Merge bitcoin/bitcoin#19438: Introduce deploymentstatus

e48826ad87 tests: remove ComputeBlockVersion shortcut from versionbits tests (Anthony Towns)
c5f36725e8 [refactor] Move ComputeBlockVersion into VersionBitsCache (Anthony Towns)
4a69b4dbe0 [move-only] Move ComputeBlockVersion from validation to versionbits (Anthony Towns)
0cfd6c6a8f [refactor] versionbits: make VersionBitsCache a full class (Anthony Towns)
8ee3e0bed5 [refactor] rpc/blockchain.cpp: SoftForkPushBack (Anthony Towns)
92f48f360d deploymentinfo: Add DeploymentName() (Anthony Towns)
ea68b3a572 [move-only] Rename versionbitsinfo to deploymentinfo (Anthony Towns)
c64b2c6a0f scripted-diff: rename versionbitscache (Anthony Towns)
de55304f6e [refactor] Add versionbits deployments to deploymentstatus.h (Anthony Towns)
2b0d291da8 [refactor] Add deploymentstatus.h (Anthony Towns)
eccd736f3d versionbits: Use dedicated lock instead of cs_main (Anthony Towns)
36a4ba0aaa versionbits: correct doxygen comments (Anthony Towns)

Pull request description:

  Introduces helper functions to make it easy to bury future deployments, along the lines of the suggestion from [11398](https://github.com/bitcoin/bitcoin/pull/11398#issuecomment-335599326) "I would prefer it if a buried deployment wouldn't require all code paths that check the BIP9 status to require changing".

  This provides three functions: `DeploymentEnabled()` which tests if a deployment can ever be active, `DeploymentActiveAt()` which checks if a deployment should be enforced in the given block, and `DeploymentActiveAfter()` which checks if a deployment should be enforced in the block following the given block, and overloads all three to work both with buried deployments and versionbits deployments.

  This adds a dedicated lock for the versionbits cache, which is acquired internally by the versionbits functions, rather than relying on `cs_main`. It also moves moves versionbitscache into deploymentstatus to avoid a circular dependency with validation.

ACKs for top commit:
  jnewbery:
    ACK e48826ad87
  gruve-p:
    ACK e48826ad87
  MarcoFalke:
    re-ACK e48826ad87 🥈

Tree-SHA512: c846ba64436d36f8180046ad551d8b0d9e20509b9bc185aa2639055fc28803dd8ec2d6771ab337e80da0b40009ad959590d5772f84a0bf6199b65190d4155bed

src/consensus/params.h

@@ -11,13 +11,25 @@
 
 namespace Consensus {
 
-enum DeploymentPos
+enum BuriedDeployment : int16_t
+{
+    // buried deployments get negative values to avoid overlap with DeploymentPos
+    DEPLOYMENT_HEIGHTINCB = std::numeric_limits<int16_t>::min(),
+    DEPLOYMENT_CLTV,
+    DEPLOYMENT_DERSIG,
+    DEPLOYMENT_CSV,
+    DEPLOYMENT_SEGWIT,
+};
+constexpr bool ValidDeployment(BuriedDeployment dep) { return DEPLOYMENT_HEIGHTINCB <= dep && dep <= DEPLOYMENT_SEGWIT; }
+
+enum DeploymentPos : uint16_t
 {
     DEPLOYMENT_TESTDUMMY,
     DEPLOYMENT_TAPROOT, // Deployment of Schnorr/Taproot (BIPs 340-342)
-    // NOTE: Also add new deployments to VersionBitsDeploymentInfo in versionbits.cpp
+    // NOTE: Also add new deployments to VersionBitsDeploymentInfo in deploymentinfo.cpp
     MAX_VERSION_BITS_DEPLOYMENTS
 };
+constexpr bool ValidDeployment(DeploymentPos dep) { return DEPLOYMENT_TESTDUMMY <= dep && dep <= DEPLOYMENT_TAPROOT; }
 
 /**
  * Struct for each individual consensus rule change using BIP9.
@@ -100,7 +112,25 @@ struct Params {
      */
     bool signet_blocks{false};
     std::vector<uint8_t> signet_challenge;
+
+    int DeploymentHeight(BuriedDeployment dep) const
+    {
+        switch (dep) {
+        case DEPLOYMENT_HEIGHTINCB:
+            return BIP34Height;
+        case DEPLOYMENT_CLTV:
+            return BIP65Height;
+        case DEPLOYMENT_DERSIG:
+            return BIP66Height;
+        case DEPLOYMENT_CSV:
+            return CSVHeight;
+        case DEPLOYMENT_SEGWIT:
+            return SegwitHeight;
+        } // no default case, so the compiler can warn about missing cases
+        return std::numeric_limits<int>::max();
+    }
 };
+
 } // namespace Consensus
 
 #endif // BITCOIN_CONSENSUS_PARAMS_H