[Sema] Always allow public overrides of open methods

Author: AnthonyLatsis

lib/Sema/TypeCheckDeclOverride.cpp

@@ -861,7 +861,7 @@ static void checkOverrideAccessControl(ValueDecl *baseDecl, ValueDecl *decl,
     }
   } else if (baseHasOpenAccess &&
              classDecl->hasOpenAccess(dc) &&
-             decl->getFormalAccess() != AccessLevel::Open &&
+             decl->getFormalAccess() < AccessLevel::Public &&
              !decl->isFinal()) {
     {
       auto diag = diags.diagnose(decl, diag::override_not_accessible,

test/attr/open.swift

@@ -76,16 +76,16 @@ class SubClass : ExternalOpenClass {
   }
 }
 
-open class InvalidOpenSubClass : ExternalOpenClass {
-  public override func openMethod() {} // expected-error {{overriding instance method must be as accessible as the declaration it overrides}} {{3-9=open}}
-  public override var openProperty: Int { get{return 0} set{} } // expected-error {{overriding property must be as accessible as the declaration it overrides}} {{3-9=open}}
-  public override subscript(index: MarkerForOpenSubscripts) -> Int { // expected-error {{overriding subscript must be as accessible as the declaration it overrides}} {{3-9=open}}
+open class ValidOpenSubClass : ExternalOpenClass {
+  public override func openMethod() {}
+  public override var openProperty: Int { get{return 0} set{} }
+  public override subscript(index: MarkerForOpenSubscripts) -> Int {
     get { return 0 }
     set {}
   }
 }
 
-open class InvalidOpenSubClass2 : ExternalOpenClass {
+open class InvalidOpenSubClass : ExternalOpenClass {
   internal override func openMethod() {} // expected-error {{overriding instance method must be as accessible as the declaration it overrides}} {{3-11=open}}
   internal override var openProperty: Int { get{return 0} set{} } // expected-error {{overriding property must be as accessible as the declaration it overrides}} {{3-11=open}}
   internal override subscript(index: MarkerForOpenSubscripts) -> Int { // expected-error {{overriding subscript must be as accessible as the declaration it overrides}} {{3-11=open}}

test/decl/class/override.swift

@@ -362,10 +362,9 @@ class DerivedWithFilePrivateSetter: BaseWithFilePrivateSetter {
     }
 }
 
-// Issues with final overrides of open members
 open class OpenBase {
-  open func instanceMethod() {} // expected-note {{overridden declaration is here}}
-  open class func classMethod() {} // expected-note {{overridden declaration is here}}
+  open func instanceMethod() {}
+  open class func classMethod() {}
 }
 
 public class PublicDerived : OpenBase {
@@ -379,8 +378,8 @@ open class OpenDerived : OpenBase {
 }
 
 open class OpenDerivedPublic : OpenBase {
-  override public func instanceMethod() {} // expected-error {{overriding instance method must be as accessible as the declaration it overrides}}
-  override public class func classMethod() {} // expected-error {{overriding class method must be as accessible as the declaration it overrides}}
+  override public func instanceMethod() {} // Ok
+  override public class func classMethod() {} // Ok
 }
 
 open class OpenDerivedFinal : OpenBase {