Clang: Fallback to global completion if function call completion fails

We can not offer proper constructor completion with libclang <= 3.6, so
fall back to normal/global completion.

Change-Id: I90bb8d981ae20ed4c228f829ad4267221b92f8a1
Reviewed-by: Marco Bubke <marco.bubke@theqtcompany.com>

src/plugins/clangcodemodel/clangbackendipcintegration.cpp

@@ -145,8 +145,11 @@ void IpcReceiver::codeCompleted(const CodeCompletedCommand &command)
 
     const quint64 ticket = command.ticketNumber();
     QScopedPointer<ClangCompletionAssistProcessor> processor(m_assistProcessorsTable.take(ticket));
-    if (processor)
-        processor->handleAvailableAsyncCompletions(command.codeCompletions());
+    if (processor) {
+        const bool finished = processor->handleAvailableAsyncCompletions(command.codeCompletions());
+        if (!finished)
+            processor.take();
+    }
 }
 
 void IpcReceiver::translationUnitDoesNotExist(const TranslationUnitDoesNotExistCommand &command)

src/plugins/clangcodemodel/clangcompletionassistprocessor.cpp

@@ -232,20 +232,24 @@ IAssistProposal *ClangCompletionAssistProcessor::perform(const AssistInterface *
     return startCompletionHelper(); // == 0 if results are calculated asynchronously
 }
 
-void ClangCompletionAssistProcessor::handleAvailableAsyncCompletions(
+bool ClangCompletionAssistProcessor::handleAvailableAsyncCompletions(
         const CodeCompletions &completions)
 {
+    bool handled = true;
+
     switch (m_sentRequestType) {
     case CompletionRequestType::NormalCompletion:
         handleAvailableCompletions(completions);
         break;
     case CompletionRequestType::FunctionHintCompletion:
-        handleAvailableFunctionHintCompletions(completions);
+        handled = handleAvailableFunctionHintCompletions(completions);
         break;
     default:
         QTC_CHECK(!"Unhandled ClangCompletionAssistProcessor::CompletionRequestType");
         break;
     }
+
+    return handled;
 }
 
 const TextEditorWidget *ClangCompletionAssistProcessor::textEditorWidget() const
@@ -704,7 +708,7 @@ void ClangCompletionAssistProcessor::handleAvailableCompletions(const CodeComple
     setAsyncProposalAvailable(createProposal());
 }
 
-void ClangCompletionAssistProcessor::handleAvailableFunctionHintCompletions(
+bool ClangCompletionAssistProcessor::handleAvailableFunctionHintCompletions(
         const CodeCompletions &completions)
 {
     QTC_CHECK(!m_functionName.isEmpty());
@@ -715,9 +719,13 @@ void ClangCompletionAssistProcessor::handleAvailableFunctionHintCompletions(
         auto *proposal = new FunctionHintProposal(m_positionForProposal, model);
 
         setAsyncProposalAvailable(proposal);
+        return true;
     } else {
-        QTC_CHECK(!"Function completion failed. Would fallback to global completion here...");
-        // TODO: If we need this, the processor can't be deleted in IpcClient.
+        m_addSnippets = false;
+        m_functionName.clear();
+        m_sentRequestType = NormalCompletion;
+        sendCompletionRequest(m_interface->position(), QByteArray());
+        return false; // We are not yet finished.
     }
 }
 

src/plugins/clangcodemodel/clangcompletionassistprocessor.h

@@ -59,7 +59,7 @@ public:
 
     TextEditor::IAssistProposal *perform(const TextEditor::AssistInterface *interface) override;
 
-    void handleAvailableAsyncCompletions(const CodeCompletions &completions);
+    bool handleAvailableAsyncCompletions(const CodeCompletions &completions);
 
     const TextEditor::TextEditorWidget *textEditorWidget() const;
 
@@ -91,7 +91,7 @@ private:
     void sendCompletionRequest(int position, const QByteArray &customFileContent);
 
     void handleAvailableCompletions(const CodeCompletions &completions);
-    void handleAvailableFunctionHintCompletions(const CodeCompletions &completions);
+    bool handleAvailableFunctionHintCompletions(const CodeCompletions &completions);
 
 private:
     QScopedPointer<const ClangCompletionAssistInterface> m_interface;

src/plugins/clangcodemodel/test/clang_tests_database.qrc

@@ -20,5 +20,6 @@
         <file>exampleIncludeDir/otherFile.h</file>
         <file>exampleIncludeDir/mylib/mylib.h</file>
         <file>globalCompletion.cpp</file>
+        <file>constructorCompletion.cpp</file>
     </qresource>
 </RCC>

src/plugins/clangcodemodel/test/clangcodecompletion_test.cpp

@@ -874,6 +874,15 @@ void ClangCodeCompletionTest::testCompleteFunctions()
     QVERIFY(hasItem(t.proposal, "TType<QString> f(bool)"));
 }
 
+void ClangCodeCompletionTest::testCompleteConstructorAndFallbackToGlobalCompletion()
+{
+    ProjectLessCompletionTest t("constructorCompletion.cpp");
+
+    QVERIFY(hasItem(t.proposal, "globalVariable"));
+    QVERIFY(hasItem(t.proposal, "GlobalClassWithCustomConstructor"));
+    QVERIFY(!hasSnippet(t.proposal, "class"));
+}
+
 void ClangCodeCompletionTest::testProjectDependentCompletion()
 {
     const TestDocument testDocument("completionWithProject.cpp");

src/plugins/clangcodemodel/test/clangcodecompletion_test.h

@@ -57,6 +57,7 @@ private slots:
     void testCompleteGlobals();
     void testCompleteMembers();
     void testCompleteFunctions();
+    void testCompleteConstructorAndFallbackToGlobalCompletion();
 
     void testProjectDependentCompletion();
     void testChangingProjectDependentCompletion();

src/plugins/clangcodemodel/test/constructorCompletion.cpp

@@ -0,0 +1,9 @@
+int globalVariable;
+
+struct GlobalClassWithCustomConstructor {
+    GlobalClassWithCustomConstructor(int) {}
+};
+
+void f() {
+    GlobalClassWithCustomConstructor foo( /* COMPLETE HERE */
+}