Merge bitcoin#21679: rpc: Keep default argument value in correct type

bee56c7 rpc: Check default value type againts argument type (João Barbosa)
f81ef43 rpc: Keep default argument value in correct type (João Barbosa)

Pull request description:

  Store default values of RPC arguments in the corresponding type instead of a string. The value is then serialized when the help output is needed. This change simplifies bitcoin#20017.

  The following examples illustrates how to use the new `RPCArg::Default` and `RPCArg::DefaultHint`:

  ```diff
  - {"verbose", RPCArg::Type::BOOL, /* default */ "false", "True for a json object, false for array of transaction ids"}
  + {"verbose", RPCArg::Type::BOOL, RPCArg::Default(false), "True for a json object, false for array of transaction ids"}
  ```

  ```diff
  - {"nblocks", RPCArg::Type::NUM, /* default */ "one month", "Size of the window in number of blocks"}
  + {"nblocks", RPCArg::Type::NUM, RPCArg::DefaultHint("one month"), "Size of the window in number of blocks"}
  ```

  No behavior change is expected.

ACKs for top commit:
  LarryRuane:
    ACK bee56c7
  MarcoFalke:
    ACK bee56c7 🦅

Tree-SHA512: c47d78c918e996d36631d4ad3c933b270a34c5b446b8d736be94cf4a0a7b8c0e33d954149ec786cf9550639865b79deb6a130ad044de6030f95aac33f524293a

Author: MarcoFalke

src/rpc/blockchain.cpp

@@ -289,7 +289,7 @@ static RPCHelpMan waitfornewblock()
         "\nWaits for a specific new block and returns useful info about it.\n"
         "\nReturns the current block on timeout or exit.\n",
         {
-            {"timeout", RPCArg::Type::NUM, /* default */ "0", "Time in milliseconds to wait for a response. 0 indicates no timeout."},
+            {"timeout", RPCArg::Type::NUM, RPCArg::Default{0}, "Time in milliseconds to wait for a response. 0 indicates no timeout."},
         },
         RPCResult{
             RPCResult::Type::OBJ, "", "",
@@ -332,7 +332,7 @@ static RPCHelpMan waitforblock()
         "\nReturns the current block on timeout or exit.\n",
         {
             {"blockhash", RPCArg::Type::STR_HEX, RPCArg::Optional::NO, "Block hash to wait for."},
-            {"timeout", RPCArg::Type::NUM, /* default */ "0", "Time in milliseconds to wait for a response. 0 indicates no timeout."},
+            {"timeout", RPCArg::Type::NUM, RPCArg::Default{0}, "Time in milliseconds to wait for a response. 0 indicates no timeout."},
         },
         RPCResult{
             RPCResult::Type::OBJ, "", "",
@@ -379,7 +379,7 @@ static RPCHelpMan waitforblockheight()
         "\nReturns the current block on timeout or exit.\n",
         {
             {"height", RPCArg::Type::NUM, RPCArg::Optional::NO, "Block height to wait for."},
-            {"timeout", RPCArg::Type::NUM, /* default */ "0", "Time in milliseconds to wait for a response. 0 indicates no timeout."},
+            {"timeout", RPCArg::Type::NUM, RPCArg::Default{0}, "Time in milliseconds to wait for a response. 0 indicates no timeout."},
         },
         RPCResult{
             RPCResult::Type::OBJ, "", "",
@@ -572,6 +572,7 @@ UniValue MempoolToJSON(const CTxMemPool& pool, llmq::CInstantSendManager* isman,
             return o;
         }
     }
+
 }
 
