ba01b00d45 refactor: use for loops in FindMostWorkChain (stratospher)
aa0eef735b test: add InvalidateBlock/ReconsiderBlock asymmetry test (stratospher)
1b0b3e2c2c validation: remove redundant marking in FindMostWorkChain (stratospher)
Pull request description:
recent PRs like #31405, #30666 mark all `m_block_index` descendants as invalid immediately whenever an invalid block is encountered in `SetBlockFailureFlags`. so by the time we reach `FindMostWorkChain`, the block in `setBlockIndexCandidates` already has `BLOCK_FAILED_VALID` set on it - not just on its ancestor. this means `pindexTest = pindexFailed` whenever `fFailedChain` fires, and the inner `while (pindexTest != pindexFailed)` loop body is never reached!
I think we can remove it but I've just replaced it with `Assume` in this PR for safety + good to document this invariant in case the code changes in future. (noticed by @ stickies-v in https://github.com/bitcoin/bitcoin/pull/32950#discussion_r2815053885)
the second commit is unrelated and adds a unit test for the situation in https://github.com/bitcoin/bitcoin/issues/32173
ACKs for top commit:
fjahr:
re-ACK ba01b00d45
optout21:
crACK ba01b00d45
w0xlt:
ACK ba01b00d45
ryanofsky:
Code review ACK ba01b00d45, just tweaking comment and for loop condition since last review.
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141fbe4d53