[clang/AST] Make it possible to use SwiftAttr in type context

Expands allowed use of SwiftAttr to type context from declarations
only, this enables use of the attribute on generic parameters,
in Objective-C blocks, typedefs etc.

Author: xedin

clang/include/clang/Basic/Attr.td

@@ -2519,7 +2519,7 @@ def SwiftAsyncName : InheritableAttr {
   let Documentation = [SwiftAsyncNameDocs];
 }
 
-def SwiftAttr : InheritableAttr {
+def SwiftAttr : DeclOrTypeAttr {
   let Spellings = [GNU<"swift_attr">];
   let Args = [StringArgument<"Attribute">];
   let Documentation = [SwiftAttrDocs];

clang/lib/AST/TypePrinter.cpp

@@ -1784,6 +1784,14 @@ 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)
@@ -1826,6 +1834,7 @@ void TypePrinter::printAttributedAfter(const AttributedType *T,
   case attr::AnnotateType:
   case attr::WebAssemblyFuncref:
   case attr::ArmStreaming:
+  case attr::SwiftAttr:
     llvm_unreachable("This attribute should have been handled already");
 
   case attr::NSReturnsRetained:

clang/lib/Sema/SemaDeclAttr.cpp

@@ -6347,11 +6347,16 @@ static void handleObjCPreciseLifetimeAttr(Sema &S, Decl *D,
 }
 
 static void handleSwiftAttrAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
+  if (AL.isInvalid() || AL.isUsedAsTypeAttr())
+    return;
+
   // Make sure that there is a string literal as the annotation's single
   // argument.
   StringRef Str;
-  if (!S.checkStringLiteralArgumentAttr(AL, 0, Str))
+  if (!S.checkStringLiteralArgumentAttr(AL, 0, Str)) {
+    AL.setInvalid();
     return;
+  }
 
   D->addAttr(::new (S.Context) SwiftAttrAttr(S.Context, AL, Str));
 }

clang/lib/Sema/SemaType.cpp

@@ -7438,6 +7438,21 @@ static bool HandleWebAssemblyFuncrefAttr(TypeProcessingState &State,
   return false;
 }
 
+static void HandleSwiftAttr(TypeProcessingState &State, QualType &QT,
+                            ParsedAttr &PAttr) {
+  Sema &S = State.getSema();
+
+  StringRef Str;
+  if (!S.checkStringLiteralArgumentAttr(PAttr, 0, Str)) {
+    PAttr.setInvalid();
+    return;
+  }
+
+  auto *A = ::new (S.Context) SwiftAttrAttr(S.Context, PAttr, Str);
+  QT = State.getAttributedType(A, QT, QT);
+  PAttr.setUsedAsTypeAttr();
+}
+
 /// Rebuild an attributed type without the nullability attribute on it.
 static QualType rebuildAttributedTypeWithoutNullability(ASTContext &ctx,
                                                         QualType type) {
@@ -8819,6 +8834,11 @@ static void processTypeAttrs(TypeProcessingState &state, QualType &type,
       break;
     }
 
+    case ParsedAttr::AT_SwiftAttr: {
+      HandleSwiftAttr(state, type, attr);
+      break;
+    }
+
     MS_TYPE_ATTRS_CASELIST:
       if (!handleMSPointerTypeQualifierAttr(state, attr, type))
         attr.setUsedAsTypeAttr();

clang/test/AST/attr-swift_attr.m

@@ -14,3 +14,27 @@ @interface Contact
 
 // CHECK-LABEL: InterfaceDecl {{.*}} Contact
 // CHECK-NEXT: SwiftAttrAttr {{.*}} "@sendable"
+
+#define SWIFT_SENDABLE __attribute__((swift_attr("@Sendable")))
+#define MAIN_ACTOR __attribute__((swift_attr("@MainActor")))
+
+@interface InTypeContext
+- (nullable id)test:(nullable SWIFT_SENDABLE id)obj SWIFT_SENDABLE;
+@end
+
+// CHECK-LABEL: InterfaceDecl {{.*}} InTypeContext
+// CHECK-NEXT: MethodDecl {{.*}} - test: 'id _Nullable':'id'
+// CHECK-NEXT: ParmVarDecl {{.*}} obj 'id _Nullable':'id'
+// CHECK-NEXT: SwiftAttrAttr {{.*}} "@Sendable"
+
+@interface Generic<T: SWIFT_SENDABLE id>
+@end
+
+// CHECK-LABEL: InterfaceDecl {{.*}} Generic
+// CHECK-NEXT: TypeParamDecl {{.*}} T bounded 'SWIFT_SENDABLE id':'id'
+
+typedef SWIFT_SENDABLE Generic<id> Alias;
+
+// CHECK-LABEL: TypedefDecl {{.*}} Alias 'Generic<id>'
+// CHECK-NEXT: ObjectType {{.*}} 'Generic<id>'
+// CHECK-NEXT: SwiftAttrAttr {{.*}} "@Sendable"

clang/test/SemaObjC/validate-attr-swift_attr.m

@@ -9,3 +9,7 @@ @interface I
 __attribute__((swift_attr(1)))
 @interface J
 @end
+
+@interface Error<T: __attribute__((swift_attr(1))) id>
+// expected-error@-1 {{'swift_attr' attribute requires a string}}
+@end