diff --git a/src/script/descriptor.cpp b/src/script/descriptor.cpp
index be0a75d8b..e188201ca 100644
--- a/src/script/descriptor.cpp
+++ b/src/script/descriptor.cpp
@@ -1,892 +1,893 @@
 // Copyright (c) 2018 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include <script/descriptor.h>
 
 #include <chainparams.h> // For Params()
 #include <config.h>
 #include <key_io.h>
 #include <pubkey.h>
 #include <script/script.h>
 #include <script/standard.h>
 #include <span.h>
 #include <util/strencodings.h>
 #include <util/system.h>
 
 #include <memory>
 #include <string>
 #include <vector>
 
 namespace {
 
 ////////////////////////////////////////////////////////////////////////////
 // Internal representation                                                //
 ////////////////////////////////////////////////////////////////////////////
 
 typedef std::vector<uint32_t> KeyPath;
 
 std::string FormatKeyPath(const KeyPath &path) {
     std::string ret;
     for (auto i : path) {
         ret += strprintf("/%i", (i << 1) >> 1);
         if (i >> 31) {
             ret += '\'';
         }
     }
     return ret;
 }
 
 /** Interface for public key objects in descriptors. */
 struct PubkeyProvider {
     virtual ~PubkeyProvider() = default;
 
     /** Derive a public key. */
     virtual bool GetPubKey(int pos, const SigningProvider &arg, CPubKey &key,
                            KeyOriginInfo &info) const = 0;
 
     /** Whether this represent multiple public keys at different positions. */
     virtual bool IsRange() const = 0;
 
     /** Get the size of the generated public key(s) in bytes (33 or 65). */
     virtual size_t GetSize() const = 0;
 
     /** Get the descriptor string form. */
     virtual std::string ToString() const = 0;
 
     /**
      * Get the descriptor string form including private data (if available in
      * arg).
      */
     virtual bool ToPrivateString(const SigningProvider &arg,
                                  std::string &out) const = 0;
 };
 
 class OriginPubkeyProvider final : public PubkeyProvider {
     KeyOriginInfo m_origin;
     std::unique_ptr<PubkeyProvider> m_provider;
 
     std::string OriginString() const {
         return HexStr(std::begin(m_origin.fingerprint),
                       std::end(m_origin.fingerprint)) +
                FormatKeyPath(m_origin.path);
     }
 
 public:
     OriginPubkeyProvider(KeyOriginInfo info,
                          std::unique_ptr<PubkeyProvider> provider)
         : m_origin(std::move(info)), m_provider(std::move(provider)) {}
     bool GetPubKey(int pos, const SigningProvider &arg, CPubKey &key,
                    KeyOriginInfo &info) const override {
         if (!m_provider->GetPubKey(pos, arg, key, info)) {
             return false;
         }
         std::copy(std::begin(m_origin.fingerprint),
                   std::end(m_origin.fingerprint), info.fingerprint);
         info.path.insert(info.path.begin(), m_origin.path.begin(),
                          m_origin.path.end());
         return true;
     }
     bool IsRange() const override { return m_provider->IsRange(); }
     size_t GetSize() const override { return m_provider->GetSize(); }
     std::string ToString() const override {
         return "[" + OriginString() + "]" + m_provider->ToString();
     }
     bool ToPrivateString(const SigningProvider &arg,
                          std::string &ret) const override {
         std::string sub;
         if (!m_provider->ToPrivateString(arg, sub)) {
             return false;
         }
         ret = "[" + OriginString() + "]" + std::move(sub);
         return true;
     }
 };
 
