ascii_char contracts

library/core/src/ascii/ascii_char.rs

@@ -453,6 +453,7 @@ impl AsciiChar {
  /// or returns `None` if it's too large.
  #[unstable(feature = "ascii_char", issue = "110998")]
  #[inline]
+ #[ensures(|result| (b <= 127) == (result.is_some() && result.unwrap() as u8 == b))]
  pub const fn from_u8(b: u8) -> Option<Self> {
  if b <= 127 {
  // SAFETY: Just checked that `b` is in-range
@@ -470,6 +471,8 @@ impl AsciiChar {
  /// `b` must be in `0..=127`, or else this is UB.
  #[unstable(feature = "ascii_char", issue = "110998")]
  #[inline]
+ #[requires(b <= 127)]
+ #[ensures(|result| *result as u8 == b)]
  pub const unsafe fn from_u8_unchecked(b: u8) -> Self {
  // SAFETY: Our safety precondition is that `b` is in-range.
  unsafe { transmute(b) }