[clang/AST] Make it possible to use SwiftAttr in type context (#108631)

xedin · web-flow · commit d3daa3c4435a · 2024-10-31T11:15:22.000Z
Swift ClangImporter now supports concurrency annotations on imported
declarations and their parameters/results, to make it possible to use
imported APIs in Swift safely there has to be a way to annotate
individual parameters and result types with relevant attributes that
indicate that e.g. a block is called on a particular actor or it accepts
a `Sendable` parameter.

To faciliate that `SwiftAttr` is switched from `InheritableAttr` which
is a declaration attribute to `DeclOrTypeAttr`. To support this
attribute in type context we need access to its "Attribute" argument
which requires `AttributedType` to be extended to include `Attr *` when
available instead of just `attr::Kind` otherwise it won't be possible to
determine what attribute should be imported.
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
@@ -338,6 +338,19 @@ Removed Compiler Flags
 Attribute Changes in Clang
 --------------------------
 
+- The ``swift_attr`` can now be applied to types. To make it possible to use imported APIs
+  in Swift safely there has to be a way to annotate individual parameters and result types
+  with relevant attributes that indicate that e.g. a block is called on a particular actor
+  or it accepts a Sendable or global-actor (i.e. ``@MainActor``) isolated parameter.
+
+  For example:
+
+  .. code-block:: objc
+
+     @interface MyService
+       -(void) handle: (void (^ __attribute__((swift_attr("@Sendable"))))(id)) handler;
+     @end
+
 - Clang now disallows more than one ``__attribute__((ownership_returns(class, idx)))`` with
   different class names attached to one function.
 
diff --git a/clang/include/clang/AST/ASTContext.h b/clang/include/clang/AST/ASTContext.h
@@ -1719,8 +1719,15 @@ class ASTContext : public RefCountedBase<ASTContext> {
   QualType getInjectedClassNameType(CXXRecordDecl *Decl, QualType TST) const;
 
   QualType getAttributedType(attr::Kind attrKind, QualType modifiedType,
+                             QualType equivalentType,
+                             const Attr *attr = nullptr) const;
+
+  QualType getAttributedType(const Attr *attr, QualType modifiedType,
                              QualType equivalentType) const;
 
+  QualType getAttributedType(NullabilityKind nullability, QualType modifiedType,
+                             QualType equivalentType);
+
   QualType getBTFTagAttributedType(const BTFTypeTagAttr *BTFAttr,
                                    QualType Wrapped) const;
 
diff --git a/clang/include/clang/AST/PropertiesBase.td b/clang/include/clang/AST/PropertiesBase.td
@@ -76,6 +76,7 @@ def APValue : PropertyType { let PassByReference = 1; }
 def APValueKind : EnumPropertyType<"APValue::ValueKind">;
 def ArraySizeModifier : EnumPropertyType<"ArraySizeModifier">;
 def AttrKind : EnumPropertyType<"attr::Kind">;
+def Attr : PropertyType<"const Attr *">;
 def AutoTypeKeyword : EnumPropertyType;
 def Bool : PropertyType<"bool">;
 def BuiltinTypeKind : EnumPropertyType<"BuiltinType::Kind">;
diff --git a/clang/include/clang/AST/Type.h b/clang/include/clang/AST/Type.h
@@ -69,6 +69,7 @@ class ValueDecl;
 class TagDecl;
 class TemplateParameterList;
 class Type;
+class Attr;
 
 enum {
   TypeAlignmentInBits = 4,
@@ -6130,21 +6131,29 @@ class AttributedType : public Type, public llvm::FoldingSetNode {
 private:
   friend class ASTContext; // ASTContext creates these
 
+  const Attr *Attribute;
+
   QualType ModifiedType;
   QualType EquivalentType;
 