 /** An object representing a parsed constant public key in a descriptor. */
 class ConstPubkeyProvider final : public PubkeyProvider {
     CPubKey m_pubkey;
 
 public:
     ConstPubkeyProvider(const CPubKey &pubkey) : m_pubkey(pubkey) {}
     bool GetPubKey(int pos, const SigningProvider &arg, CPubKey &key,
                    KeyOriginInfo &info) const override {
         key = m_pubkey;
         info.path.clear();
         CKeyID keyid = m_pubkey.GetID();
         std::copy(keyid.begin(), keyid.begin() + sizeof(info.fingerprint),
                   info.fingerprint);
         return true;
     }
     bool IsRange() const override { return false; }
     size_t GetSize() const override { return m_pubkey.size(); }
     std::string ToString() const override {
         return HexStr(m_pubkey.begin(), m_pubkey.end());
     }
     bool ToPrivateString(const SigningProvider &arg,
                          std::string &ret) const override {
         CKey key;
         if (!arg.GetKey(m_pubkey.GetID(), key)) {
             return false;
         }
         ret = EncodeSecret(key);
         return true;
     }
 };
 
 enum class DeriveType {
     NO,
     UNHARDENED,
     HARDENED,
 };
 
 /** An object representing a parsed extended public key in a descriptor. */
 class BIP32PubkeyProvider final : public PubkeyProvider {
     CExtPubKey m_extkey;
     KeyPath m_path;
     DeriveType m_derive;
 
     bool GetExtKey(const SigningProvider &arg, CExtKey &ret) const {
         CKey key;
         if (!arg.GetKey(m_extkey.pubkey.GetID(), key)) {
             return false;
         }
         ret.nDepth = m_extkey.nDepth;
         std::copy(m_extkey.vchFingerprint,
                   m_extkey.vchFingerprint + sizeof(ret.vchFingerprint),
                   ret.vchFingerprint);
         ret.nChild = m_extkey.nChild;
         ret.chaincode = m_extkey.chaincode;
         ret.key = key;
         return true;
     }
 
     bool IsHardened() const {
         if (m_derive == DeriveType::HARDENED) {
             return true;
         }
         for (auto entry : m_path) {
             if (entry >> 31) {
                 return true;
             }
         }
         return false;
     }
 
 public:
     BIP32PubkeyProvider(const CExtPubKey &extkey, KeyPath path,
                         DeriveType derive)
         : m_extkey(extkey), m_path(std::move(path)), m_derive(derive) {}
     bool IsRange() const override { return m_derive != DeriveType::NO; }
     size_t GetSize() const override { return 33; }
     bool GetPubKey(int pos, const SigningProvider &arg, CPubKey &key,
                    KeyOriginInfo &info) const override {
         if (IsHardened()) {
             CExtKey extkey;
             if (!GetExtKey(arg, extkey)) {
                 return false;
             }
             for (auto entry : m_path) {
                 extkey.Derive(extkey, entry);
             }
             if (m_derive == DeriveType::UNHARDENED) {
                 extkey.Derive(extkey, pos);
             }
             if (m_derive == DeriveType::HARDENED) {
                 extkey.Derive(extkey, pos | 0x80000000UL);
             }
             key = extkey.Neuter().pubkey;
         } else {
             // TODO: optimize by caching
             CExtPubKey extkey = m_extkey;
             for (auto entry : m_path) {
                 extkey.Derive(extkey, entry);
             }
             if (m_derive == DeriveType::UNHARDENED) {
                 extkey.Derive(extkey, pos);
             }
             assert(m_derive != DeriveType::HARDENED);
             key = extkey.pubkey;
         }
         CKeyID keyid = m_extkey.pubkey.GetID();
         std::copy(keyid.begin(), keyid.begin() + sizeof(info.fingerprint),
                   info.fingerprint);
         info.path = m_path;
         if (m_derive == DeriveType::UNHARDENED) {
             info.path.push_back(uint32_t(pos));
         }
         if (m_derive == DeriveType::HARDENED) {
             info.path.push_back(uint32_t(pos) | 0x80000000L);
         }
         return true;
     }
     std::string ToString() const override {
         std::string ret = EncodeExtPubKey(m_extkey) + FormatKeyPath(m_path);
         if (IsRange()) {
             ret += "/*";
             if (m_derive == DeriveType::HARDENED) {
                 ret += '\'';
             }
         }
         return ret;
     }
     bool ToPrivateString(const SigningProvider &arg,
                          std::string &out) const override {
         CExtKey key;
         if (!GetExtKey(arg, key)) {
             return false;
         }
         out = EncodeExtKey(key) + FormatKeyPath(m_path);
         if (IsRange()) {
             out += "/*";
             if (m_derive == DeriveType::HARDENED) {
                 out += '\'';
             }
         }
         return true;
     }
 };
 
