[PATCH] D125576: [LLVM][Casting.h] Add ForwardToPointerCast trait

[Aman LaChapelle via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rGc7587080188e: [LLVM][Casting.h] Add ForwardToPointerCast trait (authored by bzcheeseman).

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D125576/new/

https://reviews.llvm.org/D125576

Files:
  llvm/include/llvm/Support/Casting.h


Index: llvm/include/llvm/Support/Casting.h
===================================================================
--- llvm/include/llvm/Support/Casting.h
+++ llvm/include/llvm/Support/Casting.h
@@ -408,6 +408,29 @@
   }
 };
 
+/// Provides a cast trait that uses a defined pointer to pointer cast as a base
+/// for reference-to-reference casts. Note that it does not provide castFailed
+/// and doCastIfPossible because a pointer-to-pointer cast would likely just
+/// return `nullptr` which could cause nullptr dereference. You can use it like
+/// this:
+///
+///   template <> struct CastInfo<foo, bar *> { ... verbose implementation... };
+///
+///   template <>
+///   struct CastInfo<foo, bar>
+///       : public ForwardToPointerCast<foo, bar, CastInfo<foo, bar *>> {};
+///
+template <typename To, typename From, typename ForwardTo>
+struct ForwardToPointerCast {
+  static inline bool isPossible(const From &f) {
+    return ForwardTo::isPossible(&f);
+  }
+
+  static inline decltype(auto) doCast(const From &f) {
+    return *ForwardTo::doCast(&f);
+  }
+};
+
 //===----------------------------------------------------------------------===//
 // CastInfo
 //===----------------------------------------------------------------------===//


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