Merge #18787: wallet: descriptor wallet release notes and cleanups

ca2a09640fe976b1e74a33d29d9381895e71b347 Change SetType to SetInternal and remove m_address_type (Andrew Chow)
89b1ce1140535b4c902a7c5999bed335b9ddfe7c Remove unimplemented SetCrypted from DescriptorScriptPubKeyMan (Andrew Chow)
b9073c8f13fb0ba94c2ec6365666343e19fd9ddf rpc: createwallet warning that descriptor wallets are experimental (Andrew Chow)
610030d95c60ea526440d801a98ac8bd370eac48 docs: Add release notes for descriptor wallets (Andrew Chow)

Pull request description:

  Some docs and cleanup following #16528.

  * Added release notes to explain a bit of motivation for descriptor wallets, what was changed, and how users will be effected by it. Also mentions the caveats regarding multsigs and watchonly that we have discussed on IRC.
  * Adds a warning to `createwallet` that descriptor wallets are experimental.
  * Removed unused `SetCrypted` as suggestioned: https://github.com/bitcoin/bitcoin/pull/16528#discussion_r415300916
  * Removed `m_address_type` as mentioned in https://github.com/bitcoin/bitcoin/pull/18782#issuecomment-620167077

ACKs for top commit:
  Sjors:
    tACK ca2a09640fe976b1e74a33d29d9381895e71b347
  instagibbs:
    utACK https://github.com/bitcoin/bitcoin/commit/ca2a09640fe976b1e74a33d29d9381895e71b347
  meshcollider:
    utACK ca2a09640fe976b1e74a33d29d9381895e71b347

Tree-SHA512: 987188a912c191430e5d3f89bcef54ba6773692fc2d95b16a3ec11d9007ded210466ed980a3857e8b7196beef6422f07f9c85cc157f996c02d16f4dbde2e7b2a

4 files changed, 17 insertions, 18 deletions

diff --git a/src/wallet/rpcwallet.cpp b/src/wallet/rpcwallet.cpp
index 57f1b4d02f..2a9ac189ea 100644
--- a/src/wallet/rpcwallet.cpp
+++ b/src/wallet/rpcwallet.cpp
@@ -2726,6 +2726,7 @@ static UniValue createwallet(const JSONRPCRequest& request)
     }
     if (!request.params[5].isNull() && request.params[5].get_bool()) {
         flags |= WALLET_FLAG_DESCRIPTORS;
+        warnings.emplace_back(Untranslated("Wallet is an experimental descriptor wallet"));
     }
 
     bilingual_str error;
diff --git a/src/wallet/scriptpubkeyman.cpp b/src/wallet/scriptpubkeyman.cpp
index 315283514e..8a2a798644 100644
--- a/src/wallet/scriptpubkeyman.cpp
+++ b/src/wallet/scriptpubkeyman.cpp
@@ -1577,7 +1577,7 @@ std::set<CKeyID> LegacyScriptPubKeyMan::GetKeys() const
     return set_address;
 }
 
-void LegacyScriptPubKeyMan::SetType(OutputType type, bool internal) {}
+void LegacyScriptPubKeyMan::SetInternal(bool internal) {}
 
 bool DescriptorScriptPubKeyMan::GetNewDestination(const OutputType type, CTxDestination& dest, std::string& error)
 {
@@ -1589,7 +1589,9 @@ bool DescriptorScriptPubKeyMan::GetNewDestination(const OutputType type, CTxDest
     {
         LOCK(cs_desc_man);
         assert(m_wallet_descriptor.descriptor->IsSingleType()); // This is a combo descriptor which should not be an active descriptor
-        if (type != m_address_type) {
+        Optional<OutputType> desc_addr_type = m_wallet_descriptor.descriptor->GetOutputType();
+        assert(desc_addr_type);
+        if (type != *desc_addr_type) {
             throw std::runtime_error(std::string(__func__) + ": Types are inconsistent");
         }
 
@@ -1857,7 +1859,7 @@ bool DescriptorScriptPubKeyMan::AddDescriptorKeyWithDB(WalletBatch& batch, const
     }
 }
 
-bool DescriptorScriptPubKeyMan::SetupDescriptorGeneration(const CExtKey& master_key)
+bool DescriptorScriptPubKeyMan::SetupDescriptorGeneration(const CExtKey& master_key, OutputType addr_type)
 {
     LOCK(cs_desc_man);
     assert(m_storage.IsWalletFlagSet(WALLET_FLAG_DESCRIPTORS));
@@ -1874,7 +1876,7 @@ bool DescriptorScriptPubKeyMan::SetupDescriptorGeneration(const CExtKey& master_
     // Build descriptor string
     std::string desc_prefix;
     std::string desc_suffix = "/*)";
-    switch (m_address_type) {
+    switch (addr_type) {
     case OutputType::LEGACY: {
         desc_prefix = "pkh(" + xpub + "/44'";
         break;
@@ -2156,9 +2158,8 @@ uint256 DescriptorScriptPubKeyMan::GetID() const
     return id;
 }
 
