Merge bitcoin/bitcoin#22787: refactor: actual immutable pointing

54011e7aa274bdc1b921440cc8b4623aa1e0d89e refactor: use CWallet const shared pointers when possible (Karl-Johan Alm)
96461989a2de737151bc4fb216221bf49cb53ce6 refactor: const shared_ptrs (Karl-Johan Alm)

Pull request description:

  ```C++
  const std::shared_ptr<CWallet> wallet = x;
  ```
  means we can not do `wallet = y`, but we can totally do `wallet->DestructiveOperation()`, contrary to what that line looks like.

  This PR

  * introduces a new convention: always use const shared pointers to `CWallet`s (even when we mutate the pointed-to thing)
  * uses `const shared_ptr<const CWallet>` everywhere where wallets are not modified

  In the future, this should preferably apply to all shared pointers, not limited to just `CWallet`s.

  Both of these serve the same purpose: to dispell the misconception that `const shared_ptr<X>` immutates `X`. It doesn't, and it's dangerous to leave this misconception as is, for obvious reasons.

ACKs for top commit:
  theStack:
    re-ACK 54011e7aa274bdc1b921440cc8b4623aa1e0d89e

Tree-SHA512: 3bf4062fc821751be30770c6b4ead10a016847970f155a0a5156f304347d221b9830840030c2fbfba8cd1e282f4eda45f5b4107fe6df8138afdcb6c2e95a2836

5 files changed, 38 insertions, 38 deletions

diff --git a/src/wallet/rpcdump.cpp b/src/wallet/rpcdump.cpp
index 9b09bc23d6..1f13b80f3e 100644
--- a/src/wallet/rpcdump.cpp
+++ b/src/wallet/rpcdump.cpp
@@ -1788,7 +1788,7 @@ RPCHelpMan listdescriptors()
         },
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
-    std::shared_ptr<CWallet> const wallet = GetWalletForJSONRPCRequest(request);
+    const std::shared_ptr<const CWallet> wallet = GetWalletForJSONRPCRequest(request);
     if (!wallet) return NullUniValue;
 
     if (!wallet->IsWalletFlagSet(WALLET_FLAG_DESCRIPTORS)) {
diff --git a/src/wallet/rpcwallet.cpp b/src/wallet/rpcwallet.cpp
index f2f28c83ff..86bfa10d88 100644
--- a/src/wallet/rpcwallet.cpp
+++ b/src/wallet/rpcwallet.cpp
@@ -103,7 +103,7 @@ std::shared_ptr<CWallet> GetWalletForJSONRPCRequest(const JSONRPCRequest& reques
 
     std::string wallet_name;
     if (GetWalletNameFromJSONRPCRequest(request, wallet_name)) {
-        std::shared_ptr<CWallet> pwallet = GetWallet(context, wallet_name);
+        const std::shared_ptr<CWallet> pwallet = GetWallet(context, wallet_name);
         if (!pwallet) throw JSONRPCError(RPC_WALLET_NOT_FOUND, "Requested wallet does not exist or is not loaded");
         return pwallet;
     }
@@ -570,7 +570,7 @@ static RPCHelpMan listaddressgroupings()
                 },
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
-    std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
+    const std::shared_ptr<const CWallet> pwallet = GetWalletForJSONRPCRequest(request);
     if (!pwallet) return NullUniValue;
 
     // Make sure the results are valid at least up to the most recent block
@@ -627,7 +627,7 @@ static RPCHelpMan signmessage()
                 },
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
-    std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
+    const std::shared_ptr<const CWallet> pwallet = GetWalletForJSONRPCRequest(request);
     if (!pwallet) return NullUniValue;
 
     LOCK(pwallet->cs_wallet);
@@ -729,7 +729,7 @@ static RPCHelpMan getreceivedbyaddress()
                 },
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
-    std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
+    const std::shared_ptr<const CWallet> pwallet = GetWalletForJSONRPCRequest(request);
     if (!pwallet) return NullUniValue;
 