   AttributedType(QualType canon, attr::Kind attrKind, QualType modified,
                  QualType equivalent)
-      : Type(Attributed, canon, equivalent->getDependence()),
-        ModifiedType(modified), EquivalentType(equivalent) {
-    AttributedTypeBits.AttrKind = attrKind;
-  }
+      : AttributedType(canon, attrKind, nullptr, modified, equivalent) {}
+
+  AttributedType(QualType canon, const Attr *attr, QualType modified,
+                 QualType equivalent);
+
+private:
+  AttributedType(QualType canon, attr::Kind attrKind, const Attr *attr,
+                 QualType modified, QualType equivalent);
 
 public:
   Kind getAttrKind() const {
     return static_cast<Kind>(AttributedTypeBits.AttrKind);
   }
 
+  const Attr *getAttr() const { return Attribute; }
+
   QualType getModifiedType() const { return ModifiedType; }
   QualType getEquivalentType() const { return EquivalentType; }
 
@@ -6176,25 +6185,6 @@ class AttributedType : public Type, public llvm::FoldingSetNode {
 
   std::optional<NullabilityKind> getImmediateNullability() const;
 
-  /// Retrieve the attribute kind corresponding to the given
-  /// nullability kind.
-  static Kind getNullabilityAttrKind(NullabilityKind kind) {
-    switch (kind) {
-    case NullabilityKind::NonNull:
-      return attr::TypeNonNull;
-
-    case NullabilityKind::Nullable:
-      return attr::TypeNullable;
-
-    case NullabilityKind::NullableResult:
-      return attr::TypeNullableResult;
-
-    case NullabilityKind::Unspecified:
-      return attr::TypeNullUnspecified;
-    }
-    llvm_unreachable("Unknown nullability kind.");
-  }
-
   /// Strip off the top-level nullability annotation on the given
   /// type, if it's there.
   ///
@@ -6207,14 +6197,16 @@ class AttributedType : public Type, public llvm::FoldingSetNode {
   static std::optional<NullabilityKind> stripOuterNullability(QualType &T);
 
   void Profile(llvm::FoldingSetNodeID &ID) {
-    Profile(ID, getAttrKind(), ModifiedType, EquivalentType);
+    Profile(ID, getAttrKind(), ModifiedType, EquivalentType, Attribute);
   }
 
   static void Profile(llvm::FoldingSetNodeID &ID, Kind attrKind,
-                      QualType modified, QualType equivalent) {
+                      QualType modified, QualType equivalent,
+                      const Attr *attr) {
     ID.AddInteger(attrKind);
     ID.AddPointer(modified.getAsOpaquePtr());
     ID.AddPointer(equivalent.getAsOpaquePtr());
+    ID.AddPointer(attr);
   }
 
   static bool classof(const Type *T) {
diff --git a/clang/include/clang/AST/TypeProperties.td b/clang/include/clang/AST/TypeProperties.td
@@ -668,12 +668,16 @@ let Class = AttributedType in {
   def : Property<"equivalentType", QualType> {
     let Read = [{ node->getEquivalentType() }];
   }
-  def : Property<"attribute", AttrKind> {
+  def : Property<"attrKind", AttrKind> {
     let Read = [{ node->getAttrKind() }];
   }
+  def : Property<"attribute", Attr> {
+    let Read = [{ node->getAttr() }];
+  }
 
   def : Creator<[{
-    return ctx.getAttributedType(attribute, modifiedType, equivalentType);
+    return ctx.getAttributedType(attrKind, modifiedType,
+                                 equivalentType, attribute);
   }]>;
 }
 
diff --git a/clang/include/clang/Basic/Attr.td b/clang/include/clang/Basic/Attr.td
@@ -2838,7 +2838,7 @@ def SwiftAsyncName : InheritableAttr {
   let Documentation = [SwiftAsyncNameDocs];
 }
 