 /** Base class for all Descriptor implementations. */
 class DescriptorImpl : public Descriptor {
     //! Public key arguments for this descriptor (size 1 for PK, PKH; any size
     //! of Multisig).
     const std::vector<std::unique_ptr<PubkeyProvider>> m_pubkey_args;
     //! The sub-descriptor argument (nullptr for everything but SH).
-    const std::unique_ptr<Descriptor> m_script_arg;
+    const std::unique_ptr<DescriptorImpl> m_script_arg;
     //! The string name of the descriptor function.
     const std::string m_name;
 
 protected:
     //! Return a serialization of anything except pubkey and script arguments,
     //! to be prepended to those.
     virtual std::string ToStringExtra() const { return ""; }
 
     /**
      * A helper function to construct the scripts for this descriptor.
      *
      *  This function is invoked once for every CScript produced by evaluating
      *  m_script_arg, or just once in case m_script_arg is nullptr.
 
      *  @param pubkeys The evaluations of the m_pubkey_args field.
      *  @param script The evaluation of m_script_arg (or nullptr when
      m_script_arg is nullptr).
      *  @param out A FlatSigningProvider to put scripts or public keys in that
      are necessary to the solver.
      *             The script and pubkeys argument to this function are
      automatically added.
      *  @return A vector with scriptPubKeys for this descriptor.
      */
     virtual std::vector<CScript>
     MakeScripts(const std::vector<CPubKey> &pubkeys, const CScript *script,
                 FlatSigningProvider &out) const = 0;
 
 public:
     DescriptorImpl(std::vector<std::unique_ptr<PubkeyProvider>> pubkeys,
-                   std::unique_ptr<Descriptor> script, const std::string &name)
+                   std::unique_ptr<DescriptorImpl> script,
+                   const std::string &name)
         : m_pubkey_args(std::move(pubkeys)), m_script_arg(std::move(script)),
           m_name(name) {}
 
     bool IsSolvable() const override {
         if (m_script_arg) {
             if (!m_script_arg->IsSolvable()) {
                 return false;
             }
         }
         return true;
     }
 
     bool IsRange() const final {
         for (const auto &pubkey : m_pubkey_args) {
             if (pubkey->IsRange()) {
                 return true;
             }
         }
         if (m_script_arg) {
             if (m_script_arg->IsRange()) {
                 return true;
             }
         }
         return false;
     }
 
     bool ToPrivateString(const SigningProvider &arg,
                          std::string &out) const final {
         std::string extra = ToStringExtra();
         size_t pos = extra.size() > 0 ? 1 : 0;
         std::string ret = m_name + "(" + extra;
         for (const auto &pubkey : m_pubkey_args) {
             if (pos++) {
                 ret += ",";
             }
             std::string tmp;
             if (!pubkey->ToPrivateString(arg, tmp)) {
                 return false;
             }
             ret += std::move(tmp);
         }
         if (m_script_arg) {
             if (pos++) {
                 ret += ",";
             }
             std::string tmp;
             if (!m_script_arg->ToPrivateString(arg, tmp)) {
                 return false;
             }
             ret += std::move(tmp);
         }
         out = std::move(ret) + ")";
         return true;
     }
 
     std::string ToString() const final {
         std::string extra = ToStringExtra();
         size_t pos = extra.size() > 0 ? 1 : 0;
         std::string ret = m_name + "(" + extra;
         for (const auto &pubkey : m_pubkey_args) {
             if (pos++) {
                 ret += ",";
             }
             ret += pubkey->ToString();
         }
         if (m_script_arg) {
             if (pos++) {
                 ret += ",";
             }
             ret += m_script_arg->ToString();
         }
         return std::move(ret) + ")";
     }
 
     bool Expand(int pos, const SigningProvider &arg,
                 std::vector<CScript> &output_scripts,
                 FlatSigningProvider &out) const final {
         std::vector<std::pair<CPubKey, KeyOriginInfo>> entries;
         entries.reserve(m_pubkey_args.size());
 
