Add missing header

Author: pfultz2

lib/refthunk.h

@@ -0,0 +1,61 @@
+/* -*- C++ -*-
+ * Cppcheck - A tool for static C/C++ code analysis
+ * Copyright (C) 2007-2026 Cppcheck team.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+//---------------------------------------------------------------------------
+#ifndef refthunkH
+#define refthunkH
+//---------------------------------------------------------------------------
+
+#include <memory>
+
+/**
+ * Reference wrapper whose operator() returns the referenced object.
+ *
+ * It is constructed from a reference and converts implicitly back to one
+ * (like std::reference_wrapper), so it can replace a reference data member
+ * without changing the constructor or call sites that pass the member to
+ * functions taking T&. Unlike a reference member it is copyable and
+ * assignable; assignment rebinds it.
+ */
+template<class T>
+struct RefThunk {
+    RefThunk() = delete;
+
+    // cppcheck-suppress noExplicitConstructor
+    // NOLINTNEXTLINE(google-explicit-constructor)
+    constexpr RefThunk(T& t) noexcept : mPtr(std::addressof(t)) {}
+    RefThunk(T&& t) = delete;
+
+    constexpr T& operator()() const noexcept {
+        return *mPtr;
+    }
+
+    constexpr T& get() const noexcept {
+        return *mPtr;
+    }
+
+    // NOLINTNEXTLINE(google-explicit-constructor)
+    constexpr operator T&() const noexcept {
+        return *mPtr;
+    }
+
+private:
+    T* mPtr;
+};
+
+#endif