[lldb] Support plain ObjC names in LLDBTypeInfoProvider (#9320)

Extend `LLDBTypeInfoProvider` to support ObjC class names (such as "NSObject", 
"NSView") in addition to mangled Swift names.

This is to support `ObjCClassTypeRefs`, which contain the class name, but not the 
mangled name. Note that `ObjCClassTypeRefs` are typerefs for classes in the ObjC 
(`__C`) module.

Depends on swiftlang/swift#76678

Author: kastiglione

lldb/source/Plugins/LanguageRuntime/Swift/SwiftLanguageRuntimeDynamicTypeResolution.cpp

@@ -317,12 +317,26 @@ class LLDBTypeInfoProvider : public swift::remote::TypeInfoProvider {
     std::string wrapped;
     // The mangled name passed in is bare. Add global prefix ($s) and type (D).
     llvm::raw_string_ostream(wrapped) << "$s" << mangledName << 'D';
+    swift::Demangle::Demangler dem;
+    auto *node = dem.demangleSymbol(wrapped);
+    if (!node) {
+      // Try `mangledName` as plain ObjC class name. Ex: NSObject, NSView, etc.
+      auto maybeMangled = swift_demangle::mangleClass(
+          dem, swift::MANGLING_MODULE_OBJC, mangledName);
+      if (!maybeMangled.isSuccess()) {
+        LLDB_LOG(GetLog(LLDBLog::Types),
+                 "[LLDBTypeInfoProvider] invalid mangled name: {0}",
+                 mangledName);
+        return nullptr;
+      }
+      wrapped = maybeMangled.result();
+      LLDB_LOG(GetLog(LLDBLog::Types),
+               "[LLDBTypeInfoProvider] using mangled ObjC class name: {0}",
+               wrapped);
+    } else {
 #ifndef NDEBUG
-    {
       // Check that our hardcoded mangling wrapper is still up-to-date.
-      swift::Demangle::Context dem;
-      auto node = dem.demangleSymbolAsNode(wrapped);
-      assert(node && node->getKind() == swift::Demangle::Node::Kind::Global);
+      assert(node->getKind() == swift::Demangle::Node::Kind::Global);
       assert(node->getNumChildren() == 1);
       node = node->getChild(0);
       assert(node->getKind() == swift::Demangle::Node::Kind::TypeMangling);
@@ -332,8 +346,9 @@ class LLDBTypeInfoProvider : public swift::remote::TypeInfoProvider {
       assert(node->getNumChildren() == 1);
       node = node->getChild(0);
       assert(node->getKind() != swift::Demangle::Node::Kind::Type);
-    }
 #endif
+    }
+
     ConstString mangled(wrapped);
     CompilerType swift_type = typesystem.GetTypeFromMangledTypename(mangled);
     auto ts = swift_type.GetTypeSystem().dyn_cast_or_null<TypeSystemSwift>();

lldb/source/Plugins/TypeSystem/Swift/SwiftDemangle.h

@@ -70,7 +70,34 @@ static swift::Demangle::NodePointer
 GetDemangledType(swift::Demangle::Demangler &dem, llvm::StringRef name) {
   return GetType(dem.demangleSymbol(name));
 }
-  
+
+/// Wrap node in Global/TypeMangling/Type.
+static swift::Demangle::NodePointer
+mangleType(swift::Demangle::Demangler &dem,
+           swift::Demangle::NodePointer typeNode) {
+  auto *global = dem.createNode(Node::Kind::Global);
+  auto *typeMangling = dem.createNode(Node::Kind::TypeMangling);
+  global->addChild(typeMangling, dem);
+  auto *type = dem.createNode(Node::Kind::Type);
+  typeMangling->addChild(type, dem);
+  type->addChild(typeNode, dem);
+  return global;
+}
+
+/// Produce a type mangling for a class.
+inline ManglingErrorOr<std::string> mangleClass(swift::Demangle::Demangler &dem,
+                                                llvm::StringRef moduleName,
+                                                llvm::StringRef className) {
+  auto *classNode = dem.createNode(Node::Kind::Class);
+  auto *module =
+      dem.createNodeWithAllocatedText(Node::Kind::Module, moduleName);
+  auto *identifier =
+      dem.createNodeWithAllocatedText(Node::Kind::Identifier, className);
+  classNode->addChild(module, dem);
+  classNode->addChild(identifier, dem);
+  return mangleNode(mangleType(dem, classNode));
+}
+
 } // namespace swift_demangle
 } // namespace lldb_private
 

lldb/test/API/lang/swift/typerefs/objc-descendent/Makefile

@@ -0,0 +1,3 @@
+SWIFT_SOURCES := main.swift
+
+include Makefile.rules

lldb/test/API/lang/swift/typerefs/objc-descendent/TestSwiftObjCDescendantClassWithoutASTContext.py

@@ -0,0 +1,17 @@
+import lldb
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test.decorators import *
+import lldbsuite.test.lldbutil as lldbutil
+
+
+class TestCase(TestBase):
+    @swiftTest
+    @skipUnlessFoundation
+    def test(self):
+        """Print an ObjC derived object without using the AST context."""
+        self.build()
+        lldbutil.run_to_source_breakpoint(
+            self, "// break here", lldb.SBFileSpec("main.swift")
+        )
+        self.runCmd("settings set symbols.swift-enable-ast-context false")
+        self.expect("v", substrs=["num = 15"])

lldb/test/API/lang/swift/typerefs/objc-descendent/main.swift

@@ -0,0 +1,13 @@
+import Foundation
+
+class C: NSObject {
+  var num: Int = 15
+}
+
+func main() {
+  let c = C()
+  // break here
+  print(c)
+}
+
+main()