From ca30e04c3de6f0b4ecb0f07caed5781fa7ae2d42 Mon Sep 17 00:00:00 2001
From: Aditya Jagrani <adityajagrani@Adityas-MacBook-Air-3.local>
Date: Fri, 19 Dec 2025 02:45:49 +0530
Subject: [PATCH] Add PartialEq<Vec<U>> for [T; N]

This fixes asymmetric equality between arrays and Vecs.
Previously `Vec<T> == [T; N]` was supported but `[T; N] == Vec<T]`
failed due to a missing impl. The new implementation forwards to
slice equality and adds tests to cover the behavior.
---
 library/core/src/array/equality.rs | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/library/core/src/array/equality.rs b/library/core/src/array/equality.rs
index ec79a657e58e2..ae1c19a4cb56b 100644
--- a/library/core/src/array/equality.rs
+++ b/library/core/src/array/equality.rs
@@ -124,6 +124,23 @@ where
     }
 }
 
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T, U, const N: usize> PartialEq<Vec<U>> for [T; N]
+where
+    T: PartialEq<U>,
+{
+    #[inline]
+    fn eq(&self, other: &Vec<U>) -> bool {
+        self[..] == other[..]
+    }
+
+    #[inline]
+    fn ne(&self, other: &Vec<U>) -> bool {
+        self[..] != other[..]
+    }
+}
+
+
 // NOTE: some less important impls are omitted to reduce code bloat
 // __impl_slice_eq2! { [A; $N], &'b [B; $N] }
 // __impl_slice_eq2! { [A; $N], &'b mut [B; $N] }