From: Lang Hames <lhames@gmail.com>
Date: Fri, 26 Aug 2022 22:32:17 +0000 (-0700)
Subject: [ORC-RT] Add a std::identity substitute.
X-Git-Tag: upstream/17.0.6~35197
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=faabefe3c8a4755249e75cf8e2d3726460887946;p=platform%2Fupstream%2Fllvm.git

[ORC-RT] Add a std::identity substitute.

The __orc_rt::identity utility is intended to serve as a substitute for
c++20's std::identity until we can use the latter (when LLVM moves to c++20).
---

diff --git a/compiler-rt/lib/orc/stl_extras.h b/compiler-rt/lib/orc/stl_extras.h
index ad7286e..e4f8bf0 100644
--- a/compiler-rt/lib/orc/stl_extras.h
+++ b/compiler-rt/lib/orc/stl_extras.h
@@ -41,6 +41,16 @@ decltype(auto) apply_tuple(F &&f, Tuple &&t) {
                                   Indices{});
 }
 
+/// Substitute for std::identity.
+/// Switch to std::identity once we can use c++20.
+template <class Ty> struct identity {
+  using is_transparent = void;
+  using argument_type = Ty;
+
+  Ty &operator()(Ty &self) const { return self; }
+  const Ty &operator()(const Ty &self) const { return self; }
+};
+
 } // namespace __orc_rt
 
 #endif // ORC_RT_STL_EXTRAS