[lldb] Factor out iteration over runtime types from GetChildCompilerTypeAtIndex()

This patch introduces a new class SwiftRuntimeTypeVisitor that exists
to unify iteration over runtime type information. The visitor callback
has closure parameters that can be called to make additional expensive
queries on a child.

TODO: This is not the final evolution step.

- We probably should remove the "depth" parameter entirely and implement the access path computation for GetIndexOfChildMemberWithName at a different layer.

- We could cache the results for the last execution context.

Relanding with an off-by-one error fixed in
GetExistentialSyntheticChildren that was caught by ASAN!

Author: adrian-prantl

lldb/source/Plugins/LanguageRuntime/Swift/SwiftLanguageRuntime.h

@@ -67,6 +67,8 @@ struct SuperClassType;
 using ThreadSafeReflectionContext = LockGuarded<ReflectionContextInterface>;
 
 class SwiftLanguageRuntime : public LanguageRuntime {
+  friend class SwiftRuntimeTypeVisitor;
+
 protected:
   SwiftLanguageRuntime(Process &process);
 

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

@@ -8623,10 +8623,6 @@ std::string SwiftASTContext::GetSwiftName(const clang::Decl *clang_decl,
   return {};
 }
 
-CompilerType SwiftASTContext::GetBuiltinRawPointerType() {
-  return GetTypeFromMangledTypename(ConstString("$sBpD"));
-}
-
 CompilerType
 SwiftASTContext::ConvertClangTypeToSwiftType(CompilerType clang_type) {
   auto ts = GetTypeSystemSwiftTypeRef();

lldb/source/Plugins/TypeSystem/Swift/SwiftASTContext.cpp

@@ -412,7 +412,6 @@ class SwiftASTContext : public TypeSystemSwift {
   std::string GetSwiftName(const clang::Decl *clang_decl,
                            TypeSystemClang &clang_typesystem) override;
 
-  CompilerType GetBuiltinRawPointerType() override;
   CompilerType GetBuiltinIntType();
 
   /// Attempts to convert a Clang type into a Swift type.

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

@@ -98,6 +98,14 @@ bool TypeSystemSwift::IsScalarType(opaque_compiler_type_t type) {
   return (GetTypeInfo(type, nullptr) & eTypeIsScalar) != 0;
 }
 
+CompilerType TypeSystemSwift::GetBuiltinRawPointerType() {
+  return GetTypeFromMangledTypename(ConstString("$sBpD"));
+}
+
+CompilerType TypeSystemSwift::GetBuiltinUnknownObjectType() {
+  return GetTypeFromMangledTypename(ConstString("$sBOD"));
+}
+
 bool TypeSystemSwift::ShouldTreatScalarValueAsAddress(
     opaque_compiler_type_t type) {
   return Flags(GetTypeInfo(type, nullptr))

lldb/source/Plugins/TypeSystem/Swift/TypeSystemSwift.cpp

@@ -197,7 +197,8 @@ class TypeSystemSwift : public TypeSystem {
   virtual std::string GetSwiftName(const clang::Decl *clang_decl,
                                    TypeSystemClang &clang_typesystem) = 0;
 
-  virtual CompilerType GetBuiltinRawPointerType() = 0;
+  CompilerType GetBuiltinRawPointerType();
+  CompilerType GetBuiltinUnknownObjectType();
 
   /// Attempts to convert a Clang type into a Swift type.
   /// For example, int is converted to Int32.

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

@@ -1445,11 +1445,6 @@ TypeSystemSwiftTypeRef::GetSwiftName(const clang::Decl *clang_decl,
   return {};
 }
 
-CompilerType TypeSystemSwiftTypeRef::GetBuiltinRawPointerType() {
-  return GetTypeFromMangledTypename(ConstString("$sBpD"));
-}
-
-
 static bool IsImportedType(swift::Demangle::NodePointer node) {
   if (!node)
     return false;

lldb/source/Plugins/TypeSystem/Swift/TypeSystemSwiftTypeRef.cpp

@@ -412,8 +412,6 @@ class TypeSystemSwiftTypeRef : public TypeSystemSwift {
   std::string GetSwiftName(const clang::Decl *clang_decl,
                            TypeSystemClang &clang_typesystem) override;
 
-  CompilerType GetBuiltinRawPointerType() override;
-
   /// Wrap \p node as \p Global(TypeMangling(node)), remangle the type
   /// and create a CompilerType from it.
   CompilerType RemangleAsType(swift::Demangle::Demangler &dem,

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

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

lldb/test/API/lang/swift/clangimporter/objc_protocol_fields/Makefile

@@ -0,0 +1,19 @@
+import lldb
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test.decorators import *
+import lldbsuite.test.lldbutil as lldbutil
+
+class TestSwiftObjCBaseClassMemberLookup(TestBase):
+    NO_DEBUG_INFO_TESTCASE = True
+    @skipUnlessDarwin
+    @swiftTest
+    def test(self):
+        """Test accessing a static member from a member function"""
+        self.build()
+        lldbutil.run_to_source_breakpoint(
+            self, 'break here', lldb.SBFileSpec('main.swift')
+        )
+
+        p = self.frame().FindVariable("p").GetStaticValue()
+        self.assertEqual(p.GetNumChildren(), 1)
+        self.assertEqual(p.GetChildAtIndex(0).GetSummary(), '"hello"')

lldb/test/API/lang/swift/clangimporter/objc_protocol_fields/TestSwiftObjCProtocolFields.py

@@ -0,0 +1,9 @@
+import Foundation
+
+func foo(p: NSCopying) {
+  print("break here")
+}
+
+let s : NSString = "hello"
+foo(p: s)
+

lldb/test/API/lang/swift/clangimporter/objc_protocol_fields/main.swift

@@ -72,7 +72,7 @@ def test_swift_protocol_types(self):
         self.expect("expression --dynamic-type no-dynamic-values"
                     " --raw-output --show-types -- loc3dCB",
                     substrs=['PointUtils & Swift.AnyObject) $R',
-                             '(Builtin.RawPointer) object = 0x',
+                             '(Builtin.UnknownObject) object = 0x',
                              '(Builtin.RawPointer) wtable = 0x'])
 
         self.expect("expression -- loc3dCB",