Sema: Use ExportedLevel for isLayoutExposedToClients

include/swift/AST/Decl.h

@@ -81,6 +81,7 @@ namespace swift {
   class DiagnosticEngine;
   class DynamicSelfType;
   class Type;
+  enum class ExportedLevel;
   class Expr;
   struct ExternalSourceLocs;
   class CaptureListExpr;
@@ -6749,10 +6750,7 @@ public:
   ///
   /// From the standpoint of access control and exportability checking, this
   /// var will behave as if it was public, even if it is internal or private.
-  ///
-  /// If \p applyImplicit, consider implicitly exposed layouts as well.
-  /// This applies to non-resilient modules.
-  bool isLayoutExposedToClients(bool applyImplicit = false) const;
+  ExportedLevel isLayoutExposedToClients() const;
 
   /// Is this a special debugger variable?
   bool isDebuggerVar() const { return Bits.VarDecl.IsDebuggerVar; }

include/swift/AST/DeclExportabilityVisitor.h

@@ -115,7 +115,7 @@ public:
   }
 
   bool visitVarDecl(const VarDecl *var) {
-    if (var->isLayoutExposedToClients())
+    if (var->isLayoutExposedToClients() == ExportedLevel::Exported)
       return true;
 
     // Consider all lazy var storage as exportable.

lib/AST/Availability.cpp

@@ -1006,8 +1006,7 @@ ExportedLevel swift::isExported(const ValueDecl *VD) {
 
   // Is this a stored property in a @frozen struct or class?
   if (auto *property = dyn_cast<VarDecl>(VD))
-    if (property->isLayoutExposedToClients(/*applyImplicit=*/true))
-      return ExportedLevel::Exported;
+    return property->isLayoutExposedToClients();
 
   // Case of an enum not marked @_implementationOnly in a non-resilient module?
   if (auto *EED = dyn_cast<EnumElementDecl>(VD))
@@ -1020,7 +1019,7 @@ ExportedLevel swift::isExported(const ValueDecl *VD) {
       VD->getDeclContext()->getParentModule()->getResilienceStrategy() !=
           ResilienceStrategy::Resilient &&
       !VD->getAttrs().hasAttribute<ImplementationOnlyAttr>())
-    return ExportedLevel::Exported;
+    return ExportedLevel::ImplicitlyExported;
 
   return ExportedLevel::None;
 }

lib/AST/Decl.cpp

@@ -2774,44 +2774,44 @@ bool VarDecl::isInitExposedToClients() const {
   if (getAttrs().hasAttribute<LazyAttr>())
     return false;
 
-  return hasInitialValue() && isLayoutExposedToClients();
+  return hasInitialValue() &&
+         isLayoutExposedToClients() == ExportedLevel::Exported;
 }
 
-bool VarDecl::isLayoutExposedToClients(bool applyImplicit) const {
+ExportedLevel VarDecl::isLayoutExposedToClients() const {
   auto parent = dyn_cast<NominalTypeDecl>(getDeclContext());
-  if (!parent) return false;
-  if (isStatic()) return false;
-
-  auto M = getDeclContext()->getParentModule();
-  auto nominalAccess =
-    parent->getFormalAccessScope(/*useDC=*/nullptr,
-                                 /*treatUsableFromInlineAsPublic=*/true);
-
-  // Resilient modules and classes hide layouts by default.
-  bool layoutIsHiddenByDefault = !applyImplicit ||
-    !getASTContext().LangOpts.hasFeature(Feature::CheckImplementationOnly) ||
-    M->getResilienceStrategy() == ResilienceStrategy::Resilient;
-  if (layoutIsHiddenByDefault) {
-    if (!nominalAccess.isPublic())
-      return false;
-
-    if (!parent->getAttrs().hasAttribute<FrozenAttr>() &&
-        !parent->getAttrs().hasAttribute<FixedLayoutAttr>())
-    return false;
-  } else {
-    // Non-resilient module: layouts are exposed by default unless marked
-    // otherwise.
-    if (parent->getAttrs().hasAttribute<ImplementationOnlyAttr>())
-      return false;
-  }
+  if (!parent) return ExportedLevel::None;
+  if (isStatic()) return ExportedLevel::None;
 
+  // Does it contribute to the layout?
   if (!hasStorage() &&
       !getAttrs().hasAttribute<LazyAttr>() &&
       !hasAttachedPropertyWrapper()) {
-    return false;
+    return ExportedLevel::None;
   }
 
-  return true;
+  // Is it a member of a frozen type?
+  auto nominalAccess =
+    parent->getFormalAccessScope(/*useDC=*/nullptr,
+                                 /*treatUsableFromInlineAsPublic=*/true);
+  if (nominalAccess.isPublic() &&
+      (parent->getAttrs().hasAttribute<FrozenAttr>() ||
+       parent->getAttrs().hasAttribute<FixedLayoutAttr>()))
+    return ExportedLevel::Exported;
+
+  // Is it a member of an `@_implementationOnly` type?
+  if (parent->getAttrs().hasAttribute<ImplementationOnlyAttr>())
+    return ExportedLevel::None;
+
+  auto M = getDeclContext()->getParentModule();
+  if (getASTContext().LangOpts.hasFeature(Feature::CheckImplementationOnly) &&
+      M->getResilienceStrategy() != ResilienceStrategy::Resilient) {
+    // Non-resilient module expose layouts by default.
+    return ExportedLevel::ImplicitlyExported;
+  } else {
+    // Resilient modules hide layouts by default.
+    return ExportedLevel::None;
+  }
 }
 
 /// Check whether the given type representation will be

lib/Sema/TypeCheckAccess.cpp

@@ -1498,7 +1498,7 @@ public:
   /// the struct instead of the VarDecl, and customize the diagnostics.
   static const ValueDecl *
   getFixedLayoutStructContext(const VarDecl *VD) {
-    if (VD->isLayoutExposedToClients())
+    if (VD->isLayoutExposedToClients() == ExportedLevel::Exported)
       return dyn_cast<NominalTypeDecl>(VD->getDeclContext());
 
     return nullptr;

lib/Sema/TypeCheckAttr.cpp

@@ -30,6 +30,7 @@
 #include "swift/AST/ClangModuleLoader.h"
 #include "swift/AST/ConformanceLookup.h"
 #include "swift/AST/Decl.h"
+#include "swift/AST/DeclExportabilityVisitor.h"
 #include "swift/AST/DiagnosticsParse.h"
 #include "swift/AST/DiagnosticsSema.h"
 #include "swift/AST/Effects.h"
@@ -1408,7 +1409,7 @@ void AttributeChecker::visitSPIAccessControlAttr(SPIAccessControlAttr *attr) {
     // Forbid stored properties marked SPI in frozen types.
     if (auto property = dyn_cast<VarDecl>(VD)) {
       if (auto NTD = dyn_cast<NominalTypeDecl>(D->getDeclContext())) {
-        if (property->isLayoutExposedToClients() && !NTD->isSPI()) {
+        if (property->isLayoutExposedToClients() == ExportedLevel::Exported && !NTD->isSPI()) {
           diagnoseAndRemoveAttr(attr,
                                 diag::spi_attribute_on_frozen_stored_properties,
                                 VD);