impl StableDeref for LocatedSpan

LocatedSpan is largely just a wrapper around the contained type `T`, so
this marker trait is safe to implement whenever T already implements
StableDeref.

Cargo.toml

@@ -26,3 +26,4 @@ runtime-dispatch-simd = ["bytecount/runtime-dispatch-simd"]
 bytecount = "^0.6"
 memchr = ">=1.0.1, <3.0.0" # ^1.0.0 + ^2.0
 nom = { version = "5.0.0", default-features = false }
+stable_deref_trait = "^1"

src/lib.rs

@@ -114,6 +114,7 @@ use nom::{
     AsBytes, Compare, CompareResult, Err, FindSubstring, FindToken, IResult, InputIter,
     InputLength, InputTake, InputTakeAtPosition, Offset, ParseTo, Slice,
 };
+use stable_deref_trait::StableDeref;
 
 /// A LocatedSpan is a set of meta information about the location of a token, including extra
 /// information.
@@ -146,6 +147,8 @@ impl<T, X> core::ops::Deref for LocatedSpan<T, X> {
     }
 }
 
+unsafe impl<T: StableDeref, X> StableDeref for LocatedSpan<T, X> {}
+
 impl<T: AsBytes> LocatedSpan<T, ()> {
     /// Create a span for a particular input with default `offset` and
     /// `line` values and empty extra data.