[Sema] Warn for redundant access-level modifiers on setters or used in an extension.

include/swift/AST/DiagnosticsSema.def

@@ -1187,9 +1187,19 @@ ERROR(access_control_setter_more,none,
       "%select{variable|property|subscript}1 cannot have "
       "%select{%error|a fileprivate|an internal|a public|an open}2 setter",
       (AccessLevel, unsigned, AccessLevel))
+WARNING(access_control_setter_redundant,none,
+      "'%select{private|fileprivate|internal|public|open}0(set)' modifier is "
+      "redundant for %select{a private|a fileprivate|an internal|a public|an open}2 "
+      "%1",
+      (AccessLevel, DescriptiveDeclKind, AccessLevel))
 WARNING(access_control_ext_member_more,none,
     "declaring %select{%error|a fileprivate|an internal|a public|open}0 %1 in "
-    "%select{a private|a fileprivate|an internal|public|%error}2 extension",
+    "%select{a private|a fileprivate|an internal|a public|%error}2 extension",
+    (AccessLevel, DescriptiveDeclKind, AccessLevel))
+WARNING(access_control_ext_member_redundant,none,
+    "'%select{%error|fileprivate|internal|public|%error}0' modifier is redundant "
+    "for %1 declared in %select{a private (equivalent to fileprivate)|a fileprivate"
+    "|an internal|a public|%error}2 extension",
     (AccessLevel, DescriptiveDeclKind, AccessLevel))
 ERROR(access_control_ext_requirement_member_more,none,
     "cannot declare %select{%error|a fileprivate|an internal|a public|an open}0 %1 "

lib/Sema/MiscDiagnostics.cpp

@@ -3951,7 +3951,8 @@ void swift::performStmtDiagnostics(TypeChecker &TC, const Stmt *S) {
 //===----------------------------------------------------------------------===//
 
 void swift::fixItAccess(InFlightDiagnostic &diag, ValueDecl *VD,
-                        AccessLevel desiredAccess, bool isForSetter) {
+                        AccessLevel desiredAccess, bool isForSetter,
+                        bool shouldUseDefaultAccess) {
   StringRef fixItString;
   switch (desiredAccess) {
   case AccessLevel::Private:      fixItString = "private ";      break;
@@ -3997,9 +3998,14 @@ void swift::fixItAccess(InFlightDiagnostic &diag, ValueDecl *VD,
     // this function is sometimes called to make access narrower, so assuming
     // that a broader scope is acceptable breaks some diagnostics.
     if (attr->getAccess() != desiredAccess) {
-      // This uses getLocation() instead of getRange() because we don't want to
-      // replace the "(set)" part of a setter attribute.
-      diag.fixItReplace(attr->getLocation(), fixItString.drop_back());
+      if (shouldUseDefaultAccess) {
+        // Remove the attribute if replacement is not preferred.
+        diag.fixItRemove(attr->getRange());
+      } else {
+        // This uses getLocation() instead of getRange() because we don't want to
+        // replace the "(set)" part of a setter attribute.
+        diag.fixItReplace(attr->getLocation(), fixItString.drop_back());
+      }
       attr->setInvalid();
     }
 

lib/Sema/MiscDiagnostics.h

@@ -51,8 +51,11 @@ void performTopLevelDeclDiagnostics(TypeChecker &TC, TopLevelCodeDecl *TLCD);
 /// Emit a fix-it to set the access of \p VD to \p desiredAccess.
 ///
 /// This actually updates \p VD as well.
-void fixItAccess(InFlightDiagnostic &diag, ValueDecl *VD,
-                 AccessLevel desiredAccess, bool isForSetter = false);
+void fixItAccess(InFlightDiagnostic &diag,
+                 ValueDecl *VD,
+                 AccessLevel desiredAccess,
+                 bool isForSetter = false,
+                 bool shouldUseDefaultAccess = false);
 
 /// Emit fix-its to correct the argument labels in \p expr, which is the
 /// argument tuple or single argument of a call.

