[IRGen] Reject enums with inaccessible tpye metadata in layout string…

lib/IRGen/TypeLayout.cpp

@@ -2051,6 +2051,12 @@ bool EnumTypeLayoutEntry::refCountString(IRGenModule &IGM,
   case CopyDestroyStrategy::ForwardToPayload:
     return cases[0]->refCountString(IGM, B, genericSig);
   case CopyDestroyStrategy::Normal: {
+    // TODO: this is only relevant until we properly support enums.
+    if (!ty.getASTType()->isLegalFormalType() ||
+        !IGM.getSILModule().isTypeMetadataAccessible(ty.getASTType())) {
+      return false;
+    }
+
     auto *accessor = createMetatypeAccessorFunction(IGM, ty, genericSig);
     B.addFixedEnumRefCount(accessor);
     B.addSkip(fixedSize(IGM)->getValue());

test/Interpreter/Inputs/layout_string_witnesses_types.swift

@@ -308,7 +308,6 @@ public struct MultiPayloadEnumWrapper {
     }
 }
 
-
 public struct ComplexNesting<A, B, C, D> {
     let pre: Filler = Filler()
     let a: NestedA<A>
@@ -365,6 +364,21 @@ public struct ComplexNesting<A, B, C, D> {
     }
 }
 
+internal enum InternalEnum {
+    case a(Int, AnyObject)
+    case b(Int)
+    case c(String)
+}
+
+public struct InternalEnumWrapper {
+    internal let x: InternalEnum
+    internal let y: Int = 32
+
+    public init(x: AnyObject) {
+        self.x = .a(23, x)
+    }
+}
+
 
 @inline(never)
 public func testAssign<T>(_ ptr: UnsafeMutablePointer<T>, from x: T) {

test/Interpreter/layout_string_witnesses_static.swift

@@ -1,11 +1,14 @@
 // RUN: %empty-directory(%t)
 // RUN: %target-swift-frontend -enable-experimental-feature LayoutStringValueWitnesses -enable-type-layout -parse-stdlib -emit-module -emit-module-path=%t/layout_string_witnesses_types.swiftmodule %S/Inputs/layout_string_witnesses_types.swift
-// RUN: %target-build-swift -Xfrontend -enable-experimental-feature -Xfrontend LayoutStringValueWitnesses -Xfrontend -enable-type-layout -Xfrontend -parse-stdlib -c -parse-as-library -o %t/layout_string_witnesses_types.o %S/Inputs/layout_string_witnesses_types.swift
+
+// NOTE: We have to build this as dylib to turn private external symbols into local symbols, so we can observe potential issues with linkage
+// RUN: %target-build-swift-dylib(%t/%target-library-name(layout_string_witnesses_types)) -Xfrontend -enable-experimental-feature -Xfrontend LayoutStringValueWitnesses -Xfrontend -enable-type-layout -Xfrontend -parse-stdlib -parse-as-library %S/Inputs/layout_string_witnesses_types.swift
+// RUN: %target-codesign %t/%target-library-name(layout_string_witnesses_types)
 // RUN: %target-swift-frontend -enable-experimental-feature LayoutStringValueWitnesses -enable-library-evolution -emit-module -emit-module-path=%t/layout_string_witnesses_types_resilient.swiftmodule %S/Inputs/layout_string_witnesses_types_resilient.swift
 // RUN: %target-build-swift -g -Xfrontend -enable-experimental-feature -Xfrontend LayoutStringValueWitnesses -Xfrontend -enable-library-evolution -c -parse-as-library -o %t/layout_string_witnesses_types_resilient.o %S/Inputs/layout_string_witnesses_types_resilient.swift
-// RUN: %target-build-swift -g -Xfrontend -enable-experimental-feature -Xfrontend LayoutStringValueWitnesses -Xfrontend -enable-type-layout -Xfrontend -parse-stdlib -module-name layout_string_witnesses_static %t/layout_string_witnesses_types.o %t/layout_string_witnesses_types_resilient.o -I %t -o %t/main %s
+// RUN: %target-build-swift -g -Xfrontend -enable-experimental-feature -Xfrontend LayoutStringValueWitnesses -Xfrontend -enable-type-layout -Xfrontend -parse-stdlib -module-name layout_string_witnesses_static -llayout_string_witnesses_types -L%t %t/layout_string_witnesses_types_resilient.o -I %t -o %t/main %s %target-rpath(%t)
 // RUN: %target-codesign %t/main
-// RUN: %target-run %t/main | %FileCheck %s --check-prefix=CHECK -check-prefix=CHECK-%target-os
+// RUN: %target-run %t/main %t/%target-library-name(layout_string_witnesses_types) | %FileCheck %s --check-prefix=CHECK -check-prefix=CHECK-%target-os
 
 // REQUIRES: executable_test
 
@@ -341,6 +344,39 @@ func testForwardToPayloadEnum() {
 
 testForwardToPayloadEnum()
 
+struct InternalEnumWrapperWrapper {
+    let x: InternalEnumWrapper
+}
+
+func testInternalEnumWrapper() {
+    let ptr = UnsafeMutablePointer<InternalEnumWrapperWrapper>.allocate(capacity: 1)
+
+    do {
+        let x = InternalEnumWrapper(x: SimpleClass(x: 23))
+        testInit(ptr, to: .init(x: x))
+    }
+
+    do {
+        let y = InternalEnumWrapper(x: SimpleClass(x: 28))
+
+        // CHECK: Before deinit
+        print("Before deinit")
+
+        // CHECK-NEXT: SimpleClass deinitialized!
+        testAssign(ptr, from: .init(x: y))
+    }
+
+    // CHECK-NEXT: Before deinit
+    print("Before deinit")
+
+    // CHECK-NEXT: SimpleClass deinitialized!
+    testDestroy(ptr)
+
+    ptr.deallocate()
+}
+
+testInternalEnumWrapper()
+
 #if os(macOS)
 func testObjc() {
     let ptr = UnsafeMutablePointer<ObjcWrapper>.allocate(capacity: 1)