CppEditor: Allow force highlighting if using clang

...so we can rehighlight if it's requested by the editor. This is e.g.
necessary if the font size changes.

Task-number: QTCREATORBUG-11502
Change-Id: I608921899fc37fcf1394db9ff041e6b378196bdd
Reviewed-by: Erik Verbruggen <erik.verbruggen@digia.com>

src/plugins/cppeditor/cppeditor.cpp

@@ -1591,8 +1591,12 @@ bool CPPEditorWidget::openCppEditorAt(const Link &link, bool inNextSplit)
 
 void CPPEditorWidget::semanticRehighlight(bool force)
 {
-    if (m_modelManager)
+    if (m_modelManager) {
-        m_modelManager->cppEditorSupport(editor())->recalculateSemanticInfoDetached(force);
+        const CppEditorSupport::ForceReason forceReason = force
+                ? CppEditorSupport::ForceDueEditorRequest
+                : CppEditorSupport::NoForce;
+        m_modelManager->cppEditorSupport(editor())->recalculateSemanticInfoDetached(forceReason);
+    }
 }
 
 void CPPEditorWidget::highlighterStarted(QFuture<TextEditor::HighlightingResult> *highlighter,

src/plugins/cpptools/cpptoolseditorsupport.cpp

@@ -237,7 +237,7 @@ Document::Ptr CppEditorSupport::lastSemanticInfoDocument() const
     return m_lastSemanticInfo.doc;
 }
 
-void CppEditorSupport::recalculateSemanticInfoDetached(bool force)
+void CppEditorSupport::recalculateSemanticInfoDetached(ForceReason forceReason)
 {
     // Block premature calculation caused by CppEditorPlugin::currentEditorChanged
     // when the editor is created.
@@ -245,12 +245,13 @@ void CppEditorSupport::recalculateSemanticInfoDetached(bool force)
         return;
 
     m_futureSemanticInfo.cancel();
+    const bool force = forceReason != NoForce;
     SemanticInfo::Source source = currentSource(force);
     m_futureSemanticInfo = QtConcurrent::run<CppEditorSupport, void>(
                 &CppEditorSupport::recalculateSemanticInfoDetached_helper, this, source);
 
     if (force && m_highlightingSupport && !m_highlightingSupport->requiresSemanticInfo())
-        startHighlighting();
+        startHighlighting(forceReason);
 }
 
 CppCompletionAssistProvider *CppEditorSupport::completionAssistProvider() const
@@ -352,14 +353,14 @@ void CppEditorSupport::onDocumentUpdated(Document::Ptr doc)
                  || m_lastSemanticInfo.doc->translationUnit()->ast() == 0
                  || m_lastSemanticInfo.doc->fileName() != fileName()))) {
         m_initialized = true;
-        recalculateSemanticInfoDetached(/* force = */ true);
+        recalculateSemanticInfoDetached(ForceDueToMissingSemanticInfo);
     }
 
     // notify the editor that the document is updated
     emit documentUpdated();
 }
 
-void CppEditorSupport::startHighlighting()
+void CppEditorSupport::startHighlighting(ForceReason forceReason)
 {
     if (!m_highlightingSupport)
         return;
@@ -395,8 +396,8 @@ void CppEditorSupport::startHighlighting()
         m_lastHighlightOnCompleteSemanticInfo = complete;
         emit highlighterStarted(&m_highlighter, m_lastHighlightRevision);
     } else {
-        const unsigned revision = currentSource(false).revision;
+        const unsigned revision = editorRevision();
-        if (m_lastHighlightRevision == revision)
+        if (forceReason != ForceDueEditorRequest && m_lastHighlightRevision == revision)
             return;
 
         m_highlighter.cancel();

src/plugins/cpptools/cpptoolseditorsupport.h

@@ -119,11 +119,17 @@ public:
 
     CPlusPlus::Document::Ptr lastSemanticInfoDocument() const;
 
+    enum ForceReason {
+        NoForce,
+        ForceDueToMissingSemanticInfo,
+        ForceDueEditorRequest
+    };
+
     /// Recalculates the semantic info in a future, and will emit the
     /// semanticInfoUpdated() signal when finished.
     /// Requires that initialized() is true.
-    /// \param force do not check if the old semantic info is still valid
+    /// \param forceReason the reason to force, if any
-    void recalculateSemanticInfoDetached(bool force = false);
+    void recalculateSemanticInfoDetached(ForceReason forceReason);
 
     CppCompletionAssistProvider *completionAssistProvider() const;
 
@@ -148,7 +154,7 @@ private slots:
     void updateDocumentNow();
 
     void onDocumentUpdated(CPlusPlus::Document::Ptr doc);
-    void startHighlighting();
+    void startHighlighting(ForceReason forceReason = NoForce);
 
     void onDiagnosticsChanged();