[libcxx-commits] [libcxx] [libc++] Avoid constructing additional objects when using map::at (PR #157866)

[Louis Dionne via libcxx-commits]

================
@@ -0,0 +1,46 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___TYPE_TRAITS_MAKE_TRANSPARENT_H
+#define _LIBCPP___TYPE_TRAITS_MAKE_TRANSPARENT_H
+
+#include <__config>
+#include <__type_traits/enable_if.h>
+#include <__type_traits/is_same.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+// __make_transparent tries to replace non-transparent comparator with their transparent counterparts. e.g. `less<T>` is
+// replaced with `less<>`. This is useful in cases where conversions can be avoided (e.g. a string literal to a
+// std::string).
----------------
ldionne wrote:

```suggestion
// __make_transparent tries to create a transparent comparator from its non-transparent counterpart, e.g. obtain `less<>` from `less<T>`.
// This is useful in cases where conversions can be avoided (e.g. a string literal to a
// std::string).
```

https://github.com/llvm/llvm-project/pull/157866