/src/chrome/src/third_party/llvm/clang/lib/AST/ASTContext.cpp:4823:
clang::QualType clang::ASTContext::getPackExpansionType(clang::QualType,
llvm::Optional<unsigned int>, bool): Assertion `(!ExpectPackInType ||
Pattern->containsUnexpandedParameterPack()) && "Pack expansions must expand
one or more parameter packs"' failed.

under certain scenarios with precompiled headers. At the moment I only have
a repro when we use a Chromium-specific compiler plugin (
https://bugs.chromium.org/p/chromium/issues/detail?id=1110981#c19), but
it's likely I'll have one without that soonish.

On Tue, Jul 28, 2020 at 4:23 PM Richard Smith via cfe-commits <
cfe-commits at lists.llvm.org> wrote:

>
> Author: Richard Smith
> Date: 2020-07-28T13:23:13-07:00
> New Revision: 740a164dec483225cbd02ab6c82199e2747ffacb
>
> URL:
> https://github.com/llvm/llvm-project/commit/740a164dec483225cbd02ab6c82199e2747ffacb
> DIFF:
> https://github.com/llvm/llvm-project/commit/740a164dec483225cbd02ab6c82199e2747ffacb.diff
>
> LOG: PR46377: Fix dependence calculation for function types and typedef
> types.
>
> We previously did not treat a function type as dependent if it had a
> parameter pack with a non-dependent type -- such a function type depends
> on the arity of the pack so is dependent even though none of the
> parameter types is dependent. In order to properly handle this, we now
> treat pack expansion types as always being dependent types (depending on
> at least the pack arity), and always canonically being pack expansion
> types, even in the unusual case when the pattern is not a dependent
> type. This does mean that we can have canonical types that are pack
> expansions that contain no unexpanded packs, which is unfortunate but
> not inaccurate.
>
> We also previously did not treat a typedef type as
> instantiation-dependent if its canonical type was not
> instantiation-dependent. That's wrong because instantiation-dependence
> is a property of the type sugar, not of the type; an
> instantiation-dependent type can have a non-instantiation-dependent
> canonical type.
>
> Added:
>     clang/test/SemaTemplate/alias-template-nondependent.cpp
>
> Modified:
>     clang/include/clang/AST/ASTContext.h
>     clang/include/clang/AST/Type.h
>     clang/include/clang/Basic/TypeNodes.td
>     clang/lib/AST/ASTContext.cpp
>     clang/lib/AST/Type.cpp
>     clang/lib/CodeGen/CGDebugInfo.cpp
>     clang/lib/CodeGen/CodeGenFunction.cpp
>     clang/lib/Sema/SemaExpr.cpp
>     clang/lib/Sema/SemaLambda.cpp
>     clang/lib/Sema/SemaTemplateVariadic.cpp
>     clang/lib/Sema/SemaType.cpp
>
> Removed:
>
>
>
>
> ################################################################################
> diff  --git a/clang/include/clang/AST/ASTContext.h
> b/clang/include/clang/AST/ASTContext.h
> index 59e2679ddded..6c00fe86f282 100644
> --- a/clang/include/clang/AST/ASTContext.h
> +++ b/clang/include/clang/AST/ASTContext.h
> @@ -1459,8 +1459,16 @@ class ASTContext : public
> RefCountedBase<ASTContext> {
>    void getInjectedTemplateArgs(const TemplateParameterList *Params,
>                                 SmallVectorImpl<TemplateArgument> &Args);
>
> +  /// Form a pack expansion type with the given pattern.
> +  /// \param NumExpansions The number of expansions for the pack, if
> known.
> +  /// \param ExpectPackInType If \c false, we should not expect \p
> Pattern to
> +  ///        contain an unexpanded pack. This only makes sense if the pack
> +  ///        expansion is used in a context where the arity is inferred
> from
> +  ///        elsewhere, such as if the pattern contains a placeholder
> type or
> +  ///        if this is the canonical type of another pack expansion type.
>    QualType getPackExpansionType(QualType Pattern,
> -                                Optional<unsigned> NumExpansions);
> +                                Optional<unsigned> NumExpansions,
> +                                bool ExpectPackInType = true);
>
>    QualType getObjCInterfaceType(const ObjCInterfaceDecl *Decl,
>                                  ObjCInterfaceDecl *PrevDecl = nullptr)
> const;
>
> diff  --git a/clang/include/clang/AST/Type.h
> b/clang/include/clang/AST/Type.h
> index 9a745ef20fac..7fe652492b0e 100644
> --- a/clang/include/clang/AST/Type.h
> +++ b/clang/include/clang/AST/Type.h
> @@ -4383,11 +4383,7 @@ class TypedefType : public Type {
>  protected:
>    friend class ASTContext; // ASTContext creates these.
