Use iter instead of into_iter

Clippy emits a bunch of warnings of form:

  warning: this `.into_iter()` call is equivalent to `.iter()` and will
  not consume the `slice`

As suggested, use `iter` instead of `into_iter`.

Author: tcharding

src/miniscript/iter.rs

@@ -158,7 +158,7 @@ impl<Pk: MiniscriptKey, Ctx: ScriptContext> Miniscript<Pk, Ctx> {
             Terminal::PkH(ref hash) => vec![PkPkh::HashedPubkey(hash.clone())],
             Terminal::PkK(ref key) => vec![PkPkh::PlainPubkey(key.clone())],
             Terminal::Multi(_, ref keys) | Terminal::MultiA(_, ref keys) => keys
-                .into_iter()
+                .iter()
                 .map(|key| PkPkh::PlainPubkey(key.clone()))
                 .collect(),
             _ => vec![],

src/policy/mod.rs

@@ -157,13 +157,12 @@ impl<Pk: MiniscriptKey, Ctx: ScriptContext> Liftable<Pk> for Terminal<Pk, Ctx> {
                 Semantic::Threshold(1, vec![left.node.lift()?, right.node.lift()?])
             }
             Terminal::Thresh(k, ref subs) => {
-                let semantic_subs: Result<_, Error> =
-                    subs.into_iter().map(|s| s.node.lift()).collect();
+                let semantic_subs: Result<_, Error> = subs.iter().map(|s| s.node.lift()).collect();
                 Semantic::Threshold(k, semantic_subs?)
             }
             Terminal::Multi(k, ref keys) | Terminal::MultiA(k, ref keys) => Semantic::Threshold(
                 k,
-                keys.into_iter()
+                keys.iter()
                     .map(|k| Semantic::KeyHash(k.to_pubkeyhash()))
                     .collect(),
             ),

src/policy/semantic.rs

@@ -235,7 +235,7 @@ impl<Pk: MiniscriptKey> fmt::Debug for Policy<Pk> {
                 } else {
                     write!(f, "thresh({},", k)?;
                 }
-                for (i, sub) in subs.into_iter().enumerate() {
+                for (i, sub) in subs.iter().enumerate() {
                     if i == 0 {
                         write!(f, "{}", sub)?;
                     } else {
@@ -268,7 +268,7 @@ impl<Pk: MiniscriptKey> fmt::Display for Policy<Pk> {
                 } else {
                     write!(f, "thresh({},", k)?;
                 }
-                for (i, sub) in subs.into_iter().enumerate() {
+                for (i, sub) in subs.iter().enumerate() {
                     if i == 0 {
                         write!(f, "{}", sub)?;
                     } else {