[lldb-dap] Send an Invalidated event on thread stack change. (#163976)

When the user send `thread return <expr>` command this changes the stack
length but the UI does not update.
Send stack invalidated event to the client to update the stack.

lldb/test/API/tools/lldb-dap/invalidated-event/Makefile

@@ -0,0 +1,3 @@
+CXX_SOURCES := main.cpp
+
+include Makefile.rules

lldb/test/API/tools/lldb-dap/invalidated-event/TestDAP_invalidatedEvent.py

@@ -0,0 +1,55 @@
+"""
+Test lldb-dap recieves invalidated-events when the area such as
+stack, variables, threads has changes but the client does not
+know about it.
+"""
+
+import lldbdap_testcase
+from lldbsuite.test.lldbtest import line_number
+from dap_server import Event
+
+
+class TestDAP_invalidatedEvent(lldbdap_testcase.DAPTestCaseBase):
+    def verify_top_frame_name(self, frame_name: str):
+        all_frames = self.get_stackFrames()
+        self.assertGreaterEqual(len(all_frames), 1, "Expected at least one frame.")
+        top_frame_name = all_frames[0]["name"]
+        self.assertRegex(top_frame_name, f"{frame_name}.*")
+
+    def test_invalidated_stack_area_event(self):
+        """
+        Test an invalidated event for the stack area.
+        The event is sent when the command `thread return <expr>` is sent by the user.
+        """
+        other_source = "other.h"
+        return_bp_line = line_number(other_source, "// thread return breakpoint")
+
+        program = self.getBuildArtifact("a.out")
+        self.build_and_launch(program)
+        self.set_source_breakpoints(other_source, [return_bp_line])
+        self.continue_to_next_stop()
+
+        self.verify_top_frame_name("add")
+        thread_id = self.dap_server.get_thread_id()
+        self.assertIsNotNone(thread_id, "Exepected a thread id.")
+
+        # run thread return
+        thread_command = "thread return 20"
+        eval_resp = self.dap_server.request_evaluate(thread_command, context="repl")
+        self.assertTrue(eval_resp["success"], f"Failed to evaluate `{thread_command}`.")
+
+        # wait for the invalidated stack event.
+        stack_event = self.dap_server.wait_for_event(["invalidated"])
+        self.assertIsNotNone(stack_event, "Expected an invalidated event.")
+        event_body: Event = stack_event["body"]
+        self.assertIn("stacks", event_body["areas"])
+        self.assertIn("threadId", event_body.keys())
+        self.assertEqual(
+            thread_id,
+            event_body["threadId"],
+            f"Expected the event from thread {thread_id}.",
+        )
+
+        # confirm we are back at the main frame.
+        self.verify_top_frame_name("main")
+        self.continue_to_exit()

lldb/test/API/tools/lldb-dap/invalidated-event/main.cpp

@@ -0,0 +1,9 @@
+#include "other.h"
+
+int main() {
+  int first = 5;
+  int second = 10;
+  const int result = add(first, second);
+
+  return 0;
+}

lldb/test/API/tools/lldb-dap/invalidated-event/other.h

@@ -0,0 +1,10 @@
+#ifndef OTHER_H
+#define OTHER_H
+
+int add(int a, int b) {
+  int first = a;
+  int second = b; // thread return breakpoint
+  int result = first + second;
+  return result;
+}
+#endif // OTHER_H

lldb/tools/lldb-dap/DAP.cpp

@@ -1368,6 +1368,12 @@ void DAP::EventThread() {
   broadcaster.AddListener(listener, eBroadcastBitStopEventThread);
   debugger.GetBroadcaster().AddListener(
       listener, lldb::eBroadcastBitError | lldb::eBroadcastBitWarning);
+
+  // listen for thread events.
+  listener.StartListeningForEventClass(
+      debugger, lldb::SBThread::GetBroadcasterClassName(),
+      lldb::SBThread::eBroadcastBitStackChanged);
+
   bool done = false;
   while (!done) {
     if (listener.WaitForEvent(1, event)) {
@@ -1503,6 +1509,9 @@ void DAP::EventThread() {
             SendJSON(llvm::json::Value(std::move(bp_event)));
           }
         }
+
+      } else if (lldb::SBThread::EventIsThreadEvent(event)) {
+        HandleThreadEvent(event);
       } else if (event_mask & lldb::eBroadcastBitError ||
                  event_mask & lldb::eBroadcastBitWarning) {
         lldb::SBStructuredData data =
@@ -1522,6 +1531,16 @@ void DAP::EventThread() {
   }
 }
 
