[PATCH] D132628: [ADT] Make `llvm::identity` a transparent function object

[Joe Loser via Phabricator via llvm-commits]

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`llvm::identity` is similar to `std::identity` from C++20, but one surprising
thing is that `llvm::identity` is not a transparent function object. Add the
`is_transparent` type alias to denote it can be used as a transparent function
object.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D132628

Files:
  llvm/include/llvm/ADT/identity.h


Index: llvm/include/llvm/ADT/identity.h
===================================================================
--- llvm/include/llvm/ADT/identity.h
+++ llvm/include/llvm/ADT/identity.h
@@ -18,7 +18,9 @@
 
 namespace llvm {
 
+// Similar to `std::identity` from C++20.
 template <class Ty> struct identity {
+  using is_transparent = void;
   using argument_type = Ty;
 
   Ty &operator()(Ty &self) const {


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