Improve witness destination types and use them more

Author: sipa

src/script/standard.cpp

@@ -348,19 +348,14 @@ CScript GetScriptForWitness(const CScript& redeemscript)
     std::vector<std::vector<unsigned char> > vSolutions;
     if (Solver(redeemscript, typ, vSolutions)) {
         if (typ == TX_PUBKEY) {
-            unsigned char h160[20];
-            CHash160().Write(&vSolutions[0][0], vSolutions[0].size()).Finalize(h160);
-            ret << OP_0 << std::vector<unsigned char>(&h160[0], &h160[20]);
-            return ret;
+            return GetScriptForDestination(WitnessV0KeyHash(Hash160(vSolutions[0].begin(), vSolutions[0].end())));
         } else if (typ == TX_PUBKEYHASH) {
-           ret << OP_0 << vSolutions[0];
-           return ret;
+            return GetScriptForDestination(WitnessV0KeyHash(vSolutions[0]));
         }
     }
     uint256 hash;
     CSHA256().Write(&redeemscript[0], redeemscript.size()).Finalize(hash.begin());
-    ret << OP_0 << ToByteVector(hash);
-    return ret;
+    return GetScriptForDestination(WitnessV0ScriptHash(hash));
 }
 
 bool IsValidDestination(const CTxDestination& dest) {

src/script/standard.h

@@ -73,8 +73,19 @@ class CNoDestination {
     friend bool operator<(const CNoDestination &a, const CNoDestination &b) { return true; }
 };
 
-struct WitnessV0ScriptHash : public uint256 {};
-struct WitnessV0KeyHash : public uint160 {};
+struct WitnessV0ScriptHash : public uint256
+{
+    WitnessV0ScriptHash() : uint256() {}
+    explicit WitnessV0ScriptHash(const uint256& hash) : uint256(hash) {}
+    using uint256::uint256;
+};
+
+struct WitnessV0KeyHash : public uint160
+{
+    WitnessV0KeyHash() : uint160() {}
+    explicit WitnessV0KeyHash(const uint160& hash) : uint160(hash) {}
+    using uint160::uint160;
+};
 
 //! CTxDestination subtype to encode any future Witness version
 struct WitnessUnknown
@@ -164,6 +175,9 @@ CScript GetScriptForMultisig(int nRequired, const std::vector<CPubKey>& keys);
  * Generate a pay-to-witness script for the given redeem script. If the redeem
  * script is P2PK or P2PKH, this returns a P2WPKH script, otherwise it returns a
  * P2WSH script.
+ *
+ * TODO: replace calls to GetScriptForWitness with GetScriptForDestination using
+ * the various witness-specific CTxDestination subtypes.
  */
 CScript GetScriptForWitness(const CScript& redeemscript);