qa: check parsed multipath descriptors dont share references

There's no need for it to be a shared_ptr.

src/script/miniscript.h

@@ -184,11 +184,11 @@ inline consteval Type operator"" _mst(const char* c, size_t l) {
 using Opcode = std::pair<opcodetype, std::vector<unsigned char>>;
 
 template<typename Key> struct Node;
-template<typename Key> using NodeRef = std::shared_ptr<const Node<Key>>;
+template<typename Key> using NodeRef = std::unique_ptr<const Node<Key>>;
 
 //! Construct a miniscript node as a shared_ptr.
 template<typename Key, typename... Args>
-NodeRef<Key> MakeNodeRef(Args&&... args) { return std::make_shared<const Node<Key>>(std::forward<Args>(args)...); }
+NodeRef<Key> MakeNodeRef(Args&&... args) { return std::make_unique<const Node<Key>>(std::forward<Args>(args)...); }
 
 //! The different node types in miniscript.
 enum class Fragment {
@@ -1687,6 +1687,10 @@ public:
         : Node(internal::NoDupCheck{}, ctx.MsContext(), nt, std::move(sub), val) { DuplicateKeyCheck(ctx); }
     template <typename Ctx> Node(const Ctx& ctx, Fragment nt, uint32_t val = 0)
         : Node(internal::NoDupCheck{}, ctx.MsContext(), nt, val) { DuplicateKeyCheck(ctx); }
+
+    // Delete copy constructor and assignment operator
+    Node(const Node&) = delete;
+    Node& operator=(const Node&) = delete;
 };
 
 namespace internal {

src/test/descriptor_tests.cpp

@@ -429,6 +429,20 @@ void CheckMultipath(const std::string& prv,
               /*spender_nlocktime=*/0, /*spender_nsequence=*/CTxIn::SEQUENCE_FINAL, /*preimages=*/{},
               expanded_prvs.at(i), expanded_pubs.at(i), i);
     }
+
+    // The descriptor for each path must be standalone. They should not share common references. Test this
+    // by parsing a multipath descriptor expression, deallocating all but one of the descriptors and making
+    // sure we can perform operations on it.
+    FlatSigningProvider prov, out;
+    std::string error;
+    const auto desc{[&](){
+        auto parsed{Parse(pub, prov, error)};
+        assert(parsed.size() > 1);
+        return std::move(parsed.at(0));
+    }()};
+    desc->ToString();
+    std::vector<CScript> out_scripts;
+    desc->Expand(0, prov, out_scripts, out);
 }
 