 static RPCHelpMan getrawmempool()
@@ -580,8 +581,8 @@ static RPCHelpMan getrawmempool()
         "\nReturns all transaction ids in memory pool as a json array of string transaction ids.\n"
         "\nHint: use getmempoolentry to fetch a specific transaction from the mempool.\n",
         {
-            {"verbose", RPCArg::Type::BOOL, /* default */ "false", "True for a json object, false for array of transaction ids"},
-            {"mempool_sequence", RPCArg::Type::BOOL, /* default */ "false", "If verbose=false, returns a json object with transaction list and mempool sequence number attached."},
+            {"verbose", RPCArg::Type::BOOL, RPCArg::Default{false}, "True for a json object, false for array of transaction ids"},
+            {"mempool_sequence", RPCArg::Type::BOOL, RPCArg::Default{false}, "If verbose=false, returns a json object with transaction list and mempool sequence number attached."},
         },
         {
             RPCResult{"for verbose = false",
@@ -633,7 +634,7 @@ static RPCHelpMan getmempoolancestors()
         "\nIf txid is in the mempool, returns all in-mempool ancestors.\n",
         {
             {"txid", RPCArg::Type::STR_HEX, RPCArg::Optional::NO, "The transaction id (must be in mempool)"},
-            {"verbose", RPCArg::Type::BOOL, /* default */ "false", "True for a json object, false for array of transaction ids"},
+            {"verbose", RPCArg::Type::BOOL, RPCArg::Default{false}, "True for a json object, false for array of transaction ids"},
         },
         {
             RPCResult{"for verbose = false",
@@ -700,7 +701,7 @@ static RPCHelpMan getmempooldescendants()
         "\nIf txid is in the mempool, returns all in-mempool descendants.\n",
         {
             {"txid", RPCArg::Type::STR_HEX, RPCArg::Optional::NO, "The transaction id (must be in mempool)"},
-            {"verbose", RPCArg::Type::BOOL, /* default */ "false", "True for a json object, false for array of transaction ids"},
+            {"verbose", RPCArg::Type::BOOL, RPCArg::Default{false}, "True for a json object, false for array of transaction ids"},
         },
         {
             RPCResult{"for verbose = false",
@@ -923,7 +924,7 @@ static RPCHelpMan getblockheader()
         "If verbose is true, returns an Object with information about blockheader <hash>.\n",
         {
             {"blockhash", RPCArg::Type::STR_HEX, RPCArg::Optional::NO, "The block hash"},
-            {"verbose", RPCArg::Type::BOOL, /* default */ "true", "true for a json object, false for the hex-encoded data"},
+            {"verbose", RPCArg::Type::BOOL, RPCArg::Default{true}, "true for a json object, false for the hex-encoded data"},
         },
         {
             RPCResult{"for verbose = true",
@@ -997,8 +998,8 @@ static RPCHelpMan getblockheaders()
         "If verbose is true, each item is an Object with information about a single blockheader.\n",
         {
             {"blockhash", RPCArg::Type::STR_HEX, RPCArg::Optional::NO, "The block hash"},
-            {"count", RPCArg::Type::NUM, /* default */ strprintf("%s", MAX_HEADERS_UNCOMPRESSED_RESULT), ""},
-            {"verbose", RPCArg::Type::BOOL, /* default */ "true", "true for a json object, false for the hex-encoded data"},
+            {"count", RPCArg::Type::NUM, RPCArg::DefaultHint{strprintf("%s", MAX_HEADERS_UNCOMPRESSED_RESULT)}, ""},
+            {"verbose", RPCArg::Type::BOOL, RPCArg::Default{true}, "true for a json object, false for the hex-encoded data"},
         },
         {
             RPCResult{"for verbose = true",
@@ -1135,7 +1136,7 @@ static RPCHelpMan getmerkleblocks()
         {
             {"filter", RPCArg::Type::STR_HEX, RPCArg::Optional::NO, "The hex-encoded bloom filter"},
             {"blockhash", RPCArg::Type::STR_HEX, RPCArg::Optional::NO, "The block hash"},
-            {"count", RPCArg::Type::NUM, /* default */ strprintf("%s", MAX_HEADERS_UNCOMPRESSED_RESULT), ""},
+            {"count", RPCArg::Type::NUM, RPCArg::DefaultHint{strprintf("%s", MAX_HEADERS_UNCOMPRESSED_RESULT)}, ""},
         },
         RPCResult{
                 RPCResult::Type::ARR, "", "",
@@ -1211,7 +1212,7 @@ static RPCHelpMan getblock()
                 "If verbosity is 2, returns an Object with information about block <hash> and information about each transaction. \n",
                 {
                     {"blockhash", RPCArg::Type::STR_HEX, RPCArg::Optional::NO, "The block hash"},
-                    {"verbosity|verbose", RPCArg::Type::NUM, /* default */ "1", "0 for hex-encoded data, 1 for a json object, and 2 for json object with transaction data"},
+                    {"verbosity|verbose", RPCArg::Type::NUM, RPCArg::Default{1}, "0 for hex-encoded data, 1 for a json object, and 2 for json object with transaction data"},
                 },
                 {
                     RPCResult{"for verbosity = 0",
@@ -1388,9 +1389,9 @@ static RPCHelpMan gettxoutsetinfo()
         "\nReturns statistics about the unspent transaction output set.\n"
         "Note this call may take some time if you are not using coinstatsindex.\n",
         {
-            {"hash_type", RPCArg::Type::STR, /* default */ "hash_serialized_2", "Which UTXO set hash should be calculated. Options: 'hash_serialized_2' (the legacy algorithm), 'muhash', 'none'."},
+            {"hash_type", RPCArg::Type::STR, RPCArg::Default{"hash_serialized_2"}, "Which UTXO set hash should be calculated. Options: 'hash_serialized_2' (the legacy algorithm), 'muhash', 'none'."},
             {"hash_or_height", RPCArg::Type::NUM, RPCArg::Optional::OMITTED, "The block hash or height of the target height (only available with coinstatsindex).", "", {"", "string or numeric"}},
-            {"use_index", RPCArg::Type::BOOL, /* default */ "true", "Use coinstatsindex, if available."},
+            {"use_index", RPCArg::Type::BOOL, RPCArg::Default{true}, "Use coinstatsindex, if available."},
         },
         RPCResult{
             RPCResult::Type::OBJ, "", "",
@@ -1532,7 +1533,7 @@ static RPCHelpMan gettxout()
         {
             {"txid", RPCArg::Type::STR, RPCArg::Optional::NO, "The transaction id"},
             {"n", RPCArg::Type::NUM, RPCArg::Optional::NO, "vout number"},
