From 3387f7abbba3cb9d5eddca457612112167786160 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Johannes=20M=C3=BCller?= <straightshoota@gmail.com>
Date: Wed, 22 May 2024 11:05:21 +0200
Subject: [PATCH 1/2] Fix `Hash#rehash` reset `@first`

---
 spec/std/hash_spec.cr | 29 +++++++++++++++++++----------
 src/hash.cr           |  3 +++
 2 files changed, 22 insertions(+), 10 deletions(-)

diff --git a/spec/std/hash_spec.cr b/spec/std/hash_spec.cr
index d098c8f7bf11..6d1fccd95e3c 100644
--- a/spec/std/hash_spec.cr
+++ b/spec/std/hash_spec.cr
@@ -1393,16 +1393,25 @@ describe "Hash" do
     hash.@indices_size_pow2.should eq(12)
   end
 
-  it "rehashes" do
-    a = [1]
-    h = {a => 0}
-    (10..100).each do |i|
-      h[[i]] = i
-    end
-    a << 2
-    h[a]?.should be_nil
-    h.rehash
-    h[a].should eq(0)
+  describe "#rehash" do
+    it "rehashes" do
+      a = [1]
+      h = {a => 0}
+      (10..100).each do |i|
+        h[[i]] = i
+      end
+      a << 2
+      h[a]?.should be_nil
+      h.rehash
+      h[a].should eq(0)
+    end
+
+    it "resets @first (#14602)" do
+      h = {"a" => 1, "b" => 2}
+      h.delete("a")
+      h.rehash
+      h["b"].should eq 2
+    end
   end
 
   describe "some edge cases while changing the implementation to open addressing" do
diff --git a/src/hash.cr b/src/hash.cr
index 24a658dad21d..929e84a1b455 100644
--- a/src/hash.cr
+++ b/src/hash.cr
@@ -631,6 +631,9 @@ class Hash(K, V)
       new_entry_index += 1
     end
 
+    # Reset offset to first non-deleted entry
+    @first = 0
+
     # We have to mark entries starting from the final new index
     # as deleted so the GC can collect them.
     entries_to_clear = entries_size - new_entry_index

From fe4c49d466432fc9b8bc1ed61164046f35cdb84f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Johannes=20M=C3=BCller?= <straightshoota@gmail.com>
Date: Wed, 22 May 2024 12:30:16 +0200
Subject: [PATCH 2/2] Use string comparison

---
 spec/std/hash_spec.cr | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/spec/std/hash_spec.cr b/spec/std/hash_spec.cr
index 6d1fccd95e3c..684e5af9c0d1 100644
--- a/spec/std/hash_spec.cr
+++ b/spec/std/hash_spec.cr
@@ -1410,7 +1410,8 @@ describe "Hash" do
       h = {"a" => 1, "b" => 2}
       h.delete("a")
       h.rehash
-      h["b"].should eq 2
+      # We cannot test direct equivalence here because `Hash#==(Hash)` does not depend on `@first`
+      h.to_s.should eq %({"b" => 2})
     end
   end