diff --git a/Library/.rubocop.yml b/Library/.rubocop.yml
index 0b5193ddf8fdc..ce380ccb46e24 100644
--- a/Library/.rubocop.yml
+++ b/Library/.rubocop.yml
@@ -20,7 +20,7 @@ inherit_mode:
     - Exclude
 
 AllCops:
-  TargetRubyVersion: 3.4
+  TargetRubyVersion: 4.0
   NewCops: enable
   Include:
     - "**/*.rbi"
diff --git a/Library/Homebrew/.ruby-version b/Library/Homebrew/.ruby-version
index 7921bd0c89272..1454f6ed4b751 100644
--- a/Library/Homebrew/.ruby-version
+++ b/Library/Homebrew/.ruby-version
@@ -1 +1 @@
-3.4.8
+4.0.1
diff --git a/Library/Homebrew/Gemfile b/Library/Homebrew/Gemfile
index 99e8d433c0ca8..329e2411f5b64 100644
--- a/Library/Homebrew/Gemfile
+++ b/Library/Homebrew/Gemfile
@@ -5,9 +5,9 @@ source "https://rubygems.org"
 # The default case (no envs), should always be a restrictive bound on the lowest supported minor version.
 # This is the branch that Dependabot will use.
 if ENV.fetch("HOMEBREW_USE_RUBY_FROM_PATH", "").empty?
-  ruby "~> 3.4.0"
+  ruby "~> 4.0.0"
 else
-  ruby ">= 3.4.0"
+  ruby ">= 4.0.0"
 end
 
 # disallowed gems (should not be used)
@@ -26,6 +26,9 @@ end
 group :formula_test, optional: true do
   gem "minitest", require: false
 end
+group :irb, optional: true do
+  gem "irb", require: false
+end
 group :livecheck, optional: true do
   gem "ruby-progressbar", require: false
 end
@@ -54,6 +57,7 @@ group :style, :tests, optional: true do
   gem "test-prof", require: false
 end
 group :tests, optional: true do
+  gem "ostruct", require: false
   gem "parallel_tests", require: false
   gem "rspec", require: false
   gem "rspec-core", require: false
diff --git a/Library/Homebrew/Gemfile.lock b/Library/Homebrew/Gemfile.lock
index a10de2c650787..ee79861b8c65f 100644
--- a/Library/Homebrew/Gemfile.lock
+++ b/Library/Homebrew/Gemfile.lock
@@ -11,13 +11,19 @@ GEM
     coderay (1.1.3)
     concurrent-ruby (1.3.6)
     csv (3.3.5)
+    date (3.5.1)
     diff-lcs (1.6.2)
     docile (1.4.1)
     elftools (1.3.1)
       bindata (~> 2)
+    erb (6.0.1)
     erubi (1.13.1)
     hana (1.3.7)
     io-console (0.8.2)
+    irb (1.16.0)
+      pp (>= 0.6.0)
+      rdoc (>= 4.0.0)
+      reline (>= 0.4.2)
     json (2.18.1)
     json_schemer (2.5.0)
       bigdecimal
@@ -33,6 +39,7 @@ GEM
     minitest (6.0.1)
       prism (~> 1.5)
     netrc (0.11.0)
+    ostruct (0.6.3)
     parallel (1.27.0)
     parallel_tests (5.6.0)
       parallel
@@ -43,11 +50,17 @@ GEM
       elftools (>= 1.3)
       logger (~> 1)
     plist (3.7.2)
+    pp (0.6.3)
+      prettyprint
+    prettyprint (0.2.0)
     prism (1.9.0)
     pry (0.16.0)
       coderay (~> 1.1)
       method_source (~> 1.0)
       reline (>= 0.6.0)
+    psych (5.3.1)
+      date
+      stringio
     public_suffix (7.0.2)
     pycall (1.5.2)
     racc (1.8.1)
@@ -59,6 +72,10 @@ GEM
       logger
       prism (>= 1.3.0)
       tsort
+    rdoc (7.1.0)
+      erb
+      psych (>= 4.0.0)
+      tsort
     redcarpet (3.6.1)
     regexp_parser (2.11.3)
     reline (0.6.3)
@@ -149,6 +166,7 @@ GEM
       sorbet-static-and-runtime (>= 0.5.10187)
       thor (>= 0.19.2)
     stackprof (0.2.27)
+    stringio (3.2.0)
     tapioca (0.17.10)
       benchmark
       bundler (>= 2.2.25)
@@ -184,10 +202,12 @@ DEPENDENCIES
   base64
   concurrent-ruby
   csv
+  irb
   json_schemer
   kramdown
   method_source
   minitest
+  ostruct
   parallel_tests
   patchelf
   plist
@@ -226,7 +246,7 @@ DEPENDENCIES
   yard-sorbet
 