lib/Sema/TypeCheckAttr.cpp

@@ -1512,17 +1512,23 @@ void AttributeChecker::visitAccessControlAttr(AccessControlAttr *attr) {
 
     if (auto extAttr =
         extension->getAttrs().getAttribute<AccessControlAttr>()) {
-      // Extensions are top level declarations, for which the literally lowest
-      // access level `private` is equivalent to `fileprivate`.
-      AccessLevel extAccess = std::max(extAttr->getAccess(),
-                                       AccessLevel::FilePrivate);
-      if (attr->getAccess() > extAccess) {
+      AccessLevel defaultAccess = extension->getDefaultAccessLevel();
+      if (attr->getAccess() > defaultAccess) {
         auto diag = TC.diagnose(attr->getLocation(),
                                 diag::access_control_ext_member_more,
                                 attr->getAccess(),
                                 D->getDescriptiveKind(),
                                 extAttr->getAccess());
-        swift::fixItAccess(diag, cast<ValueDecl>(D), extAccess);
+        swift::fixItAccess(diag, cast<ValueDecl>(D), defaultAccess, false,
+                           true);
+        return;
+      } else if (attr->getAccess() == defaultAccess) {
+        TC.diagnose(attr->getLocation(),
+                    diag::access_control_ext_member_redundant,
+                    attr->getAccess(),
+                    D->getDescriptiveKind(),
+                    extAttr->getAccess())
+          .fixItRemove(attr->getRange());
         return;
       }
     }
@@ -1558,6 +1564,15 @@ AttributeChecker::visitSetterAccessAttr(SetterAccessAttr *attr) {
                 getterAccess, storageKind, attr->getAccess());
     attr->setInvalid();
     return;
+
+  } else if (attr->getAccess() == getterAccess) {
+    TC.diagnose(attr->getLocation(),
+                diag::access_control_setter_redundant,
+                attr->getAccess(),
+                D->getDescriptiveKind(),
+                getterAccess)
+      .fixItRemove(attr->getRange());
+    return;
   }
 }
 

stdlib/public/SDK/AppKit/AppKit_FoundationExtensions.swift

@@ -14,7 +14,7 @@ import Foundation
 @_exported import AppKit
 
 // NSCollectionView extensions
-public extension IndexPath {
+extension IndexPath {
 
     /// Initialize for use with `NSCollectionView`.
     public init(item: Int, section: Int) {
@@ -51,7 +51,7 @@ public extension IndexPath {
 
 }
 
-public extension URLResourceValues {
+extension URLResourceValues {
     /// Returns all thumbnails as a single NSImage.
     @available(macOS 10.10, *)
     public var thumbnail : NSImage? {

stdlib/public/SDK/CloudKit/NestedNames.swift

@@ -16,7 +16,7 @@
 
 @nonobjc
 @available(macOS 10.10, iOS 8.0, watchOS 3.0, *)
-public extension CKContainer {
+extension CKContainer {
     @available(swift 4.2)
     public enum Application {
         public typealias Permissions = CKContainer_Application_Permissions

stdlib/public/SDK/CoreGraphics/CoreGraphics.swift

@@ -429,10 +429,10 @@ public extension CGRect {
   }
 
   @available(*, unavailable, renamed: "minX")
-  public var x: CGFloat { return minX }
+  var x: CGFloat { return minX }
 
   @available(*, unavailable, renamed: "minY")
-  public var y: CGFloat { return minY }
+  var y: CGFloat { return minY }
 }
 
 extension CGRect : CustomReflectable {

stdlib/public/SDK/Dispatch/Dispatch.swift

@@ -129,7 +129,7 @@ public enum DispatchTimeoutResult {
 
 /// dispatch_group
 
-public extension DispatchGroup {
+extension DispatchGroup {
 	public func notify(qos: DispatchQoS = .unspecified, flags: DispatchWorkItemFlags = [], queue: DispatchQueue, execute work: @escaping @convention(block) () -> Void) {
 		if #available(macOS 10.10, iOS 8.0, *), qos != .unspecified || !flags.isEmpty {
 			let item = DispatchWorkItem(qos: qos, flags: flags, block: work)
@@ -159,7 +159,7 @@ public extension DispatchGroup {
 
 /// dispatch_semaphore
 
-public extension DispatchSemaphore {
+extension DispatchSemaphore {
 	@discardableResult
 	public func signal() -> Int {
 		return __dispatch_semaphore_signal(self)

stdlib/public/SDK/Dispatch/IO.swift

@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-public extension DispatchIO {
+extension DispatchIO {
 
 	public enum StreamType : UInt  {
 		case stream = 0

stdlib/public/SDK/Dispatch/Queue.swift

@@ -23,7 +23,7 @@ internal class _DispatchSpecificValue<T> {
 	internal init(value: T) { self.value = value }
 }
 