         // Construct temporary data in `entries` and `subscripts`, to avoid
         // producing output in case of failure.
         for (const auto &p : m_pubkey_args) {
             entries.emplace_back();
             if (!p->GetPubKey(pos, arg, entries.back().first,
                               entries.back().second)) {
                 return false;
             }
         }
         std::vector<CScript> subscripts;
         if (m_script_arg) {
             FlatSigningProvider subprovider;
             if (!m_script_arg->Expand(pos, arg, subscripts, subprovider)) {
                 return false;
             }
             out = Merge(out, subprovider);
         }
 
         std::vector<CPubKey> pubkeys;
         pubkeys.reserve(entries.size());
         for (auto &entry : entries) {
             pubkeys.push_back(entry.first);
             out.origins.emplace(entry.first.GetID(), std::move(entry.second));
             out.pubkeys.emplace(entry.first.GetID(), entry.first);
         }
         if (m_script_arg) {
             for (const auto &subscript : subscripts) {
                 out.scripts.emplace(CScriptID(subscript), subscript);
                 std::vector<CScript> addscripts =
                     MakeScripts(pubkeys, &subscript, out);
                 for (auto &addscript : addscripts) {
                     output_scripts.push_back(std::move(addscript));
                 }
             }
         } else {
             output_scripts = MakeScripts(pubkeys, nullptr, out);
         }
         return true;
     }
 };
 
 /** Construct a vector with one element, which is moved into it. */
 template <typename T> std::vector<T> Singleton(T elem) {
     std::vector<T> ret;
     ret.emplace_back(std::move(elem));
     return ret;
 }
 
 /** A parsed addr(A) descriptor. */
 class AddressDescriptor final : public DescriptorImpl {
     const CTxDestination m_destination;
 
 protected:
     std::string ToStringExtra() const override {
         return EncodeDestination(m_destination, GetConfig());
     }
     std::vector<CScript> MakeScripts(const std::vector<CPubKey> &,
                                      const CScript *,
                                      FlatSigningProvider &) const override {
         return Singleton(GetScriptForDestination(m_destination));
     }
 
 public:
     AddressDescriptor(CTxDestination destination)
         : DescriptorImpl({}, {}, "addr"),
           m_destination(std::move(destination)) {}
     bool IsSolvable() const final { return false; }
 };
 
 /** A parsed raw(H) descriptor. */
 class RawDescriptor final : public DescriptorImpl {
     const CScript m_script;
 
 protected:
     std::string ToStringExtra() const override {
         return HexStr(m_script.begin(), m_script.end());
     }
     std::vector<CScript> MakeScripts(const std::vector<CPubKey> &,
                                      const CScript *,
                                      FlatSigningProvider &) const override {
         return Singleton(m_script);
     }
 
 public:
     RawDescriptor(CScript script)
         : DescriptorImpl({}, {}, "raw"), m_script(std::move(script)) {}
     bool IsSolvable() const final { return false; }
 };
 
 /** A parsed pk(P) descriptor. */
 class PKDescriptor final : public DescriptorImpl {
 protected:
     std::vector<CScript> MakeScripts(const std::vector<CPubKey> &keys,
                                      const CScript *,
                                      FlatSigningProvider &) const override {
         return Singleton(GetScriptForRawPubKey(keys[0]));
     }
 
 public:
     PKDescriptor(std::unique_ptr<PubkeyProvider> prov)
         : DescriptorImpl(Singleton(std::move(prov)), {}, "pk") {}
 };
 
