https://github.com/bitcoin/bitcoin/blob/68f3c7eb080e461cfeac37f8db7034fe507241d0/src/prevector.h#L152-L158

I'm opening an issue as its fix is too tiny to become a pull request.

Can be solved by renaming the struct to
```c
     struct indirect_contents { 
         size_type capacity; 
         char* indirect; 
     }; 
```
{
    return FlatFileSeq(GetBlocksDir(), "rev", UNDOFILE_CHUNK_SIZE);
}
FILE* OpenBlockFile(const FlatFilePos &pos, bool fReadOnly) {
    return BlockFileSeq().Open(pos, fReadOnly);
}
static FILE* OpenUndoFile(const FlatFilePos &pos, bool fReadOnly) {
    return UndoFileSeq().Open(pos, fReadOnly);
}
fs::path GetBlockPosFilename(const FlatFilePos &pos)
{
    return BlockFileSeq().FileName(pos);
}
CBlockIndex * BlockManager::InsertBlockIndex(const uint256& hash)
{
    AssertLockHeld(cs_main);
    if (hash.IsNull())
        return nullptr;
    
    BlockMap::iterator mi = m_block_index.find(hash);
    if (mi != m_block_index.end())
        return (*mi).second;
    
    CBlockIndex* pindexNew = new CBlockIndex();
    mi = m_block_index.insert(std::make_pair(hash, pindexNew)).first;
    pindexNew->phashBlock = &((*mi).first);
    return pindexNew;
}
bool BlockManager::LoadBlockIndex(