-public extension DispatchQueue {
+extension DispatchQueue {
 	public struct Attributes : OptionSet {
 		public let rawValue: UInt64
 		public init(rawValue: UInt64) { self.rawValue = rawValue }

stdlib/public/SDK/Dispatch/Source.swift

@@ -13,8 +13,8 @@
 // import Foundation
 import _SwiftDispatchOverlayShims
 
-public extension DispatchSourceProtocol {
-	typealias DispatchSourceHandler = @convention(block) () -> Void
+extension DispatchSourceProtocol {
+	public typealias DispatchSourceHandler = @convention(block) () -> Void
 
 	public func setEventHandler(qos: DispatchQoS = .unspecified, flags: DispatchWorkItemFlags = [], handler: DispatchSourceHandler?) {
 		if #available(macOS 10.10, iOS 8.0, *),
@@ -98,7 +98,7 @@ public extension DispatchSourceProtocol {
 	}
 }
 
-public extension DispatchSource {
+extension DispatchSource {
 	public struct MachSendEvent : OptionSet, RawRepresentable {
 		public let rawValue: UInt
 		public init(rawValue: UInt) { self.rawValue = rawValue }
@@ -210,7 +210,7 @@ public extension DispatchSource {
 	}
 }
 
-public extension DispatchSourceMachSend {
+extension DispatchSourceMachSend {
 	public var handle: mach_port_t {
 		return mach_port_t(__dispatch_source_get_handle(self as! DispatchSource))
 	}
@@ -226,13 +226,13 @@ public extension DispatchSourceMachSend {
 	}
 }
 
-public extension DispatchSourceMachReceive {
+extension DispatchSourceMachReceive {
 	public var handle: mach_port_t {
 		return mach_port_t(__dispatch_source_get_handle(self as! DispatchSource))
 	}
 }
 
-public extension DispatchSourceMemoryPressure {
+extension DispatchSourceMemoryPressure {
 	public var data: DispatchSource.MemoryPressureEvent {
 		let data = __dispatch_source_get_data(self as! DispatchSource)
 		return DispatchSource.MemoryPressureEvent(rawValue: data)
@@ -244,7 +244,7 @@ public extension DispatchSourceMemoryPressure {
 	}
 }
 
-public extension DispatchSourceProcess {
+extension DispatchSourceProcess {
 	public var handle: pid_t {
 		return pid_t(__dispatch_source_get_handle(self as! DispatchSource))
 	}
@@ -260,7 +260,7 @@ public extension DispatchSourceProcess {
 	}
 }
 
-public extension DispatchSourceTimer {
+extension DispatchSourceTimer {
 	///
 	/// Sets the deadline and leeway for a timer event that fires once.
 	///
@@ -599,7 +599,7 @@ public extension DispatchSourceTimer {
 	}
 }
 
-public extension DispatchSourceFileSystemObject {
+extension DispatchSourceFileSystemObject {
 	public var handle: Int32 {
 		return Int32(__dispatch_source_get_handle(self as! DispatchSource))
 	}
@@ -615,7 +615,7 @@ public extension DispatchSourceFileSystemObject {
 	}
 }
 
-public extension DispatchSourceUserDataAdd {
+extension DispatchSourceUserDataAdd {
 	/// @function add
 	///
 	/// @abstract
@@ -630,7 +630,7 @@ public extension DispatchSourceUserDataAdd {
 	}
 }
 
-public extension DispatchSourceUserDataOr {
+extension DispatchSourceUserDataOr {
 	/// @function or
 	///
 	/// @abstract
@@ -645,7 +645,7 @@ public extension DispatchSourceUserDataOr {
 	}
 }
 
-public extension DispatchSourceUserDataReplace {
+extension DispatchSourceUserDataReplace {
 	/// @function replace
 	///
 	/// @abstract

stdlib/public/SDK/Foundation/Codable.swift

@@ -22,7 +22,7 @@ extension DecodingError : LocalizedError {}
 // Error Utilities
 //===----------------------------------------------------------------------===//
 