 /** A parsed pkh(P) descriptor. */
 class PKHDescriptor final : public DescriptorImpl {
 protected:
     std::vector<CScript> MakeScripts(const std::vector<CPubKey> &keys,
                                      const CScript *,
                                      FlatSigningProvider &) const override {
         return Singleton(GetScriptForDestination(keys[0].GetID()));
     }
 
 public:
     PKHDescriptor(std::unique_ptr<PubkeyProvider> prov)
         : DescriptorImpl(Singleton(std::move(prov)), {}, "pkh") {}
 };
 
 /** A parsed combo(P) descriptor. */
 class ComboDescriptor final : public DescriptorImpl {
 protected:
     std::vector<CScript> MakeScripts(const std::vector<CPubKey> &keys,
                                      const CScript *,
                                      FlatSigningProvider &out) const override {
         std::vector<CScript> ret;
         CKeyID id = keys[0].GetID();
         // P2PK
         ret.emplace_back(GetScriptForRawPubKey(keys[0]));
         // P2PKH
         ret.emplace_back(GetScriptForDestination(id));
         return ret;
     }
 
 public:
     ComboDescriptor(std::unique_ptr<PubkeyProvider> prov)
         : DescriptorImpl(Singleton(std::move(prov)), {}, "combo") {}
 };
 
 /** A parsed multi(...) descriptor. */
 class MultisigDescriptor final : public DescriptorImpl {
     const int m_threshold;
 
 protected:
     std::string ToStringExtra() const override {
         return strprintf("%i", m_threshold);
     }
     std::vector<CScript> MakeScripts(const std::vector<CPubKey> &keys,
                                      const CScript *,
                                      FlatSigningProvider &) const override {
         return Singleton(GetScriptForMultisig(m_threshold, keys));
     }
 
 public:
     MultisigDescriptor(int threshold,
                        std::vector<std::unique_ptr<PubkeyProvider>> providers)
         : DescriptorImpl(std::move(providers), {}, "multi"),
           m_threshold(threshold) {}
 };
 
 /** A parsed sh(...) descriptor. */
 class SHDescriptor final : public DescriptorImpl {
 protected:
     std::vector<CScript> MakeScripts(const std::vector<CPubKey> &,
                                      const CScript *script,
                                      FlatSigningProvider &) const override {
         return Singleton(GetScriptForDestination(CScriptID(*script)));
     }
 
 public:
-    SHDescriptor(std::unique_ptr<Descriptor> desc)
+    SHDescriptor(std::unique_ptr<DescriptorImpl> desc)
         : DescriptorImpl({}, std::move(desc), "sh") {}
 };
 
 ////////////////////////////////////////////////////////////////////////////
 // Parser                                                                 //
 ////////////////////////////////////////////////////////////////////////////
 
 enum class ParseScriptContext {
     TOP,
     P2SH,
 };
 
 /**
  * Parse a constant. If successful, sp is updated to skip the constant and
  * return true.
  */
 bool Const(const std::string &str, Span<const char> &sp) {
     if ((size_t)sp.size() >= str.size() &&
         std::equal(str.begin(), str.end(), sp.begin())) {
         sp = sp.subspan(str.size());
         return true;
     }
     return false;
 }
 
 /**
  * Parse a function call. If successful, sp is updated to be the function's
  * argument(s).
  */
 bool Func(const std::string &str, Span<const char> &sp) {
     if ((size_t)sp.size() >= str.size() + 2 && sp[str.size()] == '(' &&
         sp[sp.size() - 1] == ')' &&
         std::equal(str.begin(), str.end(), sp.begin())) {
         sp = sp.subspan(str.size() + 1, sp.size() - str.size() - 2);
         return true;
     }
     return false;
 }
 
