Should eventually be replaced by upstream fix, see https://bugreports.qt.io/browse/QTBUG-129146.

diff --git a/src/linguist/lupdate/clangtoolastreader.cpp b/src/linguist/lupdate/clangtoolastreader.cpp
index 6b85c6c..63ddf3d 100644
--- a/src/linguist/lupdate/clangtoolastreader.cpp
+++ b/src/linguist/lupdate/clangtoolastreader.cpp
@@ -782,7 +782,7 @@ bool LupdateVisitor::VisitNamedDecl(clang::NamedDecl *namedDeclaration)
     if (!fullLocation.isValid() || !fullLocation.getFileEntry())
         return true;
 
-    if (!LupdatePrivate::isFileSignificant(fullLocation.getFileEntry()->getName().str()))
+    if (!LupdatePrivate::isFileSignificant(fullLocation.getFileEntry()->tryGetRealPathName().str()))
         return true;
 
     qCDebug(lcClang) << "NamedDecl Name:   " << QString::fromStdString(namedDeclaration->getQualifiedNameAsString());
diff --git a/src/qdoc/qdoc/src/qdoc/clangcodeparser.cpp b/src/qdoc/qdoc/src/qdoc/clangcodeparser.cpp
index bd3cc63..c5ec3d4 100644
--- a/src/qdoc/qdoc/src/qdoc/clangcodeparser.cpp
+++ b/src/qdoc/qdoc/src/qdoc/clangcodeparser.cpp
@@ -168,7 +168,11 @@ static std::string get_expression_as_string(const clang::Expr* expression, const
  */
 static std::string get_default_value_initializer_as_string(const clang::TemplateTypeParmDecl* parameter) {
     return (parameter && parameter->hasDefaultArgument()) ?
+#if LIBCLANG_VERSION_MAJOR >= 19
+                get_fully_qualified_type_name(parameter->getDefaultArgument().getTypeSourceInfo()->getType(), parameter->getASTContext()) :
+#else
                 get_fully_qualified_type_name(parameter->getDefaultArgument(), parameter->getASTContext()) :
+#endif
                 "";
 
 }
@@ -184,7 +188,11 @@ static std::string get_default_value_initializer_as_string(const clang::Template
  */
 static std::string get_default_value_initializer_as_string(const clang::NonTypeTemplateParmDecl* parameter) {
     return (parameter && parameter->hasDefaultArgument()) ?
+#if LIBCLANG_VERSION_MAJOR >= 19
+        get_expression_as_string(parameter->getDefaultArgument().getLocInfo().getAsExpr(), parameter->getASTContext()) : "";
+#else
         get_expression_as_string(parameter->getDefaultArgument(), parameter->getASTContext()) : "";
+#endif
 
 }
 
@@ -204,7 +212,7 @@ static std::string get_default_value_initializer_as_string(const clang::Template
         const clang::TemplateName template_name = parameter->getDefaultArgument().getArgument().getAsTemplate();
 
         llvm::raw_string_ostream ss{default_value};
-        template_name.print(ss, parameter->getASTContext().getPrintingPolicy(), clang::TemplateName::Qualified::Fully);
+        template_name.print(ss, parameter->getASTContext().getPrintingPolicy(), clang::TemplateName::Qualified::AsWritten);
     }
 
     return default_value;