The following sections might be updated with supplementary metadata relevant to reviewers and maintainers.

Conflicts

Reviewers, this pull request conflicts with the following ones:

• #14942 (wallet: Return a ScanResult from CWallet::RescanFromTime by Empact)
• #14384 (Resolve validationinterface circular dependencies by 251Labs)
• #14121 (Index for BIP 157 block filters by jimpo)
• #14111 (index: Create IndexRunner class for activing indexes. by jimpo)
• #13949 (Introduce MempoolObserver interface to break "policy/fees -> txmempool -> policy/fees" circular dependency by Empact)
• #13743 (refactor: Replace boost::bind with std::bind by ken2812221)
• #13088 (Log early messages with -printtoconsole by ajtowns)
• #10973 (Refactor: separate wallet from node by ryanofsky)

If you consider this pull request important, please also help to review the conflicting pull requests. Ideally, start with the one that should be merged first.

Might be wortwhile to update it to using output descriptors, like scantxoutset: https://github.com/bitcoin/bitcoin/blob/master/src/rpc/blockchain.cpp#L2035

@instagibbs Thanks for the remarks, how about adding support for descriptors in separate PR?

@mgrychow, I recently started working on an address-based index (not just for UTXOs) at #14053. I can improve my PR quite a bit using your changes to the ValidationInterface. If you separated that change (adding CBlockUndo's) into it's own commit this PR would be a bit cleaner, and I could use it for the address index :)

Anyway, will be reviewing this since it's pretty similar to the PR I just made.

@mgrychow Not going to bikeshed this PR to death, just noting it in case you've missed it.

Rebased

There hasn't been much activity lately and the patch still needs rebase, so I am closing this for now. Please let me know when you want to continue working on this, so the pull request can be re-opened.