Merge pull request swiftlang#23722 from jrose-apple/type-disadvantage

Implementation-only import checking for types used in decls

Author: jrose-apple

include/swift/AST/AccessScopeChecker.h

@@ -23,47 +23,79 @@
 
 namespace swift {
 
-class AbstractStorageDecl;
-class ExtensionDecl;
+class BoundGenericType;
+class ComponentIdentTypeRepr;
+class NominalType;
 class SourceFile;
-class ValueDecl;
+class TypeAliasType;
 
 class AccessScopeChecker {
   const SourceFile *File;
   bool TreatUsableFromInlineAsPublic;
 
-protected:
-  ASTContext &Context;
   Optional<AccessScope> Scope = AccessScope::getPublic();
 
   AccessScopeChecker(const DeclContext *useDC,
                      bool treatUsableFromInlineAsPublic);
-  bool visitDecl(ValueDecl *VD);
-};
-
-class TypeReprAccessScopeChecker : private ASTWalker, AccessScopeChecker {
-  TypeReprAccessScopeChecker(const DeclContext *useDC,
-                             bool treatUsableFromInlineAsPublic);
-
-  bool walkToTypeReprPre(TypeRepr *TR) override;
-  bool walkToTypeReprPost(TypeRepr *TR) override;
+  bool visitDecl(const ValueDecl *VD);
 
 public:
   static Optional<AccessScope>
   getAccessScope(TypeRepr *TR, const DeclContext *useDC,
                  bool treatUsableFromInlineAsPublic = false);
+  static Optional<AccessScope>
+  getAccessScope(Type T, const DeclContext *useDC,
+                 bool treatUsableFromInlineAsPublic = false);
 };
 
-class TypeAccessScopeChecker : private TypeWalker, AccessScopeChecker {
-  TypeAccessScopeChecker(const DeclContext *useDC,
-                         bool treatUsableFromInlineAsPublic);
+/// Walks a Type to find all NominalTypes, BoundGenericTypes, and
+/// TypeAliasTypes.
+class TypeDeclFinder : public TypeWalker {
+  Action walkToTypePre(Type T) override;
+
+public:
+  virtual Action visitNominalType(const NominalType *ty) {
+    return Action::Continue;
+  }
+  virtual Action visitBoundGenericType(const BoundGenericType *ty) {
+    return Action::Continue;
+  }
+  virtual Action visitTypeAliasType(const TypeAliasType *ty) {
+    return Action::Continue;
+  }
+};
 
-  Action walkToTypePre(Type T);
+/// A TypeDeclFinder for use cases where all types should be treated
+/// equivalently and where generic arguments can be walked to separately from
+/// the generic type.
+class SimpleTypeDeclFinder : public TypeDeclFinder {
+  /// The function to call when a ComponentIdentTypeRepr is seen.
+  llvm::function_ref<Action(const TypeDecl *)> Callback;
+
+  Action visitNominalType(const NominalType *ty) override;
+  Action visitBoundGenericType(const BoundGenericType *ty) override;
+  Action visitTypeAliasType(const TypeAliasType *ty) override;
 
 public:
-  static Optional<AccessScope>
-  getAccessScope(Type T, const DeclContext *useDC,
-                 bool treatUsableFromInlineAsPublic = false);
+  explicit SimpleTypeDeclFinder(
+      llvm::function_ref<Action(const TypeDecl *)> callback)
+    : Callback(callback) {}
+};
+
+/// Walks a TypeRepr to find all ComponentIdentTypeReprs with bound TypeDecls.
+///
+/// Subclasses can either override #visitTypeDecl if they only care about
+/// types on their own, or #visitComponentIdentTypeRepr if they want to keep
+/// the TypeRepr around.
+class TypeReprIdentFinder : public ASTWalker {
+  /// The function to call when a ComponentIdentTypeRepr is seen.
+  llvm::function_ref<bool(const ComponentIdentTypeRepr *)> Callback;
+
+  bool walkToTypeReprPost(TypeRepr *TR) override;
+public:
+  explicit TypeReprIdentFinder(
+      llvm::function_ref<bool(const ComponentIdentTypeRepr *)> callback)
+    : Callback(callback) {}
 };
 
 }

include/swift/AST/DiagnosticsSema.def

@@ -2392,6 +2392,11 @@ NOTE(enum_raw_value_incrementing_from_zero,none,
 NOTE(construct_raw_representable_from_unwrapped_value,none,
      "construct %0 from unwrapped %1 value", (Type, Type))
 
+ERROR(decl_from_implementation_only_module,none,
+      "cannot use %0 here; %1 has been imported as "
+      "'@_implementationOnly'",
+      (DeclName, Identifier))
+
 // Derived conformances
 ERROR(cannot_synthesize_init_in_extension_of_nonfinal,none,
       "implementation of %0 for non-final class cannot be automatically "

lib/AST/AccessScopeChecker.cpp

@@ -24,68 +24,76 @@ using namespace swift;
 AccessScopeChecker::AccessScopeChecker(const DeclContext *useDC,
                                        bool treatUsableFromInlineAsPublic)
   : File(useDC->getParentSourceFile()),
-    TreatUsableFromInlineAsPublic(treatUsableFromInlineAsPublic),
-    Context(File->getASTContext()) {}
+    TreatUsableFromInlineAsPublic(treatUsableFromInlineAsPublic) {}
 
 bool
-AccessScopeChecker::visitDecl(ValueDecl *VD) {
-  if (!VD || isa<GenericTypeParamDecl>(VD))
+AccessScopeChecker::visitDecl(const ValueDecl *VD) {
+  if (isa<GenericTypeParamDecl>(VD))
     return true;
 
   auto AS = VD->getFormalAccessScope(File, TreatUsableFromInlineAsPublic);
   Scope = Scope->intersectWith(AS);
   return Scope.hasValue();
 }
 
