Fix exception description in lldb-vscode

There is a bug in lldb-vscode that only shows stop reason ("exception") in
stopped event without showing the stop description of thrown exception. This
causes VSCode UI to only show "Paused on Exception" general message in
callstack window UI.

This patch fixes the bug so that VSCode callstack will show the detailed
exceptioni description, like "signal SIGABRT" or "EXC_BAD_ACCESS..." which
aligns with command line lldb experience.

I use C++ exception in testcase because the hardware exception description is
platform dependent and hard to verify.

Differential Revision: https://reviews.llvm.org/D136295

lldb/packages/Python/lldbsuite/test/tools/lldb-vscode/lldbvscode_testcase.py

@@ -93,10 +93,10 @@ class VSCodeTestCaseBase(TestBase):
                         return
         self.assertTrue(False, "breakpoint not hit")
 
-    def verify_exception_breakpoint_hit(self, filter_label):
+    def verify_stop_exception_info(self, expected_description):
         '''Wait for the process we are debugging to stop, and verify the stop
            reason is 'exception' and that the description matches
-           'filter_label'
+           'expected_description'
         '''
         stopped_events = self.vscode.wait_for_stopped()
         for stopped_event in stopped_events:
@@ -109,7 +109,7 @@ class VSCodeTestCaseBase(TestBase):
                 if 'description' not in body:
                     continue
                 description = body['description']
-                if filter_label == description:
+                if expected_description == description:
                     return True
         return False
 
@@ -236,7 +236,7 @@ class VSCodeTestCaseBase(TestBase):
 
     def continue_to_exception_breakpoint(self, filter_label):
         self.vscode.request_continue()
-        self.assertTrue(self.verify_exception_breakpoint_hit(filter_label),
+        self.assertTrue(self.verify_stop_exception_info(filter_label),
                         'verify we got "%s"' % (filter_label))
 
     def continue_to_exit(self, exitCode=0):

lldb/test/API/tools/lldb-vscode/exception/Makefile

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

lldb/test/API/tools/lldb-vscode/exception/TestVSCode_exception.py

@@ -0,0 +1,24 @@
+"""
+Test exception behavior in VSCode
+"""
+
+
+from lldbsuite.test.decorators import *
+from lldbsuite.test.lldbtest import *
+import lldbvscode_testcase
+
+
+class TestVSCode_exception(lldbvscode_testcase.VSCodeTestCaseBase):
+
+    @skipIfWindows
+    def test_stopped_description(self):
+        '''
+            Test that exception description is shown correctly in stopped
+            event.
+        '''
+        program = self.getBuildArtifact("a.out")
+        print("test_stopped_description called", flush=True)
+        self.build_and_launch(program)
+
+        self.vscode.request_continue()
+        self.assertTrue(self.verify_stop_exception_info("signal SIGABRT"))

lldb/test/API/tools/lldb-vscode/exception/main.cpp

@@ -0,0 +1,6 @@
+#include <signal.h>
+
+int main() {
+  raise(SIGABRT);
+  return 0;
+}

lldb/tools/lldb-vscode/JSONUtils.cpp

@@ -930,7 +930,7 @@ llvm::json::Value CreateThreadStopped(lldb::SBThread &thread,
   // If no description has been set, then set it to the default thread stopped
   // description. If we have breakpoints that get hit and shouldn't be reported
   // as breakpoints, then they will set the description above.
-  if (ObjectContainsKey(body, "description")) {
+  if (!ObjectContainsKey(body, "description")) {
     char description[1024];
     if (thread.GetStopDescription(description, sizeof(description))) {
       EmplaceSafeString(body, "description", std::string(description));