Merge pull request #16997 from DougGregor/resolve-fewer-decl-signatures

[AST] Resolve fewer decl signatures

Author: DougGregor

include/swift/AST/ClangModuleLoader.h

@@ -24,6 +24,8 @@ class Sema;
 
 namespace swift {
 
+class DeclContext;
+
 class ClangModuleLoader : public ModuleLoader {
 private:
   virtual void anchor();
@@ -46,6 +48,16 @@ class ClangModuleLoader : public ModuleLoader {
   /// \returns true if there was an error adding the search path.
   virtual bool addSearchPath(StringRef newSearchPath, bool isFramework,
                              bool isSystem) = 0;
+
+  /// Determine whether \c overlayDC is within an overlay module for the
+  /// imported context enclosing \c importedDC.
+  ///
+  /// This routine is used for various hacks that are only permitted within
+  /// overlays of imported modules, e.g., Objective-C bridging conformances.
+  virtual bool isInOverlayModuleForImportedModule(
+                                            const DeclContext *overlayDC,
+                                            const DeclContext *importedDC) = 0;
+
 };
 
 } // namespace swift

include/swift/AST/LazyResolver.h

@@ -65,6 +65,12 @@ class LazyResolver {
   /// consistency and provides the value a type.
   virtual void resolveDeclSignature(ValueDecl *VD) = 0;
 
+  /// Resolve the "overridden" declaration of the given declaration.
+  virtual void resolveOverriddenDecl(ValueDecl *VD) = 0;
+
+  /// Resolve the "is Objective-C" bit for the given declaration.
+  virtual void resolveIsObjC(ValueDecl *VD) = 0;
+
   /// Resolve the types in the inheritance clause of the given
   /// declaration context, which will be a type declaration or
   /// extension declaration.

include/swift/ClangImporter/ClangImporter.h

@@ -143,6 +143,15 @@ class ClangImporter final : public ClangModuleLoader {
                         ArrayRef<std::pair<Identifier, SourceLoc>> path)
                       override;
 
+  /// Determine whether \c overlayDC is within an overlay module for the
+  /// imported context enclosing \c importedDC.
+  ///
+  /// This routine is used for various hacks that are only permitted within
+  /// overlays of imported modules, e.g., Objective-C bridging conformances.
+  bool isInOverlayModuleForImportedModule(
+                                      const DeclContext *overlayDC,
+                                      const DeclContext *importedDC) override;
+
   /// \brief Look for declarations associated with the given name.
   ///
   /// \param name The name we're searching for.
@@ -350,14 +359,6 @@ class ClangImporter final : public ClangModuleLoader {
 ImportDecl *createImportDecl(ASTContext &Ctx, DeclContext *DC, ClangNode ClangN,
                              ArrayRef<clang::Module *> Exported);
 
-/// Determine whether \c overlayDC is within an overlay module for the
-/// imported context enclosing \c importedDC.
-///
-/// This routine is used for various hacks that are only permitted within
-/// overlays of imported modules, e.g., Objective-C bridging conformances.
-bool isInOverlayModuleForImportedModule(const DeclContext *overlayDC,
-                                        const DeclContext *importedDC);
-
 } // end namespace swift
 
 #endif

lib/AST/ConformanceLookupTable.cpp

@@ -161,8 +161,6 @@ void ConformanceLookupTable::forEachInStage(ConformanceStage stage,
       SmallVector<ProtocolConformance *, 2> conformances;
       loader.first->loadAllConformances(nominal, loader.second, conformances);
       loadAllConformances(nominal, conformances);
-    } else if (nominal->getParentSourceFile() && resolver) {
-      resolver->resolveDeclSignature(nominal);
     }
 
     nominalFunc(nominal);

lib/AST/Decl.cpp

@@ -3495,19 +3495,7 @@ bool ProtocolDecl::existentialTypeSupportedSlow(LazyResolver *resolver) {
   if (isObjC())
     return true;
 
-  // Resolve the protocol's type.
-  if (resolver && !hasInterfaceType())
-    resolver->resolveDeclSignature(this);
-
   for (auto member : getMembers()) {
-    if (auto vd = dyn_cast<ValueDecl>(member)) {
-      if (resolver && !vd->hasInterfaceType())
-        resolver->resolveDeclSignature(vd);
-    }
-
-    if (member->isInvalid())
-      continue;
-
     // Check for associated types.
     if (isa<AssociatedTypeDecl>(member)) {
       // An existential type cannot be used if the protocol has an
@@ -3524,6 +3512,9 @@ bool ProtocolDecl::existentialTypeSupportedSlow(LazyResolver *resolver) {
           continue;
       }
 