-internal extension DecodingError {
+extension DecodingError {
     /// Returns a `.typeMismatch` error describing the expected type.
     ///
     /// - parameter path: The path of `CodingKey`s taken to decode a value of this type.

stdlib/public/SDK/Foundation/JSONEncoder.swift

@@ -2432,7 +2432,7 @@ fileprivate var _iso8601Formatter: ISO8601DateFormatter = {
 // Error Utilities
 //===----------------------------------------------------------------------===//
 
-fileprivate extension EncodingError {
+extension EncodingError {
     /// Returns a `.invalidValue` error describing the given invalid floating-point value.
     ///
     ///

stdlib/public/SDK/Foundation/NSError.swift

@@ -463,7 +463,7 @@ extension _BridgedStoredNSError {
 }
 
 /// Implementation of _ObjectiveCBridgeableError for all _BridgedStoredNSErrors.
-public extension _BridgedStoredNSError {
+extension _BridgedStoredNSError {
   /// Default implementation of ``init(_bridgedNSError:)`` to provide
   /// bridging from NSError.
   public init?(_bridgedNSError error: NSError) {
@@ -617,7 +617,7 @@ public extension CocoaError {
   }
 }
 
-public extension CocoaError {
+extension CocoaError {
     public static func error(_ code: CocoaError.Code, userInfo: [AnyHashable : Any]? = nil, url: URL? = nil) -> Error {
         var info: [AnyHashable : Any] = userInfo ?? [:]
         if let url = url {
@@ -1821,7 +1821,7 @@ public struct URLError : _BridgedStoredNSError {
   }
 }
 
-public extension URLError.Code {
+extension URLError.Code {
   public static var unknown: URLError.Code {
     return URLError.Code(rawValue: -1)
   }
@@ -1984,7 +1984,7 @@ public extension URLError.Code {
   }
 }
 
-public extension URLError {
+extension URLError {
   private var _nsUserInfo: [AnyHashable : Any] {
     return (self as NSError).userInfo
   }
@@ -2009,7 +2009,7 @@ public extension URLError {
   }
 }
 
-public extension URLError {
+extension URLError {
   public static var unknown: URLError.Code {
     return .unknown
   }

stdlib/public/SDK/Foundation/NSObject.swift

@@ -179,7 +179,7 @@ public class NSKeyValueObservation : NSObject {
     }
 }
 
-public extension _KeyValueCodingAndObserving {
+extension _KeyValueCodingAndObserving {
 
     ///when the returned NSKeyValueObservation is deinited or invalidated, it will stop observing
     public func observe<Value>(

stdlib/public/SDK/Foundation/Progress.swift

@@ -12,7 +12,7 @@
 
 @_exported import Foundation // Clang module
 
-public extension Progress {
+extension Progress {
     @available(macOS 10.13, iOS 11.0, watchOS 4.0, tvOS 11.0, *)
     public var estimatedTimeRemaining: TimeInterval? {
         get {

stdlib/public/SDK/Intents/INIntent.swift

@@ -17,7 +17,7 @@ import Foundation
 
 public protocol _INIntentSetImageKeyPath { }
 
-public extension _INIntentSetImageKeyPath {
+extension _INIntentSetImageKeyPath {
 
     @available(iOS 12.0, watchOS 5.0, macOS 10.14, *)
     public func setImage<Value>(_ image: INImage?, forParameterNamed parameterName: KeyPath<Self, Value>) {

stdlib/public/SDK/XCTest/XCTest.swift

@@ -17,7 +17,7 @@ import _SwiftXCTestOverlayShims
 
 // --- XCTest API Swiftification ---
 
-public extension XCTContext {
+extension XCTContext {
 
   /// Create and run a new activity with provided name and block.
   public class func runActivity<Result>(named name: String, block: (XCTActivity) throws -> Result) rethrows -> Result {
@@ -40,7 +40,7 @@ public extension XCTContext {
 #if os(macOS)
 @available(swift 4.0)
 @available(macOS 10.11, *)
-public extension XCUIElement {
+extension XCUIElement {
   /// Types a single key from the XCUIKeyboardKey enumeration with the specified modifier flags.
   @nonobjc public func typeKey(_ key: XCUIKeyboardKey, modifierFlags: XCUIElement.KeyModifierFlags) {
     // Call the version of the method defined in XCTest.framework.