-def SwiftAttr : InheritableAttr {
+def SwiftAttr : DeclOrTypeAttr {
   let Spellings = [GNU<"swift_attr">];
   let Args = [StringArgument<"Attribute">];
   let Documentation = [SwiftAttrDocs];
diff --git a/clang/include/clang/Basic/AttrDocs.td b/clang/include/clang/Basic/AttrDocs.td
@@ -4507,8 +4507,8 @@ def SwiftAttrDocs : Documentation {
   let Heading = "swift_attr";
   let Content = [{
 The ``swift_attr`` provides a Swift-specific annotation for the declaration
-to which the attribute appertains to. It can be used on any declaration
-in Clang. This kind of annotation is ignored by Clang as it doesn't have any
+or type to which the attribute appertains to. It can be used on any declaration
+or type in Clang. This kind of annotation is ignored by Clang as it doesn't have any
 semantic meaning in languages supported by Clang. The Swift compiler can
 interpret these annotations according to its own rules when importing C or
 Objective-C declarations.
diff --git a/clang/include/clang/Serialization/ASTRecordWriter.h b/clang/include/clang/Serialization/ASTRecordWriter.h
@@ -128,6 +128,8 @@ class ASTRecordWriter
     AddStmt(const_cast<Stmt*>(S));
   }
 
+  void writeAttr(const Attr *A) { AddAttr(A); }
+
   /// Write an BTFTypeTagAttr object.
   void writeBTFTypeTagAttr(const BTFTypeTagAttr *A) { AddAttr(A); }
 
diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
@@ -3552,7 +3552,8 @@ ASTContext::adjustType(QualType Orig,
     const auto *AT = dyn_cast<AttributedType>(Orig);
     return getAttributedType(AT->getAttrKind(),
                              adjustType(AT->getModifiedType(), Adjust),
-                             adjustType(AT->getEquivalentType(), Adjust));
+                             adjustType(AT->getEquivalentType(), Adjust),
+                             AT->getAttr());
   }
 
   case Type::BTFTagAttributed: {
@@ -5197,24 +5198,54 @@ QualType ASTContext::getUnresolvedUsingType(
 
 QualType ASTContext::getAttributedType(attr::Kind attrKind,
                                        QualType modifiedType,
-                                       QualType equivalentType) const {
+                                       QualType equivalentType,
+                                       const Attr *attr) const {
   llvm::FoldingSetNodeID id;
-  AttributedType::Profile(id, attrKind, modifiedType, equivalentType);
+  AttributedType::Profile(id, attrKind, modifiedType, equivalentType, attr);
 
   void *insertPos = nullptr;
   AttributedType *type = AttributedTypes.FindNodeOrInsertPos(id, insertPos);
   if (type) return QualType(type, 0);
 
+  assert(!attr || attr->getKind() == attrKind);
+
   QualType canon = getCanonicalType(equivalentType);
-  type = new (*this, alignof(AttributedType))
-      AttributedType(canon, attrKind, modifiedType, equivalentType);
+	type = new (*this, alignof(AttributedType))
+      AttributedType(canon, attrKind, attr, modifiedType, equivalentType);
 
   Types.push_back(type);
   AttributedTypes.InsertNode(type, insertPos);
 
   return QualType(type, 0);
 }
 
+QualType ASTContext::getAttributedType(const Attr *attr, QualType modifiedType,
+                                       QualType equivalentType) const {
+  return getAttributedType(attr->getKind(), modifiedType, equivalentType, attr);
+}
+
+QualType ASTContext::getAttributedType(NullabilityKind nullability,
+                                       QualType modifiedType,
+                                       QualType equivalentType) {
+  switch (nullability) {
+  case NullabilityKind::NonNull:
+    return getAttributedType(attr::TypeNonNull, modifiedType, equivalentType);
+
+  case NullabilityKind::Nullable:
+    return getAttributedType(attr::TypeNullable, modifiedType, equivalentType);
+
+  case NullabilityKind::NullableResult:
+    return getAttributedType(attr::TypeNullableResult, modifiedType,
+                             equivalentType);
+
+  case NullabilityKind::Unspecified:
+    return getAttributedType(attr::TypeNullUnspecified, modifiedType,
+                             equivalentType);
+  }
+
+  llvm_unreachable("Unknown nullability kind");
+}
+
 QualType ASTContext::getBTFTagAttributedType(const BTFTypeTagAttr *BTFAttr,
                                              QualType Wrapped) const {
   llvm::FoldingSetNodeID ID;
@@ -7537,8 +7568,8 @@ QualType ASTContext::getArrayDecayedType(QualType Ty) const {
 