 /** Return the expression that sp begins with, and update sp to skip it. */
 Span<const char> Expr(Span<const char> &sp) {
     int level = 0;
     auto it = sp.begin();
     while (it != sp.end()) {
         if (*it == '(') {
             ++level;
         } else if (level && *it == ')') {
             --level;
         } else if (level == 0 && (*it == ')' || *it == ',')) {
             break;
         }
         ++it;
     }
     Span<const char> ret = sp.first(it - sp.begin());
     sp = sp.subspan(it - sp.begin());
     return ret;
 }
 
 /** Split a string on every instance of sep, returning a vector. */
 std::vector<Span<const char>> Split(const Span<const char> &sp, char sep) {
     std::vector<Span<const char>> ret;
     auto it = sp.begin();
     auto start = it;
     while (it != sp.end()) {
         if (*it == sep) {
             ret.emplace_back(start, it);
             start = it + 1;
         }
         ++it;
     }
     ret.emplace_back(start, it);
     return ret;
 }
 
 /**
  * Parse a key path, being passed a split list of elements (the first element is
  * ignored).
  */
 NODISCARD bool ParseKeyPath(const std::vector<Span<const char>> &split,
                             KeyPath &out) {
     for (size_t i = 1; i < split.size(); ++i) {
         Span<const char> elem = split[i];
         bool hardened = false;
         if (elem.size() > 0 &&
             (elem[elem.size() - 1] == '\'' || elem[elem.size() - 1] == 'h')) {
             elem = elem.first(elem.size() - 1);
             hardened = true;
         }
         uint32_t p;
         if (!ParseUInt32(std::string(elem.begin(), elem.end()), &p) ||
             p > 0x7FFFFFFFUL) {
             return false;
         }
         out.push_back(p | (uint32_t(hardened) << 31));
     }
     return true;
 }
 
 /** Parse a public key that excludes origin information. */
 std::unique_ptr<PubkeyProvider> ParsePubkeyInner(const Span<const char> &sp,
                                                  FlatSigningProvider &out) {
     auto split = Split(sp, '/');
     std::string str(split[0].begin(), split[0].end());
     if (split.size() == 1) {
         if (IsHex(str)) {
             std::vector<uint8_t> data = ParseHex(str);
             CPubKey pubkey(data);
             if (pubkey.IsFullyValid()) {
                 return std::make_unique<ConstPubkeyProvider>(pubkey);
             }
         }
         CKey key = DecodeSecret(str);
         if (key.IsValid()) {
             CPubKey pubkey = key.GetPubKey();
             out.keys.emplace(pubkey.GetID(), key);
             return std::make_unique<ConstPubkeyProvider>(pubkey);
         }
     }
     CExtKey extkey = DecodeExtKey(str);
     CExtPubKey extpubkey = DecodeExtPubKey(str);
     if (!extkey.key.IsValid() && !extpubkey.pubkey.IsValid()) {
         return nullptr;
     }
     KeyPath path;
     DeriveType type = DeriveType::NO;
     if (split.back() == MakeSpan("*").first(1)) {
         split.pop_back();
         type = DeriveType::UNHARDENED;
     } else if (split.back() == MakeSpan("*'").first(2) ||
                split.back() == MakeSpan("*h").first(2)) {
         split.pop_back();
         type = DeriveType::HARDENED;
     }
     if (!ParseKeyPath(split, path)) {
         return nullptr;
     }
     if (extkey.key.IsValid()) {
         extpubkey = extkey.Neuter();
         out.keys.emplace(extpubkey.pubkey.GetID(), extkey.key);
     }
     return std::make_unique<BIP32PubkeyProvider>(extpubkey, std::move(path),
                                                  type);
 }
 
