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

src/rpc/blockchain.cpp

@@ -345,7 +345,7 @@ 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, "", "",
@@ -388,7 +388,7 @@ 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, "", "",
@@ -435,7 +435,7 @@ 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, "", "",
@@ -622,7 +622,7 @@ 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"},
+            {"verbose", RPCArg::Type::BOOL, RPCArg::Default{false}, "True for a json object, false for array of transaction ids"},
         },
         {
             RPCResult{"for verbose = false",
@@ -660,7 +660,7 @@ 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",
@@ -727,7 +727,7 @@ 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",
@@ -897,7 +897,7 @@ 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",
@@ -972,7 +972,7 @@ static RPCHelpMan getblockheaders()
         {
             {"blockhash", RPCArg::Type::STR_HEX, RPCArg::Optional::NO, "The block hash"},
             {"count", RPCArg::Type::NUM, /* default */ strprintf("%s", MAX_HEADERS_RESULTS), ""},
-            {"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",
@@ -1183,7 +1183,7 @@ 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",
@@ -1360,9 +1360,9 @@ 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, "", "",
@@ -1504,7 +1504,7 @@ 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{
             RPCResult::Type::OBJ, "", "",
@@ -1589,9 +1589,9 @@ 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", Join(CHECKLEVEL_DOC, "\n- "))},
-            {"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"},
@@ -2142,8 +2142,8 @@ 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, "", "",
@@ -2282,7 +2282,7 @@ 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"},
@@ -2715,7 +2715,7 @@ 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])"},
                         },
                     },
                 },
@@ -2848,7 +2848,7 @@ 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/mining.cpp

