Merge pull request #59283 from tshortli/diagnose-back-deploy-on-init-deinit

Sema: Diagnose `@_backDeploy` attributes on initializers and deinitializers

Author: tshortli

include/swift/AST/DiagnosticsSema.def

@@ -1524,6 +1524,9 @@ WARNING(access_control_non_objc_open_member,none,
 
 ERROR(invalid_decl_attribute,none,
       "'%0' attribute cannot be applied to this declaration", (DeclAttribute))
+ERROR(attr_invalid_on_decl_kind,none,
+      "'%0' attribute cannot be applied to %1 declarations",
+      (DeclAttribute, DescriptiveDeclKind))
 ERROR(invalid_decl_modifier,none,
       "%0 modifier cannot be applied to this declaration", (DeclAttribute))
 ERROR(attribute_does_not_apply_to_type,none,

lib/Sema/TypeCheckAttr.cpp

@@ -3662,6 +3662,12 @@ void AttributeChecker::checkBackDeployAttrs(ArrayRef<BackDeployAttr *> Attrs) {
       }
     }
 
+    if (isa<DestructorDecl>(D) || isa<ConstructorDecl>(D)) {
+      diagnoseAndRemoveAttr(Attr, diag::attr_invalid_on_decl_kind, Attr,
+                            D->getDescriptiveKind());
+      continue;
+    }
+
     auto AtLoc = Attr->AtLoc;
     auto Platform = Attr->Platform;
 

test/attr/attr_backDeploy.swift

@@ -128,6 +128,16 @@ extension TopLevelProtocol {
 @_backDeploy(before: macOS 12.0) // expected-error {{'@_backDeploy' attribute cannot be applied to this declaration}}
 public class CannotBackDeployClass {}
 
+public final class CannotBackDeployClassInitDeinit {
+  @available(macOS 11.0, *)
+  @_backDeploy(before: macOS 12.0) // expected-error {{'@_backDeploy' attribute cannot be applied to initializer declarations}}
+  public init() {}
+
+  @available(macOS 11.0, *)
+  @_backDeploy(before: macOS 12.0) // expected-error {{'@_backDeploy' attribute cannot be applied to deinitializer declarations}}
+  deinit {}
+}
+
 @_backDeploy(before: macOS 12.0) // expected-error {{'@_backDeploy' attribute cannot be applied to this declaration}}
 public struct CannotBackDeployStruct {
   @_backDeploy(before: macOS 12.0) // expected-error {{'@_backDeploy' must not be used on stored properties}}