-            {"include_mempool", RPCArg::Type::BOOL, /* default */ "true", "Whether to include the mempool. Note that an unspent output that is spent in the mempool won't appear."},
+            {"include_mempool", RPCArg::Type::BOOL, RPCArg::Default{true}, "Whether to include the mempool. Note that an unspent output that is spent in the mempool won't appear."},
         },
         {
             RPCResult{"If the UTXO was not found", RPCResult::Type::NONE, "", ""},
@@ -1619,10 +1620,10 @@ static RPCHelpMan verifychain()
     return RPCHelpMan{"verifychain",
         "\nVerifies blockchain database.\n",
         {
-            {"checklevel", RPCArg::Type::NUM, /* default */ strprintf("%d, range=0-4", DEFAULT_CHECKLEVEL),
+            {"checklevel", RPCArg::Type::NUM, RPCArg::DefaultHint{strprintf("%d, range=0-4", DEFAULT_CHECKLEVEL)},
                         strprintf("How thorough the block verification is:\n - %s", MakeUnorderedList(CHECKLEVEL_DOC))},
-            {"nblocks", RPCArg::Type::NUM, /* default */ strprintf("%d, 0=all", DEFAULT_CHECKBLOCKS), "The number of blocks to check."},
-        },
+            {"nblocks", RPCArg::Type::NUM, RPCArg::DefaultHint{strprintf("%d, 0=all", DEFAULT_CHECKBLOCKS)}, "The number of blocks to check."},
+       },
         RPCResult{
             RPCResult::Type::BOOL, "", "Verified or not"},
         RPCExamples{
@@ -1872,8 +1873,8 @@ static RPCHelpMan getchaintips()
         "Return information about all known tips in the block tree,"
         " including the main chain as well as orphaned branches.\n",
         {
-            {"count", RPCArg::Type::NUM, /* default */ "", "only show this much of latest tips"},
-            {"branchlen", RPCArg::Type::NUM, /* default */ "", "only show tips that have equal or greater length of branch"},
+            {"count", RPCArg::Type::NUM, RPCArg::DefaultHint{""}, "only show this much of latest tips"},
+            {"branchlen", RPCArg::Type::NUM, RPCArg::DefaultHint{""}, "only show tips that have equal or greater length of branch"},
         },
         RPCResult{
             RPCResult::Type::ARR, "", "",
@@ -2174,8 +2175,8 @@ static RPCHelpMan getchaintxstats()
     return RPCHelpMan{"getchaintxstats",
                 "\nCompute statistics about the total number and rate of transactions in the chain.\n",
                 {
-                    {"nblocks", RPCArg::Type::NUM, /* default */ "one month", "Size of the window in number of blocks"},
-                    {"blockhash", RPCArg::Type::STR_HEX, /* default */ "chain tip", "The hash of the block that ends the window."},
+                    {"nblocks", RPCArg::Type::NUM, RPCArg::DefaultHint{"one month"}, "Size of the window in number of blocks"},
+                    {"blockhash", RPCArg::Type::STR_HEX, RPCArg::DefaultHint{"chain tip"}, "The hash of the block that ends the window."},
                 },
                 RPCResult{
                     RPCResult::Type::OBJ, "", "",
@@ -2324,7 +2325,7 @@ static RPCHelpMan getblockstats()
                 "It won't work for some heights with pruning.\n",
                 {
                     {"hash_or_height", RPCArg::Type::NUM, RPCArg::Optional::NO, "The block hash or height of the target block", "", {"", "string or numeric"}},
-                    {"stats", RPCArg::Type::ARR, /* default */ "all values", "Values to plot (see result below)",
+                    {"stats", RPCArg::Type::ARR, RPCArg::DefaultHint{"all values"}, "Values to plot (see result below)",
                         {
                             {"height", RPCArg::Type::STR, RPCArg::Optional::OMITTED, "Selected statistic"},
                             {"time", RPCArg::Type::STR, RPCArg::Optional::OMITTED, "Selected statistic"},
@@ -2542,10 +2543,10 @@ static RPCHelpMan getspecialtxes()
         "If verbosity is 2, returns an Object with information for each transaction.\n",
         {
             {"blockhash", RPCArg::Type::STR_HEX, RPCArg::Optional::NO, "The block hash"},
-            {"type", RPCArg::Type::NUM, /* default */ "-1", "Filter special txes by type, -1 means all types"},
-            {"count", RPCArg::Type::NUM, /* default */ "10", "The number of transactions to return"},
-            {"skip", RPCArg::Type::NUM, /* default */ "0", "The number of transactions to skip"},
-            {"verbosity", RPCArg::Type::NUM, /* default */ "0", "0 for hashes, 1 for hex-encoded data, and 2 for json object"},
+            {"type", RPCArg::Type::NUM, RPCArg::Default{-1}, "Filter special txes by type, -1 means all types"},
+            {"count", RPCArg::Type::NUM, RPCArg::Default{10}, "The number of transactions to return"},
+            {"skip", RPCArg::Type::NUM, RPCArg::Default{0}, "The number of transactions to skip"},
+            {"verbosity", RPCArg::Type::NUM, RPCArg::Default{0}, "0 for hashes, 1 for hex-encoded data, and 2 for json object"},
         },
         {
             RPCResult{"for verbosity = 0",
@@ -2767,7 +2768,7 @@ static RPCHelpMan scantxoutset()
                     {"", RPCArg::Type::OBJ, RPCArg::Optional::OMITTED, "An object with output descriptor and metadata",
                         {
                             {"desc", RPCArg::Type::STR, RPCArg::Optional::NO, "An output descriptor"},
-                            {"range", RPCArg::Type::RANGE, /* default */ "1000", "The range of HD chain indexes to explore (either end or [begin,end])"},
+                            {"range", RPCArg::Type::RANGE, RPCArg::Default{1000}, "The range of HD chain indexes to explore (either end or [begin,end])"},
                         },
                     },
                 },
@@ -2913,7 +2914,7 @@ static RPCHelpMan getblockfilter()
         "\nRetrieve a BIP 157 content filter for a particular block.\n",
         {
             {"blockhash", RPCArg::Type::STR, RPCArg::Optional::NO, "The hash of the block"},
-            {"filtertype", RPCArg::Type::STR, /* default */ "basic", "The type name of the filter"},
+            {"filtertype", RPCArg::Type::STR, RPCArg::Default{"basic"}, "The type name of the filter"},
         },
         RPCResult{
             RPCResult::Type::OBJ, "", "",