@@ -101,8 +101,8 @@ static RPCHelpMan getnetworkhashps()
         "Pass in [blocks] to override # of blocks, -1 specifies since last difficulty change.\n"
         "Pass in [height] to estimate the network speed at the time when a certain block was found.\n",
         {
-            {"nblocks", RPCArg::Type::NUM, /* default */ "120", "The number of blocks, or -1 for blocks since last difficulty change."},
-            {"height", RPCArg::Type::NUM, /* default */ "-1", "To estimate at the time of the given height."},
+            {"nblocks", RPCArg::Type::NUM, RPCArg::Default{120}, "The number of blocks, or -1 for blocks since last difficulty change."},
+            {"height", RPCArg::Type::NUM, RPCArg::Default{-1}, "To estimate at the time of the given height."},
         },
         RPCResult{
             RPCResult::Type::NUM, "", "Hashes per second estimated"},
@@ -231,7 +231,7 @@ static RPCHelpMan generatetodescriptor()
         {
             {"num_blocks", RPCArg::Type::NUM, RPCArg::Optional::NO, "How many blocks are generated immediately."},
             {"descriptor", RPCArg::Type::STR, RPCArg::Optional::NO, "The descriptor to send the newly generated coins to."},
-            {"maxtries", RPCArg::Type::NUM, /* default */ ToString(DEFAULT_MAX_TRIES), "How many iterations to try."},
+            {"maxtries", RPCArg::Type::NUM, RPCArg::Default{DEFAULT_MAX_TRIES}, "How many iterations to try."},
         },
         RPCResult{
             RPCResult::Type::ARR, "", "",
@@ -268,7 +268,7 @@ static RPCHelpMan generatetoaddress()
         {
             {"nblocks", RPCArg::Type::NUM, RPCArg::Optional::NO, "How many blocks are generated immediately."},
             {"address", RPCArg::Type::STR, RPCArg::Optional::NO, "The address to send the newly generated coins to."},
-            {"maxtries", RPCArg::Type::NUM, /* default */ ToString(DEFAULT_MAX_TRIES), "How many iterations to try."},
+            {"maxtries", RPCArg::Type::NUM, RPCArg::Default{DEFAULT_MAX_TRIES}, "How many iterations to try."},
         },
         RPCResult{
             RPCResult::Type::ARR, "", "hashes of blocks generated",
@@ -559,7 +559,7 @@ static RPCHelpMan getblocktemplate()
         "    https://github.com/bitcoin/bips/blob/master/bip-0023.mediawiki\n"
         "    https://github.com/bitcoin/bips/blob/master/bip-0009.mediawiki#getblocktemplate_changes\n",
         {
-            {"template_request", RPCArg::Type::OBJ, /* default_val */ "", "Format of the template",
+            {"template_request", RPCArg::Type::OBJ, RPCArg::Default{UniValue::VOBJ}, "Format of the template",
                 {
                     {"mode", RPCArg::Type::STR, /* treat as named arg */ RPCArg::Optional::OMITTED_NAMED_ARG, "This must be set to \"template\", \"proposal\" (see BIP 23), or omitted"},
                     {"capabilities", RPCArg::Type::ARR, /* treat as named arg */ RPCArg::Optional::OMITTED_NAMED_ARG, "A list of strings",
@@ -1013,7 +1013,7 @@ static RPCHelpMan submitblock()
         "See https://en.bitcoin.it/wiki/BIP_0022 for full specification.\n",
         {
             {"hexdata", RPCArg::Type::STR_HEX, RPCArg::Optional::NO, "the hex-encoded block data to submit"},
-            {"dummy", RPCArg::Type::STR, /* default */ "ignored", "dummy value, for compatibility with BIP22. This value is ignored."},
+            {"dummy", RPCArg::Type::STR, RPCArg::DefaultHint{"ignored"}, "dummy value, for compatibility with BIP22. This value is ignored."},
         },
         RPCResult{RPCResult::Type::NONE, "", "Returns JSON Null when valid, a string according to BIP22 otherwise"},
         RPCExamples{
@@ -1110,7 +1110,7 @@ static RPCHelpMan estimatesmartfee()
         "for which the estimate is valid.\n",
         {
             {"conf_target", RPCArg::Type::NUM, RPCArg::Optional::NO, "Confirmation target in blocks (1 - 1008)"},
-            {"estimate_mode", RPCArg::Type::STR, /* default */ "conservative", "The fee estimate mode.\n"
+            {"estimate_mode", RPCArg::Type::STR, RPCArg::Default{"conservative"}, "The fee estimate mode.\n"
     "                   Whether to return a more conservative estimate which also satisfies\n"
     "                   a longer history. A conservative estimate potentially returns a\n"
     "                   higher feerate and is more likely to be sufficient for the desired\n"
@@ -1180,7 +1180,7 @@ static RPCHelpMan estimaterawfee()
         "confirmation within conf_target blocks if possible.\n",
         {
             {"conf_target", RPCArg::Type::NUM, RPCArg::Optional::NO, "Confirmation target in blocks (1 - 1008)"},
-            {"threshold", RPCArg::Type::NUM, /* default */ "0.95", "The proportion of transactions in a given feerate range that must have been\n"
+            {"threshold", RPCArg::Type::NUM, RPCArg::Default{0.95}, "The proportion of transactions in a given feerate range that must have been\n"
     "               confirmed within conf_target in order to consider those feerates as high enough and proceed to check\n"
     "               lower buckets."},
         },

src/rpc/misc.cpp

@@ -1219,7 +1219,7 @@ static RPCHelpMan getmemoryinfo()
     return RPCHelpMan{"getmemoryinfo",
         "Returns an object containing information about memory usage.\n",
         {
-            {"mode", RPCArg::Type::STR, /* default */ "\"stats\"", "determines what kind of information is returned.\n"
+            {"mode", RPCArg::Type::STR, RPCArg::Default{"stats"}, "determines what kind of information is returned.\n"
     "  - \"stats\" returns general statistics about memory usage in the daemon.\n"
     "  - \"mallocinfo\" returns an XML string describing low-level heap state (only available if compiled with glibc 2.10+)."},
         },