[lldb] Add synthetic formatter for Swift.CheckedContinuation

Author: kastiglione

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

@@ -1021,6 +1021,92 @@ class UnsafeContinuationSyntheticFrontEnd : public SyntheticChildrenFrontEnd {
   ValueObjectSP m_task_sp;
 };
 
+class CheckedContinuationSyntheticFrontEnd : public SyntheticChildrenFrontEnd {
+public:
+  CheckedContinuationSyntheticFrontEnd(lldb::ValueObjectSP valobj_sp)
+      : SyntheticChildrenFrontEnd(*valobj_sp.get()) {
+    bool is_64bit = false;
+    if (auto target_sp = m_backend.GetTargetSP())
+      is_64bit = target_sp->GetArchitecture().GetTriple().isArch64Bit();
+
+    std::optional<uint32_t> concurrency_version;
+    if (auto process_sp = m_backend.GetProcessSP())
+      concurrency_version =
+          SwiftLanguageRuntime::FindConcurrencyDebugVersion(*process_sp);
+
+    bool is_supported_target = is_64bit && concurrency_version.value_or(0) == 1;
+    if (!is_supported_target)
+      return;
+
+    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 CheckedContinuation "
+            "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 (!m_task_type)
+      return ChildCacheState::eReuse;
+
+    size_t canary_task_offset = 0x10;
+    Status status;
+    if (auto canary_sp = m_backend.GetChildMemberWithName("canary"))
+      if (addr_t canary_addr = canary_sp->GetValueAsUnsigned(0))
+        if (addr_t task_addr = m_backend.GetProcessSP()->ReadPointerFromMemory(
+                canary_addr + canary_task_offset, status))
+          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)
@@ -1276,6 +1362,14 @@ lldb_private::formatters::swift::UnsafeContinuationSyntheticFrontEndCreator(
   return new UnsafeContinuationSyntheticFrontEnd(valobj_sp);
 }
 
+SyntheticChildrenFrontEnd *
+lldb_private::formatters::swift::CheckedContinuationSyntheticFrontEndCreator(
+    CXXSyntheticChildren *, lldb::ValueObjectSP valobj_sp) {
+  if (!valobj_sp)
+    return nullptr;
+  return new CheckedContinuationSyntheticFrontEnd(valobj_sp);
+}
+
 SyntheticChildrenFrontEnd *
 lldb_private::formatters::swift::TaskGroupSyntheticFrontEndCreator(
     CXXSyntheticChildren *, lldb::ValueObjectSP valobj_sp) {

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

@@ -124,6 +124,10 @@ SyntheticChildrenFrontEnd *
 UnsafeContinuationSyntheticFrontEndCreator(CXXSyntheticChildren *,
                                            lldb::ValueObjectSP);
 
+SyntheticChildrenFrontEnd *
+CheckedContinuationSyntheticFrontEndCreator(CXXSyntheticChildren *,
+                                            lldb::ValueObjectSP);
+
 SyntheticChildrenFrontEnd *
 TaskGroupSyntheticFrontEndCreator(CXXSyntheticChildren *, lldb::ValueObjectSP);
 }

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

@@ -422,6 +422,12 @@ static void LoadSwiftFormatters(lldb::TypeCategoryImplSP swift_category_sp) {
                   "Swift.UnsafeContinuation synthetic children",
                   ConstString("^Swift\\.UnsafeContinuation<.+,.+>"),
                   synth_flags, true);
+  AddCXXSynthetic(swift_category_sp,
+                  lldb_private::formatters::swift::
+                      CheckedContinuationSyntheticFrontEndCreator,
+                  "Swift.CheckedContinuation synthetic children",
+                  ConstString("^Swift\\.CheckedContinuation<.+,.+>"),
+                  synth_flags, true);
   AddCXXSynthetic(
       swift_category_sp,
       lldb_private::formatters::swift::TaskGroupSyntheticFrontEndCreator,

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

@@ -7,11 +7,11 @@
 class TestCase(TestBase):
 
     @swiftTest
-    def test_value_printing(self):
+    def test_unsafe_continuation_printing(self):
         """Print an UnsafeContinuation and verify its children."""
         self.build()
         lldbutil.run_to_source_breakpoint(
-            self, "break here", lldb.SBFileSpec("main.swift")
+            self, "break unsafe continuation", lldb.SBFileSpec("main.swift")
         )
         self.expect(
             "v cont",
@@ -21,3 +21,19 @@ def test_value_printing(self):
                 "isFuture = true",
             ],
         )
+
+    @swiftTest
+    def test_checked_continuation_printing(self):
+        """Print an CheckedContinuation and verify its children."""
+        self.build()
+        lldbutil.run_to_source_breakpoint(
+            self, "break checked continuation", lldb.SBFileSpec("main.swift")
+        )
+        self.expect(
+            "v cont",
+            substrs=[
+                "(CheckedContinuation<Int, Never>) cont = {",
+                "task = {",
+                "isFuture = true",
+            ],
+        )

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

@@ -1,8 +1,13 @@
 @main struct Main {
   static func main() async {
     await withUnsafeContinuation { (cont: UnsafeContinuation<Void, Never>) in
-      print("break here")
+      print("break unsafe continuation")
       cont.resume()
     }
+
+    _ = await withCheckedContinuation { (cont: CheckedContinuation<Int, Never>) in
+      print("break checked continuation")
+      cont.resume(returning: 15)
+    }
   }
 }