Avoid panic when policies containing x-only keys are compiled for Segwitv0

Temporary workaround pending rust-bitcoin/rust-miniscript#761

Author: shesek

src/error.rs

@@ -202,6 +202,10 @@ pub enum RuntimeError {
     #[error("sh() can only wrap wsh() or wpkh()")]
     InvalidShUse,
 
+    // Can be removed once this is handled as an Err by rust-miniscript (https://github.com/rust-bitcoin/rust-miniscript/pull/761)
+    #[error("x-only keys not allowed in Segwitv0 wsh()")]
+    InvalidWshXonly,
+
     #[error("Transaction input #{0} does not exists")]
     TxInputNotFound(usize),
 

src/playground.rs

@@ -5,12 +5,10 @@ use serde_wasm_bindgen::to_value;
 use wasm_bindgen::prelude::*;
 
 use miniscript::bitcoin::{Address, Network, ScriptBuf};
-use miniscript::{Descriptor, MiniscriptKey};
+use miniscript::{Descriptor, ForEachKey, MiniscriptKey};
 
-use crate::util::{DescriptorExt, TapInfoExt};
-use crate::{
-    parse, Error, Evaluate, Execute, ExprRepr, Library, PrettyDisplay, Scope, ScopeRef, Value,
-};
+use crate::util::{DescriptorExt, PrettyDisplay, TapInfoExt};
+use crate::{parse, Error, Evaluate, Execute, ExprRepr, Library, Scope, ScopeRef, Value};
 
 #[derive(Serialize)]
 pub struct PlaygroundResult {
@@ -29,15 +27,18 @@ pub fn run_playground(code: &str, network: &str) -> Result<JsValue, JsValue> {
     let _run_playground = || -> Result<PlaygroundResult, Error> {
         let network = Network::from_str(network)?;
 
-        let value = eval(code)?;
-
         let (mut policy, mut desc, mut script, mut addr, mut key, mut tapinfo, mut other) =
             (None, None, None, None, None, None, None);
 
-        match value {
+        match eval(code)? {
             Value::Policy(policy_) => {
-                // Convert policies into a wsh() descriptor
-                desc = Some(Descriptor::new_wsh(policy_.compile()?)?);
+                // Compile policies into a wsh() descriptor
+                if policy_.for_each_key(|pk| !pk.is_x_only_key()) {
+                    // Has to explicitly check for x-only keys as a temporary workaround to avoid panicking
+                    // https://github.com/rust-bitcoin/rust-miniscript/pull/761
+                    let ms = policy_.compile().ok();
+                    desc = ms.and_then(|ms| Descriptor::new_wsh(ms).ok());
+                }
                 policy = Some(policy_);
             }
             Value::Descriptor(desc_) => desc = Some(desc_),

src/stdlib/miniscript.rs

@@ -3,7 +3,7 @@ use std::{fmt, sync::Arc};
 
 use bitcoin::ScriptBuf;
 use miniscript::descriptor::{DescriptorType, ShInner, WshInner};
-use miniscript::{ScriptContext, Threshold};
+use miniscript::{ForEachKey, MiniscriptKey, ScriptContext, Threshold};
 
 use crate::runtime::scope::{Mutable, ScopeRef};
 use crate::runtime::{Array, Error, Evaluate, ExprRepr, FieldAccess, Result, Value};
@@ -170,6 +170,11 @@ pub mod fns {
     pub fn wsh(args: Array, _: &ScopeRef) -> Result<Value> {
         Ok(match args.arg_into()? {
             Value::Policy(policy) => {
+                // Temporary workaround to avoid panicking (https://github.com/rust-bitcoin/rust-miniscript/pull/761)
+                ensure!(
+                    policy.for_each_key(|pk| !pk.is_x_only_key()),
+                    Error::InvalidWshXonly
+                );
                 let miniscript = policy.compile()?;
                 Descriptor::new_wsh(miniscript)?.into()
             }