>
> -  TypedefType(TypeClass tc, const TypedefNameDecl *D, QualType can)
> -      : Type(tc, can, can->getDependence() &
> ~TypeDependence::UnexpandedPack),
> -        Decl(const_cast<TypedefNameDecl *>(D)) {
> -    assert(!isa<TypedefType>(can) && "Invalid canonical type");
> -  }
> +  TypedefType(TypeClass tc, const TypedefNameDecl *D, QualType can);
>
>  public:
>    TypedefNameDecl *getDecl() const { return Decl; }
> @@ -5624,7 +5620,8 @@ class PackExpansionType : public Type, public
> llvm::FoldingSetNode {
>    PackExpansionType(QualType Pattern, QualType Canon,
>                      Optional<unsigned> NumExpansions)
>        : Type(PackExpansion, Canon,
> -             (Pattern->getDependence() | TypeDependence::Instantiation) &
> +             (Pattern->getDependence() | TypeDependence::Dependent |
> +              TypeDependence::Instantiation) &
>                   ~TypeDependence::UnexpandedPack),
>          Pattern(Pattern) {
>      PackExpansionTypeBits.NumExpansions =
> @@ -5645,8 +5642,8 @@ class PackExpansionType : public Type, public
> llvm::FoldingSetNode {
>      return None;
>    }
>
> -  bool isSugared() const { return !Pattern->isDependentType(); }
> -  QualType desugar() const { return isSugared() ? Pattern :
> QualType(this, 0); }
> +  bool isSugared() const { return false; }
> +  QualType desugar() const { return QualType(this, 0); }
>
>    void Profile(llvm::FoldingSetNodeID &ID) {
>      Profile(ID, getPattern(), getNumExpansions());
>
> diff  --git a/clang/include/clang/Basic/TypeNodes.td
> b/clang/include/clang/Basic/TypeNodes.td
> index a4e3002b9075..011394c3ef45 100644
> --- a/clang/include/clang/Basic/TypeNodes.td
> +++ b/clang/include/clang/Basic/TypeNodes.td
> @@ -100,7 +100,7 @@ def DeducedTemplateSpecializationType :
> TypeNode<DeducedType>;
>  def InjectedClassNameType : TypeNode<Type>, AlwaysDependent, LeafType;
>  def DependentNameType : TypeNode<Type>, AlwaysDependent;
>  def DependentTemplateSpecializationType : TypeNode<Type>, AlwaysDependent;
> -def PackExpansionType : TypeNode<Type>, NeverCanonicalUnlessDependent;
> +def PackExpansionType : TypeNode<Type>, AlwaysDependent;
>  def ObjCTypeParamType : TypeNode<Type>, NeverCanonical;
>  def ObjCObjectType : TypeNode<Type>;
>  def ObjCInterfaceType : TypeNode<ObjCObjectType>, LeafType;
>
> diff  --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
> index e7518a538fe6..25bf71519d1c 100644
> --- a/clang/lib/AST/ASTContext.cpp
> +++ b/clang/lib/AST/ASTContext.cpp
> @@ -4817,37 +4817,27 @@ ASTContext::getInjectedTemplateArgs(const
> TemplateParameterList *Params,
>  }
>
>  QualType ASTContext::getPackExpansionType(QualType Pattern,
> -                                          Optional<unsigned>
> NumExpansions) {
> +                                          Optional<unsigned>
> NumExpansions,
> +                                          bool ExpectPackInType) {
> +  assert((!ExpectPackInType ||
> Pattern->containsUnexpandedParameterPack()) &&
> +         "Pack expansions must expand one or more parameter packs");
> +
>    llvm::FoldingSetNodeID ID;
>    PackExpansionType::Profile(ID, Pattern, NumExpansions);
>
> -  // A deduced type can deduce to a pack, eg
> -  //   auto ...x = some_pack;
> -  // That declaration isn't (yet) valid, but is created as part of
> building an
> -  // init-capture pack:
> -  //   [...x = some_pack] {}
> -  assert((Pattern->containsUnexpandedParameterPack() ||
> -          Pattern->getContainedDeducedType()) &&
> -         "Pack expansions must expand one or more parameter packs");
>    void *InsertPos = nullptr;
> -  PackExpansionType *T
> -    = PackExpansionTypes.FindNodeOrInsertPos(ID, InsertPos);
> +  PackExpansionType *T = PackExpansionTypes.FindNodeOrInsertPos(ID,
> InsertPos);
>    if (T)
>      return QualType(T, 0);
>
>    QualType Canon;
>    if (!Pattern.isCanonical()) {
> -    Canon = getCanonicalType(Pattern);
> -    // The canonical type might not contain an unexpanded parameter pack,
> if it
> -    // contains an alias template specialization which ignores one of its
> -    // parameters.
