[PATCH perlmod 1/4] ffi: implement ExactSizeIterator for StackIter

["Max R. Carrara" <m.carrara@proxmox.com>]

Since we know how many remaining values there are on the stack, we can
confidently implement `ExactSizeIterator` on `StackIter`.

Signed-off-by: Max R. Carrara <m.carrara@proxmox.com>
---
 perlmod/src/ffi.rs | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/perlmod/src/ffi.rs b/perlmod/src/ffi.rs
index 1c68518..1b1066d 100644
--- a/perlmod/src/ffi.rs
+++ b/perlmod/src/ffi.rs
@@ -468,8 +468,15 @@ impl Iterator for StackIter {
             }
         }
     }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        let remaining = self.end - self.at;
+        (remaining, Some(remaining))
+    }
 }
 
+impl ExactSizeIterator for StackIter {}
+
 /// Pop the current argument marker off of the argument marker stack.
 ///
 /// # Safety
-- 
2.47.3