evaluate litecoin 0.21 branch

[chappjc]

https://github.com/litecoin-project/litecoin/tree/0.21 appears to have reached v0.21 final as of April 29, 2021, but was not tagged.

This Litecoin Core dev's branch catches litecoin up with BTC. We should evaluate this branch, particularly for getbalances, estimatesmartfee, and "safe" in the listunspent result (in the commit logs).

The branch only builds with benchmarks and GUI disabled.

[chappjc]

The estimatesmartfee RPC seems fine with litecoind 0.20:

$   ./litecoin-cli -testnet estimatesmartfee 1 "CONSERVATIVE"
{
  "feerate": 0.00021063,
  "blocks": 2
}

As does getbalances (but that wallet really is empty, so this needs more testing):

$   ./litecoin-cli -testnet getbalances
{
  "mine": {
    "trusted": 0.00000000,
    "untrusted_pending": 0.00000000,
    "immature": 0.00000000
  }
}

[chappjc]

untrusted / safe appears to be working as expected too, after receiving coins from a faucet (https://testnet-faucet.com/ltc-testnet/):

$   ./litecoin-cli -testnet getbalances
{
  "mine": {
    "trusted": 0.00000000,
    "untrusted_pending": 4.06121000,
    "immature": 0.00000000
  }
}

$   ./litecoin-cli -testnet listunspent 0
[
  {
    "txid": "4ad4697492338fea4f30b9bdc2d4dbfd692c096d7eb805ae2c94b5e54ae97442",
    "vout": 1,
    "address": "QPbicm2tVmNNmvPLpucWzJrZXHoNKRCLFN",
    "label": "",
    "redeemScript": "001436f0fd3c79e133e0e3befd7489e0c8d4f9f3f0f5",
    "scriptPubKey": "a91420db71fb35bf87a391f4084dea42bd9ad1b1b95887",
    "amount": 4.06121000,
    "confirmations": 0,
    "spendable": true,
    "solvable": true,
    "desc": "sh(wpkh([73f7a87d/0'/0'/3']03b97c730963f6f924db4e6ac0634b8b6397b877c6cf19dc300ecb78cc7dde6ba3))#2n84zpfl",
    "safe": false
  }
]

Note that the coins in 4ad4697492338fea4f30b9bdc2d4dbfd692c096d7eb805ae2c94b5e54ae97442:1 are counted as "safe": false" in the listunspent output of unconfirmed coins, and in the "untrusted_pending" category of the getbalances result.

With 1 confirm they switch to safe/trusted:

$   ./litecoin-cli -testnet listunspent 0
[
  {
    "txid": "4ad4697492338fea4f30b9bdc2d4dbfd692c096d7eb805ae2c94b5e54ae97442",
    "vout": 1,
    "address": "QPbicm2tVmNNmvPLpucWzJrZXHoNKRCLFN",
    "label": "",
    "redeemScript": "001436f0fd3c79e133e0e3befd7489e0c8d4f9f3f0f5",
    "scriptPubKey": "a91420db71fb35bf87a391f4084dea42bd9ad1b1b95887",
    "amount": 4.06121000,
    "confirmations": 1,
    "spendable": true,
    "solvable": true,
    "desc": "sh(wpkh([73f7a87d/0'/0'/3']03b97c730963f6f924db4e6ac0634b8b6397b877c6cf19dc300ecb78cc7dde6ba3))#2n84zpfl",
    "safe": true
  }
]
$   ./litecoin-cli -testnet getbalances
{
  "mine": {
    "trusted": 4.06121000,
    "untrusted_pending": 0.00000000,
    "immature": 0.00000000
  }
}