CppEditor: Render forward decls less prominently in outline

Fixes: QTCREATORBUG-312
Change-Id: I9bb77add24737881eeee008620941b55118ee0e5
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>
Reviewed-by: David Schulz <david.schulz@qt.io>

src/plugins/clangcodemodel/clangdclient.cpp

@@ -62,6 +62,7 @@
 #include <utils/fileutils.h>
 #include <utils/itemviews.h>
 #include <utils/runextensions.h>
+#include <utils/theme/theme.h>
 #include <utils/utilsicons.h>
 
 #include <QAction>
@@ -135,9 +136,16 @@ class ClangdOutlineItem : public LanguageClientOutlineItem
 private:
     QVariant data(int column, int role) const override
     {
-        if (role == Qt::DisplayRole) {
+        switch (role) {
+        case Qt::DisplayRole:
             return ClangdClient::displayNameFromDocumentSymbol(
                 static_cast<SymbolKind>(type()), name(), detail());
+        case Qt::ForegroundRole:
+            if ((detail().endsWith("class") || detail().endsWith("struct"))
+                && range().end() == selectionRange().end()) {
+                return creatorTheme()->color(Theme::TextColorDisabled);
+            }
+            break;
         }
         return LanguageClientOutlineItem::data(column, role);
     }

src/plugins/cppeditor/cppoutlinemodel.cpp

@@ -11,6 +11,7 @@
 
 #include <utils/linecolumn.h>
 #include <utils/link.h>
+#include <utils/theme/theme.h>
 
 #include <QTimer>
 
@@ -103,6 +104,24 @@ public:
             return name;
         }
 
+        case Qt::ForegroundRole: {
+            const auto isFwdDecl = [&] {
+                const FullySpecifiedType type = symbol->type();
+                if (type->asForwardClassDeclarationType())
+                    return true;
+                if (const Template * const tmpl = type->asTemplateType())
+                    return tmpl->declaration() && tmpl->declaration()->asForwardClassDeclaration();
+                if (type->asObjCForwardClassDeclarationType())
+                    return true;
+                if (type->asObjCForwardProtocolDeclarationType())
+                    return true;
+                return false;
+            };
+            if (isFwdDecl())
+                return Utils::creatorTheme()->color(Utils::Theme::TextColorDisabled);
+            return TreeItem::data(column, role);
+        }
+
         case Qt::DecorationRole:
             return Icons::iconForSymbol(symbol);
 

src/plugins/languageclient/languageclientoutline.cpp

@@ -404,6 +404,7 @@ LanguageClientOutlineItem::LanguageClientOutlineItem(Client *client, const Docum
     , m_name(info.name())
     , m_detail(info.detail().value_or(QString()))
     , m_range(info.range())
+    , m_selectionRange(info.selectionRange())
     , m_type(info.kind())
 {
     const QList<LanguageServerProtocol::DocumentSymbol> children = sortedSymbols(

src/plugins/languageclient/languageclientoutline.h

@@ -27,6 +27,7 @@ public:
     LanguageClientOutlineItem(Client *client, const LanguageServerProtocol::DocumentSymbol &info);
 
     LanguageServerProtocol::Range range() const { return m_range; }
+    LanguageServerProtocol::Range selectionRange() const { return m_selectionRange; }
     LanguageServerProtocol::Position pos() const { return m_range.start(); }
     bool contains(const LanguageServerProtocol::Position &pos) const {
         return m_range.contains(pos);
@@ -46,6 +47,7 @@ private:
     QString m_name;
     QString m_detail;
     LanguageServerProtocol::Range m_range;
+    LanguageServerProtocol::Range m_selectionRange;
     int m_type = -1;
 };