Editor: Fix dangling completion widgets

Set the correct assist reason when rerequesting a code assist to be able
to detect perfect matches. Also destroy the code assist context when the
processor is not running and has not returned a proposal after perform.

Change-Id: Ieb04203269076655ac3d7ffc54ea8a1d055194a4
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>

src/plugins/texteditor/codeassist/codeassistant.cpp

@@ -284,6 +284,7 @@ void CodeAssistantPrivate::requestProposal(AssistReason reason,
             displayProposal(newProposal, reason);
             delete processor;
         } else if (!processor->running()) {
+            destroyContext();
             delete processor;
         } else { // ...async request was triggered
             if (IAssistProposal *newProposal = processor->immediateProposal(assistInterface))
@@ -354,6 +355,7 @@ void CodeAssistantPrivate::displayProposal(IAssistProposal *newProposal, AssistR
 
     clearAbortedPosition();
     m_proposal.reset(proposalCandidate.take());
+    m_proposal->setReason(reason);
 
     if (m_proposal->isCorrective(m_editorWidget))
         m_proposal->makeCorrection(m_editorWidget);
@@ -485,7 +487,7 @@ void CodeAssistantPrivate::notifyChange()
             if (!isDisplayingProposal())
                 requestActivationCharProposal();
         } else {
-            requestProposal(ExplicitlyInvoked, m_assistKind, m_requestProvider);
+            requestProposal(m_proposal->reason(), m_assistKind, m_requestProvider);
         }
     }
 }

src/plugins/texteditor/codeassist/iassistproposal.h

@@ -57,11 +57,15 @@ public:
 
     Utils::Id id() const { return m_id; }
 
+    AssistReason reason() const { return m_reason; }
+    void setReason(const AssistReason &reason) { m_reason = reason; }
+
 protected:
     Utils::Id m_id;
     int m_basePosition;
     bool m_isFragile = false;
     bool m_supportsPrefix = true;
+    AssistReason m_reason;
 };
 
 } // TextEditor