Add a small part of the real rust std

crates/std/src/io.rs

@@ -12,7 +12,7 @@ impl IoBase for Stdin {
 }
 
 impl Read for Stdin {
-    fn read(&mut self, buf: &mut [u8]) -> Result<usize, Self::Error> {
+    fn read(&mut self, buf: &mut [u8]) -> core::result::Result<usize, Self::Error> {
         unsafe { File::from_raw_fd(0).read(buf) }
     }
 }
@@ -20,3 +20,20 @@ impl Read for Stdin {
 pub fn stdin() -> Stdin {
     Stdin
 }
+
+pub type Result<T> = core::result::Result<T, ()>;
+
+pub(super) struct Repr();
+
+// Part took from the real std
+#[rustc_macro_transparency = "semiopaque"]
+#[unstable(feature = "io_const_error", issue = "133448")]
+#[allow_internal_unstable(hint_must_use, io_const_error_internals)]
+pub macro const_error($kind:expr, $message:expr $(,)?) {
+    ()
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+pub struct Error {
+    repr: Repr,
+}