Merge #12128: Refactor: One CBaseChainParams should be enough

Summary:
1687cb4 Refactor: One CBaseChainParams should be enough (Jorge Timón)

Pull request description:

  There's no need for class hierarchy with CBaseChainParams, it is just a struct with 2 fields.
  This starts as a +10-43 diff

Tree-SHA512: 0a7dd64ab785416550b541787c6083540e4962d76b6cffa806bb3593aec2daf1752dfe65ac5cd51b34ad5c31dd8292c422b483fdd2d37d0b7e68725498ed4c2d

Backport of Core PR12128
bitcoin/bitcoin#12128

Test Plan:
  make check

Reviewers: deadalnix, Fabien, jasonbcox, O1 Bitcoin ABC, #bitcoin_abc

Reviewed By: jasonbcox, O1 Bitcoin ABC, #bitcoin_abc

Differential Revision: https://reviews.bitcoinabc.org/D3804

src/chainparamsbase.cpp

@@ -24,36 +24,6 @@ void SetupChainParamsBaseOptions() {
                  OptionsCategory::CHAINPARAMS);
 }
 
-/**
- * Main network
- */
-class CBaseMainParams : public CBaseChainParams {
-public:
-    CBaseMainParams() { nRPCPort = 3339; }
-};
-
-/**
- * Testnet (v3)
- */
-class CBaseTestNetParams : public CBaseChainParams {
-public:
-    CBaseTestNetParams() {
-        nRPCPort = 13339;
-        strDataDir = "testnet1";
-    }
-};
-
-/*
- * Regression test
- */
-class CBaseRegTestParams : public CBaseChainParams {
-public:
-    CBaseRegTestParams() {
-        nRPCPort = 18332;
-        strDataDir = "regtest";
-    }
-};
-
 static std::unique_ptr<CBaseChainParams> globalChainBaseParams;
 
 const CBaseChainParams &BaseParams() {
@@ -64,11 +34,11 @@ const CBaseChainParams &BaseParams() {
 std::unique_ptr<CBaseChainParams>
 CreateBaseChainParams(const std::string &chain) {
     if (chain == CBaseChainParams::MAIN)
-        return std::unique_ptr<CBaseChainParams>(new CBaseMainParams());
+        return std::make_unique<CBaseChainParams>("", 3339);
     else if (chain == CBaseChainParams::TESTNET)
-        return std::unique_ptr<CBaseChainParams>(new CBaseTestNetParams());
+        return std::make_unique<CBaseChainParams>("testnet1", 13339);
     else if (chain == CBaseChainParams::REGTEST)
-        return std::unique_ptr<CBaseChainParams>(new CBaseRegTestParams());
+        return std::make_unique<CBaseChainParams>("regtest", 18332);
     else
         throw std::runtime_error(
             strprintf("%s: Unknown chain %s.", __func__, chain));

src/chainparamsbase.h

@@ -23,9 +23,11 @@ class CBaseChainParams {
     const std::string &DataDir() const { return strDataDir; }
     int RPCPort() const { return nRPCPort; }
 
-protected:
-    CBaseChainParams() = default;
+    CBaseChainParams() = delete;
+    CBaseChainParams(const std::string &data_dir, int rpc_port)
+        : nRPCPort(rpc_port), strDataDir(data_dir) {}
 
+private:
     int nRPCPort;
     std::string strDataDir;
 };