From a7372372f6c3b81804c2b83f2a0e9c0bc7d08e13 Mon Sep 17 00:00:00 2001
From: Zanie Blue <contact@zanie.dev>
Date: Tue, 2 Jul 2024 19:50:39 -0500
Subject: [PATCH 1/3] Add test case demonstrating equality of paths "foo/bar"
 and "foobar"

---
 library/std/src/path/tests.rs | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/library/std/src/path/tests.rs b/library/std/src/path/tests.rs
index 92702b395dfe1..53a65c60b580c 100644
--- a/library/std/src/path/tests.rs
+++ b/library/std/src/path/tests.rs
@@ -1566,6 +1566,13 @@ pub fn test_compare() {
     relative_from: Some("bar")
     );
 
+    tc!("foo/bar", "foobar",
+    eq: false,
+    starts_with: false,
+    ends_with: false,
+    relative_from: None
+    );
+
     tc!("foo/bar/baz", "foo/bar",
     eq: false,
     starts_with: true,

From dd509c7a6399f2784fa940d27a9f463da7e81d58 Mon Sep 17 00:00:00 2001
From: Zanie Blue <contact@zanie.dev>
Date: Tue, 2 Jul 2024 23:12:06 -0500
Subject: [PATCH 2/3] Add more test cases for path comparisons

---
 library/std/src/path/tests.rs | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/library/std/src/path/tests.rs b/library/std/src/path/tests.rs
index 53a65c60b580c..87a06a9ea9153 100644
--- a/library/std/src/path/tests.rs
+++ b/library/std/src/path/tests.rs
@@ -1545,6 +1545,20 @@ pub fn test_compare() {
     relative_from: Some("")
     );
 
+    tc!("foo//", "foo",
+    eq: true,
+    starts_with: true,
+    ends_with: true,
+    relative_from: Some("")
+    );
+
+    tc!("foo///", "foo",
+    eq: true,
+    starts_with: true,
+    ends_with: true,
+    relative_from: Some("")
+    );
+
     tc!("foo/.", "foo",
     eq: true,
     starts_with: true,
@@ -1559,6 +1573,20 @@ pub fn test_compare() {
     relative_from: Some("")
     );
 
+    tc!("foo/.//bar", "foo/bar",
+    eq: true,
+    starts_with: true,
+    ends_with: true,
+    relative_from: Some("")
+    );
+
+    tc!("foo//./bar", "foo/bar",
+    eq: true,
+    starts_with: true,
+    ends_with: true,
+    relative_from: Some("")
+    );
+
     tc!("foo/bar", "foo",
     eq: false,
     starts_with: true,

From f21683432b72694b4558d779d6b5e5d49102ad7e Mon Sep 17 00:00:00 2001
From: The 8472 <git@infinite-source.de>
Date: Wed, 3 Jul 2024 22:54:15 +0200
Subject: [PATCH 3/3] stir the hash state a little to avoid prefix collisions

---
 library/std/src/path.rs | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/library/std/src/path.rs b/library/std/src/path.rs
index caae8f924d2b1..e8f0b41f1f4c3 100644
--- a/library/std/src/path.rs
+++ b/library/std/src/path.rs
@@ -3098,15 +3098,19 @@ impl Hash for Path {
         let bytes = &bytes[prefix_len..];
 
         let mut component_start = 0;
-        let mut bytes_hashed = 0;
+        // track some extra state to avoid prefix collisions.
+        // ["foo", "bar"] and ["foobar"], will have the same payload bytes
+        // but result in different chunk_bits
+        let mut chunk_bits: usize = 0;
 
         for i in 0..bytes.len() {
             let is_sep = if verbatim { is_verbatim_sep(bytes[i]) } else { is_sep_byte(bytes[i]) };
             if is_sep {
                 if i > component_start {
                     let to_hash = &bytes[component_start..i];
+                    chunk_bits = chunk_bits.wrapping_add(to_hash.len());
+                    chunk_bits = chunk_bits.rotate_right(2);
                     h.write(to_hash);
-                    bytes_hashed += to_hash.len();
                 }
 
                 // skip over separator and optionally a following CurDir item
@@ -3127,11 +3131,12 @@ impl Hash for Path {
 
         if component_start < bytes.len() {
             let to_hash = &bytes[component_start..];
+            chunk_bits = chunk_bits.wrapping_add(to_hash.len());
+            chunk_bits = chunk_bits.rotate_right(2);
             h.write(to_hash);
-            bytes_hashed += to_hash.len();
         }
 
-        h.write_usize(bytes_hashed);
+        h.write_usize(chunk_bits);
     }
 }