[NFC] Serialize ObjC selectors for protocols

The ObjCMethodLookupTable for protocols was not being serialized and rebuilt on load, so NominalTypeDecl::lookupDirect() on selectors was not working correctly for deserialized types. Correct this oversight.

Author: beccadax

include/swift/AST/ModuleLoader.h

@@ -226,11 +226,11 @@ class ModuleLoader {
   virtual void loadExtensions(NominalTypeDecl *nominal,
                               unsigned previousGeneration) { }
 
-  /// Load the methods within the given class that produce
+  /// Load the methods within the given type that produce
   /// Objective-C class or instance methods with the given selector.
   ///
-  /// \param classDecl The class in which we are searching for @objc methods.
-  /// The search only considers this class and its extensions; not any
+  /// \param typeDecl The type in which we are searching for @objc methods.
+  /// The search only considers this type and its extensions; not any
   /// superclasses.
   ///
   /// \param selector The selector to search for.
@@ -246,7 +246,7 @@ class ModuleLoader {
   /// selector and are instance/class methods as requested. This list will be
   /// extended with any methods found in subsequent generations.
   virtual void loadObjCMethods(
-                 ClassDecl *classDecl,
+                 NominalTypeDecl *typeDecl,
                  ObjCSelector selector,
                  bool isInstanceMethod,
                  unsigned previousGeneration,

include/swift/ClangImporter/ClangImporter.h

@@ -309,7 +309,7 @@ class ClangImporter final : public ClangModuleLoader {
                               unsigned previousGeneration) override;
 
   virtual void loadObjCMethods(
-                 ClassDecl *classDecl,
+                 NominalTypeDecl *typeDecl,
                  ObjCSelector selector,
                  bool isInstanceMethod,
                  unsigned previousGeneration,

include/swift/Sema/SourceLoader.h

@@ -85,7 +85,7 @@ class SourceLoader : public ModuleLoader {
                               unsigned previousGeneration) override;
 
   virtual void loadObjCMethods(
-                 ClassDecl *classDecl,
+                 NominalTypeDecl *typeDecl,
                  ObjCSelector selector,
                  bool isInstanceMethod,
                  unsigned previousGeneration,

include/swift/Serialization/SerializedModuleLoader.h

@@ -190,7 +190,7 @@ class SerializedModuleLoaderBase : public ModuleLoader {
                               unsigned previousGeneration) override;
 
   virtual void loadObjCMethods(
-                 ClassDecl *classDecl,
+                 NominalTypeDecl *typeDecl,
                  ObjCSelector selector,
                  bool isInstanceMethod,
                  unsigned previousGeneration,

lib/AST/ASTContext.cpp

@@ -1919,24 +1919,12 @@ void ASTContext::loadObjCMethods(
   PrettyStackTraceSelector stackTraceSelector("looking for", selector);
   PrettyStackTraceDecl stackTraceDecl("...in", tyDecl);
 
-  // @objc protocols cannot have @objc extension members, so if we've recorded
-  // everything in the protocol definition, we've recorded everything. And we
-  // only ever use the ObjCSelector version of `NominalTypeDecl::lookupDirect()`
-  // on protocols in primary file typechecking, so we don't care about protocols
-  // that need to be loaded from files.
-  // TODO: Rework `ModuleLoader::loadObjCMethods()` to support protocols too if
-  //       selector-based `NominalTypeDecl::lookupDirect()` ever needs to work
-  //       in more situations.
-  ClassDecl *classDecl = dyn_cast<ClassDecl>(tyDecl);
-  if (!classDecl)
-    return;
-
   for (auto &loader : getImpl().ModuleLoaders) {
     // Ignore the Clang importer if we've been asked for Swift-only results.
     if (swiftOnly && loader.get() == getClangModuleLoader())
       continue;
 
