SIL: Enum case constructors are fragile if the enum is public or @_versioned

Author: slavapestov

lib/SIL/SILDeclRef.cpp

@@ -499,9 +499,16 @@ bool SILDeclRef::isFragile() const {
   DeclContext *dc;
   if (auto closure = getAbstractClosureExpr())
     dc = closure->getLocalContext();
-  else
+  else {
     dc = getDecl()->getInnermostDeclContext();
 
+    // Enum case constructors are serialized if the enum is @_versioned
+    // or public.
+    if (isEnumElement())
+      if (cast<EnumDecl>(dc)->getEffectiveAccess() >= Accessibility::Public)
+        return true;
+  }
+
   // This is stupid
   return (dc->getResilienceExpansion() == ResilienceExpansion::Minimal);
 }

test/SILGen/inlineable_attribute.swift

@@ -24,3 +24,15 @@ public class MyCls {
   // CHECK-LABEL: sil [fragile] @_T020inlineable_attribute5MyClsCfD : $@convention(method) (@owned MyCls) -> ()
   @_inlineable deinit {}
 }
+
+// Make sure enum case constructors for public and versioned enums are
+// [fragile].
+@_versioned enum MyEnum {
+  case c(MySt)
+}
+
+// CHECK-LABEL: sil shared [transparent] [fragile] [thunk] @_T020inlineable_attribute6MyEnumO1cAcA0C2StVcACmFTc : $@convention(thin) (@thin MyEnum.Type) -> @owned @callee_owned (MySt) -> MyEnum
+
+@_inlineable public func referencesMyEnum() {
+  _ = MyEnum.c
+}