Merge #16128: Delete error-prone CScript constructor only used with FindAndDelete

e1a55690e66ca962179bc8170695b92af8a3caa8 Delete error-prone CScript constructor (Gregory Sanders)

Pull request description:

  The behavior of this constructor is not the expected behavior compared to the other constructors which directly interpret the vector as a CScript, rather than serialize it into a new CScript. It has only four uses in the entire codebase. Delete this constructor and replace its four uses with the more clear serialization construction.

ACKs for top commit:
  Empact:
    ACK https://github.com/bitcoin/bitcoin/pull/16128/commits/e1a55690e66ca962179bc8170695b92af8a3caa8
  sipa:
    Concept and code review ACK e1a55690e66ca962179bc8170695b92af8a3caa8, but I'd like to make sure we have tests covering the FindAndDelete usage.

Tree-SHA512: b6721e343c867ca401a80ec87c25939d7f1fc798f3bf7e5feb0ea6f8280eecb6bd65afc8286912c76ff8119ccea50ad7726b1a4137cae70c9d4fed7d960e10d3

3 files changed, 9 insertions, 5 deletions

diff --git a/src/qt/coincontroldialog.cpp b/src/qt/coincontroldialog.cpp
index 6b9f79aaf8..03d18d2845 100644
--- a/src/qt/coincontroldialog.cpp
+++ b/src/qt/coincontroldialog.cpp
@@ -418,7 +418,8 @@ void CoinControlDialog::updateLabels(WalletModel *model, QDialog* dialog)
 
         if (amount > 0)
         {
-            CTxOut txout(amount, static_cast<CScript>(std::vector<unsigned char>(24, 0)));
+            // Assumes a p2pkh script size
+            CTxOut txout(amount, CScript() << std::vector<unsigned char>(24, 0));
             txDummy.vout.push_back(txout);
             fDust |= IsDust(txout, model->node().getDustRelayFee());
         }
@@ -509,7 +510,8 @@ void CoinControlDialog::updateLabels(WalletModel *model, QDialog* dialog)
             // Never create dust outputs; if we would, just add the dust to the fee.
             if (nChange > 0 && nChange < MIN_CHANGE)
             {
-                CTxOut txout(nChange, static_cast<CScript>(std::vector<unsigned char>(24, 0)));
+                // Assumes a p2pkh script size
+                CTxOut txout(nChange, CScript() << std::vector<unsigned char>(24, 0));
                 if (IsDust(txout, model->node().getDustRelayFee()))
                 {
                     nPayFee += nChange;
diff --git a/src/script/interpreter.cpp b/src/script/interpreter.cpp
index 95b25b4911..f8701b6d01 100644
--- a/src/script/interpreter.cpp
+++ b/src/script/interpreter.cpp
@@ -926,7 +926,7 @@ bool EvalScript(std::vector<std::vector<unsigned char> >& stack, const CScript&
 
                     // Drop the signature in pre-segwit scripts but not segwit scripts
                     if (sigversion == SigVersion::BASE) {
-                        int found = FindAndDelete(scriptCode, CScript(vchSig));
+                        int found = FindAndDelete(scriptCode, CScript() << vchSig);
                         if (found > 0 && (flags & SCRIPT_VERIFY_CONST_SCRIPTCODE))
                             return set_error(serror, SCRIPT_ERR_SIG_FINDANDDELETE);
                     }
@@ -992,7 +992,7 @@ bool EvalScript(std::vector<std::vector<unsigned char> >& stack, const CScript&
                     {
                         valtype& vchSig = stacktop(-isig-k);
                         if (sigversion == SigVersion::BASE) {
-                            int found = FindAndDelete(scriptCode, CScript(vchSig));
+                            int found = FindAndDelete(scriptCode, CScript() << vchSig);
                             if (found > 0 && (flags & SCRIPT_VERIFY_CONST_SCRIPTCODE))
                                 return set_error(serror, SCRIPT_ERR_SIG_FINDANDDELETE);
                         }
diff --git a/src/script/script.h b/src/script/script.h
index 11e8661a5b..6355b8a704 100644
--- a/src/script/script.h
+++ b/src/script/script.h
@@ -437,7 +437,9 @@ public:
 
     explicit CScript(opcodetype b)     { operator<<(b); }
     explicit CScript(const CScriptNum& b) { operator<<(b); }
-    explicit CScript(const std::vector<unsigned char>& b) { operator<<(b); }
+    // delete non-existent constructor to defend against future introduction
+    // e.g. via prevector
+    explicit CScript(const std::vector<unsigned char>& b) = delete;
 
 
     CScript& operator<<(int64_t b) { return push_int64(b); }