stdlib: Adopt ExtensionImportVisibility experimental feature

include/swift/Basic/Features.def

@@ -367,7 +367,7 @@ CONDITIONALLY_SUPPRESSIBLE_EXPERIMENTAL_FEATURE(IsolatedAny, true)
 
 
 // Whether members of extensions respect the enclosing file's imports.
-EXPERIMENTAL_FEATURE(ExtensionImportVisibility, true)
+EXPERIMENTAL_FEATURE_EXCLUDED_FROM_MODULE_INTERFACE(ExtensionImportVisibility, true)
 
 // Alias for IsolatedAny
 EXPERIMENTAL_FEATURE(IsolatedAny2, true)

stdlib/cmake/modules/SwiftSource.cmake

@@ -628,6 +628,8 @@ function(_compile_swift_files
     list(APPEND swift_flags "-enable-experimental-feature" "NonescapableTypes")
   endif()
 
+  list(APPEND swift_flags "-enable-experimental-feature" "ExtensionImportVisiblity")
+
   if (SWIFT_STDLIB_ENABLE_STRICT_CONCURRENCY_COMPLETE)
     list(APPEND swift_flags "-strict-concurrency=complete")
   endif()

test/NameLookup/Inputs/Categories/Categories_A.h

@@ -0,0 +1,8 @@
+@import Foundation;
+
+@interface X
+@end
+
+@interface X (A)
+- (void)fromA;
+@end

test/NameLookup/Inputs/Categories/Categories_A.swift

@@ -0,0 +1,6 @@
+@_exported import Categories_A
+
+extension X {
+  public func fromOverlayForA() {}
+  @objc public func fromOverlayForAObjC() {}
+}

test/NameLookup/Inputs/Categories/Categories_B.h

@@ -0,0 +1,5 @@
+@import Categories_A;
+
+@interface X (B)
+- (void)fromB;
+@end

test/NameLookup/Inputs/Categories/Categories_B.swift

@@ -0,0 +1,6 @@
+@_exported import Categories_B
+
+extension X {
+  public func fromOverlayForB() {}
+  @objc public func fromOverlayForBObjC() {}
+}

test/NameLookup/Inputs/Categories/Categories_C.h

@@ -0,0 +1,5 @@
+@import Categories_A;
+
+@interface X (C)
+- (void)fromC;
+@end

test/NameLookup/Inputs/Categories/Categories_C.swift

@@ -0,0 +1,6 @@
+@_exported import Categories_C
+
+extension X {
+  public func fromOverlayForC() {}
+  @objc public func fromOverlayForCObjC() {}
+}

test/NameLookup/Inputs/Categories/Categories_D.swift

@@ -0,0 +1 @@
+import Categories_C

test/NameLookup/Inputs/Categories/module.modulemap

@@ -0,0 +1,14 @@
+module Categories_A {
+  header "Categories_A.h"
+  export *
+}
+
+module Categories_B {
+  header "Categories_B.h"
+  export *
+}
+
+module Categories_C {
+  header "Categories_C.h"
+  export *
+}

test/NameLookup/Inputs/extensions_A.swift

@@ -7,3 +7,11 @@ public struct Y<T> { }
 extension Y: P where T: P { }
 
 public struct Z: P { }
+
+extension X {
+  public func XinA() { }
+}
+
+extension Y {
+  public func YinA() { }
+}

test/NameLookup/Inputs/extensions_B.swift

@@ -1,10 +1,10 @@
 import extensions_A
 
-public extension X {
+extension X {
   public func XinB() { }
 }
 
-public extension Y {
+extension Y {
   public func YinB() { }
 }
 

test/NameLookup/Inputs/extensions_C.swift

@@ -1,11 +1,11 @@
-import extensions_A
+@_exported import extensions_A
 import extensions_B
 
-public extension X {
+extension X {
   public func XinC() { }
 }
 
-public extension Y {
+extension Y {
   public func YinC() { }
 }
 

test/NameLookup/extensions_transitive.swift

@@ -4,10 +4,12 @@
 // RUN: %target-swift-frontend -emit-module -I %t -o %t %S/Inputs/extensions_C.swift
 // RUN: %target-swift-frontend -typecheck %s -I %t -verify -enable-experimental-feature ExtensionImportVisibility
 
-import extensions_A
 import extensions_C
 // expected-note 2{{add import of module 'extensions_B'}}{{1-1=import extensions_B\n}}
 func test(x: X, y: Y<Z>) {
+  x.XinA()
+  y.YinA()
+
   x.XinB() // expected-error{{instance method 'XinB()' is not available due to missing import of defining module 'extensions_B'}}
   y.YinB() // expected-error{{instance method 'YinB()' is not available due to missing import of defining module 'extensions_B'}}
 

test/NameLookup/extensions_transitive_objc.swift

@@ -0,0 +1,32 @@
+// RUN: %empty-directory(%t)
+// RUN: %target-swift-frontend -emit-module -I %t -I %S/Inputs/Categories -o %t %S/Inputs/Categories/Categories_A.swift
+// RUN: %target-swift-frontend -emit-module -I %t -I %S/Inputs/Categories -o %t %S/Inputs/Categories/Categories_B.swift
+// RUN: %target-swift-frontend -emit-module -I %t -I %S/Inputs/Categories -o %t %S/Inputs/Categories/Categories_C.swift
+// RUN: %target-swift-frontend -emit-module -I %t -I %S/Inputs/Categories -o %t %S/Inputs/Categories/Categories_D.swift
+// RUN: %target-swift-frontend -typecheck %s -I %t -I %S/Inputs/Categories -verify -enable-experimental-feature ExtensionImportVisibility
+
+// REQUIRES: objc_interop
+
+import Categories_B
+import Categories_D
+// expected-note 2 {{add import of module 'Categories_C'}}{{1-1=import Categories_C\n}}
+func test(x: X) {
+  x.fromA()
+  x.fromOverlayForA()
+  x.fromB()
+  x.fromOverlayForB()
+  x.fromC() // expected-error {{class method 'fromC()' is not available due to missing import of defining module 'Categories_C'}}
+  x.fromOverlayForC() // expected-error {{instance method 'fromOverlayForC()' is not available due to missing import of defining module 'Categories_C'}}
+}
+
+func testAnyObject(a: AnyObject) {
+  a.fromA()
+  a.fromOverlayForAObjC()
+  a.fromB()
+  a.fromOverlayForBObjC()
+  // FIXME: Better diagnostics?
+  // Name lookup for AnyObject already ignored transitive imports, so
+  // ExtensionImportVisibility has no effect on these diagnostics.
+  a.fromC() // expected-error {{value of type 'AnyObject' has no member 'fromC'}}
+  a.fromOverlayForCObjC() // expected-error {{value of type 'AnyObject' has no member 'fromOverlayForCObjC'}}
+}