Merge bitcoin/bitcoin#22421: Make IsSegWitOutput return true for taproot outputs

8465978 Make IsSegWitOutput return true for taproot outputs (Pieter Wuille)

Pull request description:

  This fixes a bug: currently `utxoupdatepsbt` will not fill in UTXO data for PSBTs spending taproot outputs.

ACKs for top commit:
  achow101:
    Code Review ACK 8465978
  jonatack:
    ACK 8465978
  meshcollider:
    utACK 8465978

Tree-SHA512: 2f8f873450bef4b5a4ce5962a231297b386c6b1445e69ce5f36ab28eca7343be3a11bc09c38534b0f75e6f99ba15d78d3ba5d484f6c63e5a9775e1f3f55a74e0

Author: meshcollider

src/script/sign.cpp

@@ -612,15 +612,18 @@ bool IsSolvable(const SigningProvider& provider, const CScript& script)
 
 bool IsSegWitOutput(const SigningProvider& provider, const CScript& script)
 {
-    std::vector<valtype> solutions;
-    auto whichtype = Solver(script, solutions);
-    if (whichtype == TxoutType::WITNESS_V0_SCRIPTHASH || whichtype == TxoutType::WITNESS_V0_KEYHASH || whichtype == TxoutType::WITNESS_UNKNOWN) return true;
-    if (whichtype == TxoutType::SCRIPTHASH) {
-        auto h160 = uint160(solutions[0]);
-        CScript subscript;
-        if (provider.GetCScript(CScriptID{h160}, subscript)) {
-            whichtype = Solver(subscript, solutions);
-            if (whichtype == TxoutType::WITNESS_V0_SCRIPTHASH || whichtype == TxoutType::WITNESS_V0_KEYHASH || whichtype == TxoutType::WITNESS_UNKNOWN) return true;
+    int version;
+    valtype program;
+    if (script.IsWitnessProgram(version, program)) return true;
+    if (script.IsPayToScriptHash()) {
+        std::vector<valtype> solutions;
+        auto whichtype = Solver(script, solutions);
+        if (whichtype == TxoutType::SCRIPTHASH) {
+            auto h160 = uint160(solutions[0]);
+            CScript subscript;
+            if (provider.GetCScript(CScriptID{h160}, subscript)) {
+                if (subscript.IsWitnessProgram(version, program)) return true;
+            }
         }
     }
     return false;