Merge #11389: Support having SegWit always active in regtest (sipa, ajtowns, jnewbery)

d61845818 Have SegWit active by default (Pieter Wuille)
4bd89210a Unit tests for always-active versionbits. (Anthony Towns)
d07ee77ab Always-active versionbits support (Pieter Wuille)
18e071841 [consensus] Pin P2SH activation to block 173805 on mainnet (John Newbery)
526023aa7 Improve handling of BIP9Deployment limits (Anthony Towns)

Pull request description:

  Most tests shouldn't have to deal with the now-historical SegWit activation transition (and other deployments, but SegWit is certainly the hardest one to accomodate).

  This PR makes a versionbits starttime of -1 equal to "always active", and enables it by default for SegWit on regtest. Individual tests can override this by using the existing `-vbparams` option.

  A few unit tests and functional tests are adapted to indeed override vbparams, as they specifically test the transition.

  This is in preparation for wallet SegWit support, but I thought having earlier eyes on it would be useful.

Tree-SHA512: 3f07a7b41cf46476e6c7a5c43244e68c9f41d223482cedaa4c02a3a7b7cd0e90cbd06b84a1f3704620559636a2268f5767d4c52d09c1b354945737046f618fe5

1 files changed, 10 insertions, 0 deletions

diff --git a/src/versionbits.cpp b/src/versionbits.cpp
index 64ae939672..fc1acb3258 100644
--- a/src/versionbits.cpp
+++ b/src/versionbits.cpp
@@ -27,6 +27,11 @@ ThresholdState AbstractThresholdConditionChecker::GetStateFor(const CBlockIndex*
     int64_t nTimeStart = BeginTime(params);
     int64_t nTimeTimeout = EndTime(params);
 
+    // Check if this deployment is always active.
+    if (nTimeStart == Consensus::BIP9Deployment::ALWAYS_ACTIVE) {
+        return THRESHOLD_ACTIVE;
+    }
+
     // A block's state is always the same as that of the first of its period, so it is computed based on a pindexPrev whose height equals a multiple of nPeriod - 1.
     if (pindexPrev != nullptr) {
         pindexPrev = pindexPrev->GetAncestor(pindexPrev->nHeight - ((pindexPrev->nHeight + 1) % nPeriod));
@@ -136,6 +141,11 @@ BIP9Stats AbstractThresholdConditionChecker::GetStateStatisticsFor(const CBlockI
 
 int AbstractThresholdConditionChecker::GetStateSinceHeightFor(const CBlockIndex* pindexPrev, const Consensus::Params& params, ThresholdConditionCache& cache) const
 {
+    int64_t start_time = BeginTime(params);
+    if (start_time == Consensus::BIP9Deployment::ALWAYS_ACTIVE) {
+        return 0;
+    }
+
     const ThresholdState initialState = GetStateFor(pindexPrev, params, cache);
 
     // BIP 9 about state DEFINED: "The genesis block is by definition in this state for each deployment."