Clang: Highlight invalid declarations as text

...instead of the corresponding declaration color.

Task-number: QTCREATORBUG-18686
Change-Id: Ice4d84816351af79efa286f49516c392bd80da86
Reviewed-by: Ivan Donchevskii <ivan.donchevskii@qt.io>

src/tools/clangbackend/source/cursor.cpp

@@ -29,6 +29,8 @@
 #include "sourcelocation.h"
 #include "sourcerange.h"
 
+#include "clangbackend_global.h"
+
 #include <ostream>
 
 namespace ClangBackEnd {
@@ -103,6 +105,15 @@ bool Cursor::isDeclaration() const
     return clang_isDeclaration(kind());
 }
 
+bool Cursor::isInvalidDeclaration() const
+{
+#ifdef IS_INVALIDDECL_SUPPORTED
+    return clang_isInvalidDeclaration(cxCursor);
+#else
+    return false;
+#endif
+}
+
 bool Cursor::isLocalVariable() const
 {
     switch (semanticParent().kind()) {