LSP: fix codeassists running check

Since MessageId is always valid (needs to be fixed separately)
use an optional to store whether we have a request running.

Change-Id: I7a1f136a09d776b33509bc914247d11076abeaa5
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

src/plugins/languageclient/languageclientfunctionhint.cpp

@@ -57,7 +57,9 @@ private:
 
 QString FunctionHintProposalModel::text(int index) const
 {
-    return m_sigis.signatures().size() > index ? m_sigis.signatures().at(index).label() : QString();
+    if (index < 0 || m_sigis.signatures().size() >= index)
+        return {};
+    return m_sigis.signatures().at(index).label();
 }
 
 class FunctionHintProcessor : public IAssistProcessor
@@ -65,7 +67,7 @@ class FunctionHintProcessor : public IAssistProcessor
 public:
     explicit FunctionHintProcessor(Client *client) : m_client(client) {}
     IAssistProposal *perform(const AssistInterface *interface) override;
-    bool running() override { return m_currentRequest.isValid(); }
+    bool running() override { return m_currentRequest.has_value(); }
     bool needsRestart() const override { return true; }
     void cancel() override;
 
@@ -73,7 +75,7 @@ private:
     void handleSignatureResponse(const SignatureHelpRequest::Response &response);
 
     QPointer<Client> m_client;
-    MessageId m_currentRequest;
+    Utils::optional<MessageId> m_currentRequest;
     int m_pos = -1;
 };
 
@@ -95,15 +97,15 @@ IAssistProposal *FunctionHintProcessor::perform(const AssistInterface *interface
 void FunctionHintProcessor::cancel()
 {
     if (running()) {
-        m_client->cancelRequest(m_currentRequest);
+        m_client->cancelRequest(m_currentRequest.value());
         m_client->removeAssistProcessor(this);
-        m_currentRequest = MessageId();
+        m_currentRequest.reset();
     }
 }
 
 void FunctionHintProcessor::handleSignatureResponse(const SignatureHelpRequest::Response &response)
 {
-    m_currentRequest = MessageId();
+    m_currentRequest.reset();
     if (auto error = response.error())
         m_client->log(error.value());
     m_client->removeAssistProcessor(this);