TextEditor: Introduce shortcut for forcing a function hint proposal

... and support it in the ClangCodeModel.
This allows users to get function signature(s) displayed regardless of
where exactly the cursor is on the function call.

Fixes: QTCREATORBUG-19394
Change-Id: I033e8774db93680bfc3ee52610b817e0ef8ccc76
Reviewed-by: David Schulz <david.schulz@qt.io>

src/plugins/cpptools/cppbuiltinmodelmanagersupport.cpp

@@ -74,6 +74,12 @@ CppCompletionAssistProvider *BuiltinModelManagerSupport::completionAssistProvide
     return m_completionAssistProvider.data();
 }
 
+
+CppCompletionAssistProvider *BuiltinModelManagerSupport::functionHintAssistProvider()
+{
+    return nullptr;
+}
+
 TextEditor::BaseHoverHandler *BuiltinModelManagerSupport::createHoverHandler()
 {
     return new CppHoverHandler;

src/plugins/cpptools/cppbuiltinmodelmanagersupport.h

@@ -41,6 +41,7 @@ public:
     ~BuiltinModelManagerSupport() override;
 
     CppCompletionAssistProvider *completionAssistProvider() final;
+    CppCompletionAssistProvider *functionHintAssistProvider() override;
     TextEditor::BaseHoverHandler *createHoverHandler() final;
     BaseEditorDocumentProcessor *createEditorDocumentProcessor(
             TextEditor::TextDocument *baseTextDocument) final;

src/plugins/cpptools/cppmodelmanager.cpp

@@ -1442,6 +1442,11 @@ CppCompletionAssistProvider *CppModelManager::completionAssistProvider() const
     return d->m_activeModelManagerSupport->completionAssistProvider();
 }
 
+CppCompletionAssistProvider *CppModelManager::functionHintAssistProvider() const
+{
+    return d->m_activeModelManagerSupport->functionHintAssistProvider();
+}
+
 TextEditor::BaseHoverHandler *CppModelManager::createHoverHandler() const
 {
     return d->m_activeModelManagerSupport->createHoverHandler();

src/plugins/cpptools/cppmodelmanager.h

@@ -180,6 +180,7 @@ public:
 
     void activateClangCodeModel(ModelManagerSupportProvider *modelManagerSupportProvider);
     CppCompletionAssistProvider *completionAssistProvider() const;
+    CppCompletionAssistProvider *functionHintAssistProvider() const;
     BaseEditorDocumentProcessor *createEditorDocumentProcessor(
                     TextEditor::TextDocument *baseTextDocument) const;
     TextEditor::BaseHoverHandler *createHoverHandler() const;

src/plugins/cpptools/cppmodelmanagersupport.h

@@ -54,6 +54,7 @@ public:
     virtual ~ModelManagerSupport() = 0;
 
     virtual CppCompletionAssistProvider *completionAssistProvider() = 0;
+    virtual CppCompletionAssistProvider *functionHintAssistProvider() = 0;
     virtual TextEditor::BaseHoverHandler *createHoverHandler() = 0;
     virtual BaseEditorDocumentProcessor *createEditorDocumentProcessor(
                 TextEditor::TextDocument *baseTextDocument) = 0;