From c6983e66b491ba6bd6d2cccbc9d2f9f1bafb280c Mon Sep 17 00:00:00 2001
From: Nobuyoshi Nakada <nobu@ruby-lang.org>
Date: Sat, 17 Oct 2026 12:15:34 +0900
Subject: [PATCH 1/3] Drop `UnboundMethod#bind_call` fallback definition

---
 lib/debug/session.rb | 9 ---------
 1 file changed, 9 deletions(-)

diff --git a/lib/debug/session.rb b/lib/debug/session.rb
index 99c78af1d..d13bcffb4 100644
--- a/lib/debug/session.rb
+++ b/lib/debug/session.rb
@@ -2664,12 +2664,3 @@ class Binding
   alias break debugger
   alias b debugger
 end
-
-# for Ruby 2.6 compatibility
-unless method(:p).unbind.respond_to? :bind_call
-  class UnboundMethod
-    def bind_call(obj, *args)
-      self.bind(obj).call(*args)
-    end
-  end
-end

From 52a44f3063ebd64552e5661bd962ca484c95a3ab Mon Sep 17 00:00:00 2001
From: Nobuyoshi Nakada <nobu@ruby-lang.org>
Date: Sat, 17 Oct 2026 12:15:45 +0900
Subject: [PATCH 2/3] Drop `DEBUGGER__::MethodBreakpoint#override` definition
 for 2.6

---
 lib/debug/breakpoint.rb | 25 +++++++------------------
 1 file changed, 7 insertions(+), 18 deletions(-)

diff --git a/lib/debug/breakpoint.rb b/lib/debug/breakpoint.rb
index 78c4d2174..224c35e58 100644
--- a/lib/debug/breakpoint.rb
+++ b/lib/debug/breakpoint.rb
@@ -476,24 +476,13 @@ def enable
       try_enable
     end
 
-    if RUBY_VERSION.to_f <= 2.6
-      def override klass
-        sig_method_name = @sig_method_name
-        klass.prepend Module.new{
-          define_method(sig_method_name) do |*args, &block|
-            super(*args, &block)
-          end
-        }
-      end
-    else
-      def override klass
-        sig_method_name = @sig_method_name
-        klass.prepend Module.new{
-          define_method(sig_method_name) do |*args, **kw, &block|
-            super(*args, **kw, &block)
-          end
-        }
-      end
+    def override klass
+      sig_method_name = @sig_method_name
+      klass.prepend Module.new{
+        define_method(sig_method_name) do |*args, **kw, &block|
+          super(*args, **kw, &block)
+        end
+      }
     end
 
     def try_enable added: false

From 3b62bbf7bf9f68f4044fb77af926408436f9ba10 Mon Sep 17 00:00:00 2001
From: Nobuyoshi Nakada <nobu@ruby-lang.org>
Date: Sat, 17 Oct 2026 12:16:39 +0900
Subject: [PATCH 3/3] Drop fallback for `$:.resolve_feature_path`

---
 exe/rdbg | 16 +++++-----------
 1 file changed, 5 insertions(+), 11 deletions(-)

diff --git a/exe/rdbg b/exe/rdbg
index 14b5e978c..0d753c171 100755
--- a/exe/rdbg
+++ b/exe/rdbg
@@ -13,18 +13,12 @@ when :start
   start_mode = config[:open] ? "open" : 'start'
   cmd = config[:command] ? ARGV.shift : (ENV['RUBY'] || RbConfig.ruby)
 
-  if defined?($:.resolve_feature_path)
-    begin
-      _, sopath = $:.resolve_feature_path('debug/debug.so')
-    rescue LoadError
-      # raises LoadError before 3.1 (2.7 and 3.0)
-    else
-      sopath = File.dirname(File.dirname(sopath)) if sopath
-    end
+  begin
+    _, sopath = $:.resolve_feature_path('debug/debug.so')
+  rescue LoadError
+    # raises LoadError before 3.1 (2.7 and 3.0)
   else
-    # `$:.resolve_feature_path` is not defined in 2.6 or earlier.
-    so = "debug/debug.#{RbConfig::CONFIG['DLEXT']}"
-    sopath = $:.find {|dir| File.exist?(File.join(dir, so))}
+    sopath = File.dirname(File.dirname(sopath)) if sopath
   end
   added = "-r #{libpath}/#{start_mode}"
   added = "-I #{sopath} #{added}" if sopath