[Mangling] Consider overlays when determining retroactive conformances.

When determining whether a given normal protocol conformance is “retroactive”,
consider an overlay module to be equivalent to its underlying Clang module.
Therefore, don’t classify conformances within the overlay as “retroactive”,
simplifying some common manglings (e.g., NSObject’s Hashable conformance is
no longer considered retroactive) and better capturing the intent.

Author: DougGregor

lib/AST/ProtocolConformance.cpp

@@ -363,7 +363,19 @@ bool NormalProtocolConformance::isRetroactive() const {
   // If the conformance occurs in the same module as the conforming type
   // definition, this is not a retroactive conformance.
   if (auto nominal = getType()->getAnyNominal()) {
-    if (module == nominal->getParentModule())
+    auto nominalModule = nominal->getParentModule();
+
+    // Consider the overlay module to be the "home" of a nominal type
+    // defined in a Clang module.
+    if (auto nominalClangModule =
+          dyn_cast<ClangModuleUnit>(nominal->getModuleScopeContext())) {
+      if (auto clangLoader = nominal->getASTContext().getClangModuleLoader()) {
+        if (auto overlayModule = nominalClangModule->getAdapterModule())
+          nominalModule = overlayModule;
+      }
+    }
+
+    if (module == nominalModule)
       return false;
   }
 

test/IRGen/objc_bridge.swift

@@ -88,7 +88,7 @@ import Foundation
 // CHECK:     { i8*, i8*, i8* } {
 // CHECK:       i8* getelementptr inbounds ([11 x i8], [11 x i8]* @"\01L_selector_data(acceptSet:)", i64 0, i64 0),
 // CHECK:       i8* getelementptr inbounds ([11 x i8], [11 x i8]* @{{[0-9]+}}, i64 0, i64 0),
-// CHECK:       i8* bitcast (void (%3*, i8*, %4*)* @"$s11objc_bridge3BasC9acceptSetyyShyA2CSH10ObjectiveCyHCg_GFTo" to i8*)
+// CHECK:       i8* bitcast (void (%3*, i8*, %4*)* @"$s11objc_bridge3BasC9acceptSetyyShyACGFTo" to i8*)
 // CHECK:     }
 // CHECK:     { i8*, i8*, i8* } { 
 // CHECK:       i8* getelementptr inbounds ([14 x i8], [14 x i8]* @"\01L_selector_data(.cxx_destruct)", i64 0, i64 0), 

test/SILGen/Inputs/Foundation.swift

@@ -113,12 +113,6 @@ extension Set : _ObjectiveCBridgeable {
   }
 }
 
-extension NSObject : Hashable {
-  public var hashValue: Int { return 0 }
-}
-
-public func == (x: NSObject, y: NSObject) -> Bool { return true }
-
 extension NSError : Error {
   public var _domain: String { return domain }
   public var _code: Int { return code }

test/SILGen/Inputs/ObjectiveC.swift

@@ -33,3 +33,9 @@ public struct Selector : ExpressibleByStringLiteral {
     self = sel_registerName(value)
   }
 }
+
+extension NSObject : Hashable {
+  public var hashValue: Int { return 0 }
+  public static func == (x: NSObject, y: NSObject) -> Bool { return true }
+}
+

test/SILGen/mangling_retroactive_overlay.swift

@@ -0,0 +1,13 @@
+// RUN: %empty-directory(%t)
+// RUN: %build-silgen-test-overlays
+// RUN: %target-swift-emit-silgen(mock-sdk: -sdk %S/Inputs -I %t) %s -enable-sil-ownership | %FileCheck %s
+
+import ObjectiveC
+
+struct RequiresEq<T: Equatable> { }
+
+// Note: the NSObject: Equatable conformance from the overlay is not considered
+// to be a "retroactive" conformance, so ensure that it isn't mangled as such.
+// CHECK: sil hidden @$s28mangling_retroactive_overlay4testyyAA10RequiresEqVySo8NSObjectCGF 
+func test(_: RequiresEq<NSObject>) { }
+

test/SILGen/objc_dictionary_bridging.swift

@@ -53,12 +53,12 @@ import gizmo
   @objc var property: Dictionary<Foo, Foo> = [:]
 
