1 files changed, 72 insertions, 0 deletions
diff --git a/src/corelib/global/q20map.h b/src/corelib/global/q20map.h
new file mode 100644
index 0000000000..c719067480
--- /dev/null
+++ b/src/corelib/global/q20map.h
@@ -0,0 +1,72 @@
+// Copyright (C) 2023 Ahmad Samir <a.samirh78@gmail.com>
+// Copyright (C) 2023 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
+
+#ifndef Q20MAP_H
+#define Q20MAP_H
+
+#include <QtCore/qtconfigmacros.h>
+
+#include <map>
+#if __has_include(<memory_resource>)
+#  include <memory_resource>
+#endif
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API. Types and functions defined in this
+// file can reliably be replaced by their std counterparts, once available.
+// You may use these definitions in your own code, but be aware that we
+// will remove them once Qt depends on the C++ version that supports
+// them in namespace std. There will be NO deprecation warning, the
+// definitions will JUST go away.
+//
+// If you can't agree to these terms, don't use these definitions!
+//
+// We mean it.
+//
+
+QT_BEGIN_NAMESPACE
+
+namespace q20 {
+// like std::erase/std::erase_if for std::map
+#if defined(__cpp_lib_erase_if) && __cpp_lib_erase_if >= 202002L // the one returning size_type
+using std::erase_if;
+#else
+
+// Make it more specialized than the compiler's, so that our implementation is preferred over
+// the compiler's (which may be present, but return void instead of the number of erased elements).
+
+#define MAKE_OVERLOAD(map, allocator) \
+    template <typename Key, typename T, typename Compare, typename Pred> \
+    constexpr typename std::map<Key, T, Compare, std::allocator<std::pair<const Key, T>>>::size_type \
+    erase_if(std::map<Key, T, Compare, std::allocator<std::pair<const Key, T>>> &c, Pred p) \
+    { \
+        const auto origSize = c.size(); \
+        for (auto it = c.begin(), end = c.end(); it != end; /* erasing */) { \
+            if (p(*it)) \
+                it = c.erase(it); \
+            else \
+                ++it; \
+        } \
+        return origSize - c.size(); \
+    } \
+    /* end */
+
+MAKE_OVERLOAD(map, allocator)
+MAKE_OVERLOAD(multimap, allocator)
+#ifdef __cpp_lib_polymorphic_allocator
+MAKE_OVERLOAD(map, pmr::polymorphic_allocator)
+MAKE_OVERLOAD(multimap, pmr::polymorphic_allocator)
+#endif // __cpp_lib_polymorphic_allocator
+
+#undef MAKE_OVERLOAD
+
+#endif // __cpp_lib_erase_if
+} // namespace q20
+
+QT_END_NAMESPACE
+
+#endif /* Q20MAP_H */