-    loader->loadObjCMethods(classDecl, selector, isInstanceMethod,
+    loader->loadObjCMethods(tyDecl, selector, isInstanceMethod,
                             previousGeneration, methods);
   }
 }

lib/AST/NameLookup.cpp

@@ -1310,7 +1310,24 @@ class swift::ObjCMethodLookupTable
         : public llvm::DenseMap<std::pair<ObjCSelector, char>,
                                 StoredObjCMethods>,
           public ASTAllocated<ObjCMethodLookupTable>
-{};
+{
+  SWIFT_DEBUG_DUMP {
+    llvm::errs() << "ObjCMethodLookupTable:\n";
+    for (auto pair : *this) {
+      auto selector = pair.getFirst().first;
+      auto isInstanceMethod = pair.getFirst().second;
+      auto &methods = pair.getSecond();
+
+      llvm::errs() << "  \"" << (isInstanceMethod ? "-" : "+") << selector
+                   << "\":\n";
+      for (auto method : methods.Methods) {
+        llvm::errs() << "  - \"";
+        method->dumpRef(llvm::errs());
+        llvm::errs() << "\"\n";
+      }
+    }
+  }
+};
 
 MemberLookupTable::MemberLookupTable(ASTContext &ctx) {
   // Register a cleanup with the ASTContext to call the lookup table

lib/ClangImporter/ClangImporter.cpp

@@ -3569,11 +3569,16 @@ void ClangImporter::loadExtensions(NominalTypeDecl *nominal,
 }
 
 void ClangImporter::loadObjCMethods(
-       ClassDecl *classDecl,
+       NominalTypeDecl *typeDecl,
        ObjCSelector selector,
        bool isInstanceMethod,
        unsigned previousGeneration,
        llvm::TinyPtrVector<AbstractFunctionDecl *> &methods) {
+  // TODO: We don't currently need to load methods from imported ObjC protocols.
+  auto classDecl = dyn_cast<ClassDecl>(typeDecl);
+  if (!classDecl)
+    return;
+
   const auto *objcClass =
       dyn_cast_or_null<clang::ObjCInterfaceDecl>(classDecl->getClangDecl());
   if (!objcClass)

lib/Serialization/ModuleFile.cpp

@@ -613,7 +613,7 @@ void ModuleFile::loadExtensions(NominalTypeDecl *nominal) {
 }
 
 void ModuleFile::loadObjCMethods(
-       ClassDecl *classDecl,
+       NominalTypeDecl *typeDecl,
        ObjCSelector selector,
        bool isInstanceMethod,
        llvm::TinyPtrVector<AbstractFunctionDecl *> &methods) {
@@ -627,7 +627,7 @@ void ModuleFile::loadObjCMethods(
     return;
   }
 
-  std::string ownerName = Mangle::ASTMangler().mangleNominalType(classDecl);
+  std::string ownerName = Mangle::ASTMangler().mangleNominalType(typeDecl);
   auto results = *known;
   for (const auto &result : results) {
     // If the method is the wrong kind (instance vs. class), skip it.

lib/Serialization/ModuleFile.h

@@ -634,7 +634,7 @@ class ModuleFile
   ///
   /// \param methods The list of @objc methods in this class that have this
   /// selector and are instance/class methods as requested.
-  void loadObjCMethods(ClassDecl *classDecl,
+  void loadObjCMethods(NominalTypeDecl *typeDecl,
                        ObjCSelector selector,
                        bool isInstanceMethod,
                        llvm::TinyPtrVector<AbstractFunctionDecl *> &methods);

lib/Serialization/ModuleFormat.h

@@ -58,7 +58,7 @@ const uint16_t SWIFTMODULE_VERSION_MAJOR = 0;
 /// describe what change you made. The content of this comment isn't important;
 /// it just ensures a conflict if two people change the module format.
 /// Don't worry about adhering to the 80-column limit for this line.
-const uint16_t SWIFTMODULE_VERSION_MINOR = 693; // witness enter isolation
+const uint16_t SWIFTMODULE_VERSION_MINOR = 694; // add @objc protocol methods to objc method tables
 
 /// A standard hash seed used for all string hashes in a serialized module.
 ///