CppTypeHierarchy: Don't create/store QIcon in non-GUI thread

Store Utils::CodeModelIcon::Type enum instead.
Drop unneeded CPlusPlus::Symbol *declaration from CppDeclarableElement.
Remove unused CppClass::operator==().

Task-number: QTCREATORBUG-28529
Change-Id: Ie3487fa5f73d714ef375c42f1e64023ccc4194ee
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>

src/plugins/cppeditor/cppelementevaluator.cpp

@@ -94,8 +94,7 @@ public:
 // CppDeclarableElement
 CppDeclarableElement::CppDeclarableElement(Symbol *declaration)
     : CppElement()
-    , declaration(declaration)
-    , icon(Icons::iconForSymbol(declaration))
+    , iconType(Icons::iconTypeForSymbol(declaration))
 {
     Overview overview;
     overview.showArgumentNames = true;
@@ -135,11 +134,6 @@ CppClass::CppClass(Symbol *declaration) : CppDeclarableElement(declaration)
     tooltip = qualifiedName;
 }
 
-bool CppClass::operator==(const CppClass &other)
-{
-    return this->declaration == other.declaration;
-}
-
 CppClass *CppClass::toCppClass()
 {
     return this;

src/plugins/cppeditor/cppelementevaluator.h

@@ -5,6 +5,7 @@
 
 #include <coreplugin/helpitem.h>
 #include <texteditor/texteditor.h>
+#include <utils/utilsicons.h>
 
 #include <cplusplus/CppDocument.h>
 
@@ -76,11 +77,10 @@ public:
     explicit CppDeclarableElement(CPlusPlus::Symbol *declaration);
 
 public:
-    CPlusPlus::Symbol *declaration;
+    Utils::CodeModelIcon::Type iconType;
     QString name;
     QString qualifiedName;
     QString type;
-    QIcon icon;
 };
 
 class CppClass : public CppDeclarableElement
@@ -89,8 +89,6 @@ public:
     CppClass();
     explicit CppClass(CPlusPlus::Symbol *declaration);
 
-    bool operator==(const CppClass &other);
-
     CppClass *toCppClass() final;
 
     void lookupBases(QFutureInterfaceBase &futureInterface,

src/plugins/cppeditor/cpptypehierarchy.cpp

@@ -44,7 +44,7 @@ QStandardItem *itemForClass(const CppClass &cppClass)
     item->setData(cppClass.name, Qt::DisplayRole);
     if (cppClass.name != cppClass.qualifiedName)
         item->setData(cppClass.qualifiedName, AnnotationRole);
-    item->setData(cppClass.icon, Qt::DecorationRole);
+    item->setData(iconForType(cppClass.iconType), Qt::DecorationRole);
     QVariant link;
     link.setValue(Link(cppClass.link));
     item->setData(link, LinkRole);