     // Make sure the results are valid at least up to the most recent block
@@ -767,7 +767,7 @@ static RPCHelpMan getreceivedbylabel()
                 },
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
-    std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
+    const std::shared_ptr<const CWallet> pwallet = GetWalletForJSONRPCRequest(request);
     if (!pwallet) return NullUniValue;
 
     // Make sure the results are valid at least up to the most recent block
@@ -807,7 +807,7 @@ static RPCHelpMan getbalance()
                 },
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
-    std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
+    const std::shared_ptr<const CWallet> pwallet = GetWalletForJSONRPCRequest(request);
     if (!pwallet) return NullUniValue;
 
     // Make sure the results are valid at least up to the most recent block
@@ -846,7 +846,7 @@ static RPCHelpMan getunconfirmedbalance()
                 RPCExamples{""},
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
-    std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
+    const std::shared_ptr<const CWallet> pwallet = GetWalletForJSONRPCRequest(request);
     if (!pwallet) return NullUniValue;
 
     // Make sure the results are valid at least up to the most recent block
@@ -1234,7 +1234,7 @@ static RPCHelpMan listreceivedbyaddress()
                 },
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
-    std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
+    const std::shared_ptr<const CWallet> pwallet = GetWalletForJSONRPCRequest(request);
     if (!pwallet) return NullUniValue;
 
     // Make sure the results are valid at least up to the most recent block
@@ -1276,7 +1276,7 @@ static RPCHelpMan listreceivedbylabel()
                 },
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
-    std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
+    const std::shared_ptr<const CWallet> pwallet = GetWalletForJSONRPCRequest(request);
     if (!pwallet) return NullUniValue;
 
     // Make sure the results are valid at least up to the most recent block
@@ -1461,7 +1461,7 @@ static RPCHelpMan listtransactions()
                 },
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
-    std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
+    const std::shared_ptr<const CWallet> pwallet = GetWalletForJSONRPCRequest(request);
     if (!pwallet) return NullUniValue;
 
     // Make sure the results are valid at least up to the most recent block
@@ -1577,7 +1577,7 @@ static RPCHelpMan listsinceblock()
                 },
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
-    std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
+    const std::shared_ptr<const CWallet> pwallet = GetWalletForJSONRPCRequest(request);
     if (!pwallet) return NullUniValue;
 
     const CWallet& wallet = *pwallet;
@@ -1718,7 +1718,7 @@ static RPCHelpMan gettransaction()
                 },
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
-    std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
+    const std::shared_ptr<const CWallet> pwallet = GetWalletForJSONRPCRequest(request);
     if (!pwallet) return NullUniValue;
 
     // Make sure the results are valid at least up to the most recent block
@@ -1829,7 +1829,7 @@ static RPCHelpMan backupwallet()
                 },
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
-    std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
+    const std::shared_ptr<const CWallet> pwallet = GetWalletForJSONRPCRequest(request);
     if (!pwallet) return NullUniValue;
 
     // Make sure the results are valid at least up to the most recent block
@@ -2331,7 +2331,7 @@ static RPCHelpMan listlockunspent()
                 },
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
-    std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
+    const std::shared_ptr<const CWallet> pwallet = GetWalletForJSONRPCRequest(request);
     if (!pwallet) return NullUniValue;
 
     LOCK(pwallet->cs_wallet);
@@ -2424,9 +2424,9 @@ static RPCHelpMan getbalances()
             HelpExampleRpc("getbalances", "")},
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
-    std::shared_ptr<CWallet> const rpc_wallet = GetWalletForJSONRPCRequest(request);
+    const std::shared_ptr<const CWallet> rpc_wallet = GetWalletForJSONRPCRequest(request);
     if (!rpc_wallet) return NullUniValue;
-    CWallet& wallet = *rpc_wallet;
+    const CWallet& wallet = *rpc_wallet;
 
     // Make sure the results are valid at least up to the most recent block
     // the user could have gotten from another RPC command prior to now
@@ -2500,7 +2500,7 @@ static RPCHelpMan getwalletinfo()
                 },
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
-    std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
+    const std::shared_ptr<const CWallet> pwallet = GetWalletForJSONRPCRequest(request);
     if (!pwallet) return NullUniValue;
 
