[lldb] Add synthetic formatter for Swift.UnsafeContinuation

Author: kastiglione

lldb/source/Plugins/Language/Swift/SwiftFormatters.cpp

@@ -955,6 +955,72 @@ class TaskSyntheticFrontEnd : public SyntheticChildrenFrontEnd {
   ValueObjectSP m_is_running_sp;
 };
 
+class UnsafeContinuationSyntheticFrontEnd : public SyntheticChildrenFrontEnd {
+public:
+  UnsafeContinuationSyntheticFrontEnd(lldb::ValueObjectSP valobj_sp)
+      : SyntheticChildrenFrontEnd(*valobj_sp.get()) {
+    if (auto target_sp = m_backend.GetTargetSP()) {
+      if (auto ts_or_err =
+              target_sp->GetScratchTypeSystemForLanguage(eLanguageTypeSwift)) {
+        if (auto *ts = llvm::dyn_cast_or_null<TypeSystemSwiftTypeRef>(
+                ts_or_err->get()))
+          // TypeMangling for "Swift.UnsafeCurrentTask"
+          m_task_type = ts->GetTypeFromMangledTypename(ConstString("$sSctD"));
+      } else {
+        LLDB_LOG_ERROR(GetLog(LLDBLog::DataFormatters | LLDBLog::Types),
+                       ts_or_err.takeError(),
+                       "could not get Swift type system for UnsafeContinuation "
+                       "synthetic provider: {0}");
+      }
+    }
+  }
+
+  llvm::Expected<uint32_t> CalculateNumChildren() override {
+    if (!m_task_sp)
+      return m_backend.GetNumChildren();
+
+    return 1;
+  }
+
+  bool MightHaveChildren() override { return true; }
+
+  lldb::ValueObjectSP GetChildAtIndex(uint32_t idx) override {
+    if (!m_task_sp)
+      return m_backend.GetChildAtIndex(idx);
+
+    if (idx == 0)
+      return m_task_sp;
+
+    return {};
+  }
+
+  size_t GetIndexOfChildWithName(ConstString name) override {
+    if (!m_task_sp)
+      return m_backend.GetIndexOfChildWithName(name);
+
+    if (name == "task")
+      return 0;
+
+    return UINT32_MAX;
+  }
+
+  lldb::ChildCacheState Update() override {
+    if (auto context_sp = m_backend.GetChildMemberWithName("context"))
+      if (addr_t task_addr = context_sp->GetValueAsUnsigned(0)) {
+        m_task_sp = ValueObject::CreateValueObjectFromAddress(
+            "task", task_addr, m_backend.GetExecutionContextRef(), m_task_type,
+            false);
+        if (auto synthetic_sp = m_task_sp->GetSyntheticValue())
+          m_task_sp = synthetic_sp;
+      }
+    return ChildCacheState::eRefetch;
+  }
+
+private:
+  CompilerType m_task_type;
+  ValueObjectSP m_task_sp;
+};
+
 class TaskGroupSyntheticFrontEnd : public SyntheticChildrenFrontEnd {
 public:
   TaskGroupSyntheticFrontEnd(lldb::ValueObjectSP valobj_sp)
@@ -1202,6 +1268,14 @@ lldb_private::formatters::swift::TaskSyntheticFrontEndCreator(
   return new TaskSyntheticFrontEnd(valobj_sp);
 }
 
+SyntheticChildrenFrontEnd *
+lldb_private::formatters::swift::UnsafeContinuationSyntheticFrontEndCreator(
+    CXXSyntheticChildren *, lldb::ValueObjectSP valobj_sp) {
+  if (!valobj_sp)
+    return nullptr;
+  return new UnsafeContinuationSyntheticFrontEnd(valobj_sp);
+}
+
 SyntheticChildrenFrontEnd *
 lldb_private::formatters::swift::TaskGroupSyntheticFrontEndCreator(
     CXXSyntheticChildren *, lldb::ValueObjectSP valobj_sp) {

lldb/source/Plugins/Language/Swift/SwiftFormatters.h

@@ -120,6 +120,10 @@ SyntheticChildrenFrontEnd *EnumSyntheticFrontEndCreator(CXXSyntheticChildren *,
 SyntheticChildrenFrontEnd *TaskSyntheticFrontEndCreator(CXXSyntheticChildren *,
                                                         lldb::ValueObjectSP);
 
+SyntheticChildrenFrontEnd *
+UnsafeContinuationSyntheticFrontEndCreator(CXXSyntheticChildren *,
+                                           lldb::ValueObjectSP);
+
 SyntheticChildrenFrontEnd *
 TaskGroupSyntheticFrontEndCreator(CXXSyntheticChildren *, lldb::ValueObjectSP);
 }

lldb/source/Plugins/Language/Swift/SwiftLanguage.cpp

@@ -416,6 +416,12 @@ static void LoadSwiftFormatters(lldb::TypeCategoryImplSP swift_category_sp) {
                   lldb_private::formatters::swift::TaskSyntheticFrontEndCreator,
                   "Swift.UnsafeCurrentTask synthetic children",
                   ConstString("Swift.UnsafeCurrentTask"), synth_flags);
+  AddCXXSynthetic(swift_category_sp,
+                  lldb_private::formatters::swift::
+                      UnsafeContinuationSyntheticFrontEndCreator,
+                  "Swift.UnsafeContinuation synthetic children",
+                  ConstString("^Swift\\.UnsafeContinuation<.+,.+>"),
+                  synth_flags, true);
   AddCXXSynthetic(
       swift_category_sp,
       lldb_private::formatters::swift::TaskGroupSyntheticFrontEndCreator,

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

@@ -3671,7 +3671,8 @@ lldb::Encoding TypeSystemSwiftTypeRef::GetEncoding(opaque_compiler_type_t type,
       if (node->getText() == swift::BUILTIN_TYPE_NAME_RAWPOINTER ||
           node->getText() == swift::BUILTIN_TYPE_NAME_NATIVEOBJECT ||
           node->getText() == swift::BUILTIN_TYPE_NAME_UNSAFEVALUEBUFFER ||
-          node->getText() == swift::BUILTIN_TYPE_NAME_BRIDGEOBJECT)
+          node->getText() == swift::BUILTIN_TYPE_NAME_BRIDGEOBJECT ||
+          node->getText() == swift::BUILTIN_TYPE_NAME_RAWUNSAFECONTINUATION)
         return lldb::eEncodingUint;
       if (node->getText().starts_with(swift::BUILTIN_TYPE_NAME_VEC)) {
         count = 0;

lldb/test/API/lang/swift/async/continuations/Makefile

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

lldb/test/API/lang/swift/async/continuations/TestSwiftContinuationSynthetic.py

@@ -0,0 +1,23 @@
+import lldb
+from lldbsuite.test.decorators import *
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test import lldbutil
+
+
+class TestCase(TestBase):
+
+    @swiftTest
+    def test_value_printing(self):
+        """Print an UnsafeContinuation and verify its children."""
+        self.build()
+        lldbutil.run_to_source_breakpoint(
+            self, "break here", lldb.SBFileSpec("main.swift")
+        )
+        self.expect(
+            "v cont",
+            substrs=[
+                "(UnsafeContinuation<Void, Never>) cont = {",
+                "task = {",
+                "isFuture = true",
+            ],
+        )

lldb/test/API/lang/swift/async/continuations/main.swift

@@ -0,0 +1,8 @@
+@main struct Main {
+  static func main() async {
+    await withUnsafeContinuation { (cont: UnsafeContinuation<Void, Never>) in
+      print("break here")
+      cont.resume()
+    }
+  }
+}