replace other Unprintable check with upstream impl

Author: RCasatta

src/descriptor/checksum.rs

@@ -8,6 +8,8 @@
 use core::fmt;
 use core::iter::FromIterator;
 
+use bitcoin_miniscript::expression::check_valid_chars;
+
 use crate::Error;
 
 const INPUT_CHARSET: &str =  "0123456789()[],'/*abcdefgh@:$%{}IJKLMNOPQRSTUVWXYZ&+-.;<=>?!^_|~ijklmnopqrstuvwxyzABCDEFGH`#\"\\ ";
@@ -51,11 +53,7 @@ pub fn desc_checksum(desc: &str) -> Result<String, Error> {
 /// if it is present and returns the descriptor string
 /// without the checksum
 pub(crate) fn verify_checksum(s: &str) -> Result<&str, Error> {
-    for ch in s.as_bytes() {
-        if *ch < 20 || *ch > 127 {
-            return Err(Error::Unprintable(*ch));
-        }
-    }
+    check_valid_chars(s)?;
 
     let mut parts = s.splitn(2, '#');
     let desc_str = parts.next().unwrap();

src/policy/concrete.rs

@@ -7,6 +7,7 @@
 use std::collections::HashSet;
 use std::{error, fmt, str};
 
+use bitcoin_miniscript::expression::check_valid_chars;
 use elements::{LockTime, Sequence};
 #[cfg(feature = "compiler")]
 use {
@@ -1098,11 +1099,7 @@ impl_from_str!(
     Policy<Pk>,
     type Err = Error;,
     fn from_str(s: &str) -> Result<Policy<Pk>, Error> {
-        for ch in s.as_bytes() {
-            if *ch < 20 || *ch > 127 {
-                return Err(Error::Unprintable(*ch));
-            }
-        }
+        check_valid_chars(s)?;
 
         let tree = expression::Tree::from_str(s)?;
         let policy: Policy<Pk> = FromTree::from_tree(&tree)?;

src/policy/semantic.rs

@@ -6,6 +6,7 @@
 use std::str::FromStr;
 use std::{fmt, str};
 
+use bitcoin_miniscript::expression::check_valid_chars;
 use elements::{LockTime, Sequence};
 
 use super::concrete::PolicyError;
@@ -287,11 +288,7 @@ impl_from_str!(
     Policy<Pk>,
     type Err = Error;,
     fn from_str(s: &str) -> Result<Policy<Pk>, Error> {
-        for ch in s.as_bytes() {
-            if *ch < 20 || *ch > 127 {
-                return Err(Error::Unprintable(*ch));
-            }
-        }
+        check_valid_chars(s)?;
 
         let tree = expression::Tree::from_str(s)?;
         expression::FromTree::from_tree(&tree)