src/rpc/coinjoin.cpp

@@ -207,7 +207,7 @@ static RPCHelpMan coinjoinsalt_generate()
         "\nGenerate new CoinJoin salt and store it in the wallet database\n"
         "Cannot generate new salt if CoinJoin mixing is in process or wallet has private keys disabled.\n",
         {
-            {"overwrite", RPCArg::Type::BOOL, /* default */ "false", "Generate new salt even if there is an existing salt and/or there is CoinJoin balance"},
+            {"overwrite", RPCArg::Type::BOOL, RPCArg::Default{false}, "Generate new salt even if there is an existing salt and/or there is CoinJoin balance"},
         },
         RPCResult{
             RPCResult::Type::BOOL, "", "Status of CoinJoin salt generation and commitment"
@@ -309,7 +309,7 @@ static RPCHelpMan coinjoinsalt_set()
         "Will overwrite existing salt. The presence of a CoinJoin balance will cause the wallet to rescan.\n",
         {
             {"salt", RPCArg::Type::STR, RPCArg::Optional::NO, "Desired CoinJoin salt value for the wallet"},
-            {"overwrite", RPCArg::Type::BOOL, /* default */ "false", "Overwrite salt even if CoinJoin balance present"},
+            {"overwrite", RPCArg::Type::BOOL, RPCArg::Default{false}, "Overwrite salt even if CoinJoin balance present"},
         },
         RPCResult{
             RPCResult::Type::BOOL, "", "Status of CoinJoin salt change request"