Fix MSRV issue

src/uu/echo/src/echo.rs

@@ -11,7 +11,7 @@ use std::io::{self, StdoutLock, Write};
 use std::iter::Peekable;
 use std::ops::ControlFlow;
 use std::slice::Iter;
-use uucore::error::{FromIo, UResult};
+use uucore::error::{UResult, USimpleError};
 use uucore::{format_usage, help_about, help_section, help_usage};
 
 const ABOUT: &str = help_about!("echo.md");
@@ -179,8 +179,7 @@ pub fn uumain(args: impl uucore::Args) -> UResult<()> {
 
  match matches.get_many::<OsString>(options::STRING) {
  Some(va) => {
- execute(&mut stdout_lock, no_newline, escaped, va)
- .map_err_context(|| "could not write to stdout".to_string())?;
+ execute(&mut stdout_lock, no_newline, escaped, va)?;
  }
  None => {
  // No strings to print, so just handle newline setting
@@ -239,9 +238,14 @@ fn execute(
  no_newline: bool,
  escaped: bool,
  non_option_arguments: ValuesRef<'_, OsString>,
-) -> io::Result<()> {
+) -> UResult<()> {
  for (i, input) in non_option_arguments.into_iter().enumerate() {
- let bytes = bytes_from_os_string(input.as_os_str());
+ let Some(bytes) = bytes_from_os_string(input.as_os_str()) else {
+ return Err(USimpleError::new(
+ 1,
+ "Non-UTF-8 arguments provided, but this platform does not support them",
+ ));
+ };
 
  if i > 0 {
  stdout_lock.write_all(b" ")?;
@@ -263,22 +267,24 @@ fn execute(
  Ok(())
 }
 
-fn bytes_from_os_string(input: &OsStr) -> &[u8] {
- let bytes = {
+fn bytes_from_os_string(input: &OsStr) -> Option<&[u8]> {
+ let option = {
  #[cfg(target_family = "unix")]
  {
  use std::os::unix::ffi::OsStrExt;
 
- input.as_bytes()
+ Some(input.as_bytes())
  }
 
  #[cfg(not(target_family = "unix"))]
  {
  // TODO
- // Verify
- input.as_encoded_bytes()
+ match input.to_str() {
+ Some(st) => Some(st.as_bytes()),
+ None => None,
+ }
  }
  };
 
- bytes
+ option
 }