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.

diff --git a/clang/include/clang/AST/ASTContext.h b/clang/include/clang/AST/ASTContext.h
index 59e2679..6c00fe8 100644 (file)
--- a/clang/include/clang/AST/ASTContext.h
+++ b/clang/include/clang/AST/ASTContext.h
@@ -1459,8 +1459,16 @@ public:
   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 9a745ef..7fe6524 100644 (file)
--- 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 @@ public:
     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 a4e3002..011394c 100644 (file)
--- 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 e7518a5..25bf715 100644 (file)
--- 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 0122d2e..d40ba4c 100644 (file)
--- a/clang/lib/AST/Type.cpp
+++ b/clang/lib/AST/Type.cpp
@@ -1187,9 +1187,6 @@ public:
                            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 6965c4a..780e0c6 100644 (file)
--- 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 8ce488f..8f79cc7 100644 (file)
--- 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 21d3bbf..bb0b1fa 100644 (file)
--- 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 657ed13..dc74f6e 100644 (file)
--- 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 7b77d1c..259cc51 100644 (file)
--- 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 3eabe7c..4c7eece 100644 (file)
--- 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 (file)
index 0000000..e8ea164
--- /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}}
+}