+      if (resolver && !valueMember->hasInterfaceType())
+        resolver->resolveDeclSignature(valueMember);
+
       if (!isAvailableInExistential(valueMember)) {
         Bits.ProtocolDecl.ExistentialTypeSupported = false;
         return false;

lib/AST/GenericSignatureBuilder.cpp

@@ -7465,6 +7465,12 @@ GenericSignature *GenericSignatureBuilder::computeRequirementSignature(
                                                      ProtocolDecl *proto) {
   GenericSignatureBuilder builder(proto->getASTContext());
 
+  if (!proto->hasInterfaceType()) {
+    // FIXME: Overkill.
+    if (auto lazyResolver = proto->getASTContext().getLazyResolver())
+      lazyResolver->resolveDeclSignature(proto);
+  }
+
   // Add the 'self' parameter.
   auto selfType =
     proto->getSelfInterfaceType()->castTo<GenericTypeParamType>();

lib/AST/NameLookup.cpp

@@ -15,11 +15,11 @@
 //===----------------------------------------------------------------------===//
 
 #include "NameLookupImpl.h"
-#include "swift/ClangImporter/ClangImporter.h"
 #include "swift/AST/NameLookup.h"
 #include "swift/AST/ASTContext.h"
 #include "swift/AST/ASTScope.h"
 #include "swift/AST/ASTVisitor.h"
+#include "swift/AST/ClangModuleLoader.h"
 #include "swift/AST/DebuggerClient.h"
 #include "swift/AST/ExistentialLayout.h"
 #include "swift/AST/LazyResolver.h"
@@ -81,11 +81,16 @@ static void forAllVisibleModules(const DeclContext *DC, const Fn &fn) {
 }
 
 bool swift::removeOverriddenDecls(SmallVectorImpl<ValueDecl*> &decls) {
-  if (decls.empty())
+  if (decls.size() < 2)
     return false;
 
+  auto lazyResolver = decls.front()->getASTContext().getLazyResolver();
   llvm::SmallPtrSet<ValueDecl*, 8> overridden;
   for (auto decl : decls) {
+    // Compute enough information to make the overridden-declaration available.
+    if (lazyResolver)
+      lazyResolver->resolveOverriddenDecl(decl);
+
     while (auto overrides = decl->getOverriddenDecl()) {
       overridden.insert(overrides);
 
@@ -100,6 +105,10 @@ bool swift::removeOverriddenDecls(SmallVectorImpl<ValueDecl*> &decls) {
         ///        cause instead (incomplete circularity detection).
         assert(decl != overrides && "Circular class inheritance?");
         decl = overrides;
+
+        if (lazyResolver)
+          lazyResolver->resolveOverriddenDecl(decl);
+
         continue;
       }
 
@@ -299,13 +308,18 @@ bool swift::removeShadowedDecls(SmallVectorImpl<ValueDecl*> &decls,
         // Prefer declarations in an overlay to similar declarations in
         // the Clang module it customizes.
         if (firstDecl->hasClangNode() != secondDecl->hasClangNode()) {
-          if (isInOverlayModuleForImportedModule(firstDecl->getDeclContext(),
-                                                 secondDecl->getDeclContext())){
+          auto clangLoader = ctx.getClangModuleLoader();
+          if (!clangLoader) continue;
+
+          if (clangLoader->isInOverlayModuleForImportedModule(
+                                                firstDecl->getDeclContext(),
+                                                secondDecl->getDeclContext())) {
             shadowed.insert(secondDecl);
             continue;
           }
 
