Use std::io::Error for Debug and Display when it is available.

Author: briansmith

src/error.rs

@@ -1,3 +1,6 @@
+#[cfg(feature = "std")]
+extern crate std;
+
 use core::{fmt, num::NonZeroU32};
 
 /// A small and `no_std` compatible error type
@@ -103,6 +106,8 @@ impl fmt::Debug for Error {
         let mut dbg = f.debug_struct("Error");
         if let Some(errno) = self.raw_os_error() {
             dbg.field("os_error", &errno);
+            #[cfg(feature = "std")]
+            dbg.field("description", &std::io::Error::from_raw_os_error(errno));
         } else if let Some(desc) = internal_desc(*self) {
             dbg.field("internal_code", &self.0.get());
             dbg.field("description", &desc);
@@ -116,7 +121,13 @@ impl fmt::Debug for Error {
 impl fmt::Display for Error {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         if let Some(errno) = self.raw_os_error() {
-            write!(f, "OS Error: {}", errno)
+            cfg_if! {
+                if #[cfg(feature = "std")] {
+                    std::io::Error::from_raw_os_error(errno).fmt(f)
+                } else {
+                    write!(f, "OS Error: {}", errno)
+                }
+            }
         } else if let Some(desc) = internal_desc(*self) {
             f.write_str(desc)
         } else {