[lldb] Unify implementation of GetNumChildren and GetNumFields

These functions had incredibly similar implementations, but
GetNumFields was missing some of the edge cases implemented in
GetNumChildren.

rdar://147771956

Author: adrian-prantl

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

@@ -376,7 +376,9 @@ class SwiftLanguageRuntime : public LanguageRuntime {
 
   /// Ask Remote Mirrors about the children of a composite type.
   llvm::Expected<uint32_t> GetNumChildren(CompilerType type,
-                                          ExecutionContextScope *exe_scope);
+                                          ExecutionContextScope *exe_scope,
+                                          bool include_superclass = true,
+                                          bool include_clang_types = true);
 
   /// Determine the enum case name for the \p data value of the enum \p type.
   /// This is performed using Swift reflection.
@@ -422,7 +424,7 @@ class SwiftLanguageRuntime : public LanguageRuntime {
       uint64_t &language_flags);
 
   /// Ask Remote Mirrors about the fields of a composite type.
-  std::optional<unsigned> GetNumFields(CompilerType type,
+  llvm::Expected<unsigned> GetNumFields(CompilerType type,
                                         ExecutionContext *exe_ctx);
 
   /// Ask Remote Mirrors for the size of a Swift type.

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

@@ -709,8 +709,17 @@ CompilerType GetTypedefedTypeRecursive(CompilerType type) {
 } // namespace
 
 llvm::Expected<uint32_t>
-SwiftLanguageRuntime::GetNumChildren(CompilerType type,
-                                     ExecutionContextScope *exe_scope) {
+SwiftLanguageRuntime::GetNumFields(CompilerType type,
+                                   ExecutionContext *exe_ctx) {
+  if (exe_ctx)
+    return GetNumChildren(type, exe_ctx->GetBestExecutionContextScope(), false,
+                          false);
+ return llvm::createStringError("no execution context");
+}
+
+llvm::Expected<uint32_t> SwiftLanguageRuntime::GetNumChildren(
+    CompilerType type, ExecutionContextScope *exe_scope,
+    bool include_superclass, bool include_clang_types) {
   LLDB_SCOPED_TIMER();
 
   auto ts_sp = type.GetTypeSystem().dyn_cast_or_null<TypeSystemSwiftTypeRef>();
@@ -726,7 +735,7 @@ SwiftLanguageRuntime::GetNumChildren(CompilerType type,
       return pack_type->count;
 
   // Deal with Clang types.
-  {
+  if (include_clang_types) {
     CompilerType clang_type =
         LookupAnonymousClangType(type.GetMangledTypeName().AsCString());
     if (!clang_type)
@@ -806,7 +815,7 @@ SwiftLanguageRuntime::GetNumChildren(CompilerType type,
       if (GetWeakReferent(ts, type))
         return 1;
       break;
-    default:
+    case swift::reflection::ReferenceKind::Strong:
       break;
     }
 
@@ -838,7 +847,8 @@ SwiftLanguageRuntime::GetNumChildren(CompilerType type,
                type.GetMangledTypeName(), rti->getNumFields());
 
       // The superclass, if any, is an extra child.
-      if (reflection_ctx->LookupSuperclass(*tr, ts.GetDescriptorFinder()))
+      if (include_superclass &&
+          reflection_ctx->LookupSuperclass(*tr, ts.GetDescriptorFinder()))
         return rti->getNumFields() + 1;
       return rti->getNumFields();
     }
@@ -867,91 +877,6 @@ SwiftLanguageRuntime::GetNumChildren(CompilerType type,
                                  type.GetMangledTypeName().GetString());
 }
 