     // Make sure the results are valid at least up to the most recent block
@@ -2840,7 +2840,7 @@ static RPCHelpMan createwallet()
     options.create_passphrase = passphrase;
     bilingual_str error;
     std::optional<bool> load_on_start = request.params[6].isNull() ? std::nullopt : std::optional<bool>(request.params[6].get_bool());
-    std::shared_ptr<CWallet> wallet = CreateWallet(context, request.params[0].get_str(), load_on_start, options, status, error, warnings);
+    const std::shared_ptr<CWallet> wallet = CreateWallet(context, request.params[0].get_str(), load_on_start, options, status, error, warnings);
     if (!wallet) {
         RPCErrorCode code = status == DatabaseStatus::FAILED_ENCRYPT ? RPC_WALLET_ENCRYPTION_FAILED : RPC_WALLET_ERROR;
         throw JSONRPCError(code, error.original);
@@ -3030,7 +3030,7 @@ static RPCHelpMan listunspent()
                 },
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
-    std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
+    const std::shared_ptr<const CWallet> pwallet = GetWalletForJSONRPCRequest(request);
     if (!pwallet) return NullUniValue;
 
     int nMinDepth = 1;
@@ -3593,7 +3593,7 @@ RPCHelpMan signrawtransactionwithwallet()
                 },
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
-    std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
+    const std::shared_ptr<const CWallet> pwallet = GetWalletForJSONRPCRequest(request);
     if (!pwallet) return NullUniValue;
 
     RPCTypeCheck(request.params, {UniValue::VSTR, UniValue::VARR, UniValue::VSTR}, true);
@@ -4058,7 +4058,7 @@ RPCHelpMan getaddressinfo()
                 },
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
-    std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
+    const std::shared_ptr<const CWallet> pwallet = GetWalletForJSONRPCRequest(request);
     if (!pwallet) return NullUniValue;
 
     LOCK(pwallet->cs_wallet);
@@ -4165,7 +4165,7 @@ static RPCHelpMan getaddressesbylabel()
                 },
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
-    std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
+    const std::shared_ptr<const CWallet> pwallet = GetWalletForJSONRPCRequest(request);
     if (!pwallet) return NullUniValue;
 
     LOCK(pwallet->cs_wallet);
@@ -4226,7 +4226,7 @@ static RPCHelpMan listlabels()
                 },
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
-    std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
+    const std::shared_ptr<const CWallet> pwallet = GetWalletForJSONRPCRequest(request);
     if (!pwallet) return NullUniValue;
 
     LOCK(pwallet->cs_wallet);
@@ -4555,7 +4555,7 @@ static RPCHelpMan walletprocesspsbt()
                 },
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
-    std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
+    const std::shared_ptr<const CWallet> pwallet = GetWalletForJSONRPCRequest(request);
     if (!pwallet) return NullUniValue;
 
     const CWallet& wallet{*pwallet};
diff --git a/src/wallet/test/wallet_tests.cpp b/src/wallet/test/wallet_tests.cpp
index 0965128ade..7a658c10a2 100644
--- a/src/wallet/test/wallet_tests.cpp
+++ b/src/wallet/test/wallet_tests.cpp
@@ -41,7 +41,7 @@ static_assert(WALLET_INCREMENTAL_RELAY_FEE >= DEFAULT_INCREMENTAL_RELAY_FEE, "wa
 
 BOOST_FIXTURE_TEST_SUITE(wallet_tests, WalletTestingSetup)
 
