Auto merge of #60318 - jethrogb:jb/try-from-slice-to-infallible, r=sfackler

impl From<Infallible> for TryFromSliceError

I believe this was missed when TryFrom was stabilized. I think `TryFromSliceError` and `TryFromIntError` are the only two `TryFrom` error types that appear in `std`. I think trait implementations have to be insta-stable, but I'm not sure.

src/libcore/array.rs

@@ -8,7 +8,7 @@
 
 use crate::borrow::{Borrow, BorrowMut};
 use crate::cmp::Ordering;
-use crate::convert::TryFrom;
+use crate::convert::{Infallible, TryFrom};
 use crate::fmt;
 use crate::hash::{Hash, self};
 use crate::marker::Unsize;
@@ -74,6 +74,13 @@ impl TryFromSliceError {
     }
 }
 
+#[stable(feature = "try_from_slice_error", since = "1.36.0")]
+impl From<Infallible> for TryFromSliceError {
+    fn from(x: Infallible) -> TryFromSliceError {
+        match x {}
+    }
+}
+
 macro_rules! __impl_slice_eq1 {
     ($Lhs: ty, $Rhs: ty) => {
         __impl_slice_eq1! { $Lhs, $Rhs, Sized }