Merge pull request #3468 from swiftix/master

Author: swift-ci

lib/IRGen/GenProto.cpp

@@ -511,7 +511,13 @@ void EmitPolymorphicParameters::bindExtraSource(const MetadataSource &source,
       auto selfTy = FnType->getSelfInstanceType();
       CanType argTy = getTypeInContext(selfTy);
       setTypeMetadataName(IGF.IGM, metadata, argTy);
-      IGF.bindLocalTypeDataFromTypeMetadata(argTy, IsExact, metadata);
+      auto *CD = selfTy.getClassOrBoundGenericClass();
+      // The self metadata here corresponds to the conforming type.
+      // For an inheritable conformance, that may be a subclass of the static
+      // type, and so the self metadata will be inexact. Currently, all
+      // conformances are inheritable.
+      IGF.bindLocalTypeDataFromTypeMetadata(
+          argTy, (!CD || CD->isFinal()) ? IsExact : IsInexact, metadata);
       return;
     }
 

test/IRGen/metadata_dominance.swift

@@ -1,4 +1,5 @@
 // RUN: %target-swift-frontend -emit-ir -primary-file %s | FileCheck %s
+// RUN: %target-swift-frontend -O -emit-ir -primary-file %s | FileCheck %s --check-prefix=CHECK-OPT
 
 func use_metadata<F>(_ f: F) {}
 
@@ -49,3 +50,35 @@ func test2() {
 // CHECK: call void @_TF18metadata_dominance12use_metadataurFxT_(%swift.opaque* {{.*}}, %swift.type* [[T2]])
   use_metadata(voidToVoid)
 }
+
+protocol P {
+    func makeFoo() -> Foo
+}
+
+class Foo: P {
+    func makeFoo() -> Foo {
+        fatalError()
+    }
+}
+
+class SubFoo: Foo {
+    final override func makeFoo() -> Foo {
+        // Check that it creates an instance of type Foo,
+        // and not an instance of a Self type involved
+        // in this protocol conformance.
+        return Foo()
+    }
+}
+
+@inline(never)
+func testMakeFoo(_ p: P) -> Foo.Type {
+  let foo = p.makeFoo()
+  return foo.dynamicType
+}
+
+// The protocol witness for metadata_dominance.P.makeFoo () -> metadata_dominance.Foo in
+// conformance metadata_dominance.Foo : metadata_dominance.P should not use the Self type
+// as the type of the object to be created. It should dynamically obtain the type.
+// CHECK-OPT-LABEL: define hidden %C18metadata_dominance3Foo* @_TTWC18metadata_dominance3FooS_1PS_FS1_7makeFoofT_S0_
+// CHECK-OPT-NOT: tail call noalias %swift.refcounted* @rt_swift_allocObject(%swift.type* %Self
+