[lldb-vscode] Fix handling of RestartRequest arguments.

[jgorbe]

Summary

According to the spec, RestartRequest has an optional "arguments" field, which
is a RestartArguments object. RestartArguments has its own optional "arguments"
field, which is a (LaunchRequestArguments | AttachRequestArguments) object. So
we need to to the "arguments" lookup twice to get to the actual launch
arguments.

[rupprecht]

Is there a test case you can add for this?

[jgorbe]

Added test case.

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

def request_continue(self, threadId=None):
             'command': 'continue',
             'type': 'request',
             'arguments': args_dict
         }
         response = self.send_recv(command_dict)
         # Caller must still call wait_for_stopped.
         return response
 
-    def request_restart(self):
+    def request_restart(self, restartArguments=None):
         command_dict = {
             'command': 'restart',
             'type': 'request',
         }
+        if restartArguments:
+          command_dict['arguments'] = restartArguments
+
         response = self.send_recv(command_dict)
         # Caller must still call wait_for_stopped.
         return response
 
     def request_disconnect(self, terminateDebuggee=None):
         args_dict = {}
         if terminateDebuggee is not None:
             if terminateDebuggee:

lldb/test/API/tools/lldb-vscode/restart/TestVSCode_restart.py

def test_stopOnEntry(self):
             if 'body' in stopped_event:
                 body = stopped_event['body']
                 if 'reason' in body:
                     reason = body['reason']
                     self.assertNotEqual(
                         reason, 'breakpoint',
                         'verify stop after restart isn\'t "main" breakpoint')
 
+    @skipIfWindows
+    @skipIfRemote
+    def test_arguments(self):
+        '''
+            Tests that lldb-vscode will use updated launch arguments included
+            with a restart request.
+        '''
+        line_A = line_number('main.c', '// breakpoint A')
+
+        program = self.getBuildArtifact("a.out")
+        self.build_and_launch(program)
+        [bp_A] = self.set_source_breakpoints('main.c', [line_A])
+
+        # Verify we hit A, then B.
+        self.vscode.request_configurationDone()
+        self.verify_breakpoint_hit([bp_A])
+
+        # We don't set any arguments in the initial launch request, so argc
+        # should be 1.
+        self.assertEquals(int(self.vscode.get_local_variable_value('argc')),
+                          1, 'argc != 1 before restart')
+
+        # Restart with some extra 'args' and check that the new argc reflects
+        # the updated launch config.
+        self.vscode.request_restart(restartArguments={
+            'arguments': {
+                'program': program,
+                'args': ['a', 'b', 'c', 'd'],
+            }
+        })
+        self.verify_breakpoint_hit([bp_A])
+        self.assertEquals(int(self.vscode.get_local_variable_value('argc')),
+                          5, 'argc != 5 after restart')
+

lldb/tools/lldb-vscode/lldb-vscode.cpp

if (GetString(*g_vsc.last_launch_or_attach_request, "command") == "attach") {
     EmplaceSafeString(response, "message",
                       "Restarting an \"attach\" session is not supported.");
     g_vsc.SendJSON(llvm::json::Value(std::move(response)));
     return;
   }
 
   // The optional `arguments` field in RestartRequest can contain an updated
   // version of the launch arguments. If there's one, use it.
-  auto request_arguments = request.getObject("arguments");
-  if (request_arguments) {
-    llvm::json::Object arguments = *request_arguments;
+  auto restart_arguments = request.getObject("arguments");
+  if (restart_arguments) {
+    auto launch_request_arguments = restart_arguments->getObject("arguments");
+    if (launch_request_arguments) {
       (*g_vsc.last_launch_or_attach_request)["arguments"] =
-        llvm::json::Value(std::move(arguments));
+          llvm::json::Value(llvm::json::Object(*launch_request_arguments));
+    }
   }
 
   // Keep track of the old PID so when we get a "process exited" event from the
   // killed process we can detect it and not shut down the whole session.
   lldb::SBProcess process = g_vsc.target.GetProcess();
   g_vsc.restarting_process_id = process.GetProcessID();
 
   // Stop the current process if necessary. The logic here is similar to