-          if (isInOverlayModuleForImportedModule(secondDecl->getDeclContext(),
+          if (clangLoader->isInOverlayModuleForImportedModule(
+                                                 secondDecl->getDeclContext(),
                                                  firstDecl->getDeclContext())) {
             shadowed.insert(firstDecl);
             break;
@@ -1755,13 +1769,6 @@ bool DeclContext::lookupQualified(Type type,
   // criteria.
   bool onlyCompleteObjectInits = false;
   auto isAcceptableDecl = [&](NominalTypeDecl *current, ValueDecl *decl) -> bool {
-    // If the decl is currently being type checked, then we have something
-    // cyclic going on.  Instead of poking at parts that are potentially not
-    // set up, just assume it is acceptable.  This will make sure we produce an
-    // error later.
-    if (!decl->hasValidSignature())
-      return true;
-    
     // Filter out designated initializers, if requested.
     if (onlyCompleteObjectInits) {
       if (auto ctor = dyn_cast<ConstructorDecl>(decl)) {
@@ -1780,8 +1787,12 @@ bool DeclContext::lookupQualified(Type type,
     }
 
     // Check access.
-    if (!(options & NL_IgnoreAccessControl))
+    if (!(options & NL_IgnoreAccessControl)) {
+      if (typeResolver)
+        typeResolver->resolveAccessControl(decl);
+
       return decl->isAccessibleFrom(this);
+    }
 
     return true;
   };
@@ -1823,11 +1834,6 @@ bool DeclContext::lookupQualified(Type type,
       if ((options & NL_OnlyTypes) && !isa<TypeDecl>(decl))
         continue;
 
-      // Resolve the declaration signature when we find the
-      // declaration.
-      if (typeResolver)
-        typeResolver->resolveDeclSignature(decl);
-
       if (isAcceptableDecl(current, decl))
         decls.push_back(decl);
     }
@@ -1892,17 +1898,20 @@ bool DeclContext::lookupQualified(Type type,
       if ((options & NL_OnlyTypes) && !isa<TypeDecl>(decl))
         continue;
 
+      // If the declaration is not @objc, it cannot be called dynamically.
       if (typeResolver)
-        typeResolver->resolveDeclSignature(decl);
+        typeResolver->resolveIsObjC(decl);
+
+      if (!decl->isObjC())
+        continue;
 
       // If the declaration has an override, name lookup will also have
       // found the overridden method. Skip this declaration, because we
       // prefer the overridden method.
-      if (decl->getOverriddenDecl())
-        continue;
+      if (typeResolver)
+        typeResolver->resolveOverriddenDecl(decl);
 
-      // If the declaration is not @objc, it cannot be called dynamically.
-      if (!decl->isObjC())
+      if (decl->getOverriddenDecl())
         continue;
 
       auto dc = decl->getDeclContext();

lib/AST/Type.cpp

@@ -1835,7 +1835,7 @@ getObjCObjectRepresentable(Type type, const DeclContext *dc) {
   if (auto classDecl = type->getClassOrBoundGenericClass()) {
     auto &ctx = classDecl->getASTContext();
     if (auto resolver = ctx.getLazyResolver())
-      resolver->resolveDeclSignature(classDecl);
+      resolver->resolveIsObjC(classDecl);
 
     if (classDecl->isObjC())
       return ForeignRepresentableKind::Object;

lib/ClangImporter/ClangImporter.cpp

@@ -3539,7 +3539,7 @@ EffectiveClangContext ClangImporter::Implementation::getEffectiveClangContext(
 
   // Resolve the type.
   if (auto typeResolver = getTypeResolver())
-    typeResolver->resolveDeclSignature(const_cast<NominalTypeDecl *>(nominal));
+    typeResolver->resolveIsObjC(const_cast<NominalTypeDecl *>(nominal));
 
   // If it's an @objc entity, go look for it.
   if (nominal->isObjC()) {
@@ -3598,7 +3598,8 @@ importName(const clang::NamedDecl *D,
     getDeclName();
 }
 
-bool swift::isInOverlayModuleForImportedModule(const DeclContext *overlayDC,
+bool ClangImporter::isInOverlayModuleForImportedModule(
+                                               const DeclContext *overlayDC,
                                                const DeclContext *importedDC) {
   overlayDC = overlayDC->getModuleScopeContext();
   importedDC = importedDC->getModuleScopeContext();
@@ -3613,7 +3614,7 @@ bool swift::isInOverlayModuleForImportedModule(const DeclContext *overlayDC,
 