-static std::shared_ptr<CWallet> TestLoadWallet(WalletContext& context)
+static const std::shared_ptr<CWallet> TestLoadWallet(WalletContext& context)
 {
     DatabaseOptions options;
     options.create_flags = WALLET_FLAG_DESCRIPTORS;
@@ -208,7 +208,7 @@ BOOST_FIXTURE_TEST_CASE(importmulti_rescan, TestChain100Setup)
     // before the missing block, and success for a key whose creation time is
     // after.
     {
-        std::shared_ptr<CWallet> wallet = std::make_shared<CWallet>(m_node.chain.get(), "", CreateDummyWalletDatabase());
+        const std::shared_ptr<CWallet> wallet = std::make_shared<CWallet>(m_node.chain.get(), "", CreateDummyWalletDatabase());
         wallet->SetupLegacyScriptPubKeyMan();
         WITH_LOCK(wallet->cs_wallet, wallet->SetLastBlockProcessed(newTip->nHeight, newTip->GetBlockHash()));
         WalletContext context;
@@ -274,7 +274,7 @@ BOOST_FIXTURE_TEST_CASE(importwallet_rescan, TestChain100Setup)
     {
         WalletContext context;
         context.args = &gArgs;
-        std::shared_ptr<CWallet> wallet = std::make_shared<CWallet>(m_node.chain.get(), "", CreateDummyWalletDatabase());
+        const std::shared_ptr<CWallet> wallet = std::make_shared<CWallet>(m_node.chain.get(), "", CreateDummyWalletDatabase());
         {
             auto spk_man = wallet->GetOrCreateLegacyScriptPubKeyMan();
             LOCK2(wallet->cs_wallet, spk_man->cs_KeyStore);
@@ -296,7 +296,7 @@ BOOST_FIXTURE_TEST_CASE(importwallet_rescan, TestChain100Setup)
     // Call importwallet RPC and verify all blocks with timestamps >= BLOCK_TIME
     // were scanned, and no prior blocks were scanned.
     {
-        std::shared_ptr<CWallet> wallet = std::make_shared<CWallet>(m_node.chain.get(), "", CreateDummyWalletDatabase());
+        const std::shared_ptr<CWallet> wallet = std::make_shared<CWallet>(m_node.chain.get(), "", CreateDummyWalletDatabase());
         LOCK(wallet->cs_wallet);
         wallet->SetupLegacyScriptPubKeyMan();
 
@@ -606,7 +606,7 @@ BOOST_FIXTURE_TEST_CASE(ListCoinsTest, ListCoinsTestingSetup)
 BOOST_FIXTURE_TEST_CASE(wallet_disableprivkeys, TestChain100Setup)
 {
     {
-        std::shared_ptr<CWallet> wallet = std::make_shared<CWallet>(m_node.chain.get(), "", CreateDummyWalletDatabase());
+        const std::shared_ptr<CWallet> wallet = std::make_shared<CWallet>(m_node.chain.get(), "", CreateDummyWalletDatabase());
         wallet->SetupLegacyScriptPubKeyMan();
         wallet->SetMinVersion(FEATURE_LATEST);
         wallet->SetWalletFlag(WALLET_FLAG_DISABLE_PRIVATE_KEYS);
@@ -616,7 +616,7 @@ BOOST_FIXTURE_TEST_CASE(wallet_disableprivkeys, TestChain100Setup)
         BOOST_CHECK(!wallet->GetNewDestination(OutputType::BECH32, "", dest, error));
     }
     {
-        std::shared_ptr<CWallet> wallet = std::make_shared<CWallet>(m_node.chain.get(), "", CreateDummyWalletDatabase());
+        const std::shared_ptr<CWallet> wallet = std::make_shared<CWallet>(m_node.chain.get(), "", CreateDummyWalletDatabase());
         LOCK(wallet->cs_wallet);
         wallet->SetWalletFlag(WALLET_FLAG_DESCRIPTORS);
         wallet->SetMinVersion(FEATURE_LATEST);
diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
index 824f32aeae..4eb9d5560d 100644
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -221,7 +221,7 @@ std::shared_ptr<CWallet> LoadWalletInternal(WalletContext& context, const std::s
         }
 
         context.chain->initMessage(_("Loading wallet…").translated);
-        std::shared_ptr<CWallet> wallet = CWallet::Create(context, name, std::move(database), options.create_flags, error, warnings);
+        const std::shared_ptr<CWallet> wallet = CWallet::Create(context, name, std::move(database), options.create_flags, error, warnings);
         if (!wallet) {
             error = Untranslated("Wallet loading failed.") + Untranslated(" ") + error;
             status = DatabaseStatus::FAILED_LOAD;
@@ -301,7 +301,7 @@ std::shared_ptr<CWallet> CreateWallet(WalletContext& context, const std::string&
 
