[llvm] [ADT] Remove an obsolete forward declaration (NFC) (PR #156391)

[Kazu Hirata via llvm-commits]

https://github.com/kazutakahirata created https://github.com/llvm/llvm-project/pull/156391

We just removed CastInfoPointerUnionImpl in:

  commit 2d216a94f3c84037cdfb3fa5def9efb020a88537
  Author: Kazu Hirata <kazu at google.com>
  Date:   Mon Sep 1 08:04:49 2025 -0700

This patch removes the obsolete forward declaration.


>From c90e134308d3b92144824b8d80316331df531f1c Mon Sep 17 00:00:00 2001
From: Kazu Hirata <kazu at google.com>
Date: Mon, 1 Sep 2025 09:51:13 -0700
Subject: [PATCH] [ADT] Remove an obsolete forward declaration (NFC)

We just removed CastInfoPointerUnionImpl in:

  commit 2d216a94f3c84037cdfb3fa5def9efb020a88537
  Author: Kazu Hirata <kazu at google.com>
  Date:   Mon Sep 1 08:04:49 2025 -0700

This patch removes the obsolete forward declaration.
---
 llvm/include/llvm/ADT/PointerUnion.h | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/llvm/include/llvm/ADT/PointerUnion.h b/llvm/include/llvm/ADT/PointerUnion.h
index 24caa960c718d..ca0e1ed3d49d1 100644
--- a/llvm/include/llvm/ADT/PointerUnion.h
+++ b/llvm/include/llvm/ADT/PointerUnion.h
@@ -88,9 +88,6 @@ namespace pointer_union_detail {
   };
 }
 
-// This is a forward declaration of CastInfoPointerUnionImpl
-// Refer to its definition below for further details
-template <typename... PTs> struct CastInfoPointerUnionImpl;
 /// A discriminated union of two or more pointer types, with the discriminator
 /// in the low bit of the pointer.
 ///