   // int x[_Nullable] -> int * _Nullable
   if (auto Nullability = Ty->getNullability()) {
-    Result = const_cast<ASTContext *>(this)->getAttributedType(
-        AttributedType::getNullabilityAttrKind(*Nullability), Result, Result);
+    Result = const_cast<ASTContext *>(this)->getAttributedType(*Nullability,
+                                                               Result, Result);
   }
   return Result;
 }
@@ -13773,7 +13804,8 @@ static QualType getCommonSugarTypeNode(ASTContext &Ctx, const Type *X,
       return QualType();
     // FIXME: It's inefficient to have to unify the modified types.
     return Ctx.getAttributedType(Kind, Ctx.getCommonSugaredType(MX, MY),
-                                 Ctx.getQualifiedType(Underlying));
+                                 Ctx.getQualifiedType(Underlying),
+                                 AX->getAttr());
   }
   case Type::BTFTagAttributed: {
     const auto *BX = cast<BTFTagAttributedType>(X);
diff --git a/clang/lib/AST/ASTDiagnostic.cpp b/clang/lib/AST/ASTDiagnostic.cpp
@@ -85,8 +85,7 @@ QualType clang::desugarForDiagnostic(ASTContext &Context, QualType QT,
       QualType SugarRT = FT->getReturnType();
       QualType RT = desugarForDiagnostic(Context, SugarRT, DesugarReturn);
       if (auto nullability = AttributedType::stripOuterNullability(SugarRT)) {
-        RT = Context.getAttributedType(
-            AttributedType::getNullabilityAttrKind(*nullability), RT, RT);
+        RT = Context.getAttributedType(*nullability, RT, RT);
       }
 
       bool DesugarArgument = false;
@@ -97,8 +96,7 @@ QualType clang::desugarForDiagnostic(ASTContext &Context, QualType QT,
           QualType PT = desugarForDiagnostic(Context, SugarPT, DesugarArgument);
           if (auto nullability =
                   AttributedType::stripOuterNullability(SugarPT)) {
-            PT = Context.getAttributedType(
-                AttributedType::getNullabilityAttrKind(*nullability), PT, PT);
+            PT = Context.getAttributedType(*nullability, PT, PT);
           }
           Args.push_back(PT);
         }
diff --git a/clang/lib/AST/ASTImporter.cpp b/clang/lib/AST/ASTImporter.cpp
@@ -1580,8 +1580,9 @@ ExpectedType ASTNodeImporter::VisitAttributedType(const AttributedType *T) {
   if (!ToEquivalentTypeOrErr)
     return ToEquivalentTypeOrErr.takeError();
 
-  return Importer.getToContext().getAttributedType(T->getAttrKind(),
-      *ToModifiedTypeOrErr, *ToEquivalentTypeOrErr);
+  return Importer.getToContext().getAttributedType(
+      T->getAttrKind(), *ToModifiedTypeOrErr, *ToEquivalentTypeOrErr,
+      T->getAttr());
 }
 
 ExpectedType
diff --git a/clang/lib/AST/Type.cpp b/clang/lib/AST/Type.cpp
@@ -1241,8 +1241,8 @@ struct SimpleTransformVisitor : public TypeVisitor<Derived, QualType> {
           == T->getEquivalentType().getAsOpaquePtr())
       return QualType(T, 0);
 
-    return Ctx.getAttributedType(T->getAttrKind(), modifiedType,
-                                 equivalentType);
+    return Ctx.getAttributedType(T->getAttrKind(), modifiedType, equivalentType,
+                                 T->getAttr());
   }
 
   QualType VisitSubstTemplateTypeParmType(const SubstTemplateTypeParmType *T) {
@@ -1545,7 +1545,8 @@ struct SubstObjCTypeArgsVisitor
 
     // Rebuild the attributed type.
     return Ctx.getAttributedType(newAttrType->getAttrKind(),
-                                 newAttrType->getModifiedType(), newEquivType);
+                                 newAttrType->getModifiedType(), newEquivType,
+                                 newAttrType->getAttr());
   }
 };
 
@@ -4115,6 +4116,19 @@ bool RecordType::hasConstFields() const {
   return false;
 }
 
