Merge #11739: Enforce SCRIPT_VERIFY_P2SH and SCRIPT_VERIFY_WITNESS from genesis

8b56fc0b91 [qa] Test that v0 segwit outputs can't be spent pre-activation (Suhas Daftuar)
ccb8ca42a4 Always enforce SCRIPT_VERIFY_WITNESS with P2SH (Suhas Daftuar)
5c31b20a35 [qa] Remove some pre-activation segwit tests (Suhas Daftuar)
95749a5836 Separate NULLDUMMY enforcement from SEGWIT enforcement (Suhas Daftuar)
ce650182f4 Use P2SH consensus rules for all blocks (Suhas Daftuar)

Pull request description:

  As discussed at the IRC meeting back in October (https://botbot.me/freenode/bitcoin-core-dev/2017-10-12/?msg=92231929&page=2), I had looked into the feasibility of enforcing P2SH and SCRIPT_VERIFY_WITNESS back to the genesis block.

  The P2SH change is pretty straightforward -- there was only one historical block on mainnet that violated the rule, so I carved out an exception to it, similar to the way we have exceptions for the BIP30 violators.

  The segwit change is not entirely as clear.  The code changes themselves are relatively straightforward: we can just always turn on SCRIPT_VERIFY_WITNESS whenever P2SH is active.  However conceptually, this amounts to splitting up BIP141 into two parts, the part that implements new script rules, and the part that handles witness commitments in blocks.

  Arguably though the script rules are really defined in BIP 143 anyway, and so this really amounts to backdating BIP 143 -- script rules for v0 segwit outputs -- back to genesis.  So maybe conceptually this isn't so bad...

  I don't feel strongly about this change in either direction; I started working on it because I was searching for a way to simplify the way we understand and implement the consensus rules around segwit, but I'm not yet sure whether I think this achieves anything toward that goal.

  ping @TheBlueMatt

Tree-SHA512: 73551d4a983eb9792c7ac67f56005822528ac4d1fd52c27cee6d305ebee953f69687ef4ddee8bdc0fec77f77e6b5a9d669750793efee54c076533a095e233042

0 files changed, 0 insertions, 0 deletions