   // Property getter
-  // CHECK-LABEL: sil hidden [thunk] @$s24objc_dictionary_bridging3FooC8propertySDyA3CSH10FoundationyHCg_GvgTo : $@convention(objc_method) (Foo) -> @autoreleased NSDictionary
+  // CHECK-LABEL: sil hidden [thunk] @$s24objc_dictionary_bridging3FooC8propertySDyA2CGvgTo : $@convention(objc_method) (Foo) -> @autoreleased NSDictionary
   //                                 @$s24objc_dictionary_bridging3FooC8propertySDyA2CSo8NSObjectCSH10Foundationg_Gvpfi
   // CHECK: bb0([[SELF:%[0-9]+]] : @unowned $Foo):
   // CHECK:   [[SELF_COPY:%.*]] = copy_value [[SELF]]
   // CHECK:   [[BORROWED_SELF_COPY:%.*]] = begin_borrow [[SELF_COPY]]
-  // CHECK:   [[GETTER:%[0-9]+]] = function_ref @$s24objc_dictionary_bridging3FooC8propertySDyA3CSH10FoundationyHCg_Gvg : $@convention(method) (@guaranteed Foo) -> @owned Dictionary<Foo, Foo>
+  // CHECK:   [[GETTER:%[0-9]+]] = function_ref @$s24objc_dictionary_bridging3FooC8propertySDyA2CGvg : $@convention(method) (@guaranteed Foo) -> @owned Dictionary<Foo, Foo>
   // CHECK:   [[DICT:%[0-9]+]] = apply [[GETTER]]([[BORROWED_SELF_COPY]]) : $@convention(method) (@guaranteed Foo) -> @owned Dictionary<Foo, Foo>
   // CHECK:   end_borrow [[BORROWED_SELF_COPY]]
   // CHECK:   destroy_value [[SELF_COPY]]
@@ -71,7 +71,7 @@ import gizmo
   // CHECK: } // end sil function
 
   // Property setter
-  // CHECK-LABEL: sil hidden [thunk] @$s24objc_dictionary_bridging3FooC8propertySDyA3CSH10FoundationyHCg_GvsTo : $@convention(objc_method) (NSDictionary, Foo) -> ()
+  // CHECK-LABEL: sil hidden [thunk] @$s24objc_dictionary_bridging3FooC8propertySDyA2CGvsTo : $@convention(objc_method) (NSDictionary, Foo) -> ()
   // CHECK: bb0([[NSDICT:%[0-9]+]] : @unowned $NSDictionary, [[SELF:%[0-9]+]] : @unowned $Foo):
   // CHECK:   [[NSDICT_COPY:%.*]] = copy_value [[NSDICT]]
   // CHECK:   [[SELF_COPY:%.*]] = copy_value [[SELF]]
@@ -81,7 +81,7 @@ import gizmo
   // CHECK:   [[DICT:%[0-9]+]] = apply [[CONVERTER]]<Foo, Foo>([[OPT_NSDICT]], [[DICT_META]])
 
   // CHECK:   [[BORROWED_SELF_COPY:%.*]] = begin_borrow [[SELF_COPY]]
-  // CHECK:   [[SETTER:%[0-9]+]] = function_ref @$s24objc_dictionary_bridging3FooC8propertySDyA3CSH10FoundationyHCg_Gvs : $@convention(method) (@owned Dictionary<Foo, Foo>, @guaranteed Foo) -> ()
+  // CHECK:   [[SETTER:%[0-9]+]] = function_ref @$s24objc_dictionary_bridging3FooC8propertySDyA2CGvs : $@convention(method) (@owned Dictionary<Foo, Foo>, @guaranteed Foo) -> ()
   // CHECK:   [[RESULT:%[0-9]+]] = apply [[SETTER]]([[DICT]], [[BORROWED_SELF_COPY]]) : $@convention(method) (@owned Dictionary<Foo, Foo>, @guaranteed Foo) -> ()
   // CHECK:   end_borrow [[BORROWED_SELF_COPY]]
   // CHECK:   destroy_value [[SELF_COPY]]