+AttributedType::AttributedType(QualType canon, const Attr *attr,
+                               QualType modified, QualType equivalent)
+    : AttributedType(canon, attr->getKind(), attr, modified, equivalent) {}
+
+AttributedType::AttributedType(QualType canon, attr::Kind attrKind,
+                               const Attr *attr, QualType modified,
+                               QualType equivalent)
+    : Type(Attributed, canon, equivalent->getDependence()), Attribute(attr),
+      ModifiedType(modified), EquivalentType(equivalent) {
+  AttributedTypeBits.AttrKind = attrKind;
+  assert(!attr || attr->getKind() == attrKind);
+}
+
 bool AttributedType::isQualifier() const {
   // FIXME: Generate this with TableGen.
   switch (getAttrKind()) {
diff --git a/clang/lib/AST/TypePrinter.cpp b/clang/lib/AST/TypePrinter.cpp
@@ -1934,6 +1934,14 @@ void TypePrinter::printAttributedAfter(const AttributedType *T,
     return;
   }
 
+  if (T->getAttrKind() == attr::SwiftAttr) {
+    if (auto *swiftAttr = dyn_cast_or_null<SwiftAttrAttr>(T->getAttr())) {
+      OS << " __attribute__((swift_attr(\"" << swiftAttr->getAttribute()
+         << "\")))";
+    }
+    return;
+  }
+
   OS << " __attribute__((";
   switch (T->getAttrKind()) {
 #define TYPE_ATTR(NAME)
@@ -1994,6 +2002,7 @@ void TypePrinter::printAttributedAfter(const AttributedType *T,
   case attr::NonAllocating:
   case attr::Blocking:
   case attr::Allocating:
+  case attr::SwiftAttr:
     llvm_unreachable("This attribute should have been handled already");
 
   case attr::NSReturnsRetained:
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
@@ -3332,9 +3332,7 @@ static void mergeParamDeclTypes(ParmVarDecl *NewParam,
       }
     } else {
       QualType NewT = NewParam->getType();
-      NewT = S.Context.getAttributedType(
-                         AttributedType::getNullabilityAttrKind(*Oldnullability),
-                         NewT, NewT);
+      NewT = S.Context.getAttributedType(*Oldnullability, NewT, NewT);
       NewParam->setType(NewT);
     }
   }
diff --git a/clang/lib/Sema/SemaDeclObjC.cpp b/clang/lib/Sema/SemaDeclObjC.cpp
@@ -4572,9 +4572,7 @@ static QualType mergeTypeNullabilityForRedecl(Sema &S, SourceLocation loc,
     return type;
 
   // Otherwise, provide the result with the same nullability.
-  return S.Context.getAttributedType(
-           AttributedType::getNullabilityAttrKind(*prevNullability),
-           type, type);
+  return S.Context.getAttributedType(*prevNullability, type, type);
 }
 
 /// Merge information from the declaration of a method in the \@interface
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
@@ -8757,8 +8757,7 @@ static QualType computeConditionalNullability(QualType ResTy, bool IsBin,
     ResTy = ResTy.getSingleStepDesugaredType(Ctx);
 
   // Create a new AttributedType with the new nullability kind.
-  auto NewAttr = AttributedType::getNullabilityAttrKind(MergedKind);
-  return Ctx.getAttributedType(NewAttr, ResTy, ResTy);
+  return Ctx.getAttributedType(MergedKind, ResTy, ResTy);
 }
 
 ExprResult Sema::ActOnConditionalOp(SourceLocation QuestionLoc,
diff --git a/clang/lib/Sema/SemaExprObjC.cpp b/clang/lib/Sema/SemaExprObjC.cpp
diff --git a/clang/lib/Sema/SemaObjCProperty.cpp b/clang/lib/Sema/SemaObjCProperty.cpp
diff --git a/clang/lib/Sema/SemaSwift.cpp b/clang/lib/Sema/SemaSwift.cpp
diff --git a/clang/lib/Sema/SemaType.cpp b/clang/lib/Sema/SemaType.cpp
diff --git a/clang/lib/Sema/TreeTransform.h b/clang/lib/Sema/TreeTransform.h
diff --git a/clang/test/AST/attr-swift_attr.m b/clang/test/AST/attr-swift_attr.m
diff --git a/clang/test/SemaObjC/validate-attr-swift_attr.m b/clang/test/SemaObjC/validate-attr-swift_attr.m

