CodeAssistant: add cancel to asynchronous processors

Fixes crash when the processor reports a result after the code assistant
was destroyed.

Change-Id: I8588d3d6acad69f1ec6302e8ba09d642ebbb77f1
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

1 files changed, 13 insertions, 4 deletions

diff --git a/src/plugins/languageclient/languageclientfunctionhint.cpp b/src/plugins/languageclient/languageclientfunctionhint.cpp
index 5e711adec6..3361864973 100644
--- a/src/plugins/languageclient/languageclientfunctionhint.cpp
+++ b/src/plugins/languageclient/languageclientfunctionhint.cpp
@@ -65,14 +65,15 @@ class FunctionHintProcessor : public IAssistProcessor
 public:
     explicit FunctionHintProcessor(Client *client) : m_client(client) {}
     IAssistProposal *perform(const AssistInterface *interface) override;
-    bool running() override { return m_running; }
+    bool running() override { return m_currentRequest.isValid(); }
     bool needsRestart() const override { return true; }
+    void cancel() override;
 
 private:
     void handleSignatureResponse(const SignatureHelpRequest::Response &response);
 
     QPointer<Client> m_client;
-    bool m_running = false;
+    MessageId m_currentRequest;
     int m_pos = -1;
 };
 
@@ -87,13 +88,21 @@ IAssistProposal *FunctionHintProcessor::perform(const AssistInterface *interface
     request.setParams(TextDocumentPositionParams(TextDocumentIdentifier(uri), Position(cursor)));
     request.setResponseCallback([this](auto response) { this->handleSignatureResponse(response); });
     m_client->sendContent(request);
-    m_running = true;
+    m_currentRequest = request.id();
     return nullptr;
 }
 
+void FunctionHintProcessor::cancel()
+{
+    if (running()) {
+        m_client->cancelRequest(m_currentRequest);
+        m_currentRequest = MessageId();
+    }
+}
+
 void FunctionHintProcessor::handleSignatureResponse(const SignatureHelpRequest::Response &response)
 {
-    m_running = false;
+    m_currentRequest = MessageId();
     if (auto error = response.error())
         m_client->log(error.value());
     FunctionHintProposalModelPtr model(