`compile --type=sh` produces a descriptor Bitcoin Core rejects

[vadim-anfv]

bdk-cli compile accepts --type values sh, wsh, sh-wsh and tr. Only sh produces a descriptor Bitcoin Core rejects:

$ A=$(bdk-cli --network bitcoin key generate | jq -r .xprv)
$ B=$(bdk-cli --network bitcoin key generate | jq -r .xprv)

$ D=$(bdk-cli compile "or(pk($A),pk($B))" --type=sh | jq -r .descriptor)

$ bitcoin-cli getdescriptorinfo "$D"
error code: -5
error message:
Miniscript expressions can only be used in wsh or tr.

The same policy with --type=wsh, --type=sh-wsh and --type=tr is accepted.

BIP 379 scopes Miniscript to P2WSH and Tapscript, and excludes P2SH explicitly, spec:

These specifications apply to P2WSH (BIP 141) and Tapscript (BIP 342) scripts [...] P2SH and bare scripts are excluded from this specification.

Core enforces that where it parses the Miniscript expression, src:

if (node) {
    if (ctx != ParseScriptContext::P2WSH && ctx != ParseScriptContext::P2TR) {
        error = "Miniscript expressions can only be used in wsh or tr.";
        return {};
    }

bdk-cli can still build the descriptor because rust-miniscript keeps the pre-BIP contexts. BDK also handles it end to end: wallet config --ext-descriptor "$D" followed by new_address derives a P2SH address, and the script itself is consensus-valid. Other descriptor-based wallets may not support this type though - Core rejects it outright, in both getdescriptorinfo and importdescriptors.

@tvpeter how would you like this handled?

1. drop sh from the accepted --type values
2. keep it, but warn on output and document that it is outside BIP 379 specification

Happy to open the PR once you have picked one.

[tvpeter]

@tvpeter how would you like this handled?

1. drop sh from the accepted --type values
2. keep it, but warn on output and document that it is outside BIP 379 specification

Although I haven't reviewed this yet, my initial thought is that we should retain it and document that it falls outside the BIP 379 specification. This is because BDK primarily implements descriptors from rust-miniscript. Therefore, any decision to deprecate a script type should be made at the upstream level.