From f4361bcee301ca77469ad16e5d5b1436f4cb6934 Mon Sep 17 00:00:00 2001
From: ToMe25 <ToMe25@gmx.de>
Date: Fri, 7 Jun 2024 11:54:47 +0200
Subject: [PATCH] Improve Set Difference size_hint

This implementation isn't perfect, but it is spec compliant as far as I
can tell
---
 src/set.rs | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/src/set.rs b/src/set.rs
index bd98af7d0..d3c70dc4f 100644
--- a/src/set.rs
+++ b/src/set.rs
@@ -1851,6 +1851,7 @@ where
         let (_, upper) = self.iter.size_hint();
         (0, upper)
     }
+
     #[cfg_attr(feature = "inline-more", inline)]
     fn fold<B, F>(self, init: B, mut f: F) -> B
     where
@@ -1916,9 +1917,10 @@ where
 
     #[cfg_attr(feature = "inline-more", inline)]
     fn size_hint(&self) -> (usize, Option<usize>) {
-        let (_, upper) = self.iter.size_hint();
-        (0, upper)
+        let (lower, upper) = self.iter.size_hint();
+        (lower.saturating_sub(self.other.len()), upper)
     }
+
     #[cfg_attr(feature = "inline-more", inline)]
     fn fold<B, F>(self, init: B, mut f: F) -> B
     where
@@ -1975,10 +1977,12 @@ where
     fn next(&mut self) -> Option<&'a T> {
         self.iter.next()
     }
+
     #[cfg_attr(feature = "inline-more", inline)]
     fn size_hint(&self) -> (usize, Option<usize>) {
         self.iter.size_hint()
     }
+
     #[cfg_attr(feature = "inline-more", inline)]
     fn fold<B, F>(self, init: B, f: F) -> B
     where
@@ -2048,10 +2052,12 @@ where
     fn next(&mut self) -> Option<&'a T> {
         self.iter.next()
     }
+
     #[cfg_attr(feature = "inline-more", inline)]
     fn size_hint(&self) -> (usize, Option<usize>) {
         self.iter.size_hint()
     }
+
     #[cfg_attr(feature = "inline-more", inline)]
     fn fold<B, F>(self, init: B, f: F) -> B
     where