 /** Parse a public key including origin information (if enabled). */
 std::unique_ptr<PubkeyProvider> ParsePubkey(const Span<const char> &sp,
                                             FlatSigningProvider &out) {
     auto origin_split = Split(sp, ']');
     if (origin_split.size() > 2) {
         return nullptr;
     }
     if (origin_split.size() == 1) {
         return ParsePubkeyInner(origin_split[0], out);
     }
     if (origin_split[0].size() < 1 || origin_split[0][0] != '[') {
         return nullptr;
     }
     auto slash_split = Split(origin_split[0].subspan(1), '/');
     if (slash_split[0].size() != 8) {
         return nullptr;
     }
     std::string fpr_hex =
         std::string(slash_split[0].begin(), slash_split[0].end());
     if (!IsHex(fpr_hex)) {
         return nullptr;
     }
     auto fpr_bytes = ParseHex(fpr_hex);
     KeyOriginInfo info;
     static_assert(sizeof(info.fingerprint) == 4, "Fingerprint must be 4 bytes");
     assert(fpr_bytes.size() == 4);
     std::copy(fpr_bytes.begin(), fpr_bytes.end(), info.fingerprint);
     if (!ParseKeyPath(slash_split, info.path)) {
         return nullptr;
     }
     auto provider = ParsePubkeyInner(origin_split[1], out);
     if (!provider) {
         return nullptr;
     }
     return std::make_unique<OriginPubkeyProvider>(std::move(info),
                                                   std::move(provider));
 }
 
 /** Parse a script in a particular context. */
-std::unique_ptr<Descriptor> ParseScript(Span<const char> &sp,
-                                        ParseScriptContext ctx,
-                                        FlatSigningProvider &out) {
+std::unique_ptr<DescriptorImpl> ParseScript(Span<const char> &sp,
+                                            ParseScriptContext ctx,
+                                            FlatSigningProvider &out) {
     auto expr = Expr(sp);
     if (Func("pk", expr)) {
         auto pubkey = ParsePubkey(expr, out);
         if (!pubkey) {
             return nullptr;
         }
         return std::make_unique<PKDescriptor>(std::move(pubkey));
     }
     if (Func("pkh", expr)) {
         auto pubkey = ParsePubkey(expr, out);
         if (!pubkey) {
             return nullptr;
         }
         return std::make_unique<PKHDescriptor>(std::move(pubkey));
     }
     if (ctx == ParseScriptContext::TOP && Func("combo", expr)) {
         auto pubkey = ParsePubkey(expr, out);
         if (!pubkey) {
             return nullptr;
         }
         return std::make_unique<ComboDescriptor>(std::move(pubkey));
     }
     if (Func("multi", expr)) {
         auto threshold = Expr(expr);
         uint32_t thres;
         std::vector<std::unique_ptr<PubkeyProvider>> providers;
         if (!ParseUInt32(std::string(threshold.begin(), threshold.end()),
                          &thres)) {
             return nullptr;
         }
         size_t script_size = 0;
         while (expr.size()) {
             if (!Const(",", expr)) {
                 return nullptr;
             }
             auto arg = Expr(expr);
             auto pk = ParsePubkey(arg, out);
             if (!pk) {
                 return nullptr;
             }
             script_size += pk->GetSize() + 1;
             providers.emplace_back(std::move(pk));
         }
         if (providers.size() < 1 || providers.size() > 16 || thres < 1 ||
             thres > providers.size()) {
             return nullptr;
         }
         if (ctx == ParseScriptContext::TOP) {
             if (providers.size() > 3) {
                 // Not more than 3 pubkeys for raw multisig
                 return nullptr;
             }
         }
         if (ctx == ParseScriptContext::P2SH) {
             if (script_size + 3 > 520) {
                 // Enforce P2SH script size limit
                 return nullptr;
             }
         }
         return std::make_unique<MultisigDescriptor>(thres,
                                                     std::move(providers));
     }
     if (ctx == ParseScriptContext::TOP && Func("sh", expr)) {
         auto desc = ParseScript(expr, ParseScriptContext::P2SH, out);
         if (!desc || expr.size()) {
             return nullptr;
         }
         return std::make_unique<SHDescriptor>(std::move(desc));
     }
     if (ctx == ParseScriptContext::TOP && Func("addr", expr)) {
         CTxDestination dest =
             DecodeDestination(std::string(expr.begin(), expr.end()), Params());
         if (!IsValidDestination(dest)) {
             return nullptr;
         }
         return std::make_unique<AddressDescriptor>(std::move(dest));
     }
     if (ctx == ParseScriptContext::TOP && Func("raw", expr)) {
         std::string str(expr.begin(), expr.end());
         if (!IsHex(str)) {
             return nullptr;
         }
         auto bytes = ParseHex(str);
         return std::make_unique<RawDescriptor>(
             CScript(bytes.begin(), bytes.end()));
     }
     return nullptr;
 }
 