     // Make the wallet
     context.chain->initMessage(_("Loading wallet…").translated);
-    std::shared_ptr<CWallet> wallet = CWallet::Create(context, name, std::move(database), wallet_creation_flags, error, warnings);
+    const std::shared_ptr<CWallet> wallet = CWallet::Create(context, name, std::move(database), wallet_creation_flags, error, warnings);
     if (!wallet) {
         error = Untranslated("Wallet creation failed.") + Untranslated(" ") + error;
         status = DatabaseStatus::FAILED_CREATE;
@@ -2540,7 +2540,7 @@ std::shared_ptr<CWallet> CWallet::Create(WalletContext& context, const std::stri
     int64_t nStart = GetTimeMillis();
     // TODO: Can't use std::make_shared because we need a custom deleter but
     // should be possible to use std::allocate_shared.
-    std::shared_ptr<CWallet> walletInstance(new CWallet(chain, name, std::move(database)), ReleaseWallet);
+    const std::shared_ptr<CWallet> walletInstance(new CWallet(chain, name, std::move(database)), ReleaseWallet);
     bool rescan_required = false;
     DBErrors nLoadWalletRet = walletInstance->LoadWallet();
     if (nLoadWalletRet != DBErrors::LOAD_OK) {
diff --git a/src/wallet/wallettool.cpp b/src/wallet/wallettool.cpp
index 88f0a2ce20..086415f152 100644
--- a/src/wallet/wallettool.cpp
+++ b/src/wallet/wallettool.cpp
@@ -40,7 +40,7 @@ static void WalletCreate(CWallet* wallet_instance, uint64_t wallet_creation_flag
     wallet_instance->TopUpKeyPool();
 }
 
-static std::shared_ptr<CWallet> MakeWallet(const std::string& name, const fs::path& path, DatabaseOptions options)
+static const std::shared_ptr<CWallet> MakeWallet(const std::string& name, const fs::path& path, DatabaseOptions options)
 {
     DatabaseStatus status;
     bilingual_str error;
@@ -151,7 +151,7 @@ bool ExecuteWalletToolFunc(const ArgsManager& args, const std::string& command)
             options.require_format = DatabaseFormat::SQLITE;
         }
 
-        std::shared_ptr<CWallet> wallet_instance = MakeWallet(name, path, options);
+        const std::shared_ptr<CWallet> wallet_instance = MakeWallet(name, path, options);
         if (wallet_instance) {
             WalletShowInfo(wallet_instance.get());
             wallet_instance->Close();
@@ -159,7 +159,7 @@ bool ExecuteWalletToolFunc(const ArgsManager& args, const std::string& command)
     } else if (command == "info") {
         DatabaseOptions options;
         options.require_existing = true;
-        std::shared_ptr<CWallet> wallet_instance = MakeWallet(name, path, options);
+        const std::shared_ptr<CWallet> wallet_instance = MakeWallet(name, path, options);
         if (!wallet_instance) return false;
         WalletShowInfo(wallet_instance.get());
         wallet_instance->Close();
@@ -184,7 +184,7 @@ bool ExecuteWalletToolFunc(const ArgsManager& args, const std::string& command)
     } else if (command == "dump") {
         DatabaseOptions options;
         options.require_existing = true;
-        std::shared_ptr<CWallet> wallet_instance = MakeWallet(name, path, options);
+        const std::shared_ptr<CWallet> wallet_instance = MakeWallet(name, path, options);
         if (!wallet_instance) return false;
         bilingual_str error;
         bool ret = DumpWallet(*wallet_instance, error);