consensus/params: simplify ValidDeployment check to avoid gcc warning

Github-Pull: bitcoin#22597
Rebased-From: 0591710

Author: ajtowns

src/consensus/params.h

@@ -23,15 +23,15 @@ enum BuriedDeployment : int16_t {
     DEPLOYMENT_CSV,
     DEPLOYMENT_SEGWIT,
 };
-constexpr bool ValidDeployment(BuriedDeployment dep) { return DEPLOYMENT_HEIGHTINCB <= dep && dep <= DEPLOYMENT_SEGWIT; }
+constexpr bool ValidDeployment(BuriedDeployment dep) { return 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 deploymentinfo.cpp
     MAX_VERSION_BITS_DEPLOYMENTS
 };
-constexpr bool ValidDeployment(DeploymentPos dep) { return DEPLOYMENT_TESTDUMMY <= dep && dep <= DEPLOYMENT_TAPROOT; }
+constexpr bool ValidDeployment(DeploymentPos dep) { return dep < MAX_VERSION_BITS_DEPLOYMENTS; }
 
 /**
  * Struct for each individual consensus rule change using BIP9.

src/deploymentstatus.cpp

@@ -7,6 +7,8 @@
 #include <consensus/params.h>
 #include <versionbits.h>
 
+#include <type_traits>
+
 VersionBitsCache g_versionbitscache;
 
 /* Basic sanity checking for BuriedDeployment/DeploymentPos enums and
@@ -15,3 +17,18 @@ VersionBitsCache g_versionbitscache;
 static_assert(ValidDeployment(Consensus::DEPLOYMENT_TESTDUMMY), "sanity check of DeploymentPos failed (TESTDUMMY not valid)");
 static_assert(!ValidDeployment(Consensus::MAX_VERSION_BITS_DEPLOYMENTS), "sanity check of DeploymentPos failed (MAX value considered valid)");
 static_assert(!ValidDeployment(static_cast<Consensus::BuriedDeployment>(Consensus::DEPLOYMENT_TESTDUMMY)), "sanity check of BuriedDeployment failed (overlaps with DeploymentPos)");
+
+/* ValidDeployment only checks upper bounds for ensuring validity.
+ * This checks that the lowest possible value or the type is also a
+ * (specific) valid deployment so that lower bounds don't need to be checked.
+ */
+
+template<typename T, T x>
+static constexpr bool is_minimum()
+{
+    using U = typename std::underlying_type<T>::type;
+    return x == std::numeric_limits<U>::min();
+}
+
+static_assert(is_minimum<Consensus::BuriedDeployment, Consensus::DEPLOYMENT_HEIGHTINCB>(), "heightincb is not minimum value for BuriedDeployment");
+static_assert(is_minimum<Consensus::DeploymentPos, Consensus::DEPLOYMENT_TESTDUMMY>(), "testdummy is not minimum value for DeploymentPos");