   // Is this a private module that's re-exported to the public (overlay) name?
   auto clangModule =
-    importedClangModuleUnit->getClangModule()->getTopLevelModule();
+  importedClangModuleUnit->getClangModule()->getTopLevelModule();
   return !clangModule->ExportAsModule.empty() &&
     clangModule->ExportAsModule == overlayModule->getName().str();
 }

lib/ClangImporter/ImportDecl.cpp

@@ -4395,9 +4395,6 @@ namespace {
       T *found = nullptr;
       for (auto result : results) {
         if (auto singleResult = dyn_cast<T>(result)) {
-          if (auto typeResolver = Impl.getTypeResolver())
-            typeResolver->resolveDeclSignature(singleResult);
-
           // Skip versioned variants.
           const DeclAttributes &attrs = singleResult->getAttrs();
           if (attrs.isUnavailableInSwiftVersion(languageVersion))

lib/ClangImporter/ImportType.cpp

@@ -2364,8 +2364,6 @@ getNamedSwiftTypeSpecialization(ModuleDecl *module, StringRef name,
                       NLKind::UnqualifiedLookup, results);
   if (results.size() == 1) {
     if (auto nominalDecl = dyn_cast<NominalTypeDecl>(results.front())) {
-      if (auto *typeResolver = getTypeResolver())
-        typeResolver->resolveDeclSignature(nominalDecl);
       if (auto params = nominalDecl->getGenericParams()) {
         if (params->size() == args.size()) {
           // When we form the bound generic type, make sure we get the

lib/Sema/TypeCheckAttr.cpp

@@ -18,11 +18,11 @@
 #include "MiscDiagnostics.h"
 #include "swift/AST/GenericSignatureBuilder.h"
 #include "swift/AST/ASTVisitor.h"
+#include "swift/AST/ClangModuleLoader.h"
 #include "swift/AST/GenericEnvironment.h"
 #include "swift/AST/NameLookup.h"
 #include "swift/AST/ParameterList.h"
 #include "swift/AST/Types.h"
-#include "swift/ClangImporter/ClangImporter.h"
 #include "swift/Parse/Lexer.h"
 #include "llvm/Support/Debug.h"
 
@@ -1413,7 +1413,9 @@ static bool isObjCClassExtensionInOverlay(DeclContext *dc) {
   if (!classDecl)
     return false;
 
-  return isInOverlayModuleForImportedModule(ext, classDecl);
+  auto clangLoader = dc->getASTContext().getClangModuleLoader();
+  if (!clangLoader) return false;
+  return clangLoader->isInOverlayModuleForImportedModule(ext, classDecl);
 }
 
 void AttributeChecker::visitRequiredAttr(RequiredAttr *attr) {

lib/Sema/TypeCheckDecl.cpp

@@ -3792,6 +3792,51 @@ void TypeChecker::validateDecl(PrecedenceGroupDecl *PGD) {
   if (isInvalid) PGD->setInvalid();
 }
 
+void TypeChecker::resolveOverriddenDecl(ValueDecl *VD) {
+  // Only members of classes can override other declarations.
+  if (!VD->getDeclContext()->getAsClassOrClassExtensionContext())
+    return;
+
+  // Types that aren't associated types cannot be overridden.
+  if (isa<TypeDecl>(VD) && !isa<AssociatedTypeDecl>(VD))
+    return;
+
+  // FIXME: We should check for the 'override' or 'required' keywords
+  // here, to short-circuit checking in the common case.
+
+  // FIXME: We should perform more minimal validation.
+  validateDeclForNameLookup(VD);
+}
+
+void TypeChecker::resolveIsObjC(ValueDecl *VD) {
+  // Short-circuit this operation if we already know that the entity is @objc.
+  if (VD->isObjC()) return;
+
+  auto dc = VD->getDeclContext();
+  if (dc->getAsClassOrClassExtensionContext()) {
+    // Members of classes can be @objc.
+
+    // FIXME: We
+    validateDeclForNameLookup(VD);
+  }
+  else if (isa<ClassDecl>(VD)) {
+    // Classes can be @objc.
+
+    // Protocols and enums can also be @objc, but this is covered by the
+    // isObjC() check at the beginning.
+  }
+  else if (isa<ProtocolDecl>(dc) && cast<ProtocolDecl>(dc)->isObjC()) {
+    // Members of @objc protocols are @objc.
+  }
+  else {
+    // Cannot be @objc; do nothing.
+    return;
+  }
+
+  // FIXME: Narrow this computation to just the @objc bits.
+  validateDeclForNameLookup(VD);
+}
+
 PrecedenceGroupDecl *TypeChecker::lookupPrecedenceGroup(DeclContext *dc,
                                                         Identifier name,
                                                         SourceLoc nameLoc) {