-void DescriptorScriptPubKeyMan::SetType(OutputType type, bool internal)
+void DescriptorScriptPubKeyMan::SetInternal(bool internal)
 {
-    this->m_address_type = type;
     this->m_internal = internal;
 }
 
diff --git a/src/wallet/scriptpubkeyman.h b/src/wallet/scriptpubkeyman.h
index c62c970235..2f6245bbe2 100644
--- a/src/wallet/scriptpubkeyman.h
+++ b/src/wallet/scriptpubkeyman.h
@@ -237,7 +237,7 @@ public:
 
     virtual uint256 GetID() const { return uint256(); }
 
-    virtual void SetType(OutputType type, bool internal) {}
+    virtual void SetInternal(bool internal) {}
 
     /** Prepends the wallet name in logging output to ease debugging in multi-wallet use cases */
     template<typename... Params>
@@ -396,7 +396,7 @@ public:
 
     uint256 GetID() const override;
 
-    void SetType(OutputType type, bool internal) override;
+    void SetInternal(bool internal) override;
 
     // Map from Key ID to key metadata.
     std::map<CKeyID, CKeyMetadata> mapKeyMetadata GUARDED_BY(cs_KeyStore);
@@ -524,14 +524,11 @@ private:
     PubKeyMap m_map_pubkeys GUARDED_BY(cs_desc_man);
     int32_t m_max_cached_index = -1;
 
-    OutputType m_address_type;
     bool m_internal = false;
 
     KeyMap m_map_keys GUARDED_BY(cs_desc_man);
     CryptedKeyMap m_map_crypted_keys GUARDED_BY(cs_desc_man);
 
-    bool SetCrypted();
-
     //! keeps track of whether Unlock has run a thorough check before
     bool m_decryption_thoroughly_checked = false;
 
@@ -551,9 +548,9 @@ public:
         :   ScriptPubKeyMan(storage),
             m_wallet_descriptor(descriptor)
         {}
-    DescriptorScriptPubKeyMan(WalletStorage& storage, OutputType address_type, bool internal)
+    DescriptorScriptPubKeyMan(WalletStorage& storage, bool internal)
         :   ScriptPubKeyMan(storage),
-            m_address_type(address_type), m_internal(internal)
+            m_internal(internal)
         {}
 
     mutable RecursiveMutex cs_desc_man;
@@ -578,7 +575,7 @@ public:
     bool IsHDEnabled() const override;
 
     //! Setup descriptors based on the given CExtkey
-    bool SetupDescriptorGeneration(const CExtKey& master_key);
+    bool SetupDescriptorGeneration(const CExtKey& master_key, OutputType addr_type);
 
     bool HavePrivateKeys() const override;
 
@@ -602,7 +599,7 @@ public:
 
     uint256 GetID() const override;
 
-    void SetType(OutputType type, bool internal) override;
+    void SetInternal(bool internal) override;
 
     void SetCache(const DescriptorCache& cache);
 
diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
index e1e8263ee1..255770552f 100644
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -4362,7 +4362,7 @@ void CWallet::SetupDescriptorScriptPubKeyMans()
 
     for (bool internal : {false, true}) {
         for (OutputType t : OUTPUT_TYPES) {
-            auto spk_manager = std::unique_ptr<DescriptorScriptPubKeyMan>(new DescriptorScriptPubKeyMan(*this, t, internal));
+            auto spk_manager = std::unique_ptr<DescriptorScriptPubKeyMan>(new DescriptorScriptPubKeyMan(*this, internal));
             if (IsCrypted()) {
                 if (IsLocked()) {
                     throw std::runtime_error(std::string(__func__) + ": Wallet is locked, cannot setup new descriptors");
@@ -4371,7 +4371,7 @@ void CWallet::SetupDescriptorScriptPubKeyMans()
                     throw std::runtime_error(std::string(__func__) + ": Could not encrypt new descriptors");
                 }
             }
-            spk_manager->SetupDescriptorGeneration(master_key);
+            spk_manager->SetupDescriptorGeneration(master_key, t);
             uint256 id = spk_manager->GetID();
             m_spk_managers[id] = std::move(spk_manager);
             SetActiveScriptPubKeyMan(id, t, internal);
@@ -4384,7 +4384,7 @@ void CWallet::SetActiveScriptPubKeyMan(uint256 id, OutputType type, bool interna
     WalletLogPrintf("Setting spkMan to active: id = %s, type = %d, internal = %d\n", id.ToString(), static_cast<int>(type), static_cast<int>(internal));
     auto& spk_mans = internal ? m_internal_spk_managers : m_external_spk_managers;
     auto spk_man = m_spk_managers.at(id).get();
-    spk_man->SetType(type, internal);
+    spk_man->SetInternal(internal);
     spk_mans[type] = spk_man;
 
     if (!memonly) {