+void DAP::HandleThreadEvent(const lldb::SBEvent &event) {
+  uint32_t event_type = event.GetType();
+
+  if (event_type & lldb::SBThread::eBroadcastBitStackChanged) {
+    const lldb::SBThread evt_thread = lldb::SBThread::GetThreadFromEvent(event);
+    SendInvalidatedEvent(*this, {InvalidatedEventBody::eAreaStacks},
+                         evt_thread.GetThreadID());
+  }
+}
+
 std::vector<protocol::Breakpoint> DAP::SetSourceBreakpoints(
     const protocol::Source &source,
     const std::optional<std::vector<protocol::SourceBreakpoint>> &breakpoints) {

lldb/tools/lldb-dap/DAP.h

@@ -460,6 +460,7 @@ private:
   /// Event threads.
   /// @{
   void EventThread();
+  void HandleThreadEvent(const lldb::SBEvent &event);
   void ProgressEventThread();
 
   std::thread event_thread;

lldb/tools/lldb-dap/EventHelper.cpp

@@ -276,11 +276,16 @@ void SendProcessExitedEvent(DAP &dap, lldb::SBProcess &process) {
 }
 
 void SendInvalidatedEvent(
-    DAP &dap, llvm::ArrayRef<protocol::InvalidatedEventBody::Area> areas) {
+    DAP &dap, llvm::ArrayRef<protocol::InvalidatedEventBody::Area> areas,
+    lldb::tid_t tid) {
   if (!dap.clientFeatures.contains(protocol::eClientFeatureInvalidatedEvent))
     return;
   protocol::InvalidatedEventBody body;
   body.areas = areas;
+
+  if (tid != LLDB_INVALID_THREAD_ID)
+    body.threadId = tid;
+
   dap.Send(protocol::Event{"invalidated", std::move(body)});
 }
 

lldb/tools/lldb-dap/EventHelper.h

@@ -11,6 +11,8 @@
 
 #include "DAPForward.h"
 #include "Protocol/ProtocolEvents.h"
+#include "lldb/lldb-defines.h"
+#include "lldb/lldb-types.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/Support/Error.h"
 
@@ -35,7 +37,8 @@ void SendContinuedEvent(DAP &dap);
 void SendProcessExitedEvent(DAP &dap, lldb::SBProcess &process);
 
 void SendInvalidatedEvent(
-    DAP &dap, llvm::ArrayRef<protocol::InvalidatedEventBody::Area> areas);
+    DAP &dap, llvm::ArrayRef<protocol::InvalidatedEventBody::Area> areas,
+    lldb::tid_t tid = LLDB_INVALID_THREAD_ID);
 
 void SendMemoryEvent(DAP &dap, lldb::SBValue variable);
 

lldb/tools/lldb-dap/Protocol/ProtocolEvents.cpp

@@ -51,7 +51,7 @@ llvm::json::Value toJSON(const InvalidatedEventBody::Area &IEBA) {
 llvm::json::Value toJSON(const InvalidatedEventBody &IEB) {
   json::Object Result{{"areas", IEB.areas}};
   if (IEB.threadId)
-    Result.insert({"threadID", IEB.threadId});
+    Result.insert({"threadId", IEB.threadId});
   if (IEB.stackFrameId)
     Result.insert({"stackFrameId", IEB.stackFrameId});
   return Result;

lldb/unittests/DAP/ProtocolTypesTest.cpp

@@ -1079,14 +1079,17 @@ TEST(ProtocolTypesTest, InvalidatedEventBody) {
   body.areas = {InvalidatedEventBody::eAreaStacks,
                 InvalidatedEventBody::eAreaThreads};
   body.stackFrameId = 1;
-  StringRef json = R"({
-  "areas": [
-    "stacks",
-    "threads"
-  ],
-  "stackFrameId": 1
-})";
-  EXPECT_EQ(json, pp(body));
+  body.threadId = 20;
+  Expected<json::Value> expected = json::parse(R"({
+    "areas": [
+      "stacks",
+      "threads"
+    ],
+    "stackFrameId": 1,
+    "threadId": 20
+    })");
+  ASSERT_THAT_EXPECTED(expected, llvm::Succeeded());
+  EXPECT_EQ(pp(*expected), pp(body));
 }
 
 TEST(ProtocolTypesTest, MemoryEventBody) {