 static std::unique_ptr<PubkeyProvider>
 InferPubkey(const CPubKey &pubkey, ParseScriptContext,
             const SigningProvider &provider) {
     auto key_provider = std::make_unique<ConstPubkeyProvider>(pubkey);
     KeyOriginInfo info;
     if (provider.GetKeyOrigin(pubkey.GetID(), info)) {
         return std::make_unique<OriginPubkeyProvider>(std::move(info),
                                                       std::move(key_provider));
     }
     return key_provider;
 }
 
-std::unique_ptr<Descriptor> InferScript(const CScript &script,
-                                        ParseScriptContext ctx,
-                                        const SigningProvider &provider) {
+std::unique_ptr<DescriptorImpl> InferScript(const CScript &script,
+                                            ParseScriptContext ctx,
+                                            const SigningProvider &provider) {
     std::vector<std::vector<uint8_t>> data;
     txnouttype txntype = Solver(script, data);
 
     if (txntype == TX_PUBKEY) {
         CPubKey pubkey(data[0].begin(), data[0].end());
         if (pubkey.IsValid()) {
             return std::make_unique<PKDescriptor>(
                 InferPubkey(pubkey, ctx, provider));
         }
     }
     if (txntype == TX_PUBKEYHASH) {
         uint160 hash(data[0]);
         CKeyID keyid(hash);
         CPubKey pubkey;
         if (provider.GetPubKey(keyid, pubkey)) {
             return std::make_unique<PKHDescriptor>(
                 InferPubkey(pubkey, ctx, provider));
         }
     }
     if (txntype == TX_MULTISIG) {
         std::vector<std::unique_ptr<PubkeyProvider>> providers;
         for (size_t i = 1; i + 1 < data.size(); ++i) {
             CPubKey pubkey(data[i].begin(), data[i].end());
             providers.push_back(InferPubkey(pubkey, ctx, provider));
         }
         return std::make_unique<MultisigDescriptor>((int)data[0][0],
                                                     std::move(providers));
     }
     if (txntype == TX_SCRIPTHASH && ctx == ParseScriptContext::TOP) {
         uint160 hash(data[0]);
         CScriptID scriptid(hash);
         CScript subscript;
         if (provider.GetCScript(scriptid, subscript)) {
             auto sub =
                 InferScript(subscript, ParseScriptContext::P2SH, provider);
             if (sub) {
                 return std::make_unique<SHDescriptor>(std::move(sub));
             }
         }
     }
 
     CTxDestination dest;
     if (ExtractDestination(script, dest)) {
         if (GetScriptForDestination(dest) == script) {
             return std::make_unique<AddressDescriptor>(std::move(dest));
         }
     }
 
     return std::make_unique<RawDescriptor>(script);
 }
 
 } // namespace
 
 std::unique_ptr<Descriptor> Parse(const std::string &descriptor,
                                   FlatSigningProvider &out) {
     Span<const char> sp(descriptor.data(), descriptor.size());
     auto ret = ParseScript(sp, ParseScriptContext::TOP, out);
     if (sp.size() == 0 && ret) {
-        return ret;
+        return std::unique_ptr<Descriptor>(std::move(ret));
     }
     return nullptr;
 }
 
 std::unique_ptr<Descriptor> InferDescriptor(const CScript &script,
                                             const SigningProvider &provider) {
     return InferScript(script, ParseScriptContext::TOP, provider);
 }