-std::optional<unsigned>
-SwiftLanguageRuntime::GetNumFields(CompilerType type,
-                                   ExecutionContext *exe_ctx) {
-  auto ts_sp = type.GetTypeSystem().dyn_cast_or_null<TypeSystemSwiftTypeRef>();
-  if (!ts_sp)
-    return {};
-  auto &ts = *ts_sp;
-
-  using namespace swift::reflection;
-  // Try the static type metadata.
-  const TypeRef *tr = nullptr;
-  auto ti_or_err = GetSwiftRuntimeTypeInfo(
-      type, exe_ctx ? exe_ctx->GetBestExecutionContextScope() : nullptr, &tr);
-  if (!ti_or_err) {
-    LLDB_LOG_ERRORV(GetLog(LLDBLog::Types), ti_or_err.takeError(), "{0}");
-    return {};
-  }
-  auto *ti = &*ti_or_err;
-
-  // Structs and Tuples.
-  switch (ti->getKind()) {
-  case TypeInfoKind::Record: {
-    // Structs and Tuples.
-    auto *rti = llvm::cast<RecordTypeInfo>(ti);
-    switch (rti->getRecordKind()) {
-    case RecordKind::ExistentialMetatype:
-    case RecordKind::ThickFunction:
-      // There are two fields, `function` and `context`, but they're not exposed
-      // by lldb.
-      return 0;
-    case RecordKind::OpaqueExistential:
-      // `OpaqueExistential` is documented as:
-      //     An existential is a three-word buffer followed by value metadata...
-      // The buffer is exposed as fields named `payload_data_{0,1,2}`, and
-      // the number of fields are increased to match.
-      return rti->getNumFields() + 3;
-    default:
-      return rti->getNumFields();
-    }
-  }
-  case TypeInfoKind::Builtin: {
-    // Clang types without debug info may present themselves like this.
-    return {};
-  }
-  case TypeInfoKind::Enum: {
-    auto *eti = llvm::cast<EnumTypeInfo>(ti);
-    return eti->getNumPayloadCases();
-  }
-  case TypeInfoKind::Reference: {
-    // Objects.
-    auto *rti = llvm::cast<ReferenceTypeInfo>(ti);
-    switch (rti->getReferenceKind()) {
-    case ReferenceKind::Weak:
-    case ReferenceKind::Unowned:
-    case ReferenceKind::Unmanaged:
-      if (auto referent = GetWeakReferent(ts, type))
-        return referent.GetNumFields(exe_ctx);
-      return 0;
-    case ReferenceKind::Strong:
-      ThreadSafeReflectionContext reflection_ctx = GetReflectionContext();
-      if (!reflection_ctx)
-        return {};
-      if (!tr)
-        return {};
-
-      LLDBTypeInfoProvider tip(*this, ts);
-      auto cti_or_err = reflection_ctx->GetClassInstanceTypeInfo(
-          *tr, &tip, ts.GetDescriptorFinder());
-      if (!cti_or_err) {
-        LLDB_LOG_ERRORV(GetLog(LLDBLog::Types), cti_or_err.takeError(),
-                        "GetNumFields failed: {0}");
-        return {};
-      }
-      if (auto *rti = llvm::dyn_cast_or_null<RecordTypeInfo>(&*cti_or_err))
-        return rti->getNumFields();
-
-      return {};
-    }
-  }
-  default:
-    LogUnimplementedTypeKind(__FUNCTION__, type);
-    return {};
-  }
-}
-
 static std::pair<SwiftLanguageRuntime::LookupResult, std::optional<size_t>>
 findFieldWithName(const std::vector<swift::reflection::FieldInfo> &fields,
                   const swift::reflection::TypeRef *tr, llvm::StringRef name,

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

@@ -3782,10 +3782,15 @@ uint32_t TypeSystemSwiftTypeRef::GetNumFields(opaque_compiler_type_t type,
   LLDB_SCOPED_TIMER();
   auto impl = [&]() -> std::optional<uint32_t> {
     if (exe_ctx)
-      if (auto *runtime = SwiftLanguageRuntime::Get(exe_ctx->GetProcessSP()))
-        if (auto num_fields =
-                runtime->GetNumFields(GetCanonicalType(type), exe_ctx))
-          return num_fields;
+      if (auto *runtime = SwiftLanguageRuntime::Get(exe_ctx->GetProcessSP())) {
+        auto num_fields_or_err =
+            runtime->GetNumFields(GetCanonicalType(type), exe_ctx);
+        if (num_fields_or_err)
+          return *num_fields_or_err;
+        LLDB_LOG_ERROR(GetLog(LLDBLog::Types), num_fields_or_err.takeError(),
+                       "GetNumFields failed for type {1}: {0}",
+                       AsMangledName(type));
+      }
 
     bool is_imported = false;
     if (auto clang_type = GetAsClangTypeOrNull(type, &is_imported)) {
@@ -4983,6 +4988,8 @@ bool TypeSystemSwiftTypeRef::DumpTypeValue(
             is_base_class);
       return false;
     }
+    case Node::Kind::ProtocolList:
+      return false;
     default:
       assert(false && "Unhandled node kind");
       LLDB_LOGF(GetLog(LLDBLog::Types),

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

@@ -0,0 +1,4 @@
+SWIFT_SOURCES := main.swift
+SWIFTFLAGS_EXTRAS = -Xcc -I$(SRCDIR)
+
+include Makefile.rules

lldb/test/API/lang/swift/clangimporter/objc_protocol/P.h

@@ -0,0 +1,2 @@
+@protocol P
+@end

lldb/test/API/lang/swift/clangimporter/objc_protocol/TestSwiftObjCProtocol.py

@@ -0,0 +1,16 @@
+import lldb
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test.decorators import *
+import lldbsuite.test.lldbutil as lldbutil
+
+class TestSwiftObjCProtocol(TestBase):
+    @skipUnlessDarwin
+    @swiftTest
+    def test(self):
+        """Test printing an Objective-C protocol existential member."""
+        self.build()
+        lldbutil.run_to_source_breakpoint(
+            self, 'break here', lldb.SBFileSpec('main.swift')
+        )
+
+        self.expect("v self", substrs=["obj", "0x"])

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

@@ -0,0 +1,14 @@
+import P
+
+class ImplementsP : P {}
+
+class C {
+  init(p: P) { x = p }
+  weak var x : P?
+  
+  func f() {
+    print("break here")
+  }
+}
+
+C(p: ImplementsP()).f()

lldb/test/API/lang/swift/clangimporter/objc_protocol/module.modulemap

@@ -0,0 +1 @@
+module P { header "P.h" }