[SDK] Fixes stack trace service API tests.

Fixes an issue where stack['asyncCausalFrames'] would be populated in
if --lazy-async-stacks was set.
The field should be filled iff the stack contains an async function -
regardless of whether it's sync-async.

Bug: #39525
Change-Id: Ia68f113402962c07a1e9a38ea9320b44140241e4
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/132820
Commit-Queue: Clement Skau <[email protected]>
Reviewed-by: Martin Kustermann <[email protected]>

Author: Clement Skau

runtime/observatory/tests/service/causal_async_stack_contents_test.dart

@@ -38,12 +38,7 @@ var tests = <IsolateTest>[
   (Isolate isolate) async {
     ServiceMap stack = await isolate.getStack();
     // No causal frames because we are in a completely synchronous stack.
-    if (useCausalAsyncStacks) {
-      expect(stack['asyncCausalFrames'], isNull);
-    } else {
-      // TODO(dartbug.com/37668): Implement suport for this in the debugger.
-      expect(stack['asyncCausalFrames'], isNotNull);
-    }
+    expect(stack['asyncCausalFrames'], isNull);
   },
   resumeIsolate,
   hasStoppedAtBreakpoint,

runtime/observatory/tests/service/causal_async_stack_presence_test.dart

@@ -36,12 +36,7 @@ var tests = <IsolateTest>[
   (Isolate isolate) async {
     ServiceMap stack = await isolate.getStack();
     // No causal frames because we are in a completely synchronous stack.
-    if (useCausalAsyncStacks) {
-      expect(stack['asyncCausalFrames'], isNull);
-    } else {
-      // TODO(dartbug.com/37668): Implement suport for this in the debugger.
-      expect(stack['asyncCausalFrames'], isNotNull);
-    }
+    expect(stack['asyncCausalFrames'], isNull);
   },
   resumeIsolate,
   hasStoppedAtBreakpoint,

runtime/vm/debugger.cc

@@ -2348,8 +2348,14 @@ DebuggerStackTrace* Debugger::CollectAsyncLazyStackTrace() {
       zone, GrowableObjectArray::New(kDefaultStackAllocation));
   const auto& pc_offset_array = GrowableObjectArray::ZoneHandle(
       zone, GrowableObjectArray::New(kDefaultStackAllocation));
+  bool has_async = false;
   StackTraceUtils::CollectFramesLazy(thread, code_array, pc_offset_array,
-                                     /*skip_frames=*/0, &on_sync_frame);
+                                     /*skip_frames=*/0, &on_sync_frame,
+                                     &has_async);
+
+  if (!has_async) {
+    return nullptr;
+  }
 
   const intptr_t length = code_array.Length();
   for (intptr_t i = stack_trace->Length(); i < length; ++i) {

runtime/vm/stack_trace.cc

@@ -309,7 +309,11 @@ void StackTraceUtils::CollectFramesLazy(
     const GrowableObjectArray& code_array,
     const GrowableObjectArray& pc_offset_array,
     int skip_frames,
-    std::function<void(StackFrame*)>* on_sync_frames) {
+    std::function<void(StackFrame*)>* on_sync_frames,
+    bool* has_async) {
+  if (has_async != nullptr) {
+    *has_async = false;
+  }
   Zone* zone = thread->zone();
   DartFrameIterator frames(thread, StackFrameIterator::kNoCrossThreadIteration);
   StackFrame* frame = frames.NextFrame();
@@ -363,6 +367,10 @@ void StackTraceUtils::CollectFramesLazy(
     // Either continue the loop (sync-async case) or find all await'ers and
     // return.
     if (function.IsAsyncClosure() || function.IsAsyncGenClosure()) {
+      if (has_async != nullptr) {
+        *has_async = true;
+      }
+
       // Next, look up caller's closure on the stack and walk backwards through
       // the yields.
       frame = frames.NextFrame();

runtime/vm/stack_trace.h

@@ -37,7 +37,8 @@ class StackTraceUtils : public AllStatic {
       const GrowableObjectArray& code_array,
       const GrowableObjectArray& pc_offset_array,
       int skip_frames,
-      std::function<void(StackFrame*)>* on_sync_frames = nullptr);
+      std::function<void(StackFrame*)>* on_sync_frames = nullptr,
+      bool* has_async = nullptr);
 
   /// Counts the number of stack frames.
   /// Skips over the first |skip_frames|.