> -    if (Canon->containsUnexpandedParameterPack()) {
> -      Canon = getPackExpansionType(Canon, NumExpansions);
> -
> -      // Find the insert position again, in case we inserted an element
> into
> -      // PackExpansionTypes and invalidated our insert position.
> -      PackExpansionTypes.FindNodeOrInsertPos(ID, InsertPos);
> -    }
> +    Canon = getPackExpansionType(getCanonicalType(Pattern), NumExpansions,
> +                                 /*ExpectPackInType=*/false);
> +
> +    // Find the insert position again, in case we inserted an element into
> +    // PackExpansionTypes and invalidated our insert position.
> +    PackExpansionTypes.FindNodeOrInsertPos(ID, InsertPos);
>    }
>
>    T = new (*this, TypeAlignment)
>
> diff  --git a/clang/lib/AST/Type.cpp b/clang/lib/AST/Type.cpp
> index 0122d2e7de52..d40ba4c648c4 100644
> --- a/clang/lib/AST/Type.cpp
> +++ b/clang/lib/AST/Type.cpp
> @@ -1187,9 +1187,6 @@ struct SimpleTransformVisitor : public
> TypeVisitor<Derived, QualType> {
>                             T->getTypeConstraintArguments());
>    }
>
> -  // FIXME: Non-trivial to implement, but important for C++
> -  SUGARED_TYPE_CLASS(PackExpansion)
> -
>    QualType VisitObjCObjectType(const ObjCObjectType *T) {
>      QualType baseType = recurse(T->getBaseType());
>      if (baseType.isNull())
> @@ -3348,6 +3345,12 @@ void
> FunctionProtoType::Profile(llvm::FoldingSetNodeID &ID,
>            getExtProtoInfo(), Ctx, isCanonicalUnqualified());
>  }
>
> +TypedefType::TypedefType(TypeClass tc, const TypedefNameDecl *D, QualType
> can)
> +    : Type(tc, can, D->getUnderlyingType()->getDependence()),
> +      Decl(const_cast<TypedefNameDecl *>(D)) {
> +  assert(!isa<TypedefType>(can) && "Invalid canonical type");
> +}
> +
>  QualType TypedefType::desugar() const {
>    return getDecl()->getUnderlyingType();
>  }
>
> diff  --git a/clang/lib/CodeGen/CGDebugInfo.cpp
> b/clang/lib/CodeGen/CGDebugInfo.cpp
> index 6965c4a1209c..780e0c692c05 100644
> --- a/clang/lib/CodeGen/CGDebugInfo.cpp
> +++ b/clang/lib/CodeGen/CGDebugInfo.cpp
> @@ -3252,7 +3252,6 @@ llvm::DIType *CGDebugInfo::CreateTypeNode(QualType
> Ty, llvm::DIFile *Unit) {
>    case Type::TypeOf:
>    case Type::Decltype:
>    case Type::UnaryTransform:
> -  case Type::PackExpansion:
>      break;
>    }
>
>
> diff  --git a/clang/lib/CodeGen/CodeGenFunction.cpp
> b/clang/lib/CodeGen/CodeGenFunction.cpp
> index 8ce488f35dd3..8f79cc77f0e6 100644
> --- a/clang/lib/CodeGen/CodeGenFunction.cpp
> +++ b/clang/lib/CodeGen/CodeGenFunction.cpp
> @@ -2075,7 +2075,6 @@ void
> CodeGenFunction::EmitVariablyModifiedType(QualType type) {
>      case Type::UnaryTransform:
>      case Type::Attributed:
>      case Type::SubstTemplateTypeParm:
> -    case Type::PackExpansion:
>      case Type::MacroQualified:
>        // Keep walking after single level desugaring.
>        type = type.getSingleStepDesugaredType(getContext());
>
> diff  --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
> index 21d3bbf419a9..bb0b1fa49851 100644
> --- a/clang/lib/Sema/SemaExpr.cpp
> +++ b/clang/lib/Sema/SemaExpr.cpp
> @@ -4345,7 +4345,6 @@ static void captureVariablyModifiedType(ASTContext
> &Context, QualType T,
>      case Type::UnaryTransform:
>      case Type::Attributed:
>      case Type::SubstTemplateTypeParm:
> -    case Type::PackExpansion:
>      case Type::MacroQualified:
>        // Keep walking after single level desugaring.