-TypeReprAccessScopeChecker::TypeReprAccessScopeChecker(const DeclContext *useDC,
-                                                       bool treatUsableFromInlineAsPublic)
-  : AccessScopeChecker(useDC, treatUsableFromInlineAsPublic) {
+bool TypeReprIdentFinder::walkToTypeReprPost(TypeRepr *TR) {
+  auto CITR = dyn_cast<ComponentIdentTypeRepr>(TR);
+  if (!CITR || !CITR->getBoundDecl())
+    return true;
+  return Callback(CITR);
 }
 
-bool
-TypeReprAccessScopeChecker::walkToTypeReprPre(TypeRepr *TR) {
-  if (auto CITR = dyn_cast<ComponentIdentTypeRepr>(TR))
-    return visitDecl(CITR->getBoundDecl());
-  return true;
+Optional<AccessScope>
+AccessScopeChecker::getAccessScope(TypeRepr *TR, const DeclContext *useDC,
+                                   bool treatUsableFromInlineAsPublic) {
+  AccessScopeChecker checker(useDC, treatUsableFromInlineAsPublic);
+  TR->walk(TypeReprIdentFinder([&](const ComponentIdentTypeRepr *typeRepr) {
+    return checker.visitDecl(typeRepr->getBoundDecl());
+  }));
+  return checker.Scope;
 }
 
-bool
-TypeReprAccessScopeChecker::walkToTypeReprPost(TypeRepr *TR) {
-  return Scope.hasValue();
-}
+TypeWalker::Action TypeDeclFinder::walkToTypePre(Type T) {
+  if (auto *TAT = dyn_cast<TypeAliasType>(T.getPointer()))
+    return visitTypeAliasType(TAT);
 
-Optional<AccessScope>
-TypeReprAccessScopeChecker::getAccessScope(TypeRepr *TR, const DeclContext *useDC,
-                                           bool treatUsableFromInlineAsPublic) {
-  TypeReprAccessScopeChecker checker(useDC, treatUsableFromInlineAsPublic);
-  TR->walk(checker);
-  return checker.Scope;
+  // FIXME: We're looking through sugar here so that we visit, e.g.,
+  // Swift.Array when we see `[Int]`. But that means we do redundant work when
+  // we see sugar that's purely structural, like `(Int)`. Fortunately, paren
+  // types are the only such purely structural sugar at the time this comment
+  // was written, and they're not so common in the first place.
+  if (auto *BGT = T->getAs<BoundGenericType>())
+    return visitBoundGenericType(BGT);
+  if (auto *NT = T->getAs<NominalType>())
+    return visitNominalType(NT);
+
+  return Action::Continue;
 }
 
-TypeAccessScopeChecker::TypeAccessScopeChecker(const DeclContext *useDC,
-                                               bool treatUsableFromInlineAsPublic)
-  : AccessScopeChecker(useDC, treatUsableFromInlineAsPublic) {}
+TypeWalker::Action
+SimpleTypeDeclFinder::visitNominalType(const NominalType *ty) {
+  return Callback(ty->getDecl());
+}
 
 TypeWalker::Action
-TypeAccessScopeChecker::walkToTypePre(Type T) {
-  ValueDecl *VD;
-  if (auto *BNAD = dyn_cast<TypeAliasType>(T.getPointer()))
-    VD = BNAD->getDecl();
-  else if (auto *NTD = T->getAnyNominal())
-    VD = NTD;
-  else
-    VD = nullptr;
-
-  if (!visitDecl(VD))
-    return Action::Stop;
+SimpleTypeDeclFinder::visitBoundGenericType(const BoundGenericType *ty) {
+  return Callback(ty->getDecl());
+}
 
-  return Action::Continue;
+TypeWalker::Action
+SimpleTypeDeclFinder::visitTypeAliasType(const TypeAliasType *ty) {
+  return Callback(ty->getDecl());
 }
 
+
 Optional<AccessScope>
-TypeAccessScopeChecker::getAccessScope(Type T, const DeclContext *useDC,
-                                       bool treatUsableFromInlineAsPublic) {
-  TypeAccessScopeChecker checker(useDC, treatUsableFromInlineAsPublic);
-  T.walk(checker);
+AccessScopeChecker::getAccessScope(Type T, const DeclContext *useDC,
+                                   bool treatUsableFromInlineAsPublic) {
+  AccessScopeChecker checker(useDC, treatUsableFromInlineAsPublic);
+  T.walk(SimpleTypeDeclFinder([&](const ValueDecl *VD) {
+    if (checker.visitDecl(VD))
+      return TypeWalker::Action::Continue;
+    return TypeWalker::Action::Stop;
+  }));
   return checker.Scope;
 }