IRGen: Fix multi-payload enum lowering

When we have a private resilient enum that is resilient because one of
its payloads is resilient but we have disabled resilience in the
context of lowering the enum as a class member (sigh), we must consider
it's payload's layout enum in the minimal domain (ignore the private
visibility) because we don't truly know the layout.

rdar://41308521

Author: aschwaighofer

lib/IRGen/GenEnum.cpp

@@ -5258,6 +5258,12 @@ EnumImplStrategy::get(TypeConverter &TC, SILType type, EnumDecl *theEnum) {
   // fixed-size from this resilience scope.
   ResilienceExpansion layoutScope =
       TC.IGM.getResilienceExpansionForLayout(theEnum);
+  if (TC.isCompletelyFragile()) {
+    // If we forced completely fragile layout we need to check the
+    // fixed-sized'ness in the minimal scope. Otherwise, we get wrong answer for
+    // private resilient enum types that have an resilient payload.
+    layoutScope = ResilienceExpansion::Minimal;
+  }
 
   for (auto elt : theEnum->getAllElements()) {
     numElements++;

test/IRGen/enum_resilience.swift

@@ -22,6 +22,10 @@ import resilient_struct
 // ENUM_NOT_RES-NOT: @"$S14resilient_enum6MediumO6CanvasyA2CmFWC" =
 
 // CHECK: %T15enum_resilience5ClassC = type <{ %swift.refcounted }>
+
+// Because the enum is resilient we cannot pack the tag into the pointer inside of the resilient payload.
+// CHECK: %T15enum_resilience9ContainerC5Multi33_59077B69D65A4A3BEE0C93708067D5F0LLO.0 = type <{ [8 x i8], [1 x i8] }>
+
 // CHECK: %T15enum_resilience9ReferenceV = type <{ %T15enum_resilience5ClassC* }>
 
 // Public fixed layout struct contains a public resilient struct,
@@ -326,3 +330,18 @@ private enum ProtGenEnumWithSize<T: Prot> {
 
 // CHECK-LABEL: define linkonce_odr hidden %T15enum_resilience19ProtGenEnumWithSize33_59077B69D65A4A3BEE0C93708067D5F0LLO* @"$S15enum_resilience19ProtGenEnumWithSize33_59077B69D65A4A3BEE0C93708067D5F0LLOyxGAA0C0RzlWOh"(%T15enum_resilience19ProtGenEnumWithSize
 // CHECK:   ret %T15enum_resilience19ProtGenEnumWithSize33_59077B69D65A4A3BEE0C93708067D5F0LLO* %0
+
+
+public class Container {
+  private enum Multi {
+    case none
+    case some(Container)
+    case data(ResilientRef)
+  }
+  private var e: Multi
+  var i: Int
+  init() {
+    e = .none
+    i = 0
+  }
+}

test/Inputs/resilient_struct.swift

@@ -87,3 +87,7 @@ public struct ResilientWeakRef {
     ref = r
   }
 }
+
+public struct ResilientRef {
+  public var r: Referent
+}

test/Interpreter/enum_resilience.swift

@@ -436,4 +436,28 @@ ResilientEnumTestSuite.test("ResilientEnumExtension") {
   expectEqual(Base.self, ResilientMultiPayloadGenericEnumFixedSize<Base>.A.getTypeParameter())
 }
 
+public class Container {
+  private enum Multi {
+    case none
+    case some(Container)
+    case other(ResilientRef)
+  }
+  private var m: Multi
+  var i: Int
+  init() {
+    m = .none
+    i = 0
+    switch self.m {
+      case .none:
+        print("success")
+      case .some(_), .other(_):
+        assert(false, "noooo!")
+    }
+  }
+}
+
+ResilientEnumTestSuite.test("ResilientPrivateEnumMember") {
+  _ = Container()
+}
+
 runAllTests()