validation: remove BLOCK_FAILED_CHILD

even though we have a distinction between BLOCK_FAILED_VALID
and BLOCK_FAILED_CHILD in the codebase, we don't use it for
anything. since there's no functional difference between them
and it's unnecessary code complexity to categorise them correctly,
just mark as BLOCK_FAILED_VALID instead.

Author: stratospher

src/chain.h

@@ -123,8 +123,7 @@ enum BlockStatus : uint32_t {
     BLOCK_HAVE_MASK          =   BLOCK_HAVE_DATA | BLOCK_HAVE_UNDO,
 
     BLOCK_FAILED_VALID       =   32, //!< stage after last reached validness failed
-    BLOCK_FAILED_CHILD       =   64, //!< descends from failed block
-    BLOCK_FAILED_MASK        =   BLOCK_FAILED_VALID | BLOCK_FAILED_CHILD,
+    BLOCK_FAILED_MASK        =   BLOCK_FAILED_VALID,
 
     BLOCK_OPT_WITNESS        =   128, //!< block data in blk*.dat was received with a witness-enforcing client
 

src/node/blockstorage.cpp

@@ -462,7 +462,7 @@ bool BlockManager::LoadBlockIndex(const std::optional<uint256>& snapshot_blockha
             }
         }
         if (!(pindex->nStatus & BLOCK_FAILED_MASK) && pindex->pprev && (pindex->pprev->nStatus & BLOCK_FAILED_MASK)) {
-            pindex->nStatus |= BLOCK_FAILED_CHILD;
+            pindex->nStatus |= BLOCK_FAILED_VALID;
             m_dirty_blockindex.insert(pindex);
         }
         if (pindex->pprev) {

src/test/fuzz/chain.cpp

@@ -50,7 +50,6 @@ FUZZ_TARGET(chain)
             BlockStatus::BLOCK_HAVE_UNDO,
             BlockStatus::BLOCK_HAVE_MASK,
             BlockStatus::BLOCK_FAILED_VALID,
-            BlockStatus::BLOCK_FAILED_CHILD,
             BlockStatus::BLOCK_FAILED_MASK,
             BlockStatus::BLOCK_OPT_WITNESS,
         });

src/validation.cpp

@@ -3306,7 +3306,7 @@ CBlockIndex* Chainstate::FindMostWorkChain()
                 // Remove the entire chain from the set.
                 while (pindexTest != pindexFailed) {
                     if (fFailedChain) {
-                        pindexFailed->nStatus |= BLOCK_FAILED_CHILD;
+                        pindexFailed->nStatus |= BLOCK_FAILED_VALID;
                         m_blockman.m_dirty_blockindex.insert(pindexFailed);
                     } else if (fMissingData) {
                         // If we're missing data, then add back to m_blocks_unlinked,
@@ -3817,7 +3817,7 @@ void Chainstate::SetBlockFailureFlags(CBlockIndex* invalid_block)
 
     for (auto& [_, block_index] : m_blockman.m_block_index) {
         if (block_index.GetAncestor(invalid_block->nHeight) == invalid_block && !(block_index.nStatus & BLOCK_FAILED_MASK)) {
-            block_index.nStatus |= BLOCK_FAILED_CHILD;
+            block_index.nStatus |= BLOCK_FAILED_VALID;
         }
     }
 }
@@ -4366,10 +4366,10 @@ bool ChainstateManager::AcceptBlockHeader(const CBlockHeader& block, BlockValida
          *      B1 - C1 - D1 - E1
          *
          * In the case that we attempted to reorg from E1 to F2, only to find
-         * C2 to be invalid, we would mark D2, E2, and F2 as BLOCK_FAILED_CHILD
+         * C2 to be invalid, we would mark D2, E2, and F2 as BLOCK_FAILED_VALID
          * but NOT D3 (it was not in any of our candidate sets at the time).
          *
-         * In any case D3 will also be marked as BLOCK_FAILED_CHILD at restart
+         * In any case D3 will also be marked as BLOCK_FAILED_VALID at restart
          * in LoadBlockIndex.
          */
         if (!pindexPrev->IsValid(BLOCK_VALID_SCRIPTS)) {
@@ -4382,7 +4382,7 @@ bool ChainstateManager::AcceptBlockHeader(const CBlockHeader& block, BlockValida
                     assert(failedit->nStatus & BLOCK_FAILED_VALID);
                     CBlockIndex* invalid_walk = pindexPrev;
                     while (invalid_walk != failedit) {
-                        invalid_walk->nStatus |= BLOCK_FAILED_CHILD;
+                        invalid_walk->nStatus |= BLOCK_FAILED_VALID;
                         m_blockman.m_dirty_blockindex.insert(invalid_walk);
                         invalid_walk = invalid_walk->pprev;
                     }