Original file line number	Diff line number	Diff line change
`@@ -668,12 +668,16 @@ let Class = AttributedType in {`
`668`	`668`	`def : Property<"equivalentType", QualType> {`
`669`	`669`	`let Read = [{ node->getEquivalentType() }];`
`670`	`670`	`}`
`671`		`- def : Property<"attribute", AttrKind> {`
	`671`	`+ def : Property<"attrKind", AttrKind> {`
`672`	`672`	`let Read = [{ node->getAttrKind() }];`
`673`	`673`	`}`
	`674`	`+ def : Property<"attribute", Attr> {`
	`675`	`+ let Read = [{ node->getAttr() }];`
	`676`	`+ }`
`674`	`677`
`675`	`678`	`def : Creator<[{`
`676`		`- return ctx.getAttributedType(attribute, modifiedType, equivalentType);`
	`679`	`+ return ctx.getAttributedType(attrKind, modifiedType,`
	`680`	`+ equivalentType, attribute);`
`677`	`681`	`}]>;`
`678`	`682`	`}`
`679`	`683`
Original file line number	Diff line number	Diff line change
`@@ -2838,7 +2838,7 @@ def SwiftAsyncName : InheritableAttr {`
`2838`	`2838`	`let Documentation = [SwiftAsyncNameDocs];`
`2839`	`2839`	`}`
`2840`	`2840`
`2841`		`-def SwiftAttr : InheritableAttr {`
	`2841`	`+def SwiftAttr : DeclOrTypeAttr {`
`2842`	`2842`	`let Spellings = [GNU<"swift_attr">];`
`2843`	`2843`	`let Args = [StringArgument<"Attribute">];`
`2844`	`2844`	`let Documentation = [SwiftAttrDocs];`
Original file line number	Diff line number	Diff line change
`@@ -128,6 +128,8 @@ class ASTRecordWriter`
`128`	`128`	`AddStmt(const_cast<Stmt*>(S));`
`129`	`129`	`}`
`130`	`130`
	`131`	`+ void writeAttr(const Attr *A) { AddAttr(A); }`
	`132`	`+`
`131`	`133`	`/// Write an BTFTypeTagAttr object.`
`132`	`134`	`void writeBTFTypeTagAttr(const BTFTypeTagAttr *A) { AddAttr(A); }`
`133`	`135`
Original file line number	Diff line number	Diff line change
`@@ -85,8 +85,7 @@ QualType clang::desugarForDiagnostic(ASTContext &Context, QualType QT,`
`85`	`85`	`QualType SugarRT = FT->getReturnType();`
`86`	`86`	`QualType RT = desugarForDiagnostic(Context, SugarRT, DesugarReturn);`
`87`	`87`	`if (auto nullability = AttributedType::stripOuterNullability(SugarRT)) {`
`88`		`- RT = Context.getAttributedType(`
`89`		`- AttributedType::getNullabilityAttrKind(*nullability), RT, RT);`
	`88`	`+ RT = Context.getAttributedType(*nullability, RT, RT);`
`90`	`89`	`}`
`91`	`90`
`92`	`91`	`bool DesugarArgument = false;`
`@@ -97,8 +96,7 @@ QualType clang::desugarForDiagnostic(ASTContext &Context, QualType QT,`
`97`	`96`	`QualType PT = desugarForDiagnostic(Context, SugarPT, DesugarArgument);`
`98`	`97`	`if (auto nullability =`
`99`	`98`	`AttributedType::stripOuterNullability(SugarPT)) {`
`100`		`- PT = Context.getAttributedType(`
`101`		`- AttributedType::getNullabilityAttrKind(*nullability), PT, PT);`
	`99`	`+ PT = Context.getAttributedType(*nullability, PT, PT);`
`102`	`100`	`}`
`103`	`101`	`Args.push_back(PT);`
`104`	`102`	`}`