 void CheckInferDescriptor(const std::string& script_hex, const std::string& expected_desc, const std::vector<std::string>& hex_scripts, const std::vector<std::pair<std::string, std::string>>& origin_pubkeys)
@@ -807,6 +821,31 @@ BOOST_AUTO_TEST_CASE(descriptor_test)
                 {{0x80000000UL + 48, 0x80000000UL + 1, 0x80000000UL, 0x80000000UL + 2, 1, 0}, {0x80000000UL + 48, 0x80000000UL + 1, 0x80000000UL, 0x80000000UL + 2, 1, 1}, {0x80000000UL + 48, 0x80000000UL + 1, 0x80000000UL, 0x80000000UL + 2, 1, 2}},
             }
     );
+    CheckMultipath("tr(xprv9yYge4PS54XkYT9KiLfCRwc8Jeuz8DucxQGtuEecJZYhKNiqbPxYHTPzXtskmzWBqdqkRAGsghNmZzNsfU2wstaB3XjDQFPv567aQSSuPyo/<2;3>,l:pk(xprvA1ADjaN8H3HGnZSmt4VF7YdWoV9oNq8jhqhurxsrYycBAFK555cECoaY22KWt6BTRNLuvobW5VQTF89PN3iA485LAg7epazevPyjCa4xTzd))",
+            "tr(xpub6CY33ZvKuS63kwDnpNCCo5YrrgkUXgdUKdCVhd4Dru5gCB3z8wGnqFiUP98Za5pYSYF5KmvBHTY3Ra8FAJGggzBjuHS69WzN8gscPupuZwK/<2;3>,l:pk(xpub6E9a95u27Qqa13XEz62FUgaFMWzHnHrb54dWfMHU7K9A33eDccvUkbu1sHYoByHAgJdR326rWqn9pGZgZHz1afDprW5gGwS4gUX8Ri6aGPZ))",
+            {
+                "tr(xprv9yYge4PS54XkYT9KiLfCRwc8Jeuz8DucxQGtuEecJZYhKNiqbPxYHTPzXtskmzWBqdqkRAGsghNmZzNsfU2wstaB3XjDQFPv567aQSSuPyo/2,l:pk(xprvA1ADjaN8H3HGnZSmt4VF7YdWoV9oNq8jhqhurxsrYycBAFK555cECoaY22KWt6BTRNLuvobW5VQTF89PN3iA485LAg7epazevPyjCa4xTzd))",
+                "tr(xprv9yYge4PS54XkYT9KiLfCRwc8Jeuz8DucxQGtuEecJZYhKNiqbPxYHTPzXtskmzWBqdqkRAGsghNmZzNsfU2wstaB3XjDQFPv567aQSSuPyo/3,l:pk(xprvA1ADjaN8H3HGnZSmt4VF7YdWoV9oNq8jhqhurxsrYycBAFK555cECoaY22KWt6BTRNLuvobW5VQTF89PN3iA485LAg7epazevPyjCa4xTzd))",
+            },
+            {
+                "tr(xpub6CY33ZvKuS63kwDnpNCCo5YrrgkUXgdUKdCVhd4Dru5gCB3z8wGnqFiUP98Za5pYSYF5KmvBHTY3Ra8FAJGggzBjuHS69WzN8gscPupuZwK/2,l:pk(xpub6E9a95u27Qqa13XEz62FUgaFMWzHnHrb54dWfMHU7K9A33eDccvUkbu1sHYoByHAgJdR326rWqn9pGZgZHz1afDprW5gGwS4gUX8Ri6aGPZ))",
+                "tr(xpub6CY33ZvKuS63kwDnpNCCo5YrrgkUXgdUKdCVhd4Dru5gCB3z8wGnqFiUP98Za5pYSYF5KmvBHTY3Ra8FAJGggzBjuHS69WzN8gscPupuZwK/3,l:pk(xpub6E9a95u27Qqa13XEz62FUgaFMWzHnHrb54dWfMHU7K9A33eDccvUkbu1sHYoByHAgJdR326rWqn9pGZgZHz1afDprW5gGwS4gUX8Ri6aGPZ))",
+            },
+            {
+                "tr(xpub6CY33ZvKuS63kwDnpNCCo5YrrgkUXgdUKdCVhd4Dru5gCB3z8wGnqFiUP98Za5pYSYF5KmvBHTY3Ra8FAJGggzBjuHS69WzN8gscPupuZwK/2,l:pk(xpub6E9a95u27Qqa13XEz62FUgaFMWzHnHrb54dWfMHU7K9A33eDccvUkbu1sHYoByHAgJdR326rWqn9pGZgZHz1afDprW5gGwS4gUX8Ri6aGPZ))",
+                "tr(xpub6CY33ZvKuS63kwDnpNCCo5YrrgkUXgdUKdCVhd4Dru5gCB3z8wGnqFiUP98Za5pYSYF5KmvBHTY3Ra8FAJGggzBjuHS69WzN8gscPupuZwK/3,l:pk(xpub6E9a95u27Qqa13XEz62FUgaFMWzHnHrb54dWfMHU7K9A33eDccvUkbu1sHYoByHAgJdR326rWqn9pGZgZHz1afDprW5gGwS4gUX8Ri6aGPZ))",
+            },
+            XONLY_KEYS,
+            {
+                {{"51200e3c14456bfa30f9f0bed6e55f35e1e9ca17c835e9f71b25bac0dfaab38ff2cd"}},
+                {{"51202bdda29337ecaf8fcd5aa395febac6f99b8a866a0e8fb3f7bde2e24b1a7df2ba"}},
+            },
+            OutputType::BECH32M,
+            {
+                {{2}, {}},
+                {{3}, {}},
+            }
+    );
     CheckUnparsable("pkh(xprv9s21ZrQH143K31xYSDQpPDxsXRTUcvj2iNHm5NUtrGiGG5e2DtALGdso3pGz6ssrdK4PFmM8NSpSBHNqPqm55Qn3LqFtT2emdEXVYsCzC2U/<0;1>/<2;3>)", "pkh(xpub661MyMwAqRbcFW31YEwpkMuc5THy2PSt5bDMsktWQcFF8syAmRUapSCGu8ED9W6oDMSgv6Zz8idoc4a6mr8BDzTJY47LJhkJ8UB7WEGuduB/<0;1>/<2;3>)", "pkh(): Multiple multipath key path specifiers found");
     CheckUnparsable("pkh([deadbeef/<0;1>]xprv9s21ZrQH143K31xYSDQpPDxsXRTUcvj2iNHm5NUtrGiGG5e2DtALGdso3pGz6ssrdK4PFmM8NSpSBHNqPqm55Qn3LqFtT2emdEXVYsCzC2U/0)", "pkh([deadbeef/<0;1>]xpub661MyMwAqRbcFW31YEwpkMuc5THy2PSt5bDMsktWQcFF8syAmRUapSCGu8ED9W6oDMSgv6Zz8idoc4a6mr8BDzTJY47LJhkJ8UB7WEGuduB/0)", "pkh(): Key path value \'<0;1>\' specifies multipath in a section where multipath is not allowed");
     CheckUnparsable("tr(xprv9s21ZrQH143K2Zu2kTVKcQi9nKhfgJUkYqG73wXsHuhATm1wkt6kcSZeTYEw2PL7krZtJopEYDvBdYWdAai3n3TWUTCVfHvPHqTYJv7smYe/6/*,{pk(xprvA1RpRA33e1JQ7ifknakTFpgNXPmW2YvmhqLQYMmrj4xJXXWYpDPS3xz7iAxn8L39njGVyuoseXzU6rcxFLJ8HFsTjSyQbLYnMpCqE2VbFWc/<1;2;3>/0/*),pk(xprv9s21ZrQH143K3jUwNHoqQNrtzJnJmx4Yup8NkNLdVQCymYbPbJXnPhwkfTfxZfptcs3rLAPUXS39oDLgrNKQGwbGsEmJJ8BU3RzQuvShEG4/0/0/<3;4>/*)})", "tr(xpub6B4sSbNr8XFYXqqKB7PeUemqgEaVtCLjgd5Lf2VYtezSHozC7ffCvVNCyu9TCgHntRQdimjV3tHbxmNfocxtuh6saNtZEw91gjXLRhQ3Yar/6/*,{pk(xpub6ERApfZwUNrhLCkDtcHTcxd75RbzS1ed54G1LkBUHQVHQKqhMkhgbmJbZRkrgZw4koxb5JaHWkY4ALHY2grBGRjaDMzQLcgJvLJuZZvRcEL/<1;2;3>/0/*),pk(xpub6AhFhZJJGt9YB8i85RfrJ8jT3T2FF5EejDCXqXfm1DAczFEXkk8HD3CXTg2TmKM8wTbSnSw3wPg5JuyLitUrpRmkjn2BQXyZnqJx16AGy94/0/0/<3;4>/*)})", "tr(): Multipath subscripts have mismatched lengths");