Remove CheckFinalTx

Summary:
This is a follow-up for D144. It converts the wallet to use
`ContextualCheckTransactionForCurrentBlock()` instead of the
`CheckFinalTx()` wrapper and removes the unused finaltx.cpp/h files.

This is a preamble to backporting [[ bitcoin/bitcoin#15288 | PR15288 ]] which will remove the direct call to `CheckFinalTx` in the wallet ([[ https://github.com/bitcoin/bitcoin/pull/15288/commits/80f52a2267f44a9cae4440615df3ff989be1579c| this commit ]]).
Having both `CheckFinalTx` and `ContextualCheckTransactionForCurrentBlock` is error prone when doing the node/wallet separation backports. This cleanup make it easier to backport and review.
Note that the above commit will allow to remove some of the boilerplate introduced in this diff.

Test Plan:
  ninja all check check-functional

  make check

Reviewers: #bitcoin_abc, deadalnix

Reviewed By: #bitcoin_abc, deadalnix

Subscribers: deadalnix

Differential Revision: https://reviews.bitcoinabc.org/D5804

src/Makefile.am

@@ -226,7 +226,6 @@ BITCOIN_CORE_H = \
   wallet/coinselection.h \
   wallet/crypter.h \
   wallet/db.h \
-  wallet/finaltx.h \
   wallet/rpcdump.h \
   wallet/fees.h \
   wallet/rpcwallet.h \
@@ -332,7 +331,6 @@ libbitcoin_wallet_a_SOURCES = \
   wallet/crypter.cpp \
   wallet/coinselection.cpp \
   wallet/db.cpp \
-  wallet/finaltx.cpp \
   wallet/fees.cpp \
   wallet/init.cpp \
   wallet/rpcdump.cpp \

src/interfaces/wallet.cpp

@@ -25,7 +25,6 @@
 #include <util/system.h>
 #include <validation.h>
 #include <wallet/fees.h>
-#include <wallet/finaltx.h>
 #include <wallet/rpcdump.h>
 #include <wallet/rpcwallet.h>
 #include <wallet/wallet.h>
@@ -99,7 +98,8 @@ namespace {
     static WalletTxStatus
     MakeWalletTxStatus(interfaces::Chain::Lock &locked_chain,
                        const CWalletTx &wtx) {
-        // Temporary, for CheckFinalTx below. Removed in upcoming commit.
+        // Temporary, for ContextualCheckTransactionForCurrentBlock below.
+        // Removed in upcoming commit.
         LockAnnotation lock(::cs_main);
 
         WalletTxStatus result;
@@ -110,7 +110,9 @@ namespace {
         result.depth_in_main_chain = wtx.GetDepthInMainChain(locked_chain);
         result.time_received = wtx.nTimeReceived;
         result.lock_time = wtx.tx->nLockTime;
-        result.is_final = CheckFinalTx(*wtx.tx);
+        CValidationState state;
+        result.is_final = ContextualCheckTransactionForCurrentBlock(
+            Params().GetConsensus(), *wtx.tx, state);
         result.is_trusted = wtx.IsTrusted(locked_chain);
         result.is_abandoned = wtx.isAbandoned();
         result.is_coinbase = wtx.IsCoinBase();

src/qt/transactiondesc.cpp

@@ -23,7 +23,6 @@
 #include <util/system.h>
 #include <validation.h>
 #include <wallet/db.h>
-#include <wallet/finaltx.h>
 #include <wallet/wallet.h>
 
 #include <cstdint>

src/qt/transactionrecord.cpp

@@ -12,7 +12,6 @@
 #include <key_io.h>
 #include <timedata.h>
 #include <validation.h>
-#include <wallet/finaltx.h>
 
 #include <QDateTime>
 

src/wallet/CMakeLists.txt

@@ -16,7 +16,6 @@ add_library(wallet
 	crypter.cpp
 	db.cpp
 	fees.cpp
-	finaltx.cpp
 	init.cpp
 	rpcdump.cpp
 	rpcwallet.cpp

src/wallet/wallet.cpp

@@ -34,7 +34,6 @@
 #include <wallet/coincontrol.h>
 #include <wallet/coinselection.h>
 #include <wallet/fees.h>
-#include <wallet/finaltx.h>
 
 #include <boost/algorithm/string/replace.hpp>
 
@@ -2160,11 +2159,14 @@ bool CWalletTx::InMempool() const {
 }
 
 bool CWalletTx::IsTrusted(interfaces::Chain::Lock &locked_chain) const {
-    // Temporary, for CheckFinalTx below. Removed in upcoming commit.
+    // Temporary, for ContextualCheckTransactionForCurrentBlock below. Removed
+    // in upcoming commit.
     LockAnnotation lock(::cs_main);
 
     // Quick answer in most cases
-    if (!CheckFinalTx(*tx)) {
+    CValidationState state;
+    if (!ContextualCheckTransactionForCurrentBlock(Params().GetConsensus(), *tx,
+                                                   state)) {
         return false;
     }
 
@@ -2374,16 +2376,22 @@ Amount CWallet::GetImmatureWatchOnlyBalance() const {
 // trusted.
 Amount CWallet::GetLegacyBalance(const isminefilter &filter,
                                  int minDepth) const {
-    // Temporary, for CheckFinalTx below. Removed in upcoming commit.
+    // Temporary, for ContextualCheckTransactionForCurrentBlock below. Removed
+    // in upcoming commit.
     LockAnnotation lock(::cs_main);
     auto locked_chain = chain().lock();
     LOCK(cs_wallet);
 
+    const Consensus::Params params = Params().GetConsensus();
+
     Amount balance = Amount::zero();
     for (const auto &entry : mapWallet) {
         const CWalletTx &wtx = entry.second;
         const int depth = wtx.GetDepthInMainChain(*locked_chain);
-        if (depth < 0 || !CheckFinalTx(*wtx.tx) ||
+        CValidationState state;
+        if (depth < 0 ||
+            !ContextualCheckTransactionForCurrentBlock(params, *wtx.tx,
+                                                       state) ||
             wtx.IsImmatureCoinBase(*locked_chain)) {
             continue;
         }
@@ -2438,11 +2446,15 @@ void CWallet::AvailableCoins(interfaces::Chain::Lock &locked_chain,
     vCoins.clear();
     Amount nTotal = Amount::zero();
 
+    const Consensus::Params params = Params().GetConsensus();
+
     for (const auto &entry : mapWallet) {
         const TxId &wtxid = entry.first;
         const CWalletTx *pcoin = &entry.second;
 
-        if (!CheckFinalTx(*pcoin->tx)) {
+        CValidationState state;
+        if (!ContextualCheckTransactionForCurrentBlock(params, *pcoin->tx,
+                                                       state)) {
             continue;
         }