Honor !EnableAccessControl when checking protocol witnesses

Useful in the LLDB REPL, and also for what I'm about to do to the
integrated REPL.

Author: jrose-apple

lib/Sema/TypeCheckProtocol.cpp

@@ -1156,6 +1156,8 @@ bool WitnessChecker::checkWitnessAccess(AccessScope &requiredAccessScope,
                                         ValueDecl *witness,
                                         bool *isSetter) {
   *isSetter = false;
+  if (!TC.getLangOpts().EnableAccessControl)
+    return false;
 
   // Compute the intersection of the conforming type's access scope
   // and the protocol's access scope.

test/attr/accessibility.swift

@@ -208,68 +208,6 @@ extension GenericStruct where Param: InternalProto {
 }
 
 
-public protocol ProtoWithReqs {
-  associatedtype Assoc
-  func foo()
-}
-
-public struct Adopter<T> : ProtoWithReqs {}
-// expected-error@-1 {{method 'foo()' must be declared public because it matches a requirement in public protocol 'ProtoWithReqs'}} {{none}}
-// expected-error@-2 {{type alias 'Assoc' must be declared public because it matches a requirement in public protocol 'ProtoWithReqs'}} {{none}}
-extension Adopter {
-  typealias Assoc = Int
-  // expected-note@-1 {{mark the type alias as 'public' to satisfy the requirement}} {{3-3=public }}
-  func foo() {}
-  // expected-note@-1 {{mark the instance method as 'public' to satisfy the requirement}} {{3-3=public }}
-}
-
-public class AnotherAdopterBase {
-  typealias Assoc = Int
-  // expected-note@-1 {{mark the type alias as 'public' to satisfy the requirement}} {{3-3=public }}
-  func foo() {}
-  // expected-note@-1 {{mark the instance method as 'public' to satisfy the requirement}} {{3-3=public }}
-}
-public class AnotherAdopterSub : AnotherAdopterBase, ProtoWithReqs {}
-// expected-error@-1 {{method 'foo()' must be declared public because it matches a requirement in public protocol 'ProtoWithReqs'}} {{none}}
-// expected-error@-2 {{type alias 'Assoc' must be declared public because it matches a requirement in public protocol 'ProtoWithReqs'}} {{none}}
-
-public protocol ReqProvider {}
-extension ReqProvider {
-  func foo() {}
-  // expected-note@-1 {{mark the instance method as 'public' to satisfy the requirement}} {{3-3=public }}
-}
-public struct AdoptViaProtocol : ProtoWithReqs, ReqProvider {
-  // expected-error@-1 {{method 'foo()' must be declared public because it matches a requirement in public protocol 'ProtoWithReqs'}} {{none}}
-  public typealias Assoc = Int
-}
-
-public protocol ReqProvider2 {}
-extension ProtoWithReqs where Self : ReqProvider2 {
-  func foo() {}
-  // expected-note@-1 {{mark the instance method as 'public' to satisfy the requirement}} {{3-3=public }}
-}
-public struct AdoptViaCombinedProtocol : ProtoWithReqs, ReqProvider2 {
-  // expected-error@-1 {{method 'foo()' must be declared public because it matches a requirement in public protocol 'ProtoWithReqs'}} {{none}}
-  public typealias Assoc = Int
-}
-
-public protocol PublicInitProto {
-  var value: Int { get }
-  init(value: Int)
-}
-public struct NonPublicInitStruct: PublicInitProto {
-  public var value: Int
-  init(value: Int) {
-  // expected-error@-1 {{initializer 'init(value:)' must be declared public because it matches a requirement in public protocol 'PublicInitProto'}}
-  // expected-note@-2 {{mark the initializer as 'public' to satisfy the requirement}}
-    self.value = value
-  }
-}
-public struct NonPublicMemberwiseInitStruct: PublicInitProto {
-// expected-error@-1 {{initializer 'init(value:)' must be declared public because it matches a requirement in public protocol 'PublicInitProto'}}
-  public var value: Int
-}
-
 public class OuterClass {
   class InnerClass {}
 }

test/attr/accessibility_proto.swift

@@ -0,0 +1,64 @@
+// RUN: %target-typecheck-verify-swift
+// RUN: %target-swift-frontend -typecheck -disable-access-control %s
+
+public protocol ProtoWithReqs {
+  associatedtype Assoc
+  func foo()
+}
+
+public struct Adopter<T> : ProtoWithReqs {}
+// expected-error@-1 {{method 'foo()' must be declared public because it matches a requirement in public protocol 'ProtoWithReqs'}} {{none}}
+// expected-error@-2 {{type alias 'Assoc' must be declared public because it matches a requirement in public protocol 'ProtoWithReqs'}} {{none}}
+extension Adopter {
+  typealias Assoc = Int
+  // expected-note@-1 {{mark the type alias as 'public' to satisfy the requirement}} {{3-3=public }}
+  func foo() {}
+  // expected-note@-1 {{mark the instance method as 'public' to satisfy the requirement}} {{3-3=public }}
+}
+
+public class AnotherAdopterBase {
+  typealias Assoc = Int
+  // expected-note@-1 {{mark the type alias as 'public' to satisfy the requirement}} {{3-3=public }}
+  func foo() {}
+  // expected-note@-1 {{mark the instance method as 'public' to satisfy the requirement}} {{3-3=public }}
+}
+public class AnotherAdopterSub : AnotherAdopterBase, ProtoWithReqs {}
+// expected-error@-1 {{method 'foo()' must be declared public because it matches a requirement in public protocol 'ProtoWithReqs'}} {{none}}
+// expected-error@-2 {{type alias 'Assoc' must be declared public because it matches a requirement in public protocol 'ProtoWithReqs'}} {{none}}
+
+public protocol ReqProvider {}
+extension ReqProvider {
+  func foo() {}
+  // expected-note@-1 {{mark the instance method as 'public' to satisfy the requirement}} {{3-3=public }}
+}
+public struct AdoptViaProtocol : ProtoWithReqs, ReqProvider {
+  // expected-error@-1 {{method 'foo()' must be declared public because it matches a requirement in public protocol 'ProtoWithReqs'}} {{none}}
+  public typealias Assoc = Int
+}
+
+public protocol ReqProvider2 {}
+extension ProtoWithReqs where Self : ReqProvider2 {
+  func foo() {}
+  // expected-note@-1 {{mark the instance method as 'public' to satisfy the requirement}} {{3-3=public }}
+}
+public struct AdoptViaCombinedProtocol : ProtoWithReqs, ReqProvider2 {
+  // expected-error@-1 {{method 'foo()' must be declared public because it matches a requirement in public protocol 'ProtoWithReqs'}} {{none}}
+  public typealias Assoc = Int
+}
+
+public protocol PublicInitProto {
+  var value: Int { get }
+  init(value: Int)
+}
+public struct NonPublicInitStruct: PublicInitProto {
+  public var value: Int
+  init(value: Int) {
+  // expected-error@-1 {{initializer 'init(value:)' must be declared public because it matches a requirement in public protocol 'PublicInitProto'}}
+  // expected-note@-2 {{mark the initializer as 'public' to satisfy the requirement}}
+    self.value = value
+  }
+}
+public struct NonPublicMemberwiseInitStruct: PublicInitProto {
+// expected-error@-1 {{initializer 'init(value:)' must be declared public because it matches a requirement in public protocol 'PublicInitProto'}}
+  public var value: Int
+}