1 files changed, 20 insertions, 7 deletions
diff --git a/src/chain.h b/src/chain.h
index 2d3b084b9b..f5dd0fd315 100644
--- a/src/chain.h
+++ b/src/chain.h
@@ -1,5 +1,5 @@
 // Copyright (c) 2009-2010 Satoshi Nakamoto
-// Copyright (c) 2009-2021 The Bitcoin Core developers
+// Copyright (c) 2009-2022 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
@@ -9,6 +9,7 @@
 #include <arith_uint256.h>
 #include <consensus/params.h>
 #include <flatfile.h>
+#include <kernel/cs_main.h>
 #include <primitives/block.h>
 #include <sync.h>
 #include <uint256.h>
@@ -38,8 +39,6 @@ static constexpr int64_t TIMESTAMP_WINDOW = MAX_FUTURE_BLOCK_TIME;
  */
 static constexpr int64_t MAX_BLOCK_TIME_GAP = 90 * 60;
 
-extern RecursiveMutex cs_main;
-
 class CBlockFileInfo
 {
 public:
@@ -213,10 +212,6 @@ public:
     //! (memory only) Maximum nTime in the chain up to and including this block.
     unsigned int nTimeMax{0};
 
-    CBlockIndex()
-    {
-    }
-
     explicit CBlockIndex(const CBlockHeader& block)
         : nVersion{block.nVersion},
           hashMerkleRoot{block.hashMerkleRoot},
@@ -355,6 +350,24 @@ public:
     //! Efficiently find an ancestor of this block.
     CBlockIndex* GetAncestor(int height);
     const CBlockIndex* GetAncestor(int height) const;
+
+    CBlockIndex() = default;
+    ~CBlockIndex() = default;
+
+protected:
+    //! CBlockIndex should not allow public copy construction because equality
+    //! comparison via pointer is very common throughout the codebase, making
+    //! use of copy a footgun. Also, use of copies do not have the benefit
+    //! of simplifying lifetime considerations due to attributes like pprev and
+    //! pskip, which are at risk of becoming dangling pointers in a copied
+    //! instance.
+    //!
+    //! We declare these protected instead of simply deleting them so that
+    //! CDiskBlockIndex can reuse copy construction.
+    CBlockIndex(const CBlockIndex&) = default;
+    CBlockIndex& operator=(const CBlockIndex&) = delete;
+    CBlockIndex(CBlockIndex&&) = delete;
+    CBlockIndex& operator=(CBlockIndex&&) = delete;
 };
 
 arith_uint256 GetBlockProof(const CBlockIndex& block);