>        T = T.getSingleStepDesugaredType(Context);
>
> diff  --git a/clang/lib/Sema/SemaLambda.cpp b/clang/lib/Sema/SemaLambda.cpp
> index 657ed13f207a..dc74f6e2f7dc 100644
> --- a/clang/lib/Sema/SemaLambda.cpp
> +++ b/clang/lib/Sema/SemaLambda.cpp
> @@ -803,7 +803,8 @@ QualType Sema::buildLambdaInitCaptureInitialization(
>        Diag(EllipsisLoc, getLangOpts().CPlusPlus20
>                              ? diag::warn_cxx17_compat_init_capture_pack
>                              : diag::ext_init_capture_pack);
> -      DeductType = Context.getPackExpansionType(DeductType,
> NumExpansions);
> +      DeductType = Context.getPackExpansionType(DeductType, NumExpansions,
> +
> /*ExpectPackInType=*/false);
>
>  TLB.push<PackExpansionTypeLoc>(DeductType).setEllipsisLoc(EllipsisLoc);
>      } else {
>        // Just ignore the ellipsis for now and form a non-pack variable.
> We'll
>
> diff  --git a/clang/lib/Sema/SemaTemplateVariadic.cpp
> b/clang/lib/Sema/SemaTemplateVariadic.cpp
> index 7b77d1cb482a..259cc5165776 100644
> --- a/clang/lib/Sema/SemaTemplateVariadic.cpp
> +++ b/clang/lib/Sema/SemaTemplateVariadic.cpp
> @@ -614,7 +614,8 @@ QualType Sema::CheckPackExpansion(QualType Pattern,
> SourceRange PatternRange,
>      return QualType();
>    }
>
> -  return Context.getPackExpansionType(Pattern, NumExpansions);
> +  return Context.getPackExpansionType(Pattern, NumExpansions,
> +                                      /*ExpectPackInType=*/false);
>  }
>
>  ExprResult Sema::ActOnPackExpansion(Expr *Pattern, SourceLocation
> EllipsisLoc) {
>
> diff  --git a/clang/lib/Sema/SemaType.cpp b/clang/lib/Sema/SemaType.cpp
> index 3eabe7ca6ffe..4c7eece68bca 100644
> --- a/clang/lib/Sema/SemaType.cpp
> +++ b/clang/lib/Sema/SemaType.cpp
> @@ -5516,7 +5516,7 @@ static TypeSourceInfo
> *GetFullTypeForDeclarator(TypeProcessingState &state,
>            << T <<  D.getSourceRange();
>          D.setEllipsisLoc(SourceLocation());
>        } else {
> -        T = Context.getPackExpansionType(T, None);
> +        T = Context.getPackExpansionType(T, None,
> /*ExpectPackInType=*/false);
>        }
>        break;
>      case DeclaratorContext::TemplateParamContext:
>
> diff  --git a/clang/test/SemaTemplate/alias-template-nondependent.cpp
> b/clang/test/SemaTemplate/alias-template-nondependent.cpp
> new file mode 100644
> index 000000000000..e8ea16483a09
> --- /dev/null
> +++ b/clang/test/SemaTemplate/alias-template-nondependent.cpp
> @@ -0,0 +1,24 @@
> +// RUN: %clang_cc1 -std=c++20 -verify %s
> +
> +namespace PR46377 {
> +  template<typename> using IntPtr = int*;
> +  template<typename ...T> auto non_dependent_typedef() {
> +    typedef int(*P)(IntPtr<T>...);
> +    return P();
> +  }
> +  template<typename ...T> auto non_dependent_alias() {
> +    using P = int(*)(IntPtr<T>...);
> +    return P();
> +  }
> +  template<typename ...T> auto non_dependent_via_sizeof() {
> +    using P = int(*)(int(...pack)[sizeof(sizeof(T))]); // expected-error
> {{invalid application of 'sizeof'}}
> +    return P();
> +  }
> +
> +  using a = int (*)(int*, int*);
> +  using a = decltype(non_dependent_typedef<void, void>());
> +  using a = decltype(non_dependent_alias<void, void>());
> +  using a = decltype(non_dependent_via_sizeof<float, float>());
> +
> +  using b = decltype(non_dependent_via_sizeof<float, void>()); //
> expected-note {{instantiation of}}
> +}
>
>
>
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