 RUBY VERSION
-   ruby 3.4.8p72
+  ruby 4.0.1
 
 BUNDLED WITH
-   2.6.9
+  4.0.3
diff --git a/Library/Homebrew/bundle/dumper.rb b/Library/Homebrew/bundle/dumper.rb
index 82777e5d7af1e..ec7feef214b37 100644
--- a/Library/Homebrew/bundle/dumper.rb
+++ b/Library/Homebrew/bundle/dumper.rb
@@ -2,7 +2,6 @@
 # frozen_string_literal: true
 
 require "fileutils"
-require "pathname"
 
 module Homebrew
   module Bundle
diff --git a/Library/Homebrew/dev-cmd/irb.rb b/Library/Homebrew/dev-cmd/irb.rb
index 55107b78c1849..d0986e330da97 100644
--- a/Library/Homebrew/dev-cmd/irb.rb
+++ b/Library/Homebrew/dev-cmd/irb.rb
@@ -73,6 +73,7 @@ def run
           Homebrew.install_bundler_gems!(groups: ["pry"])
           require "pry"
         else
+          Homebrew.install_bundler_gems!(groups: ["irb"])
           require "irb"
         end
 
diff --git a/Library/Homebrew/extend/os/mac/linkage_checker.rb b/Library/Homebrew/extend/os/mac/linkage_checker.rb
index b82af034b2121..6d8ecb26fb5d6 100644
--- a/Library/Homebrew/extend/os/mac/linkage_checker.rb
+++ b/Library/Homebrew/extend/os/mac/linkage_checker.rb
@@ -11,6 +11,22 @@ def system_libraries_exist_in_cache?
         # In macOS Big Sur and later, system libraries do not exist on-disk and instead exist in a cache.
         MacOS.version >= :big_sur
       end
+
+      sig { params(dylib: String).returns(T::Boolean) }
+      def dylib_found_in_shared_cache?(dylib)
+        Kernel.require "fiddle"
+        @dyld_shared_cache_contains_path ||= T.let(begin
+          libc = Fiddle.dlopen("/usr/lib/libSystem.B.dylib")
+
+          Fiddle::Function.new(
+            libc["_dyld_shared_cache_contains_path"],
+            [Fiddle::TYPE_CONST_STRING],
+            Fiddle::TYPE_BOOL,
+          )
+        end, T.nilable(Fiddle::Function))
+
+        @dyld_shared_cache_contains_path.call(dylib)
+      end
     end
   end
 end
diff --git a/Library/Homebrew/linkage_checker.rb b/Library/Homebrew/linkage_checker.rb
index b4f3174b11f09..a7bf6a78b611d 100644
--- a/Library/Homebrew/linkage_checker.rb
+++ b/Library/Homebrew/linkage_checker.rb
@@ -232,20 +232,9 @@ def system_libraries_exist_in_cache?
     false
   end
 
-  sig { params(dylib: String).returns(T::Boolean) }
-  def dylib_found_in_shared_cache?(dylib)
-    require "fiddle"
-    @dyld_shared_cache_contains_path ||= T.let(begin
-      libc = Fiddle.dlopen("/usr/lib/libSystem.B.dylib")
-
-      Fiddle::Function.new(
-        libc["_dyld_shared_cache_contains_path"],
-        [Fiddle::TYPE_CONST_STRING],
-        Fiddle::TYPE_BOOL,
-      )
-    end, T.nilable(Fiddle::Function))
-
-    @dyld_shared_cache_contains_path.call(dylib)
+  sig { params(_dylib: String).returns(T::Boolean) }
+  def dylib_found_in_shared_cache?(_dylib)
+    false
   end
 
   sig {
diff --git a/Library/Homebrew/sorbet/tapioca/require.rb b/Library/Homebrew/sorbet/tapioca/require.rb
index 705827d80b319..baf182a86bd9e 100644
--- a/Library/Homebrew/sorbet/tapioca/require.rb
+++ b/Library/Homebrew/sorbet/tapioca/require.rb
@@ -23,6 +23,9 @@
   next if name == "sorbet-static"
   next if name == "sorbet-static-and-runtime"
 
+  # We don't generate RBIs for pycall
+  next if name == "pycall"
+
   name = dependency_require_map[name] if dependency_require_map.key?(name)
   require name
   additional_requires_map[name]&.each { require(it) }
diff --git a/Library/Homebrew/utils/ruby.sh b/Library/Homebrew/utils/ruby.sh
index 9ac6e5a6ab047..65ef5fc05e286 100644
--- a/Library/Homebrew/utils/ruby.sh
+++ b/Library/Homebrew/utils/ruby.sh
@@ -2,9 +2,9 @@
 # When bumping to a new major/minor version, also update the bounds in the Gemfile
 # HOMEBREW_LIBRARY set by bin/brew
 # shellcheck disable=SC2154
-export HOMEBREW_REQUIRED_RUBY_VERSION="3.4"
+export HOMEBREW_REQUIRED_RUBY_VERSION="4.0"
 HOMEBREW_PORTABLE_RUBY_VERSION="$(cat "${HOMEBREW_LIBRARY}/Homebrew/vendor/portable-ruby-version")"
-export HOMEBREW_BUNDLER_VERSION="2.6.9"
+export HOMEBREW_BUNDLER_VERSION="4.0.3"
 
 # Disable Ruby options we don't need.
 export HOMEBREW_RUBY_DISABLE_OPTIONS="--disable=gems,rubyopt"
diff --git a/Library/Homebrew/vendor/bundle/bundler/setup.rb b/Library/Homebrew/vendor/bundle/bundler/setup.rb
index 4f7358f89eb29..33fa4ef21aef4 100644
--- a/Library/Homebrew/vendor/bundle/bundler/setup.rb
+++ b/Library/Homebrew/vendor/bundle/bundler/setup.rb
@@ -45,13 +45,27 @@ def self.extension_api_version
 $:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/gems/coderay-1.1.3/lib")
 $:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/gems/concurrent-ruby-1.3.6/lib/concurrent-ruby")
 $:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/gems/csv-3.3.5/lib")
+$:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/extensions/arm64-darwin-20/#{Gem.extension_api_version}/date-3.5.1")
+$:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/gems/date-3.5.1/lib")
 $:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/gems/diff-lcs-1.6.2/lib")
 $:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/gems/docile-1.4.1/lib")
 $:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/gems/elftools-1.3.1/lib")
+$:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/extensions/arm64-darwin-20/#{Gem.extension_api_version}/erb-6.0.1")
+$:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/gems/erb-6.0.1/lib")
 $:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/gems/erubi-1.13.1/lib")
 $:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/gems/hana-1.3.7/lib")
 $:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/extensions/arm64-darwin-20/#{Gem.extension_api_version}/io-console-0.8.2")
 $:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/gems/io-console-0.8.2/lib")
+$:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/gems/prettyprint-0.2.0/lib")
+$:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/gems/pp-0.6.3/lib")
+$:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/extensions/arm64-darwin-20/#{Gem.extension_api_version}/stringio-3.2.0")
+$:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/gems/stringio-3.2.0/lib")
+$:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/extensions/arm64-darwin-20/#{Gem.extension_api_version}/psych-5.3.1")
+$:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/gems/psych-5.3.1/lib")
+$:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/gems/tsort-0.2.0/lib")
+$:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/gems/rdoc-7.1.0/lib")
+$:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/gems/reline-0.6.3/lib")
+$:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/gems/irb-1.16.0/lib")
 $:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/extensions/arm64-darwin-20/#{Gem.extension_api_version}/json-2.18.1")
 $:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/gems/json-2.18.1/lib")
 $:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/gems/regexp_parser-2.11.3/lib")
@@ -67,6 +81,7 @@ def self.extension_api_version
 $:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/gems/prism-1.9.0/lib")
 $:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/gems/minitest-6.0.1/lib")
 $:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/gems/netrc-0.11.0/lib")
+$:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/gems/ostruct-0.6.3/lib")
 $:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/gems/parallel-1.27.0/lib")
 $:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/gems/parallel_tests-5.6.0/lib")
 $:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/extensions/arm64-darwin-20/#{Gem.extension_api_version}/racc-1.8.1")
@@ -74,12 +89,10 @@ def self.extension_api_version
 $:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/gems/parser-3.3.10.1/lib")
 $:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/gems/patchelf-1.5.2/lib")
 $:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/gems/plist-3.7.2/lib")
-$:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/gems/reline-0.6.3/lib")
 $:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/gems/pry-0.16.0/lib")
 $:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/extensions/arm64-darwin-20/#{Gem.extension_api_version}/pycall-1.5.2")
 $:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/gems/pycall-1.5.2/lib")
 $:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/gems/rainbow-3.1.1/lib")
-$:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/gems/tsort-0.2.0/lib")
 $:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/extensions/arm64-darwin-20/#{Gem.extension_api_version}/rbs-4.0.0.dev.5")
 $:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/gems/rbs-4.0.0.dev.5/lib")
 $:.unshift File.expand_path("#{__dir__}/../#{RUBY_ENGINE}/#{Gem.ruby_api_version}/gems/rbi-0.3.9/lib")
diff --git a/Library/Homebrew/vendor/portable-ruby-arm64-darwin b/Library/Homebrew/vendor/portable-ruby-arm64-darwin
index 48f06299a0f14..6e39ab2dc827e 100644
--- a/Library/Homebrew/vendor/portable-ruby-arm64-darwin
+++ b/Library/Homebrew/vendor/portable-ruby-arm64-darwin
@@ -1,2 +1,2 @@
 ruby_TAG=arm64_big_sur
-ruby_SHA=1c98fa49eacc935640a6f8e10a2bf33f14cfc276804b71ddb658ea45ba99d167
+ruby_SHA=643ad12da2e9265085a961d678f5b3219283fbc5a73cdf0615adc8609ba8539e
diff --git a/Library/Homebrew/vendor/portable-ruby-arm64-linux b/Library/Homebrew/vendor/portable-ruby-arm64-linux
index 4391d4809f296..c946ae6c4820f 100644
--- a/Library/Homebrew/vendor/portable-ruby-arm64-linux
+++ b/Library/Homebrew/vendor/portable-ruby-arm64-linux
@@ -1,2 +1,2 @@
 ruby_TAG=arm64_linux
-ruby_SHA=56b0017d634509e49272a6eccd88f888dd4031404e230f9defb3b21707781310
+ruby_SHA=7cc511b5933ecb4e857994d01ddc66accdbcdb772214ba415664993fe80442f6
diff --git a/Library/Homebrew/vendor/portable-ruby-version b/Library/Homebrew/vendor/portable-ruby-version
index 7921bd0c89272..1454f6ed4b751 100644
--- a/Library/Homebrew/vendor/portable-ruby-version
+++ b/Library/Homebrew/vendor/portable-ruby-version
@@ -1 +1 @@
-3.4.8
+4.0.1
diff --git a/Library/Homebrew/vendor/portable-ruby-x86_64-darwin b/Library/Homebrew/vendor/portable-ruby-x86_64-darwin
index 97c8ce2fcc834..582d9d741d0e4 100644
--- a/Library/Homebrew/vendor/portable-ruby-x86_64-darwin
+++ b/Library/Homebrew/vendor/portable-ruby-x86_64-darwin
@@ -1,2 +1,2 @@
 ruby_TAG=catalina
-ruby_SHA=80c194381e990a4967a1ae44b8242b688e6a17ab590865a38671137677411469
+ruby_SHA=09a5c468e76c2176c7a5a941831f28463f0035172f2fcf64f8a80f2dc1a31f01
diff --git a/Library/Homebrew/vendor/portable-ruby-x86_64-linux b/Library/Homebrew/vendor/portable-ruby-x86_64-linux
index 86eedc53c7963..bd5ef05c6aaff 100644
--- a/Library/Homebrew/vendor/portable-ruby-x86_64-linux
+++ b/Library/Homebrew/vendor/portable-ruby-x86_64-linux
@@ -1,2 +1,2 @@
 ruby_TAG=x86_64_linux
-ruby_SHA=63a9c333137e7cf8a568e0f37ec6802c22fbbdd5839f4825c863c26e415d2947
+ruby_SHA=5f52e03e2799621b7f7f103173fb9c7d660d6bc1b9748efbcaab09881bb136cc