Make MaxRecursionReached error possible to evolve in the future

Author: sosthene-nitrokey

src/lib.rs

@@ -39,8 +39,9 @@ pub use derive_arbitrary::*;
 pub use unstructured::Unstructured;
 
 /// Error indicating that the maximum recursion depth has been reached while calculating [`Arbitrary::size_hint`]()
-#[derive(Debug, Clone, Copy)]
-pub struct MaxRecursionReached;
+#[derive(Debug, Clone)]
+#[non_exhaustive]
+pub struct MaxRecursionReached {}
 
 impl core::fmt::Display for MaxRecursionReached {
     fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {

src/size_hint.rs

@@ -40,7 +40,7 @@ pub fn try_recursion_guard(
     f: impl FnOnce(usize) -> Result<(usize, Option<usize>), crate::MaxRecursionReached>,
 ) -> Result<(usize, Option<usize>), crate::MaxRecursionReached> {
     if depth > MAX_DEPTH {
-        Err(crate::MaxRecursionReached)
+        Err(crate::MaxRecursionReached {})
     } else {
         f(depth + 1)
     }