SILGen: Handle key paths with @objc optional subscript components

Author: AnthonyLatsis

lib/SILGen/SILGenExpr.cpp

@@ -2867,11 +2867,20 @@ static SILFunction *getOrCreateKeyPathGetter(SILGenModule &SGM,
 
     // Emit a dynamic method branch if the storage decl is an @objc optional
     // requirement, or just a load otherwise.
-    if (property->getAttrs().hasAttribute<OptionalAttr>() &&
-        isa<VarDecl>(property)) {
-      resultRValue = subSGF.emitDynamicMemberRef(
-          loc, baseSubstValue.getValue(), ConcreteDeclRef(property, subs),
-          propertyType, SGFContext());
+    if (property->getAttrs().hasAttribute<OptionalAttr>()) {
+      const auto declRef = ConcreteDeclRef(property, subs);
+
+      if (isa<VarDecl>(property)) {
+        resultRValue =
+            subSGF.emitDynamicMemberRef(loc, baseSubstValue.getValue(), declRef,
+                                        propertyType, SGFContext());
+      } else {
+        assert(isa<SubscriptDecl>(property));
+
+        resultRValue = subSGF.emitDynamicSubscriptGetterApply(
+            loc, baseSubstValue.getValue(), declRef,
+            std::move(subscriptIndices), propertyType, SGFContext());
+      }
     } else {
       resultRValue = subSGF.emitRValueForStorageLoad(
           loc, baseSubstValue, baseType, /*super*/ false, property,
@@ -3635,8 +3644,14 @@ SILGenModule::emitKeyPathComponentForDecl(SILLocation loc,
       baseSubscriptTy = genSubscriptTy->substGenericArgs(subs);
     auto baseSubscriptInterfaceTy = cast<AnyFunctionType>(
       baseSubscriptTy->mapTypeOutOfContext()->getCanonicalType());
+
     auto componentTy = baseSubscriptInterfaceTy.getResult();
-  
+    if (decl->getAttrs().hasAttribute<OptionalAttr>()) {
+      // The component type for an @objc optional requirement needs to be
+      // wrapped in an optional
+      componentTy = OptionalType::get(componentTy)->getCanonicalType();
+    }
+
     SmallVector<IndexTypePair, 4> indexTypes;
     lowerKeyPathSubscriptIndexTypes(*this, indexTypes,
                                     decl, subs,

test/SILGen/keypaths_objc.swift

@@ -160,17 +160,30 @@ func dynamicMemberLookupMixedKeypaths(foo: DynamicClass<Foo>) {
 
 @objc protocol ObjCProtoOptional {
   @objc optional var optionalProperty: Bool { get }
+
+  @objc optional subscript(_: Int) -> Bool { get }
 }
 
 // CHECK-LABEL: sil hidden [ossa] @{{.*}}0B28ProtocolOptionalRequirementsyyF
 // CHECK: keypath $KeyPath<ObjCProtoOptional, Optional<Bool>>, (objc "optionalProperty"; root $ObjCProtoOptional; gettable_property $Optional<Bool>,  id #ObjCProtoOptional.optionalProperty!getter.foreign : <Self where Self : ObjCProtoOptional> (Self) -> () -> Bool, getter @$[[PROP_GETTER:[_a-zA-Z0-9]+]]
+// CHECK: keypath $KeyPath<ObjCProtoOptional, Optional<Bool>>, (root $ObjCProtoOptional; gettable_property $Optional<Bool>,  id #ObjCProtoOptional.subscript!getter.foreign : <Self where Self : ObjCProtoOptional> (Self) -> (Int) -> Bool, getter @$[[SUBSCR_GETTER:[_a-zA-Z0-9]+]]
 // CHECK: } // end sil function '${{.*}}0B28ProtocolOptionalRequirementsyyF'
 //
 // CHECK: sil shared [thunk] [ossa] @$[[PROP_GETTER]] : $@convention(thin) (@in_guaranteed ObjCProtoOptional) -> @out Optional<Bool> {
 // CHECK:   [[BASE:%[0-9]+]] = open_existential_ref {{%[0-9]+}} : $ObjCProtoOptional to $[[OPENED_TY:@opened\("[-A-F0-9]+"\) ObjCProtoOptional]]
 // CHECK:   dynamic_method_br [[BASE]] : $[[OPENED_TY]], #ObjCProtoOptional.optionalProperty!getter.foreign, bb1
 // CHECK: bb1({{%[0-9]+}} : $@convention(objc_method) ([[OPENED_TY]]) -> ObjCBool)
 // CHECK: } // end sil function '$[[PROP_GETTER]]'
+//
+// CHECK: sil shared [thunk] [ossa] @$[[SUBSCR_GETTER]] : $@convention(thin) (@in_guaranteed ObjCProtoOptional, UnsafeRawPointer) -> @out Optional<Bool> {
+// CHECK:   [[BASE:%[0-9]+]] = open_existential_ref {{%[0-9]+}} : $ObjCProtoOptional to $[[OPENED_TY:@opened\("[-A-F0-9]+"\) ObjCProtoOptional]]
+// CHECK:   [[INDEX:%[0-9]+]] = load [trivial] {{%[0-9]+}} : $*Int
+// CHECK:   dynamic_method_br [[BASE]] : $[[OPENED_TY]], #ObjCProtoOptional.subscript!getter.foreign, bb1, bb2
+// CHECK: bb1({{%[0-9]+}} : $@convention(objc_method) (Int, [[OPENED_TY]]) -> ObjCBool):
+// CHECK:   %17 = apply {{%[0-9]+}}([[INDEX]]) : $@callee_guaranteed (Int) -> Bool
+// CHECK: bb2:
+// CHECK: } // end sil function '$[[SUBSCR_GETTER]]'
 func objcProtocolOptionalRequirements() {
   _ = \ObjCProtoOptional.optionalProperty
